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The present work contains much that is new, andmuch in correction and amplification of thatwhich is old; and is intended as a closing deliveranceon some of the more important questions of geology,on the part of a veteran worker, conversant in hisyounger days with those giants of the last generation,who, in the heroic age of geological science, piled upthe mountains on which it is now the privilege of theirsuccessors to stand.

CONTENTS.

LIST OF ILLUSTRATIONS.

Non-Geological readers will find in the following table acondensed explanation of the more important technical termsused in the following pages. The order is from older tonewer.

THE STARTING-POINT.

DEDICATED TO THE MEMORY OF

PROF. ROBERT JAMESON,

Of the University of Edinburgh, my first Teacher in Geology,
whose Lectures I attended, and whose kind Advice and
Guidance I enjoyed, in the Winter of 1840-1841.

Headlands and Spurs—Popular Papers on LeadingTopics—Revisiting Old Localities—Dedications—GeneralScope of the Work« 3 »

CHAPTER I.

An explorer trudging along some line of coast, or traversingsome mountain region, may now and then reach a projectingheadland, or bold mountain spur, which may enablehim to command a wide view of shore and sea, or of hill andvalley, before and behind. On such a salient point he maysit down, note-book and glass in hand, and endeavour to correlatethe observations made on the ground he has traversed,and may strain his eyes forward in order to anticipate thefeatures of the track in advance. Such are the salient pointsin a scientific pilgrimage of more than half a century, to whichI desire to invite the attention of the readers of these papers.In doing so, I do not propose to refer, except incidentally, tosubjects which I have already discussed in books accessible togeneral readers, but rather to those which are imbedded inlittle accessible transactions, or scientific periodicals, or whichhave fallen out of print. I cannot therefore pretend to placethe reader on all the salient points of geological science, oreven on all of those I have myself reached, but merely to leadhim to some of the viewing-places which I have found particularlyinstructive to myself.

For similar reasons it is inevitable that a certain personalelement shall enter into these reminiscences, though this autobiographicalfeature will be kept as much in the backgroundas possible. It is also to be anticipated that the same subject« 4 »may appear more than once, but from different points of view,since it is often useful to contemplate certain features of thelandscape from more than one place of observation.

To drop the figure, the reader will find in these papers, in aplain and popular form, yet it is hoped not in a superficialmanner, some of the more important conclusions of a geologicalworker of the old school, who, while necessarily givingattention to certain specialties, has endeavoured to take abroad and comprehensive view of the making of the world inall its aspects.

The papers are of various dates; but in revising them forpublication I have endeavoured, without materially changingtheir original form, to bring them up to the present time, andto state any corrections or changes of view that have commendedthemselves to me in the meantime. Such changes ormodifications of view must of necessity occur to every geologicalworker. Sometimes, after long digging and hammering insome bed rich in fossils, and carrying home a bag laden withtreasures, one has returned to the spot, and turned over thedébris of previous excavation, with the result of finding somethingrare and valuable, before overlooked. Or, in carefullytrimming and chiselling out the matrix of a new fossil, so asto uncover all its parts, unexpected and novel features maydevelop themselves. Thus, if we were right or partially rightbefore, our new experience may still enable us to enlarge ourviews or to correct some misapprehensions. In that spirit Ihave endeavoured to revise these papers, and while I havebeen able to add confirmations of views long ago expressed,have been willing to accept corrections and modifications basedon later discoveries.

In the somewhat extended span of work which has beenallotted to me, I have made it my object to discover new facts,and to this end have spared no expenditure of time andlabour; but I have felt that the results of discoveries in the« 5 »works of God should not be confined to a coterie, but shouldbe made public for the benefit of all. Hence I have gladlyembraced any opportunities to popularise my results, whetherin lectures, articles, popular books, or in the instruction ofstudents, and this in a manner to give accurate knowledge,and perhaps to attract the attention of fellow-workers to pointswhich they might overlook if presented merely in dry andtechnical papers. These objects I have in view in connectionwith the present collection of papers, and also the fact that myown pilgrimage is approaching its close, and that I desire toaid others who may chance to traverse the ground I havepassed over, or who may be preparing to pass beyond thepoint I have reached.

To a naturalist of seventy years the greater part of life liesin the past, and in revising these papers I have necessarily hadmy thoughts directed to the memory of friends, teachers,guides, and companions in labour, who have passed away. Ihave therefore, as a slight token of loving and grateful remembrancededicated these papers to the memory of men I haveknown and loved, and who, I feel, would sympathise with mein spirit, in the attempt, however feeble, to direct attention tothe variety and majesty of those great works of the Creatorwhich they themselves delighted to study.

Since the design of these papers excludes special details asto Canadian geology, or that of those old eastern countries towhich I have given some attention, I must refer for them toother works, and shall append such reference of this kind asmay be necessary. At the same time it will be observed thatas my geological work has been concerned most largely withthe oldest and newest rocks of the earth, and with the historyof life rather than with rocks and minerals, there must necessarilybe some preponderance in these directions, which mighthowever, independently of personal considerations, be justifiedby the actual value of these lines of investigation, and by the« 6 »special interest attaching to them in the present state of scientificdiscovery.

Having thus defined my starting-point, I would now with allrespect and deference ask the reader to accompany me frompoint to point, and to examine for himself the objects whichmay appear either near, or in the dim uncertain distance, inillustration of what the world is, and how it became what it is.Perhaps, in doing so, he may be able to perceive much morethan I have been able to discover; and if so, I shall rejoice,even if such further insight should correct or counteract someof my own impressions. It is not given to any one age or setof men to comprehend all the mysteries of nature, or to arriveat a point where it can be said, there is no need of fartherexploration. Even in the longest journey of the most adventuroustraveller there is an end of discovery, and, in the studyof nature, cape rises beyond cape and mountain behind mountaininterminably. The finite cannot comprehend the infinite,the temporal the eternal. We need not, however, on thataccount be agnostics, for it is still true that, within the scopeof our narrow powers and opportunities, the Supreme Intelligencereveals to us in nature His power and divinity; and it isthis, and this alone, that gives attraction and dignity to naturalscience.

WORLD-MAKING.

DEDICATED TO THE MEMORY OF

ADAM SEDGWICK AND SIR RODERICK IMPEY MURCHISON,

Whose joint Labours carried
our Knowledge of the History of the Earth
two Stages farther back,
and whose Differences of Opinion served to render
more glorious their Victories.

CHAPTER II.

Geological reading, especially when of a strictlyuniformitarian character and in warm weather, sometimesbecomes monotonous; and I confess to a feeling ofdrowsiness creeping over me when preparing material for a presidentialaddress to the American Association for the Advancementof Science in August, 1883. In these circumstances Ibecame aware of the presence of an unearthly visitor, whoannounced himself as of celestial birth, and intimated to methat being himself free from those restrictions of space andtime which are so embarrassing to earthly students, he was preparedfor the moment to share these advantages with me, andto introduce me to certain outlying parts of the universe,where I might learn something of its origin and early history.He took my hand, and instantly we were in the voids of space.Turning after a moment, he pointed to a small star and said,"That is the star you call the sun; here, you see, it is only aboutthe third magnitude, and in a few seconds it will disappear."These few seconds, indeed, reduced the whole visible firmamentto a mere nebulous haze like the Milky Way, and weseemed to be in blank space. But pausing for a moment Ibecame aware that around us were multitudes of dark bodies,so black that they were, so to speak, negatively visible, evenin the almost total darkness around. Some seemed largeand massive, some a mere drift of minute particles, formlessand without distinct limits. Some were swiftly moving, others« 10 »stationary, or merely revolving on their own axes. It was a"horror of great darkness," and I trembled with fear. "This,"said my guide, "is what the old Hebrew seer calledtohu vebohu, 'formless and void,' the 'Tiamat' or abyss of the oldChaldeans, the 'chaos and old night' of the Greeks. Yourmundane physicists have not seen it, but they speculate regardingit, and occupy themselves with questions as to whetherit can be lightened and vivified by mere attractive force, or bycollision of dark bodies impinging on each other with vastmomentum. Their speculations are vain, and lead to nothing,because they have no data wherefrom to calculate the infiniteand eternal Power who determined either the attractionor the motion, or who willed which portion of this chaoswas to become cosmos, and which was to remain for everdead and dark. Let us turn, however, to a more hopefulprospect." We sped away to another scene. Here werevast luminous bodies, such as we call nebulæ. Some wereglobular, others disc-like, others annular or like spiral wisps,and some were composed of several concentric shells or rings.All were in rapid rotation, and presented a glorious and brilliantspectacle. "This," said my guide, "is matter of the samekind with that we have just been considering; but it has beenset in active motion. The fiat 'Let there be light!' has beenissued to it. Nor is its motion in vain. Each of these nebulousmasses is the material of a system of worlds, and theywill produce systems of different forms in accordance with thevarious shapes and motions which you observe. Such bodiesare well known to earthly astronomers. One of them, the greatnebula of Andromeda, has been photographed, and is a vastsystem of luminous rings of vapour placed nearly edgewise tothe earth, and hundreds of times greater than the whole solarsystem. But now let us annihilate time, and consider thesegigantic bodies as they will be in the course of many millionsof years." Instantaneously these vast nebulæ had concentrated« 11 »themselves into systems of suns and planets, but with thisdifference from ours, that the suns were very large and surroundedwith a wide luminous haze, and each of the planetswas self-luminous, like a little sun. In some the planets weredancing up and down in spiral lines. In others they weremoving in one plane. In still others, in every variety ofdirection. Some had vast numbers of little planets andsatellites. Others had a few of larger size. There were evensome of these systems that had a pair of central suns of contrastingcolours. The whole scene was so magnificent andbeautiful that I thought I could never weary of gazing on it."Here," said he, "we have the most beautiful condition ofsystems of worlds, when considered from a merely physical pointof view: the perfection of solar and planetary luminousness, butwhich is destined to pass away in the interest of things moreimportant, if less showy. This is the condition of the greatstar Sirius, which the old priest astronomers of the NileValley made so much of in their science and religion, andwhich they called Sothis. It is now known by your star-gazersto be vastly larger than your sun, and fifty times morebrilliant.[1] Let us select one of these systems somewhatsimilar to the solar system, and suppose that the luminousatmospheres of its nearer planets are beginning to wane inbrilliancy. Here is one of them, through whose halo of lightwe can see the body of the planet. What do you now perceive?"The planet referred to was somewhat larger in appearancethan our earth, and, approaching near to it, I could seethat it had a cloud-bearing firmament, and that it seemed tohave continents and oceans, though disposed in more regularforms than on our own planet, and with a smaller proportionof land. Looking at it more closely, I searched in vain for« 12 »any sign of animal life, but I saw a vast profusion of whatmight be plants, but not like those of this world.[2] These weretrees of monstrous stature, and their leaves, which were ofgreat size and shaped like fronds of seaweeds, were not usuallygreen, but variegated with red, crimson and orange. The surfaceof the land looked like beds of gigantic specimens ofColias and similar variegated-leaved plants, the whole presentinga most gorgeous yet grotesque spectacle. "This," said myguide, "is the primitive vegetation which clothes each of theplanets in its youthful state. The earth was once so clothed,in the time when vegetable life alone existed, and there wereno animals to prey upon it, and when the earth was, like theworld you now look upon, a paradise of plants; for all thingsin nature are at first in their best estate. This vegetation isknown to you on the earth only by the Carbon and Graphiteburied in your oldest rocks. It still lingers on your neighbourMars,[3] which has, however, almost passed beyond this stage,and we are looking forward before long to see a still moregigantic though paler development of it in altogether novelshapes on the great continents that are being formed on thesurface of Jupiter. But look again." And time being againannihilated, I saw the same world, now destitute of anyluminous envelope, with a few dark clouds in its atmosphere,and presenting just the same appearance which I would supposeour earth to present to an astronomer viewing it with apowerful telescope from the moon. "Here we are at homeagain," said my guide; "good-bye." I found myself noddingover my table, and that my pen had just dropped from myhand, making a large blot on my paper. My dream, however,« 13 »gave me a hint as to a subject, and I determined to devotemy address to a consideration of questions which geology hasnot solved, or has only imperfectly and hypothetically discussed.

Such unsolved or partially solved questions must necessarilyexist in a science which covers the whole history of the earthin time. At the beginning it allies itself with astronomy andphysics and celestial chemistry. At the end it runs intohuman history, and is mixed up with archæology and anthropology.Throughout its whole course it has to deal withquestions of meteorology, geography and biology. In short,there is no department of physical or biological science, withwhich this many-sided study is not allied, or at least on whichthe geologist may not presume to trespass. When, therefore,it is proposed to discuss in the present chapter some of theunsolved problems and disputed questions of this universalscience, the reader need not be surprised if it should be somewhatdiscursive.

Perhaps we may begin at the utmost limits of the subject byremarking that in matters of natural and physical science weare met at the outset with the scarcely solved question as toour own place in the nature which we study, and the bearingof this on the difficulties we encounter. The organism of manis decidedly a part of nature. We place ourselves, in thisaspect, in the sub-kingdom vertebrata and class mammalia,and recognise the fact that man is the terminal link in a chainof being, extending throughout geological time. But the organismis not all that belongs to man, and when we regard himas a scientific inquirer, we raise a new question. If the humanmind is a part of nature, then it is subject to natural law,and nature includes mind as well as matter. Indeed, withoutbeing absolute idealists we may hold that mind is more potentthan matter, and nearer to the real essence of things. Ourscience is in any case necessarily dualistic, being the product« 14 »of the reaction of mind on nature, and must be largely subjectiveand anthropomorphic. Hence, no doubt, arises muchof the controversy of science, and much of the unsolved difficulty.We recognise this when we divide science into thatwhich is experimental, or depends on apparatus, and that whichis observational and classificatory—distinctions these whichrelate not so much to the objects of science as to our methodsof pursuing them. This view also opens up to us the thoughtthat the domain of science is practically boundless, for whocan set limits to the action of mind on the universe, or of theuniverse on mind. It follows that science, as it exists at anyone time, must be limited on all sides by unsolved mysteries;and it will not serve any good purpose to meet these withclever guesses. If we so treat the enigmas of the sphinxnature, we shall surely be devoured. Nor, on the other hand,must we collapse into absolute despair, and resign ourselves tothe confession of inevitable ignorance. It becomes us ratherboldly to confront the unsolved questions of nature, and towrestle with their difficulties till we master such as we can,and cheerfully leave those we cannot overcome to be grappledwith by our successors.

Fortunately, as a geologist, I do not need to invite attentionto those transcendental questions which relate to the ultimateconstitution of matter, the nature of the ethereal medium fillingspace, the absolute difference or identity of chemical elements,the cause of gravitation, the conservation and dissipation ofenergy, the nature of life, or the primary origin of bioplasmicmatter. I may take the much more humblerôle of an inquirerinto the unsolved or partially solved problems whichmeet us in considering that short and imperfect record whichgeology studies in the rocky layers of the earth's crust, andwhich leads no farther back than to the time when a solidrind had already formed on the earth, and was already coveredwith an ocean. This record of geology covers but a small« 15 »part of the history of the earth and of the system to which itbelongs, nor does it enter at all into the more reconditeproblems involved; still it forms, I believe, some necessarypreparation at least to the comprehension of these. If we areto go farther back, we must accept the guidance of physicistsrather than of geologists, and I must say that in this physicalcosmology both geologists and general readers are likely tofind themselves perplexed with the vagaries in which the mostsober mathematicians may indulge. We are told that theoriginal condition of the solar system was that of a vaporousand nebulous cloud intensely heated and whirling rapidlyround, that it probably came into this condition by the impactof two dark solid bodies striking each other so violently, thatthey became intensely heated and resolved into the smallestpossible fragments. Lord Kelvin attributes this impact totheir being attracted together by gravitative force. Croll [4]argues that in addition to gravitation these bodies must havehad a proper motion of great velocity, which Lord Kelvinthinks "enormously" improbable, as it would require thesolid bodies to be shot against each other with a marvellouslytrue aim, and this not in the case of the sun only, but of allthe stars. It is rather more improbable than it would be toaffirm that in the artillery practice of two opposing armies,cannon balls have thousands of times struck and shatteredeach other midway between the hostile batteries. The question,we are told, is one of great moment to geologists, sinceon the one hypothesis the duration of our system has amountedto only about twenty millions of years; on the other, it mayhave lasted ten times that number.[5] In any case it seems astrange way of making systems of worlds, that they shouldresult from the chance collision of multitudes of solid bodies« 16 »rushing hither and thither in space, and it is almost equallystrange to imagine an intelligent Creator banging these bodiesabout like billiard balls in order to make worlds. Still, in thatcase we might imagine them not to be altogether aimless.The question only becomes more complicated when withGrove and Lockyer we try to reach back to an antecedentcondition, when there are neither solid masses nor nebulæ,but only an inconceivably tenuous and universally diffusedmedium made up of an embryonic matter, which has not yeteven resolved itself into chemical elements. How this couldestablish any motion within itself tending to aggregation inmasses, is quite inconceivable. To plodding geologists laboriouslycollecting facts and framing conclusions therefrom, suchflights of the mathematical mind seem like the wildest fantasiesof dreams. We are glad to turn from them to examinethose oldest rocks, which are to us the foundation stones ofthe earth's crust.

What do we know of the oldest and most primitive rocks?At this moment the question may be answered in many anddiscordant ways; yet the leading elements of the answer maybe given very simply. The oldest rock formation known togeologists is the Lower Laurentian, the Fundamental Gneiss,the Lewisian formation of Scotland, the Ottawa gneiss ofCanada, the lowest Archæan crystalline rocks. This formation,of enormous thickness, corresponds to what the oldergeologists called the fundamental granite, a name not to bescouted, for gneiss is only a stratified or laminated granite.Perhaps the main fact in relation to this old rock is that it is agneiss; that is, a rock at once bedded and crystalline, andhaving for its dominant ingredient the mineral orthoclase, acompound of silica, alumina and potash, in which are imbedded,as in a paste, grains and crystals of quartz and hornblende.We know very well from its texture and composition that itcannot be a product of mere heat, and being a bedded rock« 17 »we infer that it was laid down layer by layer in the mannerof aqueous deposits. On the other hand, its chemical compositionis quite different from that of the muds, sands andgravels usually deposited from water. Their special charactersare caused by the fact that they have resulted from theslow decay of rocks like these gneisses, under the operation ofcarbon dioxide and water, whereby the alkaline matter andthe more soluble part of the silica have been washed away,leaving a residue mainly silicious and aluminous.[6] Suchmore modern rocks tell of dry land subjected to atmosphericdecay and ram-wash. If they have any direct relation to theold gneisses, they are their grandchildren, not their parents.On the contrary, the oldest gneisses show no pebbles or sandor limestone—nothing to indicate that there was then anyland undergoing atmospheric waste, or shores with sandand gravel. For all that we know to the contrary, theseold gneisses may have been deposited in a shoreless sea, holdingin solution or suspension merely what it could derivefrom a submerged crust recently cooled from a state of fusion,still thin, and exuding here and there through its fissuresheated waters and volcanic products. This, it may be observedhere, is just what we have a right to expect, if the earth wasonce a heated or fluid mass, and if our oldest Laurentian rocksconsist of the first beds or layers deposited upon it, perhaps bya heated ocean. It has been well said that "the secret of theearth's hot youth has been well kept." But with the help ofphysical science we can guess at an originally heat-liquefiedball with denser matter at its centre, lighter and oxidisedmatter at its surface. We can imagine a scum or crust formingat the surface; and from what we know of the earth's interior,nothing is more likely to have constituted that slaggy« 18 »crust than the material of our old gneisses. As to its beddedcharacter, this may have arisen in part from the addition ofcooling layers below, in part from the action of heated waterabove, and in part from pressure or tension; while, whereverit cracked or became broken, its interstices would be injectedwith molten matter from beneath. All this may be conjecture,but it is based on known facts, and is the only probable conjecture.If correct, it would account for the fact that thegneissic rocks are the lowest and oldest that we reach in everypart of the earth.

In short, the fundamental gneiss of the Lower Laurentianmay have been the first rock ever formed; and in any case itis a rock formed under conditions which have not since recurred,except locally. It constitutes the first and best exampleof those chemico-physical, aqueous or aqueo-igneous rocks,so characteristic of the earliest period of the earth's history.Viewed in this way the Lower Laurentian gneiss is probablythe oldest kind of rock we shall ever know the limit to ourbackward progress, beyond which there remains nothing to thegeologist except physical hypotheses respecting a cooling incandescentglobe. For the chemical conditions of these primitiverocks, and what is known as to their probable origin, I mayrefer to the writings of my friends, the late Dr. Sterry Hunt andDr. J. G. Bonney, to whom we owe so much of what is knownof the older crystalline rocks [7] as well as of their literature, andthe questions which they raise. My purpose here is to sketchthe remarkable difference which we meet as we ascend into theMiddle and Upper Laurentian.

In the next succeeding formation, the middle part of theLaurentian of Logan, the Grenville series of Canada, we meetwith a great and significant change. It is true we have still apredominance of gneisses which may have been formed in the« 19 »same manner with those below them; but we find these nowassociated with great beds of limestone and dolomite, whichmust have been formed by the separation of calcium and magnesiumcarbonates from the sea water, either by chemical precipitationor by the agency of living beings. We have alsoquartzite, quartzose gneisses, and even pebble beds, which informus of sandbanks and shores. Nay, more, we have bedscontaining graphite which must be the residue of plants, andiron ores which tell of the deoxidation of iron oxide by organicmatters. In short, here we have evidence of new factors inworld-building, of land and ocean, of atmospheric decay ofrocks, of deoxidizing processes carried on by vegetable life onthe land and in the waters, of limestone-building in the sea.To afford material for such rocks, the old Ottawa gneiss musthave been lifted up into continents and mountain masses bybendings and foldings of the original crust. Under the slowbut sure action of the carbon dioxide dissolved in rainwater,its felspar had crumbled down in the course of ages. Itspotash, soda, lime, magnesia, and part Of its silica had beenwashed into the sea, there to enter into new combinationsand to form new deposits. The crumbling residue of fine clayand sand had been also washed down into the borders of theocean, and had been there deposited in beds. Thus theearth had entered into a new phase, which continues onwardthrough the geological ages; and I place in the reader's handsone key for unlocking the mystery of the world in affirmingthat this great change took place, this new era was inauguratedin the midst of the Laurentian period, the oldest of our greatdivisions of the earth's geological history.[8]

Was not this a fit period for the first appearance of life?should we not expect it to appear, independently of the evidenceof the fact, so soon at least as the temperature of the ocean fallssufficiently low to permit its existence?[9] I do not propose toenter here into that evidence. This we shall have occasionto consider in the sequel. I would merely say here thatwe should bear in mind that in this latter half of the LowerLaurentian, or if we so choose to style it, Middle Laurentianperiod, we have the conditions required for life in the seaand on the land; and since in other periods we know that lifewas always present when its conditions were present, it is notunreasonable to look for the earliest traces of life in this formation,in which we find, for the first time, the completion ofthose physical arrangements which make life, in such forms ofit as exist in the sea, possible.

This is also a proper place to say something of the disputeddoctrine of what is termed metamorphism, or the chemicaland molecular changes which old rocks have undergone.

The Laurentian rocks are undoubtedly greatly changed fromtheir original state, more especially in the matters of crystallizationand the formation of disseminated minerals, by the actionof heat and heated water. Sandstones have thus passed intoquartzites, clays into slates and schists, limestones into marbles.So far, metamorphism is not a doubtful question; butwhen theories of metamorphism go so far as to suppose anactual change of one element for another, they go beyond thebounds of chemical credibility; yet such theories of metamorphismare often boldly advanced and made the basis ofimportant conclusions. Dr. Hunt has happily given the name"metasomatosis" to this imaginary and improbable kind of« 21 »metamorphism. I would have it to be understood that, inspeaking of the metamorphism of the older crystalline rocks, itis not to this metasomatosis that I refer, and that I hold thatrocks which have been produced out of the materials decomposedby atmospheric erosion can never by any process ofmetamorphism be restored to the precise condition of theLaurentian rocks. Thus, there is in the older formations agenealogy of rocks, which, in the absence of fossils, may beused with some confidence, but which does not apply to themore modern deposits, and which gives a validity to the use ofmineral character in classifying older rocks which does nothold for later formations. Still, nothing in geology absolutelyperishes, or is altogether discontinued; and it is probablethat, down to the present day, the causes which producedthe old Laurentian gneiss may still operate in limited localities.Then, however, they were general, not exceptional. It isfurther to be observed that the term gneiss is sometimes of wideand even loose application. Beside the typical orthoclase andhornblendic gneiss of the Laurentian, there are micaceous,quartzose, garnetiferous and many other kinds of gneiss; andeven gneissose rocks, which hold labradorite or anorthite insteadof orthoclase, are sometimes, though not accurately, includedin the term.

The Grenville series, or Middle Laurentian, is succeeded bywhat Logan in Canada called the Upper Laurentian, and whichother geologists have called the Norite or Norian series. Herewe still have our old friends the gneisses, but somewhat peculiarin type, and associated with them are great beds and masses, richin lime-felspar, the so-called labradorite and anorthite rocks.The precise 'origin of these is uncertain, but this much seemsclear, namely, that they originated in circumstances in whichthe great limestones deposited in the Lower or Middle Laurentianwere beginning to be employed in the manufacture, probablyby aqueo-igneous agencies, of lime-felspars. This proves« 22 »the Norian rocks to be younger than the Lower Laurentian, andthat, as Logan supposed, considerable earth-movements hadoccurred between the two, implying lapse of time, while it isalso evident that the folding and crumpling of the Lower Laurentianhad led to great outbursts of igneous matter from belowthe crust, or from its under part.

Next to the Laurentian, but probably after an interval, therocks of which are yet scarcely known, we have the Huronianof Logan, a series much less crystalline and more fragmentary,and affording more evidence of land elevation and atmosphericand aqueous erosion than those preceding it. It hasextensive beds of volcanic rock, great conglomerates, some ofthem made up of rounded fragments of Laurentian rocks, andothers of quartz pebbles, which must have been the remains ofrocks subjected to very perfect decay. The pure quartz-rockstell the same tale, while slates and limestones speak also ofchemical separation of the materials of older rocks. The Huronianevidently tells of previous movements in the Laurentian,and changes which allowed the Huronian to be depositedalong its shores and on the edges of its beds. Yet the Huronianitself is older than the Palæozoic series, and affected by powerfulearth-movements at an earlier date. Life existed in thewaters in Huronian times. We have spicules of sponges inthe limestone, and organic markings on the slaty beds; butthey are few, and their nature is uncertain.

Succeeding the Huronian, and made up of itsdébris andthat of the Laurentian, we have the great Cambrian series,that in which we first find undoubted evidence of abundantmarine life, and which thus forms the first chapter in the greatPalæozoic book of the early history of the world. Here let itbe observed we have at least two wide gaps in our history,marked by the crumpling up, first, of the Laurentian, and thenof the Huronian beds.

After what has been said, the reader will perhaps not be« 23 »astonished that fierce geological battles have raged over theold crystalline rocks. By some geologists they are almostentirely explained away, or referred to igneous action, or to thealteration of ordinary sediments. Under the treatment ofanother school they grow to great series of Pre-Cambrianrocks, constituting vast systems of formations, distinguishablefrom each other chiefly by differences of mineral character.Facts and fossils are daily being discovered, by which thesedisputes will ultimately be settled.

After the solitary appearance of Eozoon in the Laurentian,and of a few uncertain forms in the Huronian, we find ourselves,in the Cambrian, in the presence of a nearly completeinvertebrate fauna of protozoa, polyps, echinoderms, mollusksand Crustacea, and this not confined to one locality merely,but apparently extended simultaneously throughout the ocean,over the whole world. This sudden incoming of animal life,along with the subsequent introduction of successive groups ofinvertebrates, and finally of vertebrate animals, furnishes one ofthe greatest unsolved problems of geology, which geologistswere wont to settle by the supposition of successive creations.In the sequel I shall endeavour to set forth the facts as to thissuccession, and the general principles involved in it, and toshow the insufficiency of certain theories of evolution suggestedby biologists to give any substantial aid to the geologist inthese questions. At present I propose merely to notice someof the general principles which should guide us in studying thedevelopment of life in geological time, and the causes whichhave baffled so many attempts to throw light on this obscureportion of our unsolved problems.

It has been urged on the side of rational evolution—andthere are both rational and irrational forms of this many-sideddoctrine—that this hypothesis does not profess to give anexplanation of the absolute origin of life on our planet, or evenof the original organization of a single cell, or of a simple mass« 24 »of protoplasm, living or dead. All experimental attempts toproduce by synthesis the complex albuminous substances, or toobtain the living from the non-living, have so far been fruitless,and indeed we cannot imagine any process by which suchchanges could be effected. That they have been effected weknow, but the process employed by their maker is still asmysterious to us as it probably was to him who wrote thewords:—"And God said, Let the waters swarm with swarmers."How vast is the gap in our knowledge and our practical powerimplied in this admission, which must, however, be made byevery mind not absolutely blinded by a superstitious belief inthose forms of words which too often pass current asphilosophy.

But if we are content to start with a number of organismsready made—a somewhat humiliating start, however—we stillhave to ask—How do these vary so as to give new species?It is a singular illusion, and especially in the case of men whoprofess to be believers in natural law, that variation may beboundless, aimless and fortuitous, and that it is by spontaneousselection from varieties thus produced that development arises.But surely the supposition of mere chance and magic is unworthyof science. Varieties must have causes, and theircauses and their effects must be regulated by some law or laws.Now it is easy to see that they cannot be caused by a mereinnate tendency in the organism itself. Every organism is sonicely equilibrated that it has no such spontaneous tendency,except within the limits set by its growth and the law of itsperiodical changes. There may, however, be equilibriummore or less stable. I believe all attempts hitherto made havefailed to account for the fixity of certain, nay, of very many,types throughout geological time, but the mere considerationthat one may be in a more stable state of equilibrium thananother, so far explains it. A rocking stone has no morespontaneous tendency to move than an ordinary boulder, but« 25 »it may be made to move with a touch. So it probably is withorganisms. But if so, then the causes of variation are external,as in many cases we actually know them to be, and they mustdepend on instability with change in surroundings, and this soarranged as not to be too extreme in amount, and to operatein some determinate direction. Observe how remarkable theunity of the adjustments involved in such a supposition!—howsuperior they must be to our rude and always more or lessunsuccessful attempts to produce and carry forward varietiesand races in definite directions! This cannot be chance. Ifit exists, it must depend on plans deeply laid in the nature ofthings, else it would be most monstrous magic and causelessmiracle. Still more certain is this conclusion when we considerthe vast and orderly succession made known to us bygeology, and which must have been regulated by fixed laws,only a few of which are as yet known to us.

Beyond these general considerations we have others of amore special character, based on palæontological facts, whichshow how imperfect are our attempts as yet to reach the truecauses of the introduction of genera and species.

One is the remarkable fixity of the leading types of livingbeings in geological time. If, instead of framing, like Haeckel,fanciful phylogenies, we take the trouble, with Barrande andGaudry, to trace the forms of life through the period of theirexistence, each along its own line, we shall be greatly struckwith this, and especially with the continuous existence of manylow types of life through vicissitudes of physical conditions ofthe most stupendous character, and over a lapse of timescarcely conceivable. What is still more remarkable is thatthis holds in groups which, within certain limits, are perhapsthe most variable of all. In the present world no creaturesare individually more variable than the protozoa; as, forexample, the foraminifera and the sponges. Yet these groupsare fundamentally the same, from the beginning of the Palæozoic« 26 »until now, and modern species seem scarcely at all todiffer from specimens procured from rocks at least half-wayback to the beginning of our geological record. If we supposethat the present sponges and foraminifera are the descendantsof those of the Silurian period, we can affirm that in all thatvast lapse of time they have, on the whole, made little greaterchange than that which may be observed in variable forms atpresent. The same remark applies to other low animal forms.In types somewhat higher and less variable, this is almostequally noteworthy. The pattern of the venation of the wingsof cockroaches, and the structure and form of land snails,gally-worms and decapod crustaceans were all settled in theCarboniferous age, in a way that still remains. So were thefoliage and the fructification of club mosses and ferns. If, atany time, members of these groups branched off, so as to laythe foundation of new species, this must have been a very rareand exceptional occurrence, and one demanding even somesuspension of the ordinary laws of nature.

We may perhaps be content on this question to say withGaudry,[10] that it is not yet possible to "pierce the mystery thatsurrounds the development of the great classes of animals," orwith Prof. Williamson,[11] that in reference to fossil plants "thetime has not yet arrived for the appointment of a botanicalKing-at-arms and Constructor of pedigrees." We shall, however,find that by abandoning mere hypothetical causes andcarefully noting the order of the development and the causesin operation, so far as known, we may reach to ideas as to causeand mode, and the laws of succession, even if unable to penetratethe mystery of origins.

Another caution which a palæontologist has occasion to givewith regard to theories of life, has reference to the tendency ofbiologists to infer that animals and plants were introduced« 27 »under embryonic forms, and at first in few and imperfectspecies. Facts do not substantiate this. The first appearanceof leading types of life is rarely embryonic, or of the nature ofimmature individuals. On the contrary, they often appear inhighly perfect and specialized forms, often, however, of compositetype and expressing characters afterwards so separated asto belong to higher groups. The trilobites of the Cambrian aresome of them of few segments, and so far embryonic, but thegreater part are many-segmented and very complex. Thebatrachians of the Carboniferous present many characters higherthan those of their modern successors and now appropriatedto the true reptiles. The reptiles of the Permian and Triasusurped some of the prerogatives of the mammals. The ferns,lycopods and equisetums of the Devonian and Carboniferouswere, in fructification, not inferior to their modern representatives,and in the structure of their stems far superior. Theshell-bearing cephalopods of the Palæozoic would seem tohave possessed structures now special to a higher group, thatof the cuttle-fishes. The bald and contemptuous negation ofthese facts by Haeckel and other biologists does not tend togive geologists much confidence in their dicta.

Again, we are now prepared to say that the struggle forexistence, however plausible as a theory, when put before us inconnection with the productiveness of animals and the fewsurvivors of their multitudinous progeny, has not been thedetermining cause of the introduction of new species. Theperiods of rapid introduction of new forms of marine life werenot periods of struggle, but of expansion—those periods inwhich the submergence of continents afforded new and largespace for their extension and comfortable subsistence. In likemanner, it was continental emergence that afforded the opportunityfor the introduction of land animals and plants. Further,in connection with this, it is now an established conclusionthat the great aggressive faunas and floras of the continents« 28 »have originated in the north, some of them within the arcticcircle, and this in periods of exceptional warmth, when theperpetual summer sunshine of the arctic regions coëxisted witha warm temperature. The testimony of the rocks thus is thatnot struggle but expansion furnished the requisite conditionsfor new forms of life, and that the periods of struggle werecharacterized by depauperation and extinction.

But we are sometimes told that organisms are merelymechanical, and that the discussions respecting their originhave no significance any more than if they related to rocks orcrystals, because they relate merely to the organism consideredas a machine, and not to that which may be supposed to bemore important, namely, the great determining power of mindand will. That this is a mere evasion by which we really gainnothing, will appear from a characteristic extract of an articleby an eminent biologist in the new edition of the EncyclopediaBritannica, a publication which, I am sorry to say, instead ofits properrôle as a repertory of facts, has admitted partisanpapers, stating extreme and unproved speculations as if theywere conclusions of science. The statement referred to is asfollows:—"A mass of living protoplasm is simply a molecularmachine of great complexity, the total results of the working ofwhich, or its vital phenomena, depend on the one hand on itsconstruction, and on the other, on the energy supplied to it;and to speak of vitality as anything but the name for a seriesof operations is as if one should talk of the horologity of aclock." It would, I think, scarcely be possible to put intothe same number of words a greater amount of unscientificassumption and unproved statement than in this sentence. Is"living protoplasm" different in any way from dead protoplasm,and if so, what causes the difference? What is a "machine"?Can we conceive of a self-produced or uncaused machine, orone not intended to work out some definite results? The resultsof the machine in question are said to be "vital phenomena";« 29 »certainly most wonderful results, and greater than those of anymachine man has yet been able to construct. But why "vital"?If there is no such thing as life, surely they are merely physicalresults. Can mechanical causes produce other than physicaleffects? To Aristotle life was "the cause of form in organisms."Is not this quite as likely to be true as the converse proposition?If the vital phenomena depend on the "construction"of the machine, and the "energy supplied to it," whence thisconstruction and whence this energy? The illustration of theclock does not help us to answer this question. The constructionof the clock depends on its maker, and its energy is derivedfrom the hand that winds it up. If we can think of aclock which no one has made, and which no one winds, a clockconstructed by chance, set in harmony with the universe bychance, wound up periodically by chance, we shall then havean idea parallel to that of an organism living, yet without anyvital energy or creative law; but in such a case we shouldcertainly have to assume some antecedent cause, whether wecall it "horologity" or by some other name. Perhaps the termevolution would serve as well as any other, were it not thatcommon sense teaches that nothing can be spontaneouslyevolved out of that in which it did not previously exist.

There is one other unsolved problem in the study of life bythe geologist to which it is still necessary to advert. This isthe inability of palæontology to fill up the gaps in the chain ofbeing. In this respect we are constantly taunted with the imperfectionof the record, a matter so important that it merits aseparate treatment; but facts show that this is much morecomplete than is generally supposed. Over long periods oftime and many lines of being we have a nearly continuouschain, and if this does not show the tendency desired, thefault is as likely to be in the theory as in the record. On theother hand, the abrupt and simultaneous appearance of newtypes in many specific and generic forms and over wide and« 30 »separate areas at one and the same time, is too often repeatedto be accidental. Hence palæontologists, in endeavouring toestablish evolution, have been obliged to assume periods ofexceptional activity in the introduction of species, alternatingwith others of stagnation, a doctrine differing very little fromthat of special creation, as held by the older geologists.

The attempt has lately been made to account for these breaksby the assumption that the geological record relates only toperiods of submergence, and gives no information as to those ofelevation. This is manifestly untrue. In so far as marine lifeis concerned, the periods of submergence are those in whichnew forms abound for very obvious reasons, already hinted; butthe periods of new forms of land and fresh-water life are thoseof elevation, and these have their own records and monuments,often very rich and ample, as, for example, the swamps of theCarboniferous, the transition from the great Cretaceous subsidence,when so much of the land of the Northern Hemispherewas submerged, to the new continents of the Tertiary, theTertiary lake-basins of Western America, the Terraces andraised beaches of the Pleistocene. Had I time to refer indetail to the breaks in the continuity of life which cannot beexplained by the imperfection of the record, I could show atleast that nature in this case does advanceper saltum—byleaps, rather than by a slow continuous process. Many ablereasoners, as Le Conte, in America, and Mivart and Collard inEngland, hold this view.

Here, as elsewhere, a vast amount of steady conscientiouswork is required to enable us to solve the problems of thehistory of life. But if so, the more the hope for the patientstudent and investigator. I know nothing more chilling to research,or unfavourable to progress, than the promulgation ofa dogmatic decision that there is nothing to be learned but amerely fortuitous and uncaused succession, amenable to nolaw, and only to be covered, in order to hide its shapeless and« 31 »uncertain proportions, by the mantle of bold and gratuitoushypothesis.

So soon as we find evidence of continents and oceans weraise the question, Have these continents existed from the firstin their present position and form, or have the land and waterchanged places in the course of geological time? This questionalso deserves a separate and more detailed consideration.In reality both statements are true in a certain limited sense.On the one hand, any geological map whatever suffices to showthat the general outline of the existing land began to be formedin the first and oldest crumplings of the crust. On the otherhand, the greater part of the surface of the land consists ofmarine sediments which must have been deposited when thecontinents were in great part submerged, and whose materialsmust have been derived from land that has perished in theprocess, while all the continental surfaces, except, perhaps, somehigh peaks and ridges, have been many times submerged.Both of these apparently contradictory statements are true; andwithout assuming both, it is impossible to explain the existingcontours and reliefs of the surface.

In exceptional cases even portions of deep sea have beenelevated, as in the case of the Polycistine deposits in the WestIndies; but these exceptions are as yet scarcely sufficient toprove the rule.

In the case of North America, the form of the old nucleus ofLaurentian rock in the north already marks out that of thefinished continent, and the successive later formations havebeen laid upon the edges of this, like the successive loads ofearth dumped over an embankment. But in order to give thegreat thickness of the Palæozoic sediments, the land must havebeen again and again submerged, and for long periods of time.Thus, in one sense, the continents have been fixed; in another,they have been constantly fluctuating. Hall and Dana havewell illustrated these points in so far as eastern North America« 32 »is concerned. Prof. Hull of the Geological Survey of Irelandhas had the boldness to reduce the fluctuations of land andwater, as evidenced in the British Islands, to the form of aseries of maps intended to show the physical geography of eachsuccessive period. The attempt is probably premature, andhas been met with much adverse criticism; but there can be nodoubt that it has an element of truth. When we attempt tocalculate what could have been supplied from the old Eozoicnucleus by decay and aqueous erosion, and when we take intoaccount the greater local thickness of sediments towards thepresent sea-basins, we can scarcely avoid the conclusion thatextensive areas once occupied by high land are now under thesea. But to ascertain the precise areas and position of theseperished lands may now be impossible.

In point of fact we are obliged to believe in the contemporaneousexistence in all geological periods, except perhaps thevery oldest, of three sorts of areas on the surface of the earth:(1) Oceanic areas of deep sea, which must always have occupiedthe bed of the present ocean, or parts of it; (2) Continentalplateaus sometimes existing as low flats, or as highertable-lands, and sometimes submerged; (3) Areas of plicationor folding, more especially along the borders of the oceans,forming elevated lands rarely submerged and constantly affordingthe material of sedimentary accumulations. We shall find,however, that these have changed places in a remarkable manner,though always in such a way that neither the life of theland nor of the waters was wholly extinguished in the process.

Every geologist knows the contention which has beenoccasioned by the attempts to correlate the earlier Palæozoicdeposits of the Atlantic margin of North America with thoseforming at the same time on the interior plateau, and withthose of intervening lines of plication and igneous disturbance.Stratigraphy, lithology and fossils are all more or less at faultin dealing with these questions, and while the general nature« 33 »of the problem is understood by many geologists, its solutionin particular cases is still a source of apparently endlessdebate.

The causes and mode of operation of the great movementsof the earth's crust which have produced mountains, plainsand table-lands, are still involved in some mystery. Onepatent cause is the unequal settling of the crust towards thecentre; but it is not so generally understood as it should be,that the greater settlement of the ocean-bed has necessitatedits pressure against the sides of the continents in the samemanner that a huge ice-floe crushes a ship or a pier. Thegeological map of North America shows this at a glance, andimpresses us with the fact that large portions of the earth'scrust have not only been folded but bodily pushed back forgreat distances. On looking at the extreme north, we see thatthe great Laurentian mass of central Newfoundland has actedas a projecting pier to the space immediately west of it, andhas caused the gulf of St. Lawrence to remain an undisturbedarea since Palæozoic times. Immediately to the south of this,Nova Scotia and New Brunswick are folded back. Still farthersouth, as Guyot has shown, the old sediments have beencrushed in sharp folds against the Adirondack mass, which hassheltered the table-land of the Catskills and of the great lakes.South of this again the rocks of Pennsylvania and Marylandhave been driven back in a great curve to the west. Movementsof this kind on the Pacific coast of America have beenstill more stupendous, as well as more recent. Dr. G. M.Dawson [12] thus refers to the crushing action of the Pacific bedon the rocks of British Columbia, and this especially at twoperiods, the close of the Triassic and the close of the Cretaceous:"The successive foldings and crushings which the Cordilleraregion has suffered have resulted in an actual changeof position of the rocks now composing its western margin.« 34 »This change may have amounted since the beginning ofMesozoic time to one-third of its whole present width, whichwould place the line of the coast ranges about two degrees oflongitude farther west." Here we have evidence that a tractof country 400 miles wide and consisting largely of mountainranges and table-lands, has been crushed bodily back over twodegrees of longitude; and this applies not to British Columbiamerely, but to the whole west coast from Alaska to Chili.Yet we know that any contraction of the earth's nucleus cancrumple up only a very thin superficial crust, which in thiscase must have slid over the pasty mass below.[13] Let itbe observed, however, that the whole lateral pressure of vastareas has been condensed into very narrow lines. Nothing, Ithink, can more forcibly show the enormous pressure to whichthe edges of the continents have been exposed, and at thesame time the great sinking of the hard and resisting ocean-beds.Complex and difficult to calculate though these movementsof plication are, they are more intelligible than theapparently regular pulsations of the flat continental areas,whereby they have alternately been below and above thewaters, and which must have depended on somewhat regularlyrecurring causes, connected either with the secular cooling ofthe earth or with the gradual retardation of its rotation, or withboth. There is, however, good reason to believe that the successivesubsidences alternated with the movements of plication,and depended on upward bendings of the ocean floor, andalso on the gradual slackening of the rotation of the earth.Throughout these changes, each successive elevation exposedthe rocks for long ages to the decomposing influence of theatmosphere. Each submergence swept away and deposited as« 35 »sediment the material accumulated by decay. Every changeof elevation was accompanied with changes of climate, andwith modifications of the habitats of animals and plants.Were it possible to restore accurately the physical geographyof the earth in all these respects, for each geological period,the data for the solution of many difficult questions would befurnished.

We have wandered through space and time sufficiently forone chapter, and some of the same topics must come up laterin other connections. Let us sum up in a word. In humanhistory we are dealing with the short lives and limited plans ofman. In the making of worlds we are conversant with theplans of a Creator with whom one day is as a thousand years,and a thousand years as one day. We must not measure suchthings by our microscopic scale of time. Nor should we failto see that vast though the ages of the earth are, they are partsof a continuous plan, and of a plan probably reaching in spaceand time immeasurably beyond our earth. When we trace thelong history from an incandescent fire-mist to a finished earth,and vast ages occupied by the dynasties of plant and animallife, we see not merely a mighty maze, an almost endless processionof changes, but that all of these were related to oneanother by a chain of causes and effects leading onward togreater variety and complexity, while retaining throughout thetraces of the means employed. The old rocks and the ancientlines of folding and the perished forms of life are not merely ascaffolding set up to be thrown down, but the foundationstones of a great and symmetrical structure. Is it yet completed?Who can tell? The earth may still be young, andinfinite ages of a better history may lie before it.

References [14]:—Presidential Address to the AmericanAssociation for the Advancement of Science, meeting at Minneapolis,1883. "The Story of the Earth and Man." Ninth edition, London, 1887.

THE IMPERFECTION OF THE GEOLOGICAL RECORD.

DEDICATED TO THE MEMORY OF

JOACHIN BARRANDE,

One of the most successful Labourers
in the
Completion of the History of Life
in its earlier Stages.

Nature of the Imperfection—Questions as to itsarising from Want of Continuity, from Lack ofPreservation, from Imperfect Collecting.—Examples—LandSnails, Carboniferous Batrachians,Palæozoic Sponges, Pleistocene Shells, Devonianand Carboniferous Plants—Comparative Perfectionin the Case of Marine Shells, etc.—PossibleCambrian Squids—Questions as to Want of FirstChapters of the Record—Practical Conclusions

CHAPTER III.

Complaints of the imperfection of the geologicalrecord are rife among those biologists who expect tofind continuous series of fossils representing the gradual transmutationof species. No doubt these gaps are in some casesportentous, and unfortunately they often occur just where it ismost essential to certain general conclusions that they shouldbe filled up. Instead, however, of making vague lamentationson the subject, it is well to inquire to what causes these gapsmay be due, to what extent they invalidate the completenessof geological history for scientific purposes, and how they maybest be filled.

Here we may first remark that it is not so much the physicalrecord of geology that is imperfect as the organic record. Eversince the time of Hutton and Playfair we have learned thatthe processes of mineral detrition and deposition are continuous,and have been so throughout geological time. Theerosion of the land is constantly going on, every shower carriesits tribute of earthy matter toward the sea, and every wavethat strikes against a beach or cliff does some work towardthe grinding of shells, pebbles or stone. Thus, everywherearound our continents there is a continuous deposition of bedsof earthy matter, and it is this which, when elevated into newland, has given us our chronological series of geological formations.True, the elevating process is not continuous, but, so« 40 »far as we know, intermittent; but it has been so often repeatedthat we have no reason to doubt that the wasting continentsafford a complete series of aqueous deposits, since the timewhen the dry land first appeared.

In recent years theChallenger expedition and similar dredgingshave informed us of still another continuity of depositionin the depths of the ocean. There, where no detritus fromthe land, or only a very little fine volcanic ash or pumice hasever reached, we have, going on from age to age, a deposit ofthe hard parts of abyssal animals and of those that swim inthe open sea; so that if it were possible to bore or sink a shaftin some parts of the ocean, we should find not only a continuousbed, but a continuous series of pelagic life from theLaurentian to the present day. Thus we have continuousphysical records, could we but reach or completely put themtogether, and eliminate the disturbing influence of merely localvicissitudes. It is when we begin to search the geologicalformations for fossils, that imperfection in our record firstbecomes painfully manifest.

In the case of many groups of marine animals, as, forexample, the shell-fish and the corals, and I may add thebivalve crustaceans, so admirably worked up by my friendProf. Rupert Jones, we have very complete series. With theand snails the case is altogether different. As stated in anotherpaper of this series, a few species of these animals appearin the later Palæozoic age, and after that they have no successorsknown to us in all the great periods covered by thePermian, the Trias, and the earlier Jurassic. A few air-breathingwater-snails appear in the upper Jurassic, and true landsnails are not met with again until the Tertiary. Were thereno land snails in this vast lapse of time? Have we two successivecreations, so to speak, of these creatures at distantintervals? Were they only diminished in numbers and distributionin the intervening time? Is the hiatus owing merely« 41 »to the unlikelihood of such shells being preserved? Or is itowing to the lack of diligence and care in collecting?

In this particular case we are, no doubt, disposed to saythat the series must have been continuous. But we cannotbe sure of this. In whatever way a few species of land snailswere so early introduced in the time of the Devonian or ofthe Coal formation, if from physical vicissitudes or lack ofproper pabulum they became extinct, there is no reason knownto us why, when circumstances again became favourable, theyshould not be reintroduced in the same manner as at first,whether by development from allied types or otherwise. Thefact that the few Devonian and Carboniferous species are verylike those that still exist, perhaps makes against this supposition,but does not exclude it. If we suppose that new forms of lifeof low grade are introduced from time to time in the courseof the geological ages, and if we adopt the Darwinian hypothesisof evolution, we arrive, as Naegeli has so well pointedout, at the strange paradox, that the highest forms of life mustbe the oldest of all, since they will be the descendants of theearliest of the lower animals, whereas the animals now of lowgrade may have been introduced later, and may not have hadtime to improve. But all our attempts to reduce nature toone philosophic expression necessarily lead to such paradoxes.

On the other hand, the chances of the preservation of landsnails in aqueous deposits are vastly less than those in favourof the preservation of aquatic species. The first Carboniferousspecies found [15] had been preserved in the very exceptionalcircumstances afforded by the existence of hollow trunks ofSigillariæ on the borders of the Coal formation flats, and theothers subsequently found were in beds no doubt receivingthe drainage of neighbouring land areas. Still it is not uncommonon the modern sea-shore, anywhere near the mouthsof rivers, to find a few fresh-water shells here and there. The« 42 »carbonaceous beds of the Trias, the fossil soils of the Portlandseries, the estuarine Wealden beds would seem to be as favourablysituated as those of the coal formation for preserving landshells, though possibly the flora of the Mesozoic was less suitablefor feeding such creatures than that of the Coal period,and they may consequently have become few and local. Afterall, perhaps more diligent collecting and more numerous collectorsmight succeed, and may succeed in the future, in fillingthis and similar gaps.

It is a great mistake to suppose that discoveries of this kindare made by chance. It is only by the careful and painstakingexamination of much material that the gaps in the geologicalrecord can be filled up, and I propose in the sequel of thisarticle to note a few instances, in a country where the rangeof territory is altogether out of proportion to the number ofobservers, and which have come within my own knowledge.

It was not altogether by accident that Sir C. Lyell and thewriter discovered a few reptilian bones and a land-snail inbreaking up portions of the material filling an erect Sigillariain the South Joggins coal measures. We were engaged in adeliberate survey of the section, to ascertain as far as mightbe the conditions of accumulation of coal, and one pointwhich occurred to us was to inquire as to the circumstancesof preservation of stumps of forest trees in an erect position,to trace their roots into the soils on which they stood, and toascertain the circumstances in which they had been buried,had decayed, and had been filled with mineral matter. It wasin questioning these erect trees on such subjects and this notwithout some digging and hammering that we made the discoveryreferred to.

But we found such remains only in one tree, and they werevery imperfect, and indicated only two species of batrachiansand one land-snail. There the discovery might have rested.But I undertook to follow it up. In successive visits to the« 43 »coast, a large number of trees standing in the cliff and reefs,or fallen to the shore, were broken up and examined, theresult being to discover that, with one unimportant exception,the productive trees were confined to one of the beds at CoalMine Point, that from which the original specimens had beenobtained. Attention was accordingly concentrated on this,and as many as thirty trees were at different times extractedfrom it, of which rather more than one-half proved more orless productive. By these means bones representing aboutsixty specimens and twelve species were extracted, besidesnumerous remains of land shells, millipedes, and scorpions.In this way a very complete idea was obtained of the land life,or at least of the smaller land animals, of this portion of thecoal formation of Nova Scotia. It is not too much to say thatif similar repositories could be found in the succeeding formations,and properly worked when found, our record of thehistory of land quadrupeds might be made very complete.

When in 1855 I changed my residence from Nova Scotia toMontreal, and so was removed to some distance from thecarboniferous rocks which I had been accustomed to study, Inaturally felt somewhat out of place in a Cambro-Silurian district,more especially as my friend Billings had already almostexhausted its fossils. I found, however, a congenial field inthe Pleistocene shell beds; more especially as I had givensome attention to recent marine animals when on the sea coast.The very perfect series of Pleistocene deposits in the St.Lawrence valley locally contain marine shells from the bottomof the till or boulder clay up to the overlying sands and gravels.The assemblage was a more boreal one than that on the coastof Nova Scotia, though many of the species were the same,and both the climatal and bathymetrial conditions differed indifferent parts of the Pleistocene beds themselves. The gapin the record here could at that time be filled up only by collectingrecent shells. In addition to what could be obtained« 44 »by exchanging with naturalists who had collected in Greenland,Labrador, and Norway, I employed myself, summer aftersummer, in dredging both on the south and north shore ofthe St. Lawrence, until able at length to discover in a livingstate, but under different conditions as to temperature anddepth, nearly every species found in the beds on the land,from the lower boulder clay to the top of the formation, andfrom the sea-level to the beds six hundred feet high on thehills. Not only so: I could ascertain in certain places andconditions all the peculiar varieties of the species, and thespecial modes of life which they indicated. Thus, in the casesof the Peter Redpath Museum, and in notes on the Post-plioceneof Canada, the gap between the Modern and theGlacial age was completely filled up in so far as Canadianmarine species are concerned. The net result was, as I haveelsewhere stated, that no change other than varietal hadoccurred.

In studying the fossil plants of the Carboniferous, so abundantin the fine exposures of the coal formation in Nova Scotia,two defects struck me painfully. One was the fragmentaryand imperfect state of the specimens procurable. Anotherwas the question, What preceded these plants in the olderrocks? The first of these was to be met only by thoroughexploration. When a fragment of a plant was disclosed it wasnecessary to inquire if more existed in the same bed, and todig, or blast away or break up the rock, until some remainingportions were disclosed. In this way it has been possible toobtain entire specimens of many trees of the Carboniferous;and to such an extent has the laborious and somewhat costlyprocess been effectual, that more species of carboniferous treesare probably known in their entire forms from the Coal formationsof Nova Scotia than from any other part of the world.I have been amused to find that so little are experiences ofthis kind known to some of myconfrères abroad, that they« 45 »are disposed to look with scepticism on the informationobtained by this laborious but certain process, and to supposethat they are being presented with imaginary "restorations."I think it right here to copy a remark of a German botanist,who has felt himself called to criticise my work: "Dawson'sdescription of the genus (Psilophyton) rests chiefly on theimpression made on him in his repeated researches," etc."He puts us off with an account of the general idea which hehas drawn from the study of them." This is the remark of acloset naturalist, with reference to the kind of work abovereferred to, which, of course, cannot be represented in itsentirety in figures or hand specimens.[16]

As to the precursors of the Carboniferous flora, in defaultof information already acquired, I proceeded to question theErian or Devonian rocks of Canada, in which Sir WilliamLogan had already found remains of plants which had not,however, been studied or described. Laboriously coastingalong the cliffs of Gaspé and the Baie des Chaleurs, digginginto the sandstones of Eastern Maine, and studying the plantscollected by the New York Survey, I began to find that therewas a rich Devonian flora, and that, like that of the Carboniferous,it presented different stages from the base to the summitof the formation. But here a great advance was made in asomewhat unexpected way. My then young friends, the lateProf. Hartt and Mr. Matthew, of St. John, had found a fewremains of plants in the Devonian, or at least pre-Carboniferousbeds of St. John, which were placed in my hands for description.They were so novel and curious that inquiry was stimulated,and these gentlemen, with some friends of similar tastes,explored the shales exposed in the reefs near St. John, andwhen they found the more productive beds, broke them up by« 46 »actual quarrying operations in such a way that they soonobtained the richest Devonian plant collections ever known.I think I may truly say that these young and enthusiasticexplorers worked the St. John plant-beds in a manner previouslyunexampled in the world. Their researches were notonly thus rewarded, but incidentally they discovered the firstknown Devonian insects, which could not have been foundby a less painstaking process, and one of them discoveredwhat I believe to be the oldest known land shell. Still more,their studies led to the separation from the Devonian beds ofthe Underlying Cambrian slates, previously confounded withthem; and this, followed up by the able and earnest work ofMr. Matthew, has carried back our knowledge of the olderrocks in Canada several stages, or as far as the earliestCambrian previously known in Europe, but not before fullyrecognised in America, and has discovered in these old rocksthe precursors of many forms of life not previously traced sofar back.

The moral of these statements of fact is that the imperfectionsof the record will yield only to patient and painstakingwork, and that much is in the power of local amateurs. Iwould enforce this last statement by a reference to a littleresearch, in which I have happened to take part at a summerresort on the Lower St. Lawrence, at which I have from timeto time spent a few restful vacation weeks. Little Metis is onthe Quebec Group of Sir William Logan, that peculiar localrepresentative of the lower part of the Cambro-Silurian andUpper Cambrian formations which stretches along the southside of the St. Lawrence all the way from Quebec to CapeRosier, near Gaspé, a distance of five hundred miles. Thisgreat series of rocks is a jumble of deposits belonging at thatearly time to the marginal area of what is now the Americancontinent, and indicating the action not merely of ordinarycauses of aqueous deposit, but of violent volcanic ejections,« 47 »accompanied perhaps by earthquake waves, and not improbablyby the action of heavy coast ice. The result is that mudrocks now in the form of black, grey, and red shales and slatesalternate with thick and irregular beds of hard sandstone,sometimes so coarse that it resembles the angulardébris of thefirst treatment of quartz in a crusher. With these sandstonesare thick and still more irregular conglomerates formed ofpebbles and boulders of all sizes, up to several feet in diameter,some of which are of older limestones containing Cambrianfossils, while others are of quartzite or of igneous or volcanicrocks.

The whole formation, as presented at Metis, is of the mostunpromising character as regards fossils, and after visiting theplace for ten years, and taking many long walks along theshore and into the interior, and scrutinising every exposure, Ihad found nothing more interesting than a few fragments ofgraptolites, little zoophytes, ancient representatives of our seamosses, and which are quite characteristic of several portionsof the Quebec Group. With these were some marks offucoids and tracks or burrows of worms. The explorers of theGeological Survey had been equally unsuccessful.

Quite accidentally a new light broke upon these unpromisingrocks. My friend, Dr. Harrington, strolling one day onthe shore, sat down to rest on a stone, and picked up a pieceof black slate lying at his feet. He noticed on it some faintlytraced lines which seemed peculiar. He put it in his pocketand showed it to me. On examination with a lens it provedto have on it a few spicules of a hexactinellid sponge—littlecrosses forming a sort of mesh or lattice-work similar to thatwhich Salter had many years before found in the Cambrianrocks of Wales, and had namedProtospongia—the first sponge.The discovery seemed worth following up, and we took anearly opportunity of proceeding to the place, where, after somesearch, we succeeded in tracing the loose pieces to a ledge of« 48 »shale on the beach, where there was a little band, only about aninch thick, stored with remains of sponges, a small bivalve shelland a slender branching seaweed. This was one small layerin reefs of slate more than one hundred feet thick. We subsequentlyfound two other thin layers, but less productive.Tools and workmen were procured, and we proceeded toquarry in the reef, taking out at low tide as large slabs aspossible of the most productive layer, and carefully splittingthese up. The results, as published in the Transactions ofthe Royal Society of Canada,[17] show more than twelve speciesof siliceous sponges belonging to six genera, besides fragmentsindicating other species, and all of these living at one time ona very limited space of what is practically a single surface ofmuddy sea-bottom.[18] The specimens show the parts of theseancient sponges much more perfectly than they were previouslyknown, and indeed, enable many of them to be perfectly restored.They for the first time connect the modern siliceoussponges of the deep sea with those that flourished on the oldsea-bottom of the early Cambro-Silurian, and thus bridge overa great, gap in the history of this low form of life, showing thatthe principles of construction embodied in the remarkableand beautiful siliceous sponges, like Euplectella, the "Venusflower-basket," now dredged from the deep sea, were alreadyperfectly carried out in this far-back beginning of life. Thislittle discovery further indicates that portions of the olderPalæozoic sea-bottoms were as well stored with a variedsponge life as those of any part of the modern ocean. Ifigure [19] a number of species, remains of all of which may begathered from a few yards of a single surface at Little Metis.The multitude of interesting details embodied in all this it isimpossible to enter into here, but may be judged of from« 49 »the forms reproduced. These examples tend to show that theimperfection of the record may not depend on the record itself,but on the incompleteness of our work. We must make largeallowance for imperfect collecting, and especially for the tooprevalent habit of remaining content with few and incompletespecimens, and of grudging the time and labour necessary toexplore thoroughly the contents of special beds, and to workout all the parts of forms found more or less in fragments.

The point of all this at present is that patient work is neededto fill up the breaks in our record. A collector passing alongthe shore at Metis might have picked up a fragment of a fossilsponge, and recorded it as a fossil, or possibly described thefragment. This fact alone would have been valuable, but tomake it bear its full fruit it was necessary to trace the fragmentto its source, and then to spend time and labour in extractingfrom the stubborn rock the story it had to tell. Instances ofthis kind crowd on my memory as coming within my own experienceand observation. It is hopeful to think that the recordis daily becoming less imperfect; it is stimulating toknow that so much is only waiting for investigation. The historynever can be absolutely complete. Practically, to us it isinfinite. Yet every series of facts known may be complete initself for certain purposes, however many gaps there may bein the story. Even if we cannot find a continuous series betweenthe snails of the Coal formation or the sponges of theQuebec Group and their successors to-day, we can at least seethat they are identical in plan and structure, and can note thedifferences of detail which fitted them for their places in theancient or the modern world. Nor need we be too discontentedif the order of succession, such as it is, does not exactly squarewith some theories we may have formed. Perhaps it may inthe end lead us to greater and better truths.

Another subject which merits attention here is the evidencewhich mere markings or other indications may sometimes give« 50 »as to the existence of unknown creatures, and thus may be asimportant to us as the footprints of Friday to Robinson Crusoe.As I have been taking Canadian examples, I may borrow onehere from Mr. Matthew, of St. John, New Brunswick.

He remarks in one of his papers the manner in which theTrilobites of the early Cambrian are protected with defensivespines, and asks against what enemies they were intended toguard. That there were enemies is further proved by the occurrenceof Coprolites or masses of excrement, oval or cylindricalin form, and containing fragments of shells of Trilobites,of Pteropods (Hyolithes) and of Lingula. There must thereforehave been marine animals of considerable size, whichpreyed on Trilobites. Dr. Hunt and myself have recordedsimilar facts from the Upper Cambrian and Cambro-Silurianof the Province of Quebec. No remains, however, are knownof animals which could have produced such coprolites, except,indeed, some of the larger worms of the period, and they seemscarcely large enough. In these circumstances Mr. Matthewfalls back on certain curious marks or scratches with whichlarge surfaces of these old rocks are covered, and which henames Ctenichnites or "Comb tracks." These markingsseem to indicate the rapid motion of some animal touchingthe bottom with fins or other organs; and as we know no fishesin these old rocks, the question recurs, What could it havebeen? From the form and character of the markings Mr.Matthew infers (1) That these animals lived in "schools," orwere social in their habits; (2) That they had a rapid, direct,darting motion; (3) That they had three or four (at least)flexible arms; (4) That these arms were furnished with hooksor spines; (5) That the creatures swam with an easy motion,so that sometimes the arms of one side touched the bottom,sometimes those of the other. These indications point toanimals allied to the modern squids or cuttle-fishes, and asthese animals may have had no hard parts capable of preservation,« 51 »except their horny beaks, nothing might remain toindicate their presence except these marks on the bottom.Mr. Matthew therefore conjectures that there may have beenlarge cuttle-fishes in the Cambrian. Since, however, these areanimals of very high rank in their class, and are not certainlyknown to us till a very much later period, their occurrence inthese old rocks would be a very remarkable and unexpectedfact.

A discovery made by Walcott in the Western States sinceMr. Matthew's paper was written, throws fresh light on thequestion. Remains of fishes have been found by theformer in the Cambro Silurian rocks nearly as far back asMr. Matthew's comb-tracks. Besides this, Pander in Russiahas found in these old rocks curious teeth, which he refersconjecturally to fishes (Conodonts). Why may there not havebeen in the Cambrian large fishes having, like the modernsharks, cartilage or gristle instead of bone—perhaps destituteof scales, and with small teeth which have not yet been detected.The fin rays of such fishes may have left the combtracks, and in support of this I may say that there are in theLower Carboniferous of Horton Bluff, in Nova Scotia, verysimilar tracks in beds holding many remains of fishes. Whicheverview we adopt we see good evidence that there were inthe early Cambrian animals of higher grade than we have yetdreamt of. Observe, however, that if we could complete therecord in this point it would only give us higher forms of lifeat an earlier time, and so push farther back their possibledevelopment from lower forms. I fear, indeed, that I canhold out little hopes to the evolutionists that a more completegeological record would help them in any way. It wouldpossibly only render their position more difficult.

But the saddest of all the possible defects of the geologicalrecord is that it may want the beginning, and be like theBible of some of the German historical critics, from which they« 52 »eliminate as mythical everything before the time of the laterHebrew kings. Our attention is forcibly called to this by thecondition of the fauna of the earliest Cambrian rocks. Thediscoveries in these in Wales, in Norway, and in America showus that the seas of this early period swarmed with animals representingall the great types of invertebrate marine life. Wehave here highly organized Crustaceans, Worms, Mollusks andother creatures which show us that in that early age all thesedistinct forms of life were as well separated from each otheras in later times, that eyes of different types, jointed limbswith nerves and muscles, and a vast variety of anatomicalcontrivances were as highly developed as at any subsequenttime.[20] To a Darwinian evolutionist this means nothing lessthan that these creatures must have existed through countlessages of development from their imagined simple ancestralform or forms how long it is impossible to guess, since, unlesschange was more speedy in the infancy of the earth, the termof ages required must have far exceeded that from the Cambrianto the Modern. Yet, to represent all this we have absolutelynothing except Eozoon in its solitary grandeur, and a« 53 »few other forms, possibly of Protozoa and worms. An imaginaryphylogeny of animal life from Monads to Trilobiteswould be something as long as the whole geological history.Yet it would be almost wholly imaginary, for the record of therocks tells little or nothing. In face of such an imperfectionas this, geologists should surely be humble, and make confessionof ignorance to any extent that may be desired. Yet wemay at least, with all humility and self-abasement, ask ourcritics how they know that this great blank really exists, andwhether it may not be possible that the swarming life of theearly Cambrian may, after all, have appeared suddenly on thestage in some way as yet unknown to us and to them.

References:—"Fossil Sponges from the Quebec Group of Little Metis,Lower St. Lawrence":Transactions Royal Society of Canada, 1890."Rèsumè of the Carboniferous Land Shells of North America":American Journal of Science, 1880. "Burrows and Tracks of InvertebrateAnimals":Journal Geological Society of London, 1890."Notes on the Pleistocene of Canada":Canadian Naturalist, 1876."Air-breathers of the Coal Period ":Ibid., 1863.

THE HISTORY OF THE NORTH ATLANTIC.

DEDICATED TO THE MEMORY OF

PROF. JOHN PHILLIPS,
OF OXFORD,

One of the most able, earnest, and genial of
English Geologists;
and of other Eminent Scientific Men, now passed away,
who supported him as
President of the British Association, at its
Meeting in Birmingham, in 1865.

Distribution of Land and Water—Causes of Irregularitiesof the Surface Crust and Interior—Positionof Continents—Past History of theAtlantic—Its Relations to Life—Its Future

CHAPTER IV.

I had the pleasure of being present at the meeting of theBritish Association at Birmingham, in 1865: a meetingattended by an unusually large number of eminent geologists,under the presidency of my friend Phillips. I had the furtherpleasure of being his successor at the meeting in the sameplace, in 1886; and the subject of this chapter is that towhich I directed the attention of the Association in myPresidential address. I fear it is a feeble and imperfect utterancecompared with that which might have been given forth byany of the great men present in 1865, and who have since leftus, could they have spoken with the added knowledge of theintervening twenty years.

The geological history of the Atlantic appeared to be asuitable subject for a trans-Atlantic president, and to a Societywhich had vindicated its claim to be British in the widestsense by holding a meeting in Canada, while it was alsomeditating a visit to Australia—a visit not yet accomplished,but in which it may now meet with a worthy daughter in theAustralian Association formed since the meeting of 1886. Thesubject is also one carrying our thoughts very far back ingeological time, and connecting itself with some of the latestand most important discussions and discoveries in the scienceof the earth, furnishing, indeed, too many salient points to beprofitably occupied in a single chapter.

If we imagine an observer contemplating the earth from a« 58 »convenient distance in space, and scrutinizing its features as itrolls before him, we may suppose him to be struck with thefact that eleven-sixteenths of its surface are covered with water,and that the land is so unequally distributed that from onepoint of view he would see a hemisphere almost exclusivelyoceanic, while nearly the whole of the dry land is gathered inthe opposite hemisphere. He might observe that large portionsof the great oceanic areas of the Pacific and Antarctic Oceansare dotted with islands—like a shallow pool with stones risingabove its surface—as if the general depth were small in comparisonwith the area. Other portions of these oceans hemight infer, from the colour of the water and the absence ofislands, cover deep depressions in the earth's surface. Hemight also notice that a mass or belt of land surrounds eachpole, and that the northern ring sends off to the southwardthree vast tongues of land and of mountain chains, terminatingrespectively in South America, South Africa, and Australia,towards which feebler and insular processes are given off bythe antarctic continental mass. This, as some geographershave observed,[21] gives a rudely three-ribbed aspect to the earth,though two of the ribs are crowded together, and form theEurasian mass or double continent, while the third is isolatedin the single continent of America. He might also observethat the northern girdle is cut across, so that the Atlanticopens by a wide space into the Arctic Sea, while the Pacific iscontracted toward the north, but confluent with the AntarcticOcean. The Atlantic is also relatively deeper and less cumberedwith islands than the Pacific, which has the highestridges near its shores, constituting what some visitors to thePacific coast of America have not inaptly called the "back ofthe world," while the wider slopes face the narrower ocean.The Pacific and Atlantic, though both depressions or flattenings« 59 »of the earth, are, as we shall find, different in age,character, and conditions; and the Atlantic, though the smaller,is the older, and, from the geological point of view, in somerespects, the more important of the two; while, by virtue of itslower borders and gentler slope, it is, though the smaller basin,the recipient of the greater rivers, and of a proportionatelygreat amount of the drainage of the land.[22]

If our imaginary observer had the means of knowing anythingof the rock formations of the continents, he would noticethat those bounding the North Atlantic are, in general, ofgreat age some belonging to the Laurentian system. On theother hand, he would see that many of the mountain rangesalong the Pacific are comparatively new, and that modernigneous action occurs in connection with them. Thus hemight see in the Atlantic, though comparatively narrow, amore ancient feature of the earth's surface; while the Pacificbelongs to more modern times. But he would note, in connectionwith this, that the oldest rocks of the great continentalmasses are mostly toward their northern ends; and that theborders of the northern ring of land, and certain ridges extendingsouthward from it, constitute the most ancient andpermanent elevations of the earth's crust, though now greatlysurpassed by mountains of more recent age nearer the equator,so that the continents of the northern hemisphere seem tohave grown progressively from north to south.

If the attention of our observer were directed to moremodern processes, he might notice that while the antarcticcontinent freely discharges its burden of ice to the ocean northof it, the arctic ice has fewer outlets, and that it mainly dischargesitself through the North Atlantic, where also the greatmass of Greenland stands as a huge condenser and cooler,« 60 »unexampled elsewhere in the world, throwing every spring animmense quantity of ice into the North Atlantic, and moreespecially into its western part. On the other hand, he mightlearn from the driftage of weed and the colour of the water,that the present great continuous extension and form of theAmerican continent tend to throw northward a powerful branchof the equatorial current, which, revolving around the NorthAtlantic, counteracts the great flow of ice which otherwisewould condemn it to a perpetual winter.

Further, such an observer would not fail to notice that theridges which lie along the edges of the oceans and the ebullitionsof igneous matter which proceed, or have proceededfrom them, are consequences of the settling downward of thegreat oceanic depressions, a settling ever intensified by theirreceiving more and more of deposit on their surfaces; andthat this squeezing upward of the borders of these depressionsinto folds has been followed or alternated with elevations anddepressions without any such folding, and proceeding fromother causes. On the whole, it would be apparent that theseactions are more vigorous now at the margins of the Pacificarea, while the Atlantic is backed by very old foldings, or byplains and slopes from which it has, so to speak, dried awaywithout any internal movement. Thus it would appear thatthe Pacific is the great centre of earth-movement, while theAtlantic trench is the more potent regulator of temperature,and the ocean most likely to be severely affected in this respectby small changes of its neighbouring land. Last of all, anobserver, such as I have supposed, would see that the oceansare the producers of moisture and the conveyors of heat to thenorthern regions of the world, and that in this respect and inthe immense condensation and delivery of ice at its north end,the Atlantic is by far the more active, though the smaller ofthe two.

So much could be learned by an extra-mundane observer;« 61 »but unless he had also enjoyed opportunities of studying therocks of the earth in detail and close at hand, or had beenfavoured by some mundane friend with a perusal of "Lyell'sElements," or "Dana's Manual," he would not be able to appreciateas we can the changes which the Atlantic has seen ingeological time, and in which it has been a main factor. Norcould he learn from such superficial observation certain secretsof the deep sea, which have been unveiled by the soundinglead, the inequalities of the ocean basin, its few profound depths,like inverted mountains or table-lands, its vast nearly flatabyssmal floor, and the sudden rise of this to the hundredfathom line, forming a terrace or shelf around the sides ofthe continents. These features, roughly represented in themap prefixed, he would be unable to perceive.

Before leaving this broad survey, we may make one furtherremark. An observer, looking at the earth from without,would notice that the margins of the Atlantic and the mainlines of direction of its mountain chains are north-east andsouth-west, and north-west and south-east, as if some earlycauses had determined the occurrence of elevations alonggreat circles of the earth's surface tangent to the polar circles.

We are invited by the preceding general glance at the surfaceof the earth to ask certain questions respecting the Atlantic,(1) What has at first determined its position and form? (2)What changes has it experienced in the lapse of geologicaltime? (3) What relations have these changes borne to thedevelopment of life on the land and in the water? (4) Whatis its probable future?

Before attempting to answer these questions, which I shallnot take up formally in succession, but rather in connectionwith each other, it is necessary to state, as briefly as possible,certain general conclusions respecting the interior of the earth.It is popularly supposed that we know nothing of this beyonda superficial crust perhaps averaging 50,000 to 100,000 feet in« 62 »thickness. It is true we have no means of exploration in theearth's interior, but the conjoined labours of physicists havenow proceeded sufficiently far to throw much inferential lighton the subject, and to enable us to make some general affirmationswith certainty; and these it is the more necessary tostate distinctly, since they are often treated as mere subjects ofspeculation and fruitless discussion.

(1) Since the dawn of geological science, it has been evidentthat the crust on which we live must be supported on aplastic or partially liquid mass of heated rock, approximatelyuniform in quality under the whole of its area. This is alegitimate conclusion from the wide distribution of volcanicphenomena, and from the fact that the ejections of volcanoes,while locally of various kinds, are similar in every part of theworld. It led to the old idea of a fluid interior of the earth,but this seems now generally abandoned, and this interiorheated and plastic layer is regarded as merely an under-crust,resting on a solid nucleus.[23]

(2) We have reason to believe, as the result of astronomicalinvestigations,[24] that, notwithstanding the plasticity or liquidityof the under-crust, the mass of the earth—its nucleus as wemay call it—is practically solid and of great density andhardness. Thus we have the apparent paradox of a solid yetfluid earth; solid in its astronomical relations, liquid orplastic for the purposes of volcanic action and superficial movements.

(3) The plastic sub-crust is not in a state of dry igneousfusion, but in that condition of aqueo-igneous or hydrothermicfusion which arises from the action of heat on moist substances,and which may either be regarded as a fusion or as a speciesof solution at a very high temperature. This we learn fromthe phenomena of volcanic action, and from the compositionof the volcanic and plutonic rocks, as well as from suchchemical experiments as those of Daubrée, and of Tilden, andShenstone.[25] It follows that water or steam, as well as rockymatter, may be ejected from the under-crust.

(4) The interior sub-crust is not perfectly homogeneous, butmay be roughly divided into two layers or magmas, as theyhave been called; an upper, highly silicious or acidic, of lowspecific gravity and light-coloured, and corresponding to suchkinds of plutonic and volcanic rocks as granite and trachyte;and a lower, less silicious or more basic, more dense, andmore highly charged with iron, and corresponding to suchigneous rocks as the dolerites, basalts, and kindred lavas. Itis interesting here to note that this conclusion, elaborated byDurocher and Von Waltershausen, and usually connected withtheir names, appears to have been first announced by JohnPhillips, in his "Geological Manual," and as a mere common sensededuction from the observed phenomena of volcanicaction and the probable results of the gradual cooling of theearth. It receives striking confirmation from the observedsuccession of acidic and basic volcanic rocks of all geologicalperiods and in all localities. It would even seem, from recentspectroscopic investigations of Lockyer, that there is evidenceof a similar succession of magmas in the heavenly bodies, andthe discovery by Nordenskiöld of native iron in Greenland« 64 »basalts, affords a probability that the inner magma is in partmetallic, and possibly, that vast masses of unoxidised metalsexist in the central portion of the earth.

(5) Where rents or fissures form in the upper crust, thematerial of the lower crust is forced upward by the pressureof the less supported portions of the former, giving rise tovolcanic phenomena either of an explosive or quiet character,as may be determined by contact with water. The underlyingmaterial may also be carried to the surface by the agency ofheated water, producing those quiet discharges which Hunthas named crenitic. It is to be observed here that explosivevolcanic phenomena, and the formation of cones, are, asPrestwich has well remarked, characteristic of an old andthickened crust; quiet ejection from fissures and hydro-thermalaction may have been more common in earlier periodsand with a thinner over-crust This is an important considerationwith reference to those earlier ages referred to inchapter second.

(6) The contraction of the earth's interior by cooling andby the emission of material from below the over-crust, hascaused this crust to press downward, and therefore laterally,and so to effect great bends, folds, and plications; and these,modified subsequently by surface denudation, and the pilingof sediments on portions of the crust, constitute mountainchains and continental plateaus. As Hall long ago pointedout,[26] such lines of folding have been produced more especiallywhere thick sediments had been laid down on the sea-bottom,and where, in consequence, internal expansion of the crust hadoccurred from heating below. Thus we have here anotherapparent paradox, namely, that the elevations of the earth'scrust occur in the places where the greatest burden of detritus« 65 »has been laid down upon it, and where, consequently, thecrust has been softened and depressed. We must beware, inthis connection, of exaggerated notions of the extent of contractionand of crumpling required to form mountains. Bonneyhas well shown, in lectures delivered at the London Institution,that an amount of contraction, almost inappreciable incomparison with the diameter of the earth, would be sufficient;and that, as the greatest mountain chains are less than 1/600thof the earth's radius in height, they would, on an artificialglobe a foot in diameter, be no more important than the slightinequalities that might result from the paper gores overlappingeach other at the edges. This thinness of the crushed crustagrees with the deductions of physical science as to theshallowness of the superficial layer of compression in a coolingglobe. It is perhaps not more than five miles in thickness.A singular proof of this is seen by the extension of straightcracks filled with volcanic rock in the Laurentian districts ofCanada.[27] The beds of gneiss and associated rocks are foldedand crumpled in a most complex manner, yet they are crossedby these faults, as a crack in a board may tear a sheet ofpaper or a thin veneer glued on it. We thus see that thecrumpled Laurentian crust was very thin, while the uncrushedsub-crust determined the line of fracture.

(7) The crushing and sliding of the over-crust implied inthese movements raise some serious questions of a physicalcharacter. One of these relates to the rapidity or slownessof such movements, and the consequent degree of intensityof the heat developed, as a possible cause of metamorphismof rocks. Another has reference to the possibility of changesin the equilibrium of the earth itself, as resulting from localcollapse and ridging. These questions in connection with the« 66 »present dissociation of the axis of rotation from the magneticpoles, and with changes of climate, have attracted some attention,[28]and probably deserve further consideration on the partof physicists. In so far as geological evidence is concerned,it would seem that the general association of crumpling withmetamorphism indicates a certain rapidity in the process ofmountain-making, and consequent development of heat; andthe arrangement of the older rocks around the Arctic basin forbidsus from assuming any extensive movement of the axis ofrotation, though it does not exclude changes to a limited extent.

(8) It appears from the above that mountains and continentalelevations may be of three kinds, (a) They may consistof material thrown out of volcanic rents, like earth out ofa mole burrow. Mountains like Vesuvius and Ætna are ofthis kind. (b) They may be parts of wide ridges or chainsvariously cut and modified by rains and rivers. The Lebanonand the Catskill Mountains are cases in point, (c) They maybe lines of crumpling by lateral pressure. The greatest mountains,like the Cordillera, the Alps, and the Appalachians are ofthis kind, and such mountains may represent lateral pressureoccurring at various times, and whose results have been greatlymodified subsequently.

I wish to formulate these principles as distinctly as possible,and as the result of all the long series of observations, calculations,and discussions since the time of Werner and Hutton,and in which a vast number of able physicists and naturalistshave borne a part, because they may be considered as certaindeductions from our actual knowledge, and because they lieat the foundation of a rational physical geology.

We may roughly popularise these deductions by comparingthe earth to a drupe or stone-fruit, such as a plum or peach« 67 »somewhat dried up. It has a large and intensely hard stoneand kernel, a thin pulp made up of two layers, an inner, moredense and dark-coloured, and an outer, less dense and lighter-coloured.These constitute the under-crust. On the outsideit has a thin membrane or over-crust. In the process of dryingit has slightly shrunk, so as to produce ridges and hollows ofthe outer crust, and this outer crust has cracked in some places,allowing portions of the pulp to ooze out—in some of them itslower dark substance, in others, its upper and lighter material.The analogy extends no farther, for there is nothing in ourwithered fruit to represent the oceans occupying the lower partsof the surface, or the deposits which they have laid down.

Here a most important feature demands attention. Therain, the streams, and the sea are constantly cutting down theland and depositing it in the bed of the waters. Thus weightis taken from the land, and added to the sea bed. Geologicalfacts, such as the great thickness of the coal measures, in whichwe find thousands of feet of sediment, all of which must havebeen deposited in shallow water, and the accumulation ofhundreds of feet of superficial material in deltas at the mouthof great rivers, show that the crust of the earth is so mobile asto yield downward to every pressure, however slight.[29] It maydo this slowly and gradually, or by jumps from time to time;and this yielding necessarily tends to squeeze up the edges ofthe depressed portions into ridges, and to cause lateral movementand ejection of volcanic matter at intervals.

Keeping in view these general conclusions, let us now turnto their bearing on the origin and history of the North Atlantic.

Though the Atlantic is a deep ocean, its basin does notconstitute so much a depression of the crust of the earth asa flattening of it, and this, as recent soundings have shown,with a slight ridge or elevation along its middle, and banks orterraces fringing the edges, so that its form is not so much« 68 »that of a basin as that of a shallow elongated plate with itsmiddle a little raised. Its true margins are composed ofportions of the over-crust folded, overlapped and crushed, asif by lateral pressure emanating from the sea itself. We cannot,for example, look at a geological map of America withoutperceiving that the Appalachian ridges, which intervene betweenthe Atlantic and the St. Lawrence valley, have beendriven bodily back by a force acting from the east, and thatthey have resisted this pressure only where, as in the Gulf ofSt. Lawrence and the Catskill region of New York, they havebeen protected by outlying masses of very old rocks, as, forexample, by that of the island of Newfoundland and that ofthe Adirondack Mountains. The admirable work begun bymy friend and fellow-student, Professor James Nicol, followedup by Professor Lapworth, and now, after long controversy,fully confirmed by the recent observations of the GeologicalSurvey of Scotland, has shown the most intense action of thesame kind on the east side of the ocean in the Scottish highlands;and the more widely distributed Eozoic and other oldrocks of Scandinavia may be appealed to in further evidenceof this.[30]

If we now inquire as to the cause of the Atlantic depression,we must go back to the time when the areas occupiedby the Atlantic and its bounding coasts were parts of theshoreless sea in which the earliest gneisses or stratified granitesof the Laurentian age were being laid down in vastly extendedbeds. These ancient crystalline rocks have been the subjectof much discussion and controversy, to which reference hasbeen made in a previous chapter.

It will be observed, in regard to these theories, that they do« 69 »not suppose that the old gneiss is an ordinary sediment, butthat all regard it as formed in exceptional circumstances, thesecircumstances being the absence of land and of subaërialdecay of rock, and the presence wholly or principally of thematerial of the upper surface of the recently hardened crust.This being granted, the question arises, Ought we not to combinethe several theories as to the origin of gneiss, and tobelieve that the cooling crust has hardened in successive layersfrom without inward; that at the same time fissures werelocally discharging igneous matter to the surface; that matterheld in suspension in the ocean and matter held in solution byheated waters rising from beneath the outer crust were minglingtheir materials in the deposits of the primitive ocean?[31]It would seem that the combination of all these agencies maysafely be evoked as causes of the pre-Atlantic deposits. Thisis the eclectic position I have maintained in a previous chapter,and which I hold to be in every way the most probable.

Let us suppose, then, the floor of old ocean covered witha flat pavement of gneiss, or of that material which is nowgneiss, the next question is, How and when did this originalbed become converted into sea and land? Here we have somethings certain, others most debatable. That the coolingmass, especially if it was sending out volumes of softenedrocky material, either in the form of volcanic ejections or inthat of matter dissolved in heated water, and piling this on thesurface, must soon become too small for its shell, is apparent;but when and where would the collapse, crushing and wrinklinginevitable from this cause begin? The date is indicatedby the lines of old mountain chains which traverse theLaurentian districts; but the reason why is less apparent.The more or less unequal cooling, hardening and conductivepower of the outer crust we may readily assume. The driftageunequally of water-borne detritus to the south-west by the« 70 »bottom currents of the sea is another cause, and, as we shallsoon see, most effective. Still another is the greater coolingand hardening of the crust in the polar regions, and the tendencyto collapse of the equatorial protuberance from theslackening of the earth's rotation. Besides these, the internaltides of the earth's substance at the times of solstice wouldexert an oblique pulling force on the crust, which might tendto crack it along diagonal lines. From whichever of thesecauses, or the combination of the whole, we know that, withinthe Laurentian time, folded portions of the earth's crust beganto rise above the general surface, in broad belts running fromnorth-east to south-west, and from north-west to south-east,where the older mountains of Eastern America and WesternEurope now stand, and that the subsidence of the oceanicareas, allowed by this crumpling of the crust, permitted otherareas on both sides of the Atlantic to form limited table-lands.This was the commencement of a process repeated again andagain in subsequent times, and which began in the middleLaurentian, when for the first time we find beds of quartzite,limestone, and iron ore, and graphite beds, indicating that therewas already land and water, and that the sea, and perhaps theland, swarmed with forms of animal and plant life, unknown,for the most part, now. Independently of the questions as tothe animal nature of Eozoon, I hold that we know, as certainlyas we can know anything inferentially, the existence of theseprimitive forms of life. If I were to conjecture what werethese early forms of plant and animal life, still unknown to usby actual specimens, I would suppose that, just as in the Palæozoic,the acrogens culminated in gigantic and complex foresttrees, so in the Laurentian, the algæ, the lichens, and themosses grew to dimensions and assumed complexity of structureunexampled in later times, and that, in the sea, thehumbler forms of Protozoa and Sea Mosses were the dominanttypes, but in gigantic and complex forms. The land of this« 71 »period was probably limited, for the most part, to high latitudes,and its aspect, though more rugged and abrupt, andof greater elevation, must have been of that character whichwe still see in the Laurentian hills. The distribution of thisancient land is indicated by the long lines of old Laurentianrock extending from the Labrador coast and the north shoreof the St. Lawrence, and along the eastern slopes of theAppalachians in America, and the like rocks of the Hebrides,the Western Highlands, and the Scandinavian mountains. Asmall but interesting remnant is that in the Malvern Hills, sowell described by Holl. It will be well to note here, and tofix on our minds, that these ancient ridges of Eastern Americaand Western Europe have been greatly denuded and wastedsince Laurentian times, and that it is along their eastern sidesthat the greatest sedimentary accumulations have been deposited.

From this time dates the introduction of that dominance ofexisting causes which forms the basis of uniformitarianism ingeology, and which had to go on with various and great modificationsof detail, through the successive stages of the geologicalhistory, till the land and water of the northern hemisphereattained to their present complex structure.

So soon as we have a circumpolar belt or patches of Eozoic [32]land and ridges running southward from it, we enter on newand more complicated methods of growth of the continentsand seas. Portions of the oldest crystalline rocks, raised outof the protecting water, were now eroded by atmosphericagents, and especially by the carbonic acid, then existing in theatmosphere perhaps more abundantly than at present, underwhose influence the hardest of the gneissic rocks graduallydecay. The arctic lands were subjected, in addition, to thepowerful mechanical force of frost and thaw. Thus everyshower of rain and every swollen stream would carry into the« 72 »sea the products of the waste of land, sorting them into fineclays and coarser sands; and the cold currents which cling tothe ocean bottom, now determined in their courses, not merelyby the earth's rotation, but also by the lines of folding on bothsides of the Atlantic, would carry south-westward, and pile upin marginal banks of great thickness thedébris produced fromthe rapid waste of the land already existing in the Arcticregions. The Atlantic, opening widely to the north, andhaving large rivers pouring into it, was, especially, the oceancharacterised, as time advanced, by the prevalence of thesephenomena. Thus, throughout the geological history it hashappened that, while the middle of the Atlantic has receivedmerely organic deposits of shells of foraminifera and similarorganisms, and this probably only to a small amount, itsmargins have had piled upon them beds of detritus of immensethickness. Professor Hall, of Albany, was the firstgeologist who pointed out the vast cosmic importance of thesedeposits, and that the mountains of both sides of the Atlanticowe their origin to these great lines of deposition, along withthe fact, afterwards more fully insisted on by Rogers, that theportions of the crust which received these masses ofdébrisbecame thereby weighted down and softened, and were moreliable than other parts to lateral crushing.

Thus, in the later Eozoic and early Palæozoic times, whichsucceeded the first foldings of the oldest Laurentian, greatridges were thrown up, along the edges of which were beds oflimestone, and on their summits and sides, thick masses ofejected igneous rocks. In the bed of the central Atlanticthere are no such accumulations. It must have been a flat, orslightly ridged, plate of the ancient gneiss, hard and resisting,though perhaps with a few cracks, through which igneous matterwelled up, as in Iceland and the Azores in more moderntimes. In this condition of things we have causes tending toperpetuate and extend the distinctions of ocean and continent,« 73 »mountain and plain, already begun; and of these we may moreespecially note the continued subsidence of the areas ofgreatest marine deposition. This has long attracted attention,and affords very convincing evidence of the connection of sedimentarydeposit as a cause with the subsidence of the crust.[33]

We are indebted to a French physicist, M. Faye, for an importantsuggestion on this subject. It is that the sediment accumulatedalong the shores of the ocean presented an obstacleto radiation, and consequently to cooling of the crust, whilethe ocean floor, unprotected and unweighted, and constantlybathed with currents of cold water having great power of convectionof heat, would be more rapidly cooled, and so wouldbecome thicker and stronger. This suggestion is complementaryto the theory of Professor Hall, that the areas of greatestdeposit on the margins of the ocean are necessarily those ofgreatest folding and consequent elevation. We have thus ahard, thick, resisting ocean bottom, which, as it settles down towardthe interior, under the influence of gravity, squeezesupwards and folds and plicates all the soft sediments depositedon its edges. The Atlantic area is almost an unbroken cakeof this kind. The Pacific area has cracked in many places,allowing the interior fluid matter to exude in volcanic ejections.

It may be said that all this supposes a permanent continuanceof the ocean basins, whereas many geologists postulate amid-Atlantic continent to give the thick masses of detritusfound in the older formations both in Eastern America andWestern Europe, and which thin off in proceeding into the« 74 »interior of both continents. I prefer, as already stated, toconsider these belts of sediment as the deposits of northerncurrents, and derived from arctic land, and that, like thegreat banks off the American coast at the present day, whichare being built up by the present arctic current, they had littleto do with any direct drainage from the adjacent shore. Weneed not deny, however, that such ridges of land as existedalong the Atlantic margins were contributing their quota ofriver-borne material, just as on a still greater scale the Amazonand Mississippi are doing now, and this especially on the sidestoward the present continental plateaus, though the greaterpart must have been derived from the wide tracts of Laurentianland within the Arctic Circle, or near to it. It is furtherobvious that the ordinary reasoning respecting the necessity ofcontinental areas in the present ocean basins would actuallyoblige us to suppose that the whole of the oceans and continentshad repeatedly changed places. This consideration opposesenormous physical difficulties to any theory of alternationsof the oceanic and continental areas, except locally at theirmargins.

But the permanence of the Atlantic depression does not excludethe idea of successive submergences of the continentalplateaus and marginal slopes, alternating with periods of elevation,when the ocean retreated from the continents and contractedits limits. In this respect the Atlantic of to-day ismuch smaller than it was in those times when it spread widelyover the continental plains and slopes, and much larger than ithas been in times of continental elevation. This leads us tothe further consideration that, while the ocean beds have beensinking, other areas have been better supported, and constitutethe continental plateaus; and that it has been at or near thejunctions of these sinking and rising areas that the thickest depositsof detritus, the most extensive foldings, and the greatestejections of volcanic matter have occurred. There has thus« 75 »been a permanence of the position of the continents and oceansthroughout geological time, but with many oscillations of theseareas, producing submergences and emergences of the land.In this way we can reconcile the vast vicissitudes of the continentalareas in different geological periods with that continuityof development from north to south, and from the interiorsto the margins, which is so marked a feature. We have, forthis reason, to formulate another apparent geological paradox,namely, that while, in one sense, the continental and oceanicareas are permanent, in another, they have been in continualmovement. Nor does this view exclude extension of the continentalborders or of chains of islands beyond their presentlimits, at certain periods; and indeed, the general principlealready stated, that subsidence of the ocean bed has producedelevation of the land, implies in earlier periods a shallowerocean and many possibilities as to volcanic islands, and lowcontinental margins creeping out into the sea; while it is alsoto be noted that there are, as already stated, bordering shelves,constituting shallows in the ocean, which at certain periodshave emerged as land.

We are thus compelled, as already stated, to believe in thecontemporaneous existence in all geological periods, exceptperhaps the earliest of them, of the three distinct conditions ofareas on the surface of the earth, defined in chapter secondoceanic areas of deep sea, continental plateaus and marginalshelves, and lines of plication and folding.

In the successive geological periods the continental plateaus,when submerged, owing to their vast extent of warm andshallow sea, have been the great theatres of the development ofmarine life and of the deposition of organic limestones, andwhen elevated, they have furnished the abodes of the noblestland faunas and floras. The mountain belts, especially inthe north, have been the refuge and stronghold of land lifein periods of submergence; and the deep ocean basins have« 76 »been the perennial abodes of pelagic and abyssal creatures andthe refuge of multitudes of other marine animals and plantsin times of continental elevation. These general facts are fullof importance with reference to the question of the successionof formations and of life in the geological history of the earth.

So much space has been occupied with these general views,that it would be impossible to trace the history of the Atlanticin detail through the ages of the Palæozoic, Mesozoic, andTertiary. We may, however, shortly glance at the changesof the three kinds of surface already referred to. The bed ofthe ocean seems to have remained, on the whole, abyssal; butthere were probably periods when those shallow reaches of theAtlantic which stretch across its most northern portion, andpartly separate it from the Arctic basin, presented connectingcoasts or continuous chains of islands sufficient to permitanimals and plants to pass over.[34] At certain periods also therewere, not unlikely, groups of volcanic islands, like the Azores,in the temperate or tropical Atlantic. More especially mightthis be the case in that early time when it was more like thepresent Pacific; and the line of the great volcanic belt of theMediterranean, the mid-Atlantic banks, the Azores and theWest India Islands point to the possibility of such partial connections.These were stepping stones, so to speak, over whichland organisms might cross, and some of these may be connectedwith the fabulous or pre-historic Atlantis.

In the Palæozoic period, the distinctions already referred to,into continental plateaus, mountain ridges, and ocean depths,were first developed, and we find, already, great masses of sedimentaccumulating on the seaward sides of the old Laurentianridges, and internal deposits thinning away from these ridgesover the submerged continental areas, and presenting dissimilar« 77 »conditions of sedimentation. It would seem also that, as Hickshas argued for Europe, and Logan and Hall for America, thisCambrian age was one of slow subsidence of the land previouslyelevated, accompanied with or caused by thick deposits ofdetritus along the borders of the subsiding shore, which wasprobably covered with the decomposing rock arising from longages of subaërial waste.

In the coal formation age its characteristic swampy flatsstretched in some places far into the shallower parts of theocean.[35] In the Permian, the great plicated mountain marginswere fully developed on both sides of the Atlantic. In theJurassic, the American continent probably extended farther tothe sea than at present. In the Wealden age there was muchland to the west and north of Great Britain, and ProfessorBonney has directed attention to the evidence of the existenceof this land as far back as the Trias, while Mr. Starkie Gardinerhas insisted on connecting links to the southward, as evidencedby fossil plants. So late as the Post-glacial, or early humanperiod, large tracts, now submerged, formed portions of thecontinents. On the other hand, the interior plains of Americaand Europe were often submerged. Such submergences areindicated by the great limestones of the Palæozoic, by the chalkand its representative beds in the Cretaceous, by the Nummuliticformation in the Eocene, and lastly, by the great Pleistocenesubmergence, one of the most remarkable of all, onein which nearly the whole northern hemisphere participated,and which was probably separated from the present time byonly a few thousands of years.[36] These submergences and elevations« 78 »were not always alike on the two sides of the Atlantic.The Salina period of the Silurian, for example, and the Jurassic,show continental elevation in America not shared by Europe.The great subsidences of the Cretaceous and the Eocene wereproportionally deeper and wider on the eastern continent, andthis and the direction of the land being from north to south,cause more ancient forms of life to survive in America. Theseelevations and submergences of the plateaus alternated withthe periods of mountain-making plication, which was going onat intervals, at the close of the Eozoic, at the beginning of theCambrian, at the close of the Siluro-Cambrian, in the Permian,and in Europe and Western America in the Tertiary. Theseries of changes, however, affecting all these areas was of ahighly complex character in detail.[37]

We may also note a fact which I have long ago insisted on,[38]the regular pulsation of the continental areas, giving us alternationsin each great system of deep-sea and shallow-waterbeds, so that the successive groups of formations may be dividedinto triplets of shallow-water, deep-water, and shallow-waterstrata, alternating in each period. This law of successionapplies more particularly to the formations of the continentalplateaus, rather than to those of the ocean margins, and itshows that, intervening between the great movements of plicationthere were subsidences of those plateaus, or elevations ofthe sea bottom, which allowed the waters to spread themselvesover all the inland spaces between the great folded mountainranges of the Atlantic borders.

In referring to the ocean basins we should bear in mindthat there are three of these in the northern hemisphere theArctic, the Pacific, and the Atlantic. De Ranee has ably« 79 »summed up the known facts as to Arctic geology in a series ofarticles inNature, from which it appears that this area presentsfrom without inwards a succession of older and newerformations from the Eozoic to the Tertiary, and that its extentmust have been greater in former periods than at present,while it must have enjoyed a comparatively warm climate fromthe Cambrian to the Pleistocene period. The relations of itsdeposits and fossils are closer with those of the Atlantic thanwith those of the Pacific, as might be anticipated from its wideropening into the former. Blandford has recently remarked onthe correspondence of the marginal deposits around the Pacificand Indian oceans,[39] and Dr. Dawson informs me that this isequally marked in comparison with the west coast of America,but these marginal areas have not yet gained much on theocean. In the North Atlantic, on the other hand, there is awide belt of comparatively modern rocks on both sides, moreespecially toward the south and on the American side; butwhile there appears to be a perfect correspondence on bothsides of the Atlantic, and around the Pacific respectively, thereseems to be less parallelism between the deposits and forms oflife of the two oceans, as compared with each other, and lesscorrespondence in forms of life, especially in modern times.Still, in the earlier geological ages, as might have been anticipatedfrom the imperfect development of the continents, thesame forms of life characterise the whole ocean from Australiato Arctic America, and indicate a grand unity of Pacific and« 80 »Atlantic life not equalled in later times,[40] and which speaks oftrue contemporaneity rather than of what has been termedhomotaxis or mere likeness of orders.

We may pause here for a moment to notice some of theeffects of Atlantic growth on modern geography. It hasgiven us rugged and broken shores, composed of old rocksin the north, and newer formations and softer features towardthe south. It has given us marginal mountain ridgesand internal plateaus on both sides of the sea. It has producedcertain curious and by no means accidental correspondencesof the eastern and western sides. Thus the solidbasis on which the British Islands stand may be comparedwith Newfoundland and Labrador, the English Channel withthe Gulf of St. Lawrence, the Bay of Biscay with the Bay ofMaine, Spain with the projection of the American land atCape Hatteras, the Mediterranean with the Gulf of Mexico.The special conditions of deposition and plication necessaryto these results, and their bearing on the character and productionsof the Atlantic basin, would require a volume fortheir detailed elucidation.

Thus far our discussion has been limited almost entirely tophysical causes and effects. If we now turn to the lifehistory of the Atlantic, we are met at the threshold with thequestion of climate, not as a thing fixed and immutable, butas changing from age to age in harmony with geographicalmutations, and producing long cosmic summers and winters ofalternate warmth and refrigeration.

We can scarcely doubt that the close connection of theAtlantic and Arctic oceans is one factor in those remarkablevicissitudes of climate experienced by the former, and inwhich the Pacific area has also shared in connection with the« 81 »Antarctic Sea. No geological facts are indeed at first sightmore strange and inexplicable than the changes of climate inthe Atlantic area, even in comparatively modern periods. Weknow that in the early Tertiary temperate conditions reigned asfar north as the middle of Greenland, and that in the Pleistocenethe Arctic cold advanced until an almost perennial winterprevailed half way to the equator. It is no wonder that nearlyevery cause available in the heavens and the earth has beeninvoked to account for these astounding facts. I shall, I trust,be excused if, neglecting most of these theoretical views, Iventure to invite attention, in connection with this question,chiefly to the old Lyellian doctrine of the modification ofclimate by geographical changes. Let us, at least, considerhow much these are able to account for.

The ocean is a great equalizer of extremes of temperature.It does this by its great capacity for heat, and by its coolingand heating power when passing from the solid into theliquid and gaseous states, and the reverse. It also acts by itsmobility, its currents serving to convey heat to great distances,or to cool the air by the movement of cold icy waters. Theland, on the other hand, cools or warms rapidly, and cantransmit its influence to a distance only by the winds, and theinfluence so transmitted is rather in the nature of a disturbingthan of an equalizing cause. It follows that any change in thedistribution of land and water must affect climate, more especiallyif it changes the character or course of the ocean currents.

Turning to the Atlantic, in this connection we perceive thatits present condition is peculiar and exceptional. On the onehand it is widely open to the Arctic Sea and the influence ofits cold currents, and on the other it is supplied with a heatingapparatus of enormous power to give a special elevation oftemperature, more particularly to its eastern coasts. The greatequatorial current running across from Africa is on itsnorthern side embayed in the Gulf of Mexico, as in a great« 82 »cauldron, and pouring through the mouth of this in theBahama channel, forms the gulf stream, which, widening out likea fan, forms a vast expanse of warm water, from which the prevailingwesterly winds of the North Atlantic waft a constantsupply of heated moist air to the western coasts of Europe,giving them a much more warm and uniform climate than thatwhich prevails in similar latitudes in Eastern America, wherethe cold Arctic currents hug the shore, and bring down ice fromBaffin's Bay. Now all this might be differently arranged. Weshall find that there were times, when the Isthmus of Panamabeing broken through, there was no Gulf Stream, and Norwayand England were reduced to the conditions of Greenlandand Labrador, and when refrigeration was still further increasedby subsidence of northern lands affording freer sweep to theArctic currents. On the other hand, there were times whenthe Gulf of Mexico extended much farther north than atpresent, and formed an additional surface of warm water toheat all the interior of America, as well as the Atlantic. Geographicalchanges of these kinds, have probably given us theglacial period in very recent times, and at an earlier era thosewarm climates which permitted temperate vegetation to flourishas far north as Greenland. These are, however, great topics,which must form the subject of other chapters.

I am old enough to remember the sensation caused by thedelightful revelations of Edward Forbes respecting the zonesof animal life in the sea, and the vast insight which they gaveinto the significance of the work on minute organisms previouslydone by Ehrenberg, Lonsdale and Williamson, andinto the meaning of fossil remains. A little later the soundingsfor the Atlantic cable revealed the chalky foraminiferalooze of the abyssal ocean. Still more recently, the wealth offacts disclosed by theChallenger voyage, which naturalistshave scarcely yet had time to digest, have opened up to usnew worlds of deep-sea life.

The bed of the deep Atlantic is covered, for the most part,by a mud or ooze, largely made up of thedébris of foraminiferaand other minute organisms mixed with fine clay. In theNorth Atlantic the Norwegian naturalists call this the Biloculinamud. Farther south, theChallenger naturalists speak of it asGlobigerina ooze. In point of fact it contains different speciesof foraminiferal shells, Globigerina and Orbulina being in somelocalities dominant, and in others, other species; and thesechanges are more apparent in the shallower portions of theocean.

On the other hand, there are means for disseminatingcoarse material over parts of the ocean beds. There are, inthe line of the Arctic current, on the American coast, greatsand banks, and off the coast of Norway, sand constitutes aconsiderable part of the bottom material. Soundings anddredgings off Great Britain, and also off the American coast,have shown that fragments of stone referable to Arctic landsare abundantly strewn over the bottom, along certain lines,and the Antarctic continent, otherwise almost unknown, makesits presence felt to the dredge by the abundant masses ofcrystalline rock drifted far from it to the north. These are notaltogether new discoveries. I had inferred, many years ago,from stones taken up by the hooks of fishermen on the banksof Newfoundland, that rocky material from the north is droppedon these banks by the heavy ice which drifts over them everyspring, that these are glaciated, and that after they fall to thebottom sand is drifted over them with sufficient velocity topolish the stones, and to erode the shelly coverings of Arcticanimals attached to them.[41] If, then, the Atlantic basin wereupheaved into land, we should see beds of sand, gravel andboulders with clay flats and layers of marl and limestone.According to theChallenger reports, in the Antarctic seas S.of 64 there is blue mud, with fragments of rock, in depths« 84 »of 1,200 to 2,000 fathoms. The stones, some of them glaciated,were granite, diorite, amphibolite, mica schist, gneiss andquartzite. This deposit ceases and gives place to Globigerinaooze and red clay at 46° to 47° S., but even farther north thereis sometimes as much as 49 per cent, of crystalline sand. Inthe Labrador current a block of syenite, weighing 400 lbs., wastaken up from 1,340 fathoms, and in the Arctic current, 100miles from land, was a stony deposit, some stones beingglaciated. Among these were smoky quartz, quartzite, limestone,dolomite, mica schist, and serpentine; also particles ofmonoclinic and triclinic felspar, hornblende, augite, magnetite,mica and glauconite, the latter, no doubt, formed in the seabottom, the others drifted from Eozoic and Palæozoic formationsto the north.[42]

A remarkable fact in this connection is that the great depthsof the sea are as impassable to the majority of marine animalsas the land itself. According to Murray, while twelve of theChallenger's dredgings, taken in depths greater than 2,000fathoms, gave 92 species, mostly new to science, a similarnumber of dredgings in shallower water near the land, give noless than 1,000 species. Hence arises another apparent paradoxrelating to the distribution of organic beings. While atfirst sight it might seem that the chances of wide distributionare exceptionally great for marine species, this is not so. Exceptin the case of those which enjoy a period of free locomotionwhen young, or are floating and pelagic, the deep oceansets bounds to their migrations. On the other hand, thespores of cryptogamic plants may be carried for vast distancesby the wind, and the growth of volcanic islands may effectconnections which, though only temporary, may afford opportunityfor land animals and plants to pass over.

With reference to the transmission of living beings acrossthe Atlantic, we have before us the remarkable fact that from« 85 »the Cambrian age onwards there were, on the two sides of theocean, many species of invertebrate animals which were eitheridentical or so closely allied as to be possibly varietal forms, indicatingprobably the shallowness of the ocean in these periods.In like manner, the early plants of the Upper Silurian, Devonian,and Carboniferous present many identical species; butthis identity is less marked in more modern times. Even inthe latter, however, there are remarkable connections betweenthe floras of oceanic islands and the continents. Thus theBermudas, altogether recent islands, have been stocked bythe agency chiefly of the ocean currents and of birds, withnearly 150 species of continental plants; and the facts collectedby Helmsley as to the present facilities of transmission,along with the evidence afforded by older oceanic islandswhich have been receiving animal and vegetable colonistsfor longer periods, go far to show that, time being given,the sea actually affords facilities for the migration of the inhabitantsof the land, comparable with those of continuouscontinents.

In so far as plants are concerned, it is to be observed thatthe early forests were largely composed of cryptogamousplants, and the spores of these in modern times have provedcapable of transmission from great distances. In consideringthis, we cannot fail to conclude, that the union of simple cryptogamousfructification with arboreal stems of high complexity,so well illustrated by Dr. Williamson, had a direct relation tothe necessity for a rapid and wide distribution of these ancienttrees. It seems also certain that some spores, as, for example,those of the Rhizocarps,[43] a type of vegetation abundant inthe Palæozoic, and certain kinds of seeds, as those namedÆthoetesta andPachytheca, were fitted for flotation. Further,the periods of Arctic warmth permitted the passage around« 86 »the northern belt of many temperate species of plants, just asnow happens with the Arctic flora; and when these were displacedby colder periods, they marched southward along bothsides of the sea on the mountain chains.

The same remark applies to northern forms of marine invertebrates,which are much more widely distributed in longitudethan those farther south. The late Mr. Gywn Jeffreys, in oneof his latest communications on this subject, stated that 54per cent, of the shallow-water mollusks of New England andCanada are also European, and of the deep-sea forms, 30 outof 35; these last, of course, enjoying greater facilities formigration than those which have to travel slowly along theshallows of the coast in order to cross the ocean and settlethemselves on both sides. Many of these animals, like thecommon mussel and sand clam, are old settlers which cameover in the Pleistocene period, or even earlier. Others, like thecommon periwinkle, seem to have been slowly extending themselvesin modern times, perhaps even by the agency of man.The older immigrants may possibly have taken advantage oflines of coast now submerged, or of warm periods, when theycould creep round the Arctic shores. Mr. Herbert Carpenterand other naturalists employed on theChallenger collectionshave made similar statements respecting other marine invertebrates,as, for instance, the Echinoderms, of which the deep-seacrinoids present many common species, and my own collectionsprove that many of the shallow-water forms are common.Dall and Whiteaves [44] have shown that some mollusks andEchinoderms are common even to the Atlantic and Pacificcoasts of North America; a remarkable fact, testifying at onceto the fixity of these species and to the manner in which theyhave been able to take advantage of geographical changes.Some of the species of whelks common to the Gulf of St.Lawrence and the Pacific are animals which have no special« 87 »locomotive powers, even when young, but they are northernforms not proceeding far south, so that they may have passedthrough the Arctic seas. In this connection it is well to remarkthat many species of animals have powers of locomotionin youth which they lose when adult, and that others may havespecial means of transit. I once found at Gaspé a specimenof the Pacific species of Coronula, or whale-barnacle, theC.reginæ of Darwin, attached to a whale taken in the Gulf of St.Lawrence, and which had possibly succeeded in making thatpassage around the north of America which so many navigatorshave essayed in vain.[45]

But it is to be remarked that while many plants and marineinvertebrates are common to the two sides of the Atlantic, itis different with land animals, and especially vertebrates. I donot know that any palæozoic insects or land snails or millipedesof Europe and America are specifically identical, and of thenumerous species of batrachians of the Carboniferous andreptiles of the Mesozoic, all seem to be distinct on the twosides. The same appears to be the case with the Tertiarymammals, until in the later stages of that great period we findsuch genera as the horse, the camel, and the elephant appearingon the two sides of the Atlantic; but even then the speciesseem different, except in the case of a few northern forms.

Some of the longer-lived mollusks of the Atlantic furnishsuggestions which remarkably illustrate the biological aspect ofthese questions. Our familiar friend the oyster is one of these.The first-known oysters appear in the Carboniferous in Belgiumand in the United States of America. In the Carboniferousand Permian they are few and small, and they do not culminatetill the Cretaceous, in which there are no less than ninety-oneso-called species in America alone; but some of the largestknown species are found in the Eocene. The oyster, though« 88 »an inhabitant of shallow water, and very limitedly locomotivewhen young, has survived all the changes since the Carboniferousage, and has spread itself over the whole northernhemisphere,[46] though a warm water rather than Arctic type.

I have collected fossil oysters in the Cretaceous clays of thecoulées of Western Canada, in the Lias shales of England, inthe Eocene and the Cretaceous beds of the Alps, of Egypt, ofthe Red Sea coast, of Judea, and the heights of Lebanon.Everywhere and in all formations they present forms which areso variable and yet so similar that one might suppose all theso-called species to be mere varieties. Did the oyster originateseparately on the two sides of the Atlantic, or did it cross overso promptly that its appearance seems to be identical on thetwo sides? Are all the oysters of a common ancestry, or didthe causes, whatever they were, which introduced the oyster inthe Carboniferous act over again in later periods? Who cantell? This is one of the cases where causation and development—thetwo scientific factors which constitute the basis ofwhat is called evolution—cannot easily be isolated. I wouldrecommend to those biologists who discuss these questions todevote themselves to the oyster. This familiar mollusk hassuccessfully, pursued its course, and has overcome all its enemies,from the flat-toothed selachians of the Carboniferous to theoyster dredges of the present day, has varied almost indefinitely,and yet has continued to be an oyster, unless, indeed, it may atcertain portions of its career have temporarily assumed theguise of a Gryphæa or an Exogyra. The history of such ananimal deserves to be traced with care, and much curious informationrespecting it will be found in the report which I havecited in the note.

But in these respects the oyster, is merely an example ofmany forms. Similar considerations apply to all those Plioceneand Pleistocene mollusks which are found in the raised sea« 89 »bottoms of Norway and Scotland, on the top of Moel Tryfaen,in Wales, and at similar great heights on the hills of America,many of which can be traced back to early Tertiary times, andcan be found to have extended themselves over all the seas ofthe northern hemisphere. They apply in like manner to theferns, the conifers, and the broad-leaved trees, many of whichwe can now trace without specific change to the Eocene andCretaceous. They all show that the forms of living things aremore stable than the lands and seas in which they live. If wewere to adopt some of the modern ideas of evolution, we mightcut the Gordian knot by supposing that, as like causes producelike effects, these types of life have originated more than oncein geological time, and need not be genetically connected witheach other. But while evolutionists repudiate such an applicationof their doctrine, however natural and rational, it wouldseem that nature still more strongly repudiates it, and will notallow us to assume more than one origin for one species.Thus the great question of geographical distribution remainsin all its force; and, by still another of our geological paradoxes,mountains become ephemeral things in comparison with thedelicate herbage which covers them, and seas are in their presentextent but of yesterday, when compared with the minuteand feeble organisms that creep on their sands or swim in theirwaters.

The question remains: Has the Atlantic achieved its destinyand finished its course, or are there other changes in storefor it in the future? The earth's crust is now thicker andstronger than ever before, and its great ribs of crushed andfolded rock are more firm and rigid than in any previous period.The stupendous volcanic phenomena manifested in Mesozoicand early Tertiary times along the borders of the Atlantichave apparently died out. These facts are in so far guaranteesof permanence. On the other hand, it is known that movementsof elevation, along with local depression, are in progress« 90 »in the Arctic regions, and a great weight of new sediment isbeing deposited along the borders of the Atlantic, especiallyon its western side; and this is not improbably connected withthe earthquake shocks and slight movements of depressionwhich have occurred in North America. It is possible thatthese slight and secular movements may go on uninterruptedly,or with occasional paroxysmal disturbances, until considerablechanges are produced.

It is possible, on the other hand, that after the long periodof quiescence which has elapsed, there may be a new settlementof the ocean bed, accompanied with foldings of the crust, especiallyon the western side of the Atlantic, and possibly withrenewed volcanic activity on its eastern margin. In eithercase, a long time relatively to our limited human chronologymay intervene before the occurrence of any marked change.On the whole, the experience of the past would lead us to expectmovements and eruptive discharges in the Pacific ratherthan in the Atlantic area. It is therefore not unlikely that theAtlantic may remain undisturbed, unless secondarily and indirectly,until after the Pacific area shall have attained to agreater degree of quiescence than at present. But this subjectis one too much involved in uncertainty to warrant us in followingit farther.

In the meantime the Atlantic is to us a practically permanentocean, varying only in its tides, its currents, and its winds, whichscience has already reduced to definite laws, so that we canuse if we cannot regulate them. It is ours to take advantageof this precious time of quietude, and to extend the blessingsof science and of our Christian civilisation from shore to shore,until there shall be no more sea, not in the sense of that finaldrying-up of old ocean to which some physicists look forward,but in the higher sense of its ceasing to be the emblem of unrestand disturbance, and the cause of isolation.

I must now close this chapter with a short statement of some« 91 »general truths which I have had in view in directing attentionto the geological development of the Atlantic. We cannot,I think, consider the topics to which I have referred withoutperceiving that the history of ocean and continent is anexample of progressive design, quite as much as that of livingbeings. Nor can we fail to see that, while in some importantdirections we have penetrated the great secret of nature, inreference to the general plan and structure of the earth andits waters, and the changes through which they have passed,we have still very much to learn, and perhaps quite as much tounlearn, and that the future holds out to us and to our successorshigher, grander, and clearer conceptions than those towhich we have yet attained. The vastness and the might ofocean and the manner in which it cherishes the feeblest andmost fragile beings, alike speak to us of Him who holds it inthe hollow of His hand, and gave to it of old its boundariesand its laws; but its teaching ascends to a higher tone whenwe consider its origin and history, and the manner in which ithas been made to build up continents and mountain-chains,and, at the same time, to nourish and sustain the teeming lifeof sea and land.

References:—Presidential Address to the British Association for theAdvancement of Science, Birmingham, 1886. "Geology of NovaScotia, New Brunswick, and Prince Edward Island." FourthEdition, London, 1891.

THE DAWN OF LIFE.

DEDICATED TO THE MEMORY OF

SIR WILLIAM E. LOGAN,

The unwearied Explorer of the Laurentian Rocks,
and the Founder
of the
Geological Survey of Canada.

What Are the Oldest Rocks, and where?—Conditionsof their Formation—Indications of Life—What itsprobable Nature

CHAPTER V.

Do we know the first animal? Can we name it, explainits structure, and state its relations to its successors?Can we do this by inference from the succeeding types ofbeing; and if so, do our anticipations agree with any actualreality disinterred from the earth's crust? If we could do this,either by inference or actual discovery, how strange it wouldbe to know that we had before us even the remains of the firstcreature that could feel or will, and could place itself in vitalrelation with the great powers of inanimate nature. If webelieve in a Creator, we shall feel it a solemn thing to haveaccess to the first creature into which He breathed the breathof life. If we hold that all things have been evolved fromcollision of dead forces, then the first molecules of matterwhich took upon themselves the responsibility of living, and,aiming at the enjoyment of happiness, subjected themselves tothe dread alternatives of pain and mortality, must surely evokefrom us that filial reverence which we owe to the authors ofour own being; if they do not involuntarily draw forth even asuperstitious adoration. The veneration of the old Egyptianfor his sacred animals would be a comparatively reasonableidolatry, if we could imagine any of these animals to havebeen the first that emerged from the domain of dead matter,and the first link in a reproductive chain of being that producedall the population of the world. Independently of any suchhypotheses, all students of nature must regard with surpassing« 96 »interest the first bright streaks of light that break on the longreign of primeval night and death, and presage the busy dayof teeming animal existence.

No wonder, then, that geologists have long and earnestlygroped in the rocky archives of the earth in search of somerecord of this patriarch of the animal kingdom. But afterlong and patient research there still remained a large residuumof the oldest rocks destitute of all traces of living beings, anddesignated by the hopeless name "Azoic,"—the formationsdestitute of remains of life, the stony records of a lifelessworld. So the matter remained till the Laurentian rocks ofCanada, lying at the base of these old Azoic formations,afforded forms believed to be of organic origin. The discoverywas hailed with enthusiasm by those who had beenprepared by previous study to receive it. It was regarded withfeeble and not very intelligent faith by many more, and wasmet with half-concealed or open scepticism by others. It produceda copious crop of descriptive and controversial literature,but for the most part technical, and confined to scientific transactionsand periodicals, read by very few except specialists.Thus, few even of geological and biological students have clearideas of the real nature and mode of occurrence of theseancient organisms, if organisms they are, and of their relationsto better known forms of life; while the crudest and most inaccurateideas have been current in lectures and popular books,and even in text-books.

This state of things has long ceased to be desirable in theinterests of science, since the settlement of the questions raisedis in the highest degree important to the history of life. Wecannot, it is true, affirm that Eozoon is in reality the long-soughtprototype of animal existence; but it was for us, atleast until recently, the last organic foothold, on which we canpoise ourselves, that we may look back into the abyss of the infinitepast, and forward to the long and varied progress of life in« 97 »geological time. Now, however, we have announcements to bereferred to in the sequel of other organisms discovered in theso-called Archæan rocks; and it is not improbable that thesewill rapidly increase. The discussion of its claims has alsoraised questions and introduced new points, certain, if properlyentered into, to be fruitful of interesting and valuable thought,and to form a good introduction to the history of life in connectionwith geology.

As we descend in depth and time into the earth's crust,after passing through nearly all the vast series of strata constitutingthe monuments of geological history, we at length reachthe Eozoic or Laurentian rocks,[47] deepest and oldest of all theformations known to the geologist, and more thoroughly alteredor metamorphosed by heat and heated moisture than anyothers. These rocks, at one time known as Azoic, being supposeddestitute of all remains of living things, but now moreproperly Eozoic, are those in which the first bright streaks ofthe dawn of life make their appearance.

The name Laurentian, given originally to the Canadiandevelopment of these rocks by Sir William Logan, but nowapplied to them throughout the world, is derived from a rangeof hills lying north of the St. Lawrence valley, which the oldFrench geographers named the Laurentides. In these hillsthe harder rocks of this old formation rise to considerableheights, and form the highlands separating the St. Lawrencevalley from the great plain fronting on Hudson's Bay and theArctic Sea. At first sight it may seem strange that rocks soancient should anywhere appear at the surface, especially onthe tops of hills; but this is a necessary result of the mode offormation of our continents. The most ancient sedimentsdeposited in the sea were those first elevated into land, andfirst altered and hardened. Upheaved in the folding of theearth's crust into high and rugged ridges, they have either remained« 98 »uncovered with newer sediments, or have had such aswere deposited on them washed away; and being of a hardand resisting nature, they have remained comparatively unwornwhen rocks much more modern have been swept off by denudingagencies.[48]

But the exposure of the old Laurentian skeleton of motherearth is not confined to the Laurentide Hills, though thesehave given the formation its name. The same ancient rocksappear in the Adirondack mountains of New York, and inthe patches which at lower levels protrude from beneath thenewer formations along the American coast from Newfoundlandto Maryland. The older gneisses of Norway, Sweden, andthe Hebrides, of Bavaria and Bohemia, of Egypt, Abyssiniaand Arabia, belong to the same age, and it is not unlikely thatsimilar rocks in many other parts of the old continent will befound to be of as great antiquity. In no part of the world,however, are the Laurentian rocks more extensively distributedor better known than in Canada; and to this as the grandestand most instructive development of them we may moreespecially devote our attention.

The Laurentian rocks, associated with another series only alittle younger, the Huronian, form a great belt of broken andhilly country, extending from Labrador across the north ofCanada to Lake Superior, and thence bending northward tothe Arctic Sea. Everywhere on the lower St. Lawrence theyappear as ranges of billowy rounded ridges on the north sideof the river, and as viewed from the water or the southernshore, especially when sunset deepens their tints to blue andviolet, they present a grand and massive appearance, which, inthe eye of the geologist, who knows that they have enduredthe battles and the storms of time longer than any other mountains,« 99 »invests them with the dignity which their mere elevationwould fail to give. (Fig. 1.) In the isolated mass of theAdirondacks, south of the Canadian frontier, they rise to astill greater elevation, and form an imposing mountain group,almost equal in height to their somewhat more modern rivals,the White Mountains, which face them on the opposite side ofLake Champlain.

The grandeur of the old Laurentian ranges is, however, bestdisplayed where they have been cut across by the great transversegorge of the Saguenay, and where the magnificent precipices,known as Capes Trinity and Eternity, look down fromtheir elevation of 1,500 feet on the fiord, which at their feet ismore than 100 fathoms deep. The name Eternity applied tosuch a mass is geologically scarcely a misnomer, for it datesback to the very dawn of geological time, and is of hoarantiquity in comparison with such upstart ranges as the Andesand the Alps. (SeeFrontispiece.)

On a nearer acquaintance, the Laurentian country appearsas a broken and hilly upland and highland district, clad in itspristine state with magnificent forests, but affording few attractionsto the agriculturist, except in the valleys, which follow thelines of its softer beds, while it is a favourite region for theangler, the hunter, and the lumberman. Many of the Laurentiantownships of Canada are, however, already extensivelysettled, and the traveller may pass through a succession ofmore or less cultivated valleys, bounded by rocks or woodedhills and crags, and diversified by running streams and romanticlakes and ponds, constituting a country always picturesqueand often beautiful, and rearing a strong and hardy population.To the geologist it presents in the main immensely thick bedsof gneiss, bedded diorite and quartzite, and similar crystallinerocks, contorted in the most remarkable manner, so that ifthey could be flattened out they would serve as a skin muchtoo large for mother earth in her present state, so much hasshe shrunk and wrinkled since thoseyouthful days when the Laurentian rockswere her outer covering.

I cannot describe such rocks, but theirnames, as given in the section,Fig. 2,will tell something to those who haveany knowledge of the older crystallinematerials of the earth's crust. To thosewho have not, I would advise a visit tosome cliff on the lower St. Lawrence, orthe Hebridean coasts, or the shore ofNorway, where the old hard crystallineand gnarled beds present their sharpedges to the ever raging sea, and showtheir endless alternations of various kindsand colours of strata, often diversifiedwith veins and nests of crystallineminerals. He who has seen and studiedsuch a section of Laurentian rock cannotforget it.

The elaborate stratigraphical work ofSir William Logan has proved that theseold crystalline rocks are bedded orstratified, and that they must have beendeposited in succession by some processof aqueous action. They have, however,through geological ages of vast durationbeen subjected to pressure and chemicalaction, which have, as stated in a previouschapter, much modified their structure,while it is also certain that theymust have differed originally from thesands, clays and other materials laiddown in the sea in later times.

It is interesting to notice here that the Laurentian rocksthus interpreted show that the oldest known portions of ourcontinents were formed in the waters. They are oceanic sedimentsdeposited perhaps when there was no dry land, or verylittle, and that little unknown to us, except in so far as itsdébris may have entered into the composition of the Laurentianrocks themselves. Thus the earliest condition of theearth known to the geologist is one in which old ocean wasalready dominant on its surface; and any previous conditionwhen the surface was heated, and the water constituted anabyss of vapours enveloping its surface, or any still earlier conditionin which the earth was gaseous or vaporous, is a matterof mere inference, not of actual observation. The formlessand void chaos is a deduction of chemical and physical principles,not a fact observed by the geologist. Still we know,from the great dykes and masses of igneous or molten rockwhich traverse the Laurentian beds, that even at that earlyperiod there were deep-seated fires beneath the crust; and itis quite possible that volcanic agencies then manifested themselves,not only with quite as great intensity, but also in thesame manner, as at subsequent times. It is thus not unlikelythat much of the land undergoing waste in the earlier Laurentiantime was of the same nature with recent volcanic ejections,and that it formed groups of islands in an otherwise boundlessocean.

However this may be, the distribution and extent of thesepre-Laurentian lands is, and probably ever must be, unknownto us; for it was only after the Laurentian rocks had beendeposited, and after the shrinkage and deformation of theearth's crust in subsequent times had bent and contorted them,that the foundations of the continents were laid. The rudesketch map of America given inFig. 3 will show this, and willalso show that the old Laurentian mountains mark out thefuture form of the American continent.

Some subsequent writers have, it is true, treated with disbeliefLogan's great discoveries; but no competent geologistwho has traced the regularly bedded limestones and otherrocks of his original fields of investigation could continue todoubt. On this subject I may quote from my friend Dr.Bonney, one of the most judicious of the builders who undertakehypothetically to lay the foundation stones of the earth'scrust for our enlightenment in these later days. In an addressdelivered at the Bath meeting of the British Association hesays:—

"The first deposits on the solidified crust of the earth wouldobviously be igneous. As water condensed from the atmosphereon the cooling surface, aqueous waste or condensationwould begin, and stratified deposits in the ocean would become« 104 »possible in addition to detrital volcanic material. But at thattime the crust itself, and even later stratified deposits wouldoften be kept for a considerable period at a high temperature.Thus, not only rocks of igneous origin (including volcanicashes) would predominate in the lowest foundation stones, butalso secondary changes would occur more readily, and eventhe sediments or precipitates might be greatly modified. Astime went on, true sediments would predominate over volcanicmaterials, and these would be less and less affected by chemicalchanges, and would more and more retain their original character.Thus we should expect that as we retraced the earth'scourse through 'the corridor of time' we should arrive atrocks which, though crystalline in structure, were evidently ingreat part sedimentary in origin, and should behind them findrocks of more coarsely crystalline texture and more dubiouscharacter, which, however, probably were in part of a likeorigin, and should at last reach coarsely crystalline rocks, inwhich, while occasional sediments would be possible, themajority were originally igneous, though modified at a veryearly period of their history. This corresponds with what wefind in nature, when we apply, cautiously and tentatively, theprinciples of interpretation which guide us in stratigraphicalgeology."[49]

This expresses very well the general result of the patientstratigraphical and chemical labours of Logan and SterryHunt, as applied to the vast areas of old crystalline stratifiedrocks in Canada, and which I have had abundant opportunitiesto verify on the ground. Under the undoubted Cambrianbeds of Canada lies the Huronian, a formation largely ofhardened sands, clays and gravels, now forming sandstones,slates, and conglomerates, but with great beds of igneous orvolcanic rock, and hardened and altered ash beds. Under« 105 »this, in the upper portion of the Laurentian, we have regularlybedded rocks, quartzites, limestones, and quartzose, and graphiticand ferruginous gneisses, evidently altered aqueoussediments; but intermixed with other rocks, as diorites andhornblendic gneisses, which are plainly of different origin.Lastly, on the bottom of all, we have nothing but coarsecrystalline gneiss, representing perhaps the earliest crust of acooling globe. Broadly, and without entering into details ortheoretical views as to the precise causes of formation andalteration of these rocks, this is the structure of the Archæanor Eozoic system in Canada; and it corresponds with that ofthe basement or foundation stones of our continents in everycountry that I have been able to visit, or of which I havetrustworthy accounts.

In the lower or fundamental gneiss, and in the igneous bedswhich succeed it, we need not look for any indications ofliving beings; but so soon as the sea began to deposit sand,mud, limestone, iron ore, carbon, there would be nothing toexclude the presence of some forms of marine life; while, asland must have already existed, there would be a possibility oflife on it. This, therefore, we may begin to look for so soonas we ascend to those beds of the Laurentian in which limestone,iron ore, and quartzite appear; and it is precisely at thispoint in the Laurentian of Canada that indications of life aresupposed to have been found. Certain it is that if we cannotfind some sign of life in the Laurentian or Huronian, we shallhave to face as the beginnings of life the swarms of marinecreatures that appear all over the globe at once, in the earlyCambrian age.

Is it likely, then, that such rocks should afford any traces ofliving beings, even if any such existed when they were formed?Geologists who had traced organic remains back to the lowestCambrian might hope for such remains, even in the Laurentian;but they long looked in vain for their actual discovery.« 106 »Still, as astronomers have suspected the existence of unknownplanets from observing perturbations not accounted for, andas voyagers have suspected the approach to unknown regionsby the appearance of floating wood or stray land birds, anticipationsof such discoveries have been entertained and expressedfrom time to time. Lyell, Dana, and Dr. Sterry Huntmore especially have committed themselves to such speculations.The reasons assigned may be stated thus:—

Assuming the Laurentian rocks to be altered sediments,they must, from their great extent, have been deposited in theocean; and if there had been no living creatures in the waters,we have no reason to believe that they would have consisted ofanything more than such sandy and muddydébris as may bewashed away from wasting rocks originally of igneous origin.But the Laurentian beds contain other materials than these.No formations of any geological age include thicker or moreextensive limestones. One of the beds measured by theofficers of the Geological Survey is stated to be 1,500 feet inthickness, another is 1,250 feet thick, and a third, 750 feet;making an aggregate of 3,500 feet.[50] These beds may be traced,with more or less interruption, for hundreds of miles. Whateverthe origin of such limestones, it is plain that they indicatecauses equal in extent, and comparable in power and duration,with those which have produced the greatest limestones of thelater geological periods. Now, in later formations, limestoneis usually an organic rock, accumulated by the slow gatheringfrom the sea-water, or its plants, of calcareous matter, bycorals, foraminifera, or shell fish, and the deposition of theirskeletons, either entire or in fragments, in the sea bottom.The most friable chalk and the most crystalline limestoneshave alike been formed in this way. We know of no reasonwhy it should be different in the Laurentian period. When,« 107 »therefore, we find great and conformable beds of limestone,such as those described by Sir William Logan in the Laurentianof Canada, we naturally imagine a quiet sea bottom, inwhich multitudes of animals of humble organization wereaccumulating limestone in their hard parts, and depositingthis in gradually increasing thickness from age to age. Anyattempts to account otherwise for these thick and greatlyextended beds, regularly interstratified with other deposits,have so far been failures, and have arisen either from a wantof comprehension of the nature and magnitude of the appearancesto be explained, or from the error of mistaking the truebedded limestones for veins of calcareous spar.

The Laurentian rocks contain great quantities of carbon, inthe form of graphite or plumbago. This does not occurwholly, or even principally, in veins or fissures, but in the substanceof the limestone and gneiss, and in regular layers. Soabundant is it, that I have estimated the amount of carbon inone division of the Lower Laurentian of the Ottawa district atan aggregate thickness of not less than twenty to thirty feet, anamount comparable with that in the true coal formation itself.Now we know of no agency existing in present or in pastgeological time capable of deoxidizing carbonic acid, andfixing its carbon as an ingredient in permanent rocks, exceptvegetable life. Unless, therefore, we suppose that there existedin the Laurentian age a vast abundance of vegetation, either inthe sea or on the land, we have no means of explaining theLaurentian graphite.

The Laurentian formation contains great beds of oxide ofiron, sometimes seventy feet in thickness. Here, again, wehave an evidence of organic action; for it is the deoxidizingpower of vegetable matter which has in all the later formationsbeen the efficient cause in producing bedded deposits of iron.This is the case in modern bog and lake ores, in the clay ironstonesof the coal measures, and apparently, also, in the great« 108 »ore beds of the Silurian rocks. May not similar causes havebeen at work in the Laurentian period?

Any one of these reasons might, in itself, be held insufficientto prove so great and, at first sight, unlikely a conclusion asthat of the existence of abundant animal and vegetable life inthe Laurentian; but the concurrence of the whole in a seriesof deposits unquestionably marine, forms a chain of evidenceso powerful that it might command belief even if no fragmentof any organic and living form or structure had ever beenrecognised in these ancient rocks.

Such was the condition of the matter until the existence ofsupposed organic remains was announced by Sir W. Logan, atthe American Association for the Advancement of Science, inSpringfield, in 1859; and we may now proceed to narrate themanner of this discovery, and how it has been followed up.

Before doing so, however, let us visit Eozoon in one of itshaunts among the Laurentian Hills. One of the most notedrepositories of its remains is the great Grenville band of limestone;and one of the most fruitful localities is at a placecalled Côte St. Pierre on this band. Leaving the train atPapineauville, we find ourselves on the Laurentian rocks, andpass over one of the great bands of gneiss for about twelvemiles, to the village of St. André Avelin. On the road we seeon either hand abrupt rocky ridges, partially clad with forest,and sometimes showing on their flanks the stratification of thegneiss in very distinct parallel bands, often contorted, as if therocks, when soft, had been wrung as a washerwoman wringsclothes. Between the hills are little irregular valleys, fromwhich the wheat and oats have just been reaped, and the tallIndian corn and yellow pumpkins are still standing in thefields. Where not cultivated, the land is covered with a richsecond growth of young maples, birches, and oaks, amongwhich still stand the stumps and tall scathed trunks of enormouspines, which constituted the original forest. Half way« 109 »we cross the Nation River, a stream nearly as large as theTweed, flowing placidly between wooded banks, which aremirrored in its surface; but in the distance we can hear theroar of its rapids, dreaded by lumberers in their spring drivingsof logs. Arrived at St. André, we find a wider valley, theindication of the change to the limestone band, and along this,with the gneiss hills still in view on either hand, and oftenencroaching on the road, we drive for five miles more to CôteSt. Pierre. At this place the lowest depression of the valley isoccupied by a little pond, and, hard by, the limestone, protectedby a ridge of gneiss, rises in an abrupt wooded bank bythe roadside, and a little farther forms a bare white promontory,projecting into the fields.

The limestone is here highly inclined and much contorted,and in all the excavations a thickness of about 100 feet of itmay be exposed. It is white and crystalline, varying much,however, in coarseness in different bands. It is in some layerspure and white; in others it is traversed by many grey layers ofgneissose and other matter, or by irregular bands and nodulesof pyroxene and serpentine, and it contains subordinate beds ofdolomite. In one layer only, and this but a few feet thick,does the Eozoon occur in abundance in a perfect state, though« 110 »fragments and imperfectly preserved specimens abound inother parts of the bed. It is a great mistake to suppose that itconstitutes whole beds of rock in an uninterrupted mass. Itstrue mode of occurrence is best seen on the weathered surfacesof the rock, where the serpentinous specimens project inirregular patches of various sizes, sometimes twisted by thecontortion of the beds, but often too small to suffer in this way.On such surfaces the projecting patches of the fossil exhibitlaminæ of serpentine so precisely like theStromatoporæ of theSilurian rocks, that any collector would pounce upon them atonce as fossils. In some places these small weathered specimenscan be easily chipped off from the crumbling surface ofthe limestone; and it is perhaps to be regretted that they havenot been more extensively shown to palæontologists, with thecut slices which to many of them are so problematical. Oneof the original specimens, brought from the Calumet, and nowin the Museum of the Geological Survey of Canada, was ofthis kind, and much finer specimens from Côte St. Pierre arenow in that collection and in my own. A very fine example isrepresented on the plate facing this chapter, which is takenfrom an original photograph. In some of the layers are foundother and more minute vesicular forms, which may be organic,and these, together with fragmental remains, as ingredients inthe limestone, will be discussed in the sequel. We may merelynotice here that the most abundant layer of Eozoon at thisplace occurs near the base of the great limestone band, andthat the upper layers, in so far as seen, are less rich in it.Further, there is no necessary connection between Eozoonand the occurrence of serpentine, for there are many layers fullof bands and lenticular masses of that mineral without anyEozoon except occasional fragments, while the fossil is sometimespartially mineralised with pyroxene, dolomite, or commonlimestone. The section inFig. 4 will serve to show the attitudeof the limestone at this place, while the more general« 111 »section,Fig. 2, page 101, taken from Sir William Logan, showsits relation to the other Laurentian rocks.

We may now notice the manner in which the specimensdiscovered in this and other places in the Laurentian countrycame to be regarded as organic.

It is a trite remark that most discoveries are made, not by oneperson, but by the joint exertions of many, and that they havetheir preparations made often long before they actually appear.For this reason I may be excused here for introducing somepersonal details in relation to the discovery of Eozoon, andwhich are indeed necessary in vindication of its claims. In thiscase the stable foundations were laid years before the discoveryof Eozoon, by the careful surveys made by Sir William Loganand his assistants, and the chemical examination of the rocksand minerals by Dr. Sterry Hunt, which established beyond alldoubt the great age and truly bedded character of the Laurentianrocks and their probable original nature, and the changeswhich they have experienced in the course of geological time.On the other hand, Dr. Carpenter and others in England wereexamining the structure of the shells of the humbler inhabitantsof the modern ocean, and the manner in which the pores oftheir skeletons become infiltrated with mineral matter whendeposited in the sea bottom. These laborious and apparentlydissimilar branches of scientific inquiry were destined to beunited by a series of happy discoveries, made not fortuitouslybut by painstaking and intelligent observers. The discoveryof the most ancient fossil was thus not the chance picking upof a rare and curious specimen. It was not likely to be foundin this way; and if so found, it would have remained unnoticedand of no scientific value, but for the accumulated stores ofzoological and palæontological knowledge, and the surveyspreviously made, whereby the age and distribution of theLaurentian rocks and the chemical conditions of their depositionand metamorphism were ascertained.

The first specimens of Eozoon ever procured, in so far asknown, were collected at Burgess, in Ontario, by a veteranCanadian mineralogist, Dr. Wilson, of Perth, and were sent toSir William Logan as mineral specimens. Their chief interestat that time lay in the fact that certain laminæ of a dark greenmineral present in the specimens were found, on analysis by Dr.Hunt, to be composed of a new hydrous silicate, allied to serpentine,and which he named loganite. The form of this mineralwas not suspected to be of organic origin. Some years after, in1858, other specimens, differently mineralized with the mineralsserpentine and pyroxene, were found by Mr. J. McMullen,an explorer in the service of the Geological Survey, in thelimestone of the Grand Calumet on the River Ottawa. Theseseem to have at once struck Sir W. E. Logan as resembling theSilurian fossils known asStromatopora, and he showed themto Mr. Billings, the palæontologist of the survey, and to thewriter, with this suggestion, confirming it with the sagaciousconsideration that inasmuch as the Ottawa and Burgess specimenswere mineralized by different substances, yet were alikein form, there was little probability that they were merelymineral or concretionary. Mr. Billings was naturally unwillingto risk his reputation in affirming the organic nature of suchspecimens; and my own suggestion was that they should besliced, and examined microscopically, and that if fossils, as theypresented merely concentric laminæ and no cells, they wouldprobably prove to be protozoa rather than corals. A few sliceswere accordingly made, but no definite structure could bedetected. Nevertheless, Sir William Logan took some of thespecimens to the meeting of the American Association atSpringfield, in 1859, and exhibited them as possibly Laurentianfossils; but the announcement was evidently received withsome incredulity. In 1862 they were exhibited by Sir Williamto some geological friends in London, but he remarks that"few seemed disposed to believe in their organic character,with the exception of my friend, Professor Ramsay." In 1863the general Report of the Geological Survey, summing up itswork to that time, was published, under the name of the"Geology of Canada," and in this, at page 49, will be foundtwo figures of one of the Calumet specimens, here reproduced,and which, though unaccompanied with any specific name ortechnical description, were referred to as probably Laurentianfossils. (Figs.5 and6.)

About this time Dr. Hunt happened to mention to me, inconnection with a paper on the mineralization of fossils whichhe was preparing, that he proposed to notice the mode ofpreservation of certain fossil woods and other things withwhich I was familiar, and that he would show me the paper inproof, in order that I might give him any suggestions thatoccurred to me. On reading it, I observed, among otherthings, that he alluded to the supposed Laurentian fossils,under the impression that the organic part was represented bythe serpentine or loganite, and that the calcareous matter wasthe filling of the chambers. I took exception to this, statingthat though in the slices I had examined no structure wasapparent, still my impression was that the calcareous matterwas the fossil, and the serpentine or loganite the filling. Hesaid—"In that case, would it not be well to re-examine thespecimens, and try to discover which view is correct?" Hementioned, at the same time, that Sir William had recentlyshown him some new and beautiful specimens collected by Mr.Lowe, one of the explorers on the staff of the Survey, from athird locality, at Grenville, on the Ottawa. It was supposedthat these might throw further light on the subject; andaccordingly Dr. Hunt suggested to Sir William to haveadditional slices of these new specimens made by Mr. Weston,of the Survey, whose skill as a preparer of these and otherfossils has often done good service to science. A few daysthereafter some slices were sent to me, and were at once putunder the microscope. I was delighted to find in one of thefirst specimens examined a beautiful group of tubuli penetrating« 115 »one of the calcite layers. Here was evidence, not only thatthe calcite layers represented the true skeleton of the fossil,but also of its affinities with the foraminifera, whose tubulatedsupplemental skeleton, as described and figured by Dr. Carpenter,and represented in specimens in my collection, presentedby him, was apparently of the same type with thatpreserved in the canals of these ancient fossils.Fig. 7 is anaccurate representation of the group of canals first detected byme.

On showing the structures discovered to Sir William Logan,he entered into the matter with enthusiasm, and had a greatnumber of slices, as well as decalcified specimens, prepared,which were placed in my hands for examination.

Feeling that the discovery was most important, but that itwould be met with determined scepticism by a great manygeologists, I was not content with examining the typical specimensof Eozoon, but had slices prepared of every variety of« 116 »Laurentian limestone, of altered limestones from the Primordialand Silurian, and of serpentine marbles of all the varietiesfurnished by our collections. They were examined with ordinaryand polarized light, and with every variety of illumination.They were also examined as decalcified specimens, after thecarbonate of lime had been removed by acids. An extensiveseries of notes and camera tracings were made of all theappearances observed; and of some of the more importantstructures beautiful drawings were executed by the late Mr.H. S. Smith, the then palæontological draughtsman of theSurvey. The result of the whole investigation was a firm convictionthat the structure was organic and foraminiferal, andthat it could be distinguished from any merely mineral orcrystalline forms occurring in these or other limestones.

At this stage of the matter, and after exhibiting to SirWilliam all the characteristic appearances, in comparison withsuch concretionary, dendritic and crystalline structures asmost resembled them, and also with the structure of recent andfossil Foraminifera, I suggested that the further prosecutionof the matter should be handed over to Mr. Billings, aspalæontologist of the Survey. I was engaged in other researches,not connected with the Survey or with this particulardepartment, and I knew that no little labour must be devotedto the work and to its publication, and that some controversymight be expected. Mr. Billings, however, with his characteristiccaution and modesty, declined. His hands were full ofother work. He had not given any special attention to themicroscopic appearances of Foraminifera or of mineral substances.It was finally arranged that I should prepare a descriptionof the fossil, which Sir William would take to London,along with the more important specimens, and a detailed liststating all the structures observed in each. Sir William was tosubmit the manuscript and specimens to Dr. Carpenter, or,failing him, to Prof. T. Rupert Jones, in the hope that these« 117 »eminent authorities would confirm my conclusions, and bringforward new facts which I might have overlooked or beenignorant of. Sir William saw both gentlemen, who gave theirtestimony in favour of the organic and foraminiferal characterof the specimens; and Dr. Carpenter, in particular, gave muchattention to the subject, and worked out more in detail manyof the finer structures, besides contributing valuable suggestionsas to the probable affinities of the supposed fossil.

Dr. Carpenter thus contributed in a very important mannerto the perfecting of the investigations begun in Canada, and onhim fell the greater part of their illustration and defence,[51] in sofar as Great Britain is concerned.

The immediate result was a composite paper in theProceedingsof the Geological Society, by Sir W. E. Logan, Dr. Carpenter,Dr. Hunt, and myself, in which the geology, palæontologyand mineralogy ofEozoon Canadense and its containingrocks were first given to the world.[52] It cannot be wondered atthat when geologists and palæontologists were thus required tobelieve in the existence of organic remains in rocks regarded asaltogether Azoic and hopelessly barren of fossils, and to carryback the dawn of life as far before those Primordial rocks,which were supposed to contain its first traces, as these arebefore the middle period of the earth's life history, some hesitationshould be felt. Further, the accurate appreciation of theevidence for such a fossil as Eozoon required an amount ofknowledge of minerals, of the more humble types of animals,and of the conditions of mineralization of organic remains, possessedby few even of professional geologists. Thus Eozoon hasmet with some scepticism and not a little opposition,—thoughthe latter has been weaker than we might have expected when« 118 »we consider the startling character of the facts adduced, andhas mostly come from men imperfectly informed.

But what is Eozoon, if really of animal origin? The shortestanswer to this question is, that this ancient fossil is supposedto be the skeleton of a creature belonging to that simple andhumbly organized group of animals which are known by thename Protozoa. If we take as a familiar example of these thegelatinous and microscopic creature found in stagnant ponds,and known as theAmœba [53] (Fig. 8), it will form a convenientstarting-point. Viewed under a low power, it appears as alittle patch of jelly, irregular in form, and constantly changingits aspect as it moves, by the extension of parts of its body intofinger-like processes or pseudopods which serve as extemporelimbs. When moving on the surface of a slip of glass underthe microscope, it seems, as it were, to flow along rather thancreep, and its body appears to be of a semi-fluid consistency.It may be taken as an example of the least complex forms ofanimal life known to us, and is often spoken of by naturalistsas if it were merely a little particle of living and scarcely organizedjelly or protoplasm. When minutely examined, however,it will not be found so simple as it at first sight appears. Itsouter layer is clear and transparent, and more dense than theinner mass, which seems granular. It has at one end a curiousvesicle which can be seen gradually to expand and becomefilled with a clear drop of liquid, and then suddenly to contractand expel the contained fluid through a series of pores in theadjacent part of the outer wall. This is the so-called pulsatingvesicle, and is an organ both of circulation and excretion. Inanother part of the body may be seen the nucleus, which is alittle cell capable, at certain times, of producing by its divisionnew individuals. Food, when taken in through the wall of thebody, forms little pellets, which become surrounded by a« 119 »digestive liquid exuded from the enclosing mass into roundedcavities or extemporised stomachs. Minute granules are seento circulate in the gelatinous interior, and may be substitutesfor blood-cells, and the outer layer of the body is capable ofprotrusion in any direction into long processes, which are verymobile, and used for locomotion and prehension. Further,this creature, though destitute of most of the parts which weare accustomed to regard as proper to animals, seems to exercisevolition, and to show the same appetites and passions withanimals of higher type. I have watched one of these animalculesendeavouring to swallow a one-celled plant as long as itsown body; evidently hungry and eager to devour the temptingmorsel, it stretched itself to its full extent, trying to envelopethe object of its desire. It failed again and again; but renewedthe attempt, until at length, convinced of its hopelessness, itflung itself away as if in disappointment, and made off in searchof something more manageable. With the Amœba are foundother types of equally simple Protozoa, but somewhat differentlyorganized. One of these,Actinophrys (Fig. 9), has the bodyglobular and unchanging in form, the outer wall of greater thickness;the pulsating vesicle like a blister on the surface, and thepseudopods long and thread-like. Its habits are similar tothose of the Amœba, and I introduce it to show the variationsof form and structure possible even among these simplecreatures.

The Amœba and Actinophrys are fresh-water animals, andare destitute of any shell or covering. But in the sea there existswarms of similar creatures, equally simple in organization,but gifted with the power of secreting around their soft bodiesbeautiful little shells or crusts of carbonate of lime, having oneorifice, and often in addition multitudes of microscopic poresthrough which the soft gelatinous matter can ooze, and formoutside finger-like or thread-like extensions for collecting food.In some cases the shell consists of a single cavity only, but inmost, after one cell is completed, others are added, forminga series of cells or chambers communicating with each other,and often arranged spirally or otherwise in most beautiful andsymmetrical forms. Some of these creatures, usually namedForaminifera, are locomotive, others sessile and attached.Most of them are microscopic, but some grow by multiplicationof chambers till they are a quarter of an inch or more inbreadth.

The original skeleton or primary cell wall of most of thesecreatures is seen under the microscope to be perforated withinnumerable pores, and is extremely thin. When, however,owing to the increased size of the shell, or other wants of thecreature, it is necessary to give strength, this is done by addingnew portions of carbonate of lime to the outside, and tothese Dr. Carpenter has given the appropriate name of "supplementalskeleton"; and this, when covered by new growths,becomes what he has termed an "intermediate skeleton." Thesupplemental skeleton is also traversed by tubes, but these are« 121 »often of larger size than the pores of the cell wall, and ofgreater length, and branched in a complicated manner. Thusthere are microscopic characters by which these curious shellscan be distinguished from those of other marine animals; andby applying these characters we learn that multitudes ofcreatures of this type have existed in former periods of theworld's history, and that their shells, accumulated in the bottomof the sea, constitute large portions of many limestones. Themanner in which such accumulation takes place we learn fromwhat is now going on in the ocean, more especially from theresult of the recent deep-sea dredging expeditions. TheForaminifera are vastly numerous, both near the surface andat the bottom of the sea, and multiply rapidly; and as successivegenerations die, their shells accumulate on the oceanbed, or are swept by currents into banks, and thus, in processof time, constitute thick beds of white chalky material, whichmay eventually be hardened into limestone. This processis now depositing a great thickness of white ooze in the bottomof the ocean; and in times past it has produced such vastthicknesses of calcareous matter as the chalk and nummuliticlimestone of Europe and the orbitoidal limestone of America.The chalk which alone attains a maximum thickness of 1,000feet, and, according to Lyell, can be traced across Europe for1,100 geographical miles, may be said to be entirely composedof shells of Foraminifera imbedded in a paste of smallercalcareous bodies, the Coccoliths, which are probably productsof marine vegetable life, if not of some animal organism stillsimpler than the Foraminifera.

Lastly, while we have in such modern forms as the massesof Polytrema attached to corals, and the Loftusia of theEocene and the carboniferous, large fossil foraminiferalspecies, there is some reason to believe that in the earlier geologicalages there existed much larger animals of this gradethan are found in our present seas; and that these, always« 122 »sessile on the bottom, grew by the addition of successivechambers, in the same manner with the smaller species.[54]

Let us, then, examine the structure of Eozoon, taking atypical specimen, as we find it in the limestone of Grenville orPetite Nation. In such specimens the skeleton of the animalis represented by a white crystalline marble, the cavities of thecells by green serpentine, the mode of whose introduction weshall have to consider in the sequel. The lowest layer of serpentinerepresents the first gelatinous coat of animal matterwhich grew upon the bottom, and which, if we could haveseen it before any shell was formed upon its surface, must haveresembled a minute patch of living slime. On this primarylayer grew a delicate calcareous shell, perforated by innumerableminute tubuli, and resting on the slimy matter of theanimal, though supported also by some perpendicular plates orsepta. Upon this again was built up, in order to strengthen it,a thickening or supplemental skeleton, more dense, and destituteof fine tubuli, but traversed by branching canals, throughwhich the soft gelatinous matter could pass for the nourishmentof the skeleton itself, and the extension of pseudopods beyondit. (Figs.11,12.) So was formed the first layer of Eozoon,which probably was at its beginning only of very small dimensions.On this the process of growth of successive layers ofanimal sarcode and of calcareous skeleton was repeated againand again, till in some cases even a hundred or more layerswere formed (nature-print, Chap. VI.) As the process went on,however, the vitality of the organism became exhausted, probablyby the deficient nourishment of the central and lowerlayers making greater and greater demands on those above,and so the succeeding layers became thinner, and less supplementalskeleton was developed. Finally, toward the top,the regular arrangement in layers was abandoned, and the cells« 123 »became a mass of rounded chambers, irregularly piled up inwhat Dr. Carpenter has termed an "acervuline" manner, andwith very thin walls unprotected by supplemental skeleton.Then the growth was arrested, and possibly these upper layersgave off reproductive germs, fitted to float or swim away andto establish new colonies. We may have such reproductivegerms in certain curious globular bodies, like loose cells, foundin connection with Eozoon in many of the Laurentian limestones.[55]At St. Pierre, on the Ottawa, these bodies occur onthe surface of layers of the limestone in vast numbers, as ifthey had been growing separately on the bottom, or had beendrifted over it by currents. They may have served as reproductivebuds or germs to establish new colonies of the species.Such was the general mode of growth of Eozoon, and we maynow consider more in detail some questions as to its giganticsize, its precise mode of nutrition, the arrangement of itsparts, its relations to more modern forms, and the effects ofits growth in the Laurentian seas.

With respect to the size of Eozoon, this was rivalled bysome succeeding animals of the same humble type in later geologicalages; and, as a whole, foraminiferal animals have beendiminishing in size in the lapse of geological time. This isindeed a fact of so frequent occurrence that it may almost beregarded as a law of the introduction of new forms of life,that they assume in their early history gigantic dimensions,and are afterwards continued by less magnificent species. Therelations of this to external conditions, in the case of higheranimals, are often complex and difficult to understand; but inorganisms so low as Eozoon and its allies, they lie moreon the surface. Such creatures may be regarded as thesimplest and most ready media for the conversion of vegetablematter into animal tissues, and their functions are almostentirely limited to those of nutrition. Hence it is likely thatthey will be able to appear in the most gigantic forms undersuch conditions as afford them the greatest amount of pabulumfor the nourishment of their soft parts and for their skeletons.There is reason to believe, for example, that the occurrence,both in the chalk and the deep-sea mud, of immense quantitiesof the minute bodies known as Coccoliths along withForaminifera, is not accidental. The Coccoliths appear to begrains of calcareous matter formed in minute plants adaptedto a deep-sea habitat; and these, along with the vegetableand animaldébris constantly being derived from the death ofthe living things at the surface, afford the material both ofsarcode and shell. Now if the Laurentian graphite representsan exuberance of vegetable growth in those old seas proportionate« 125 »to the great supplies of carbonic acid in the atmosphereand in the waters, and if the Eozoic ocean was even bettersupplied with salts of lime than those Silurian seas whose vastlimestones bear testimony to their richness in such material,we can easily imagine that the conditions may have been morefavourable to a creature like Eozoon than those of any otherperiod of geological time.

Growing, as Eozoon did, on the floor of the ocean, andcovering wide patches with more or less irregular masses, itmust have thrown up from its whole surface its pseudopodsto seize whatever floating particles of food the waters carriedover it. There is also reason to believe, from the outline ofcertain specimens, that it often grew upward in conical or club-shapedforms, and that the broader patches were penetrated bylarge pits or oscula, admitting the sea-water deeply into thesubstance of the masses. In this way its growth might berapid and continuous; but it does not seem to have possessedthe power of growing indefinitely by new and living layerscovering those that had died, in the manner of some corals. Itslife seems to have had a definite termination, and when thatwas reached, an entirely new colony had to be commenced.In this it had more affinity with the Foraminifera, as we nowknow them, than with the corals, though practically it had thesame power with the coral polyps of accumulating limestonein the sea bottom—a power indeed still possessed by its foraminiferalsuccessors. In the case of coral limestones weknow that a large proportion of these consist not of continuousreefs, but of fragments of coral mixed with other calcareousorganisms, spread usually by waves and currents in continuousbeds over the sea bottom. In like manner we find in thelimestones containing Eozoon, layers of fragmental matterwhich show in places the characteristic structures, and whichevidently represent thedébris swept from the Eozoic massesand reefs by the action of the waves. It is with this fragmental« 126 »matter that the small rounded organisms already referredto most frequently occur; and while they may bedistinct animals, they may also be the fry of Eozoon, or smallportions of its acervuline upper surface floated off in a livingstate, and possibly capable of living independently and offounding new colonies.

It is only by a somewhat wild poetical licence that Eozoonhas been represented as a "kind of enormous compositeanimal stretching from the shores of Labrador to LakeSuperior, and thence northward and southward to an unknowndistance, and forming masses 1,500 feet in depth." We may,it is true, readily believe in the composite nature of masses orEozoon, and we see in the corals evidence of the great size towhich composite animals of a higher grade can attain. In thecase of Eozoon we must imagine an ocean floor more uniformand level than that now existing. On this the organism wouldestablish itself in spots and patches. These might finally becomeconfluent over large areas, just as massive corals do.As individual masses attained maturity and died, their poreswould be filled up with limestone or silicious deposits, andthus could form a solid basis for new generations, and in thisway limestone to an indefinite extent might be produced.Further, wherever such masses were high enough to beattacked by the breakers, or where portions of the sea bottomwere elevated, the more fragile parts of the surface wouldbe broken up and scattered widely in beds of fragments overthe bottom of the sea, while here and there beds of mud orsand, or of volcanicdébris would be deposited over the livingor dead organic mass, and would form the layers of gneissand other schistose rocks interstratified with the Laurentianlimestone. In this way, in short, Eozoon would perform afunction combining that which corals and Foraminifera performin the modern seas; forming both reef limestones and extensivechalky beds, and probably living both in the shallow and« 127 »the deeper parts of the ocean. If in connection with this weconsider the rapidity with which the soft, simple, and almoststructureless sarcode of these Protozoa can be built up, andthe probability that they were more abundantly supplied withfood, both for nourishing their soft parts and skeletons, thanany similar creatures in later times, we can readily understandthe great volume and extent of the Laurentian limestoneswhich they aided in producing. I say aided in producing,because I would not care to commit myself to the doctrinethat the Laurentian limestones are wholly of this origin.There may have been other limestone builders than Eozoon,and there may have been limestones formed by plants like themodern Nullipores, or by merely mineral deposition.

Its relations to modern animals of its type have been veryclearly defined by Dr. Carpenter. In the structure of itsproper wall and its fine parallel perforations, it resembles theNummulites and their allies; and the organism may thereforebe regarded as an aberrant member of the Nummuline group,which affords some of the largest and most widely distributedof the fossil Foraminifera. This resemblance may be seen inFig. 11. To the Nummulites it also conforms in its tendencyto form a supplemental or intermediate skeleton with canals,« 128 »though the canals themselves in the arrangement more nearlyresemble Calcarina, which is represented inFig. 12. In itssuperposition of many layers, and in its tendency to a heapedup or acervuline irregular growth it resemblesPolytrema andTinoporus, forms of a different group in so far as shell-structureis concerned. It may thus be regarded as a compositetype, combining peculiarities now observed in two groups, orit may be regarded as representing one of these in anotherseries. At the time when Dr. Carpenter stated theseaffinities, it might be objected that Foraminifera of thesefamilies are in the main found in the modern and Tertiaryperiods. Dr. Carpenter has since shown that the curious ovalForaminifer calledFusulina, found in the coal formation, isallied to both Nummulites and Rotalines; and Mr. Brady hasdiscovered a true Nummulite in the Lower Carboniferous ofBelgium. I have myself found small Foraminifera in theSilurian and Cambro-Silurian of Canada. This group beingnow brought down to the Palæozoic, we may hope to trace it tothe Primordial, and thus to bring it still nearer to Eozoon in time.

Though Eozoon was probably not the only animal of theLaurentian seas, yet it was in all likelihood the most conspicuousand important as a collector of calcareous matter,filling the same place afterwards occupied by the reef-buildingcorals. Though probably less efficient than these as a constructorof solid limestones, from its less permanent and continuousgrowth, it formed wide floors and patches on thesea bottom, and when these were broken up, vast quantities oflimestone were formed from theirdébris. It must also be bornein mind that Eozoon was not everywhere infiltrated with serpentineor other silicious minerals; quantities of its substancewere merely filled with carbonate of lime, resembling thechamber wall so closely that it is nearly impossible to make outthe difference, and thus is likely to pass altogether unobservedby collectors, and to baffle even the microscopist. Although,therefore, the layers which contain well characterised Eozoonare few and far between, there is reason to believe that in thecomposition of the limestones of the Laurentian it bore nosmall part, and as these limestones are some of them severalhundred feet in thickness, and extend over vast areas, Eozoonmay be supposed to have been as efficient a world-builder asthe Stromatoporæ of the Silurian and Devonian, the Globigerinæand their allies in the chalk, or the Nummulitesand Miliolites in the Eocene. It is a remarkable illustrationof the constancy of natural causes and of the persistence ofanimal types, that these humble Protozoans, which began tosecrete calcareous matter in the Laurentian period, have beencontinuing their work in the ocean through all the geologicalages, and are still busy in accumulating those chalky muds withwhich recent dredging operations in the deep sea have madeus so familiar. (See Note appended.)

All this seems sufficiently reasonable, more especially since« 130 »no mineralogist has yet succeeded in giving a feasible inorganicexplanation of the combination of canals, laminæ, tubulationand varied mineral character existing in Eozoon.But then comes the strange fact of its apparent isolation withoutcompanions in highly crystalline rocks, and with apparentlyno immediate successors. This has staggered many,and it certainly, if taken thus baldly, seems in some degreeimprobable. Recent discoveries, however, are removing thisreproach from Eozoon. The Laurentian rocks have yieldedother varieties, or perhaps species of the genus, those which Ihave described as variety Acervulina, and variety Minor, andstill another form, more like a Stromatopora, which I haveprovisionally namedE. latior, from the breadth and uniformityof its plates.[56] There are also in the Laurentian limestonecylindrical bodies apparently originally tubular, and with thesides showing radiating markings in the manner of corals, orof the curious Cambrian Archæocyathus. Matthew, a mostcareful observer, has found in the Laurentian limestone ofNew Brunswick certain laminated bodies of cylindrical form,constituting great reefs in the limestone, and in the slateslinear flat objects resembling Algæ or Graptolites, and spicularstructures resembling those of sponges.[57] Britton has also describedfrom the Laurentian limestone of New Jersey certainribbon-like objects of graphite which he regards as vegetable,and namesArchæophyton Newberryii.[58] Should these objectsprove to be organic, Eozoon will no longer be alone. Besidesthis the peculiar bodies named Cryptozoum by Hall, and whichare intermediate in structure between Eozoon and Loftusia,have now been found as low as the Lower Cambrian.[59] Barrois« 131 »has also recently announced the discovery of forms which heregards as akin to the modern Radiolaria, creatures of a littlehigher grade than the Foraminifera, in the "Archæan" rocksof Brittany.[60] Thus Eozoon is no longer isolated, but hascompanions of the same great age with itself. The progress ofdiscovery is also daily carrying the life of the Cambrian tolower beds, and thus nearer to the Laurentian. It is not unlikelythat in a few years a pre-Cambrian fauna will force itselfon the attention of the most sceptical geologists.

References:—"Life's Dawn on Earth," London, 1875. (Now out ofprint.) "Specimens of Eozoon Canadense in the Peter Red pathMuseum, Montreal," 1888. (This memoir contains reference to previouspapers.)

1.Stromatoporæ. It has been usual of late to regard these as allies ofthe modern Millepores and Hydractineæ; but careful study of large seriesof specimens has convinced me that some species, notably theStromatoceriumof the Cambro-Silurian and thecryptozoum of the Cambrian,cannot be so referred. I hope to establish this in the future, if timepermit.

2.Modern Foraminifera. The discovery by Brady and Lister ofreproductive chamberlets at the margin of the modernorbitolites, tends toconnect this with Eozoon. The gigantic foraminiferal species discoveredby Agassiz at the Gallipagos, has points of affinity with Eozoon; and itsarenaceous nature does not affect this, as we know sandy species in thisgroup closely allied to others that are calcareous.

WHAT MAY BE LEARNED FROM EOZOON.

DEDICATED TO THE MEMORY OF

DR. WILLIAM B. CARPENTER,

Who, among his many Services to Science,
devoted much Time and Labour to the Investigation
of Eozoon,
and by his Knowledge of Foraminifera
and unrivalled Power of unravelling difficult
Structures
did much to Render it intelligible.

The Microscope in Geology—Contributions of theStudy of Eozoon to our Knowledge of the Modeof Preservation of Fossils—Its Teaching Relativelyto the Origin of Life and the Laws of itsIntroduction and Progress

CHAPTER VI.

The microscope has long been a recognised and valuedaid of the geological observer, and is perhaps now indanger of being somewhat overrated by enthusiastic specialists.To the present writer its use is no novelty. When, as a veryyoung geologist, collecting fossil plants in the coal fields ofNovia Scotia, I obtained access to the then recently publishedwork of Witham on the "Internal Structure of Fossil Vegetables."[61]Fired by the desire to learn something of the structureof the blocks of fossil wood in my collection, I at once procureda microscope of what would now be considered a very imperfectkind, and proceeded to make attempts to slice andexamine my specimens, and was filled with joy when theseold blackened stems for the first time revealed to me theirwonderful structures. At the same time I extended mystudies to every minute form of life that could be obtainedfrom the sea or fresh waters. A few years later (in 1841), whena student in Edinburgh, I made the acquaintance of Mr.Sanderson of that city, who had worked for Nicol and Withamin the preparation of specimens, and learnt the modes which hehad employed. Since that time I have been accustomed tosubject every rock, earth or fossil which came under my noticeto microscopic scrutiny, not as a mere specialist in that modeof observation, or with the parade of methods and details nowcustomary, but with the view of obtaining valuable facts bearing« 136 »on any investigation I might have in hand. It was thishabit which induced my old friend, Sir William Logan, in 1858and subsequent years to ask my aid in the study of the formsbelieved or suspected to be organic, which had been discoveredin the course of his surveys of the Laurentian rocks. In onerespect this was unfortunate. It occupied much time, interferedto some extent with other researches, led to unpleasantcontroversies. But these evils were more than compensated bythe insight which the study gave into the fact of the persistenceof organic structures in highly crystalline rocks, and to themodes of ascertaining and profiting, by these obscure remains,while it has guided and stimulated enquiry and thought as tothe origin and history of life. These benefits entitle the researchesand discussions on Eozoon to be regarded as markinga salient point in the history of geological discovery, and it isto these principally that I would attract attention in the presentchapter.

Perhaps nothing excites more scepticism as to the animalnature of Eozoon than the prejudice existing among geologiststhat no organism can be preserved in rocks so highly crystallineas those of the Laurentian series. I call this a prejudice, becauseany one who makes the microscopic structure of rocksand fossils a special study, soon learns that fossils and therocks containing them may undergo the most remarkable andcomplete mechanical and chemical changes without losingtheir minute structure, and that limestones, if once fossiliferous,are hardly ever so much altered as to lose all traces of theorganisms which they contained, while it is a most commonoccurrence to find highly crystalline rocks of this kind aboundingin fossils preserved as to their minute structure.

When calcareous fossils of irregular surface and porous orcellular texture, such as Eozoon may have been, or corals were« 137 »and are, become imbedded in clay, marl, or other soft sediment,they can be washed out and recovered in a conditionsimilar to that of recent specimens, except that their pores orcells, if open, may be filled with the material of the matrix, orif not so open that they can be thus filled, they may be moreor less incrusted with mineral deposits introduced by waterpercolating the mass, or may even be completely filled up inthis way. But if such fossils are contained in hard rocks, theyusually fail, when these are broken, to show their external surfaces,and, breaking across with the containing rock, they exhibittheir internal structure merely,—and this more or lessdistinctly, according to the manner in which their cells orcavities have been filled with mineral matter. Here themicroscope becomes of essential service, especially when thestructures are minute. A fragment of fossil wood which tothe naked eye is nothing but a dark stone, or a coral which ismerely a piece of grey or coloured marble, or a specimen ofcommon crystalline limestone made up originally of coral fragments,presents, when sliced and magnified, the most perfectand beautiful structure. In such cases it will be found thatordinarily the original substance of the fossil remains in a moreor less altered state. Wood may be represented by dark linesof coaly matter, or coral by its white or transparent calcareouslaminæ; while the material which has been introduced, andwhich fills the cavities, may so differ in colour, transparency, orcrystallization, as to act differently on light, and so reveal theoriginal structure. These fillings are very curious. Sometimesthey are mere earthy or muddy matter which has been washedinto the cavities. Sometimes they are transparent and crystalline.Often they are stained with oxide of iron or coalymaterials. They may consist of carbonate of lime, silica orsilicates, sulphate of baryta, oxides of iron, carbonate of iron,iron pyrite, or sulphides of copper or lead, all of which arecommon materials. They are sometimes so complicated that« 138 »I have seen even the minute cells of woody structures, eachwith several bands of differently coloured materials depositedin succession, like the coats of an onyx agate.

A further stage of mineralisation occurs when the substanceof the organism is altogether removed and replaced by foreignmatter, either little by little, or by being entirely dissolved ordecomposed, leaving a cavity to be filled by infiltration. Inthis state are some silicified woods, and those corals whichhave been not filled with but replaced by silica, and can thussometimes be obtained entire and perfect by the solution inan acid of the containing limestone, or by its removal inweathering. In this state are the beautiful silicified corals obtainedfrom the corniferous limestone of Lake Erie, which areso perfectly replaced by flinty matter that when weathered outof the limestone, or treated with acid till the latter is removed,we find the coral as perfect as when recent. It may be wellto present to the eye these different stages of fossilization. Ihave attempted to do this inFig. 13, taking a tabulate coral ofthe genus Favosites for an example, and supposing the materialemployed to be calcite and silica. Precisely the same illustrationwould apply to a piece of wood, except that the cell wallwould be carbonaceous matter instead of carbonate of lime.In this figure the dotted parts represent carbonate of lime,the diagonally shaded parts silica or a silicate. Thus we havein the natural state the walls of carbonate of lime and thecavities empty (a). When fossilized the cavities may be merelyfilled with carbonate of lime, or they may be filled with silica(b, c); or the walls themselves may be replaced by silica, andthe cavities may remain filled with carbonate of lime (d); orboth the walls and cavities may be represented by or filledwith silica or silicates (e). The ordinary specimens of Eozoonare supposed to be in the third of these stages, though someexist in the second, and I have reason to believe that somehave reached to the fifth. I have not met with any in the« 139 »fourth stage, though this is not uncommon in Silurian andDevonian fossils. I have further to remark that the reasonwhy wood and the cells of corals so readily become silicified isthat the organic matter which they contain, becoming oxidizedin decay, produces carbon dioxide, which, by its affinity foralkalies, can decompose soluble silicates and thus throw downtheir silica in an insoluble state. Thus a fragment of decayingwood imbedded in a deposit holding water and alkalinesilicates almost necessarily becomes silicified. It is also to beremarked that the ordinary specimens of Eozoon have actuallynot attained to the extreme degree of mineralization seen insome much more recent silicified woods and corals, inasmuchas the portion believed to have been the original calcareoustest has not usually been silicified, but still remains in the stateof calcium carbonate.

With regard, then, to the calcareous organisms with which wehave now more especially to do, when these are embedded inpure limestone and filled with the same, so that the whole rock,fossils and cavities, is one in composition, and when metamorphicaction has caused the whole to become crystalline,and has perhaps removed the remains of carbonaceous matter,it may be very difficult to detect any traces of structure. But« 140 »even in this case careful management of light may reveal someindications. In many instances, however, even where thelimestones have become perfectly crystalline, and the cleavageplanes cut freely across the fossils, these exhibit their formsand minute structures in great perfection. This is the case inmany of the Lower Silurian limestones of Canada, as I haveelsewhere shown.[62] The grey crystalline Trenton limestone ofMontreal, used as a building stone, is an excellent illustration.To the naked eye it is a grey marble composed of cleavablecrystals; but when examined in thin slices, it shows its organicfragments in the greatest beauty, and all their minuteparts are perfectly marked out by delicate carbonaceous lines.The only exception in this limestone is in the case of thecrinoids, in which the cellular structure is filled with transparentcalc-spar, perfectly identical with the original solidmatter, so that they appear solid and homogeneous, but thereare examples in which even the minute meshes of these become'apparent. The specimen represented inFig. 14 is a mass ofCorals, Polyzoa, and Crinoids, and shows these under a lowpower, as represented in the figure. The specimen inFig. 15shows the Laurentian Eozoon in a similar state of preservation.It is from a sketch by Dr. Carpenter, and exhibits the delicatecanals partly filled with calcite or dolomite, as clear and colourlessas that of the shell itself, and distinguishable only by carefulmanagement of the light.

In the case of recent and fossil Foraminifers, these veryfrequently have their chambers filled solid with calcareousmatter, and as Dr. Carpenter well remarks, even well-preservedTertiary Nummulites in this state often fail greatly in showingtheir structures, though in the same condition they occasionallyshow these in great perfection. Among the finest I have seenare specimens from the Mount of Olives, and Dr. Carpentermentions as equally good those of the London clay at Bracklesham.But in no condition do modern Foraminifera, or thoseof the Tertiary and Mesozoic rocks appear in greater perfectionthan when filled with the hydrous silicate of iron and potashcalled glauconite or green earth, a substance now forming insome parts of the ocean, and which gives, by the abundance ofits little bottle-green concretions the name of "greensand" toformations of the Cretaceous age both in Europe and America.« 142 »In some beds of greensand every grain seems, to have beenmoulded into the interior of a microscopic shell, and has retainedits form after the frail envelope has been removed. Insome cases the glauconite has not only filled the chambersbut has penetrated the fine tubulation, and when the shell isremoved, either naturally or by the action of an acid, thesilicious fillings of the interior of the tubes project inminute needles or bundles of threads of marvellous delicacyfrom the surface of the cast. It is in the warmer seas, andespecially in the bed of the Egean and of the Gulf Stream, thatsuch specimens are now most usually found.[63] If we ask whythis mineral glauconite should be associated with foraminiferalshells, the answer is that they are both products of one kindof locality. The same sea bottoms in which Foraminiferamost abound are also those in which the chemical conditionsfor the formation of glauconite exist. Hence, no doubt, theassociation of this mineral with the great foraminiferal formationof the chalk. It is indeed by no means unlikely that theselection by these creatures of the pure carbonate of lime fromthe sea water or its minute plants, may be the means of settingfree the silica, iron, and potash, in a state suitable for theircombination. Similar silicates are found associated withmarine limestones, as far back as the Cambro-Silurian age;and Dr. Sterry Hunt, than whom no one can be a betterauthority on chemical geology, has argued on chemical groundsthat the occurrence of serpentine with the remains of Eozoonis an association of the same character.

However this may be, the infiltration of the pores of Eozoonwith serpentine and other silicates has evidently been one mainmeans of its preservation. When so infiltrated no metamorphismshort of the complete fusion of the containing rock« 143 »could obliterate the minutest points of structure; and thatsuch fusion has not occurred, the preservation in the Laurentianrocks of the most delicate lamination of the beds shows conclusively;while, as already stated, it can be shown that thealteration which has occurred might have taken place at atemperature far short of that necessary to fuse limestone.Thus has it happened that these most ancient fossils havebeen handed down to our time in a state of preservation comparable,as Dr. Carpenter states, to that of the best preservedfossil Foraminifera from the more recent formations that havecome under his observation in the course of all his long experience.

Let us now look more minutely at the nature of the typicalspecimens of Eozoon as originally observed and described, andthen turn to those preserved in other ways, or more or less destroyedor defaced. Taking a polished specimen from PetiteNation, we find the shell represented by white limestone, andthe chambers by light green serpentine. By acting on thesurface with a dilute acid we etch out the calcareous part,leaving a cast in serpentine of the cavities originally occupiedby the soft animal substance, and when this is done in polishedslices, these may be made to print their own characters onpaper, as has actually been done in the plate prefixed, whichis an electrotype from an etched specimen, and shows boththe laminated and acervuline parts of the fossil. If the processof decalcification has been carefully executed, we find inthe excavated spaces delicate ramifying processes of opaqueserpentine or transparent dolomite, which were originally imbeddedin the calcareous substance, and which are often ofextreme fineness and complexity.[64] (Figs.18,19.) These arecasts of the canals which traversed the shell when still inhabitedby the animal, and have subsequently been filled with mineral« 144 »matter. In evidence of this we sometimes find in a single canalan outer tubular layer of serpentine and an inner filling ofdolomite, just as vessels of fossil plants are sometimes filledwith successive coats of different materials. In some wellpreserved specimens we find the original cell wall representedby a delicate white film, which under the microscope showsminute needle-like parallel processes representing its still finertubuli. It is evident that to have filled these tubuli, the serpentinemust have been introduced in a state of actual solution,and must have carried with it no foreign impurities. Consequentlywe find that in the chambers themselves the serpentineis pure; and if we examine it under polarized light, we see thatit presents a singularly curdled or irregularly laminated appearance,as if it had an imperfectly crystalline structure, and hadbeen deposited in irregular laminæ, beginning at the sides ofthe chambers, and filling them toward the middle, and hadafterward been cracked by shrinkage, and the cracks filled witha second deposit of serpentine.[65] Now, serpentine is a hydroussilicate of magnesia, and all that we need to suppose is that inthe waters of the Laurentian sea magnesia was present insteadof iron, alumina or potash, and we can understand that theLaurentian fossil has been petrified by infiltration with serpentine,as more modern Foraminifera have been with glauconite,which, though it does not contain magnesia, often has aconsiderable percentage of alumina. Further, in specimens ofEozoon from Burgess, the filling mineral is loganite, a compoundof silica, alumina, magnesia and iron with water, whilein other specimens the filling mineral is pyroxene. In like« 145 »manner, in certain Silurian limestones from New Brunswickand Wales, in which the delicate microscopic pores of theskeletons of stalked starfishes or crinoids have been filled withmineral deposits, so that when decalcified these are most beautifullyrepresented by their casts, Dr. Hunt has proved the fillingmineral to be [66] intermediate between serpentine and glauconite.We have, therefore, ample warrant for adhering to his conclusionthat the Laurentian serpentine was deposited underconditions similar to those of the modern greensand. Indeed,independently of Eozoon, it is impossible that any geologistwho has studied the manner in which this mineral is associatedwith the Laurentian limestones could believe it to have been« 146 »formed in any other way. Nor need we be astonished at thefineness of the infiltration by which these minute tubes, perhaps1/10000 of an inch in diameter, are filled with mineral matter.The micro-geologist well knows how, in more modern deposits,the finest pores of fossils are filled, and that mineral matter insolution can penetrate the smallest openings that the microscopecan detect. Wherever the fluids of the living body canpenetrate, there also mineral substances can be carried, andthis natural injection, effected under great pressure and withthe advantage of ample time, can surpass any of the feats ofthe anatomical manipulator.Fig. 16 represents a microscopicjoint of a Crinoid from the Upper Silurian of New Brunswick,injected with the hydrous silicate already referred to, andFig.17 shows a microscopic chambered or spiral shell, from aWelsh Silurian limestone, with its cavities filled with a similarsubstance.

Taking the specimens preserved by serpentine as typical, wenow turn to certain other and, in some respects, less characteristicspecimens, which are nevertheless very instructive. Atthe Calumet some of the masses are partly filled with serpentineand partly with white pyroxene, an anhydrous silicate oflime and magnesia. The two minerals can readily be distinguishedwhen viewed with polarized light; and in some slicesI have seen part of a chamber or group of canals filled withserpentine and part with pyroxene. In this case the pyroxene,or the materials which now compose it, must have been introducedby infiltration, as well as the serpentine. This is themore remarkable as pyroxene is most usually found as an ingredientof igneous rocks; but Dr. Hunt has shown that in theLaurentian limestones, and also in veins traversing them, it« 148 »occurs under conditions which imply its deposition from water,either cold or warm. Gümbel remarks on this:—"Hunt, in avery ingenious manner, compares this formation and depositionof serpentine, pyroxene, and loganite, with that of glauconite,whose formation has gone on uninterruptedly from the Silurianto the Tertiary period, and is even now taking place in thedepths of the sea; it being well known that Ehrenberg andothers have already shown that many of the grains of glauconiteare casts of the interior of foraminiferal shells. In the light ofthis comparison, the notion that the serpentine and such-likeminerals of the primitive limestones have been formed, in asimilar manner, in the chambers of Eozoic Foraminifera, losesany traces of improbability which it might at first seem topossess."

In many parts of the skeleton of Eozoon, and even in thebest infiltrated serpentine specimens, there are portions of thecell wall and canal system which have been filled with calcareousspar or with dolomite, so similar to the skeleton that itcan be detected only under the most favourable lights andwith great care (Fig. 15,supra). It is further to be remarkedthat in all the specimens of true Eozoon, as well as in manyother calcareous fossils preserved in ancient rocks, the calcareousmatter, even when its minute structures are not preserved,or are obscured, presents a minutely granular or curdledappearance, arising, no doubt, from the original presence oforganic matter, and not recognised in purely inorganiccalcite.

Other specimens of fragmental Eozoon from the PetiteNation localities have their canals filled with dolomite, whichprobably penetrated them after they were broken up and imbeddedin the rock. I have ascertained, with respect to thesefragments of Eozoon, that they occur abundantly in certainlayers of the Laurentian limestone, beds of some thicknessbeing in great part made up of them, and coarse and fine fragments« 149 »occur in alternate layers, like the broken corals in someSilurian limestones.

Finally, on this part of the subject, careful observation ofmany specimens of Laurentian limestone which present notrace of Eozoon when viewed by the naked eye, and no evidenceof structure when acted on with acids, are neverthelessorganic, and consist of fragments of Eozoon, and possibly ofother organisms, not infiltrated with silicates, but only withcarbonate of lime, and consequently revealing only obscureindications of their minute structure. I have satisfied myselfof this by long and patient investigations, which scarcely admitof any adequate representation, either by words or figures.

Every worker in those applications of the microscope togeological specimens which have been termed micro-geology, isfamiliar with the fact that crystalline forces and mechanicalmovements of material often play the most fantastic tricks withfossilized organic matter. In fossil woods, for example, weoften have the tissues disorganized, with radiating crystallizationsof calcite and little spherical concretions of quartz, or disseminatedcubes and grains of pyrite, or little veins filled withsulphate of barium or other minerals. We need not, therefore,be surprised to find that in the venerable rocks containingEozoon, such things occur in the highly crystalline Laurentianlimestones, and even in some still showing the traces of Eozoon.We find many disseminated crystals of magnetite, pyrite,spinel, mica and other minerals, curiously curved prisms ofvermicular mica, bundles of aciculi of tremolite and similarsubstances, veins of calcite and crysotile or fibrous serpentine,which often traverse the best specimens. Where these occurabundantly, we usually find no organic structures remaining, orif they exist, they are in a very defective state of preservation.Even in specimens presenting the lamination of Eozoon to thenaked eye, these crystalline actions have often destroyed theminute structure; and I fear that some microscopists have« 150 »been victimized, by having under their consideration onlyspecimens in which the actual characters had been too muchdefaced to be discernible. No mistake can be greater than tosuppose that any and every specimen of Laurentian limestonemust contain Eozoon. More especially have I hitherto failedto detect traces of it in those carbonaceous or graphitic limestoneswhich are so very abundant in the Laurentian country.Perhaps where vegetable matter was very plentiful Eozoon didnot thrive, or, on the other hand, the growth of Eozoon mayhave diminished the quantity of vegetable matter. It is alsoto be observed that much compression and distortion have occurredin the beds of Laurentian limestone and their containedfossils, and also that the specimens are often broken by faults,some of which are so small as to appear only on microscopicexamination, and to shift the plates of the fossil just as if theywere beds of rock. This, though it sometimes producespuzzling appearances, is an evidence that the fossils were hardand brittle when this faulting took place, and is consequentlyan additional proof of their extraneous origin. In some specimensit would seem that the lower and older part of the fossilhad been wholly converted into serpentine or pyroxene, or hadso nearly experienced this change that only small parts of thecalcareous wall can be recognised. These portions correspondwith fossil woods altogether silicified, not only by the filling ofthe cells, but also by the conversion of the walls into silica. Ihave specimens which manifestly show the transition from theordinary condition of filling with serpentine to one in whichthe cell walls are represented obscurely by one shade of thismineral and the cavities by another. In general, however, itwill be gathered from the above explanations that the specimensof Eozoon fall short in thoroughness of mineralization of somefossils in much more modern rocks. I have specimens ofancient sponges whose spicular skeletons, originally silicious,have been replaced by pyrite or bisulphide of iron, and of« 151 »Tertiary fossil woods retaining perfectly their most minute structures,yet entirely replaced by silica, so that not a particle ofthe original wood remains.

The above considerations as to mode of preservation ofEozoon concur with those in the previous chapter in showingits oceanic character, if really a fossil; but the ocean of theEozoic period may not have been so deep as at present, and itswaters were probably warm and well stocked with mineralmatters derived from the newly formed land, or from hotsprings in its own bottom. On this point the interesting investigationsof Dr. Hunt with reference to the chemical conditionsof the Silurian seas allow us to suppose that the Laurentianocean may have been much more richly stored, moreespecially with salts of lime and magnesia, than that of subsequenttimes. Hence the conditions of warmth, light, and nutrimentrequired by such gigantic Protozoans would all be present,and hence, also, no doubt, some of the peculiarities of theirmineralization.

I desire by the above statement of facts to show, on the onehand, that the study of Eozoon, regarded as probably an ancientform of marine life, aids us in understanding other ancientfossils, and their manner of preservation; and on the other hand,that those who deny the organic origin of Eozoon place us inthe position of being unable, in any rational manner, to accountfor these forms, so characteristic of the Laurentian limestones,and set at naught the fair conclusions deducible from the modeof preservation of fossils in the later formations. The evidenceof organic origin is perhaps not conclusive, and in the presentstate of knowledge it is certain to be met with much scepticism,more especially by certain classes of specialists, whose grasp ofknowledge is not sufficiently wide to cover, on the one hand,fossilization and metamorphism, and on the other, to understandthe lower forms of life. It may, however, be sufficient toqualify us in turning our thoughts for a few moments to considerations« 152 »suggested by the probable origin of animal life inthe seas of the Laurentian period.

Looking down from the elevation of our physiological andmental superiority, it is difficult to realize the exact conditionsin which life exists in creatures so simple as the Protozoa.There may perhaps be higher intelligences, that find it equallydifficult to realize how life and reason can manifest themselvesin such poor houses of clay as those we inhabit. But placingourselves near to these creatures, and entering, as it were, intosympathy with them, we can understand something of theirpowers and feelings. In the first place it is plain that theycan vigorously, if roughly, exercise those mechanical, chemical,and vegetative powers of life which are characteristic of theanimal. They can seize, swallow, digest, and assimilate food;and, employing its albuminous parts in nourishing theirtissues, can burn away the rest in processes akin to our respiration,or reject it from their system. Like us, they can subsistonly on food which the plant has previously produced;for in this world, from the beginning of time, the plant hasbeen the only organism which could use the solar light andheat as forces to enable it to turn the dead elements of matterinto living, growing tissues, and into organic compoundscapable of nourishing the animal. Like us, the Protozoa expendthe food which they have assimilated in the productionof animal force, and in doing so cause it to be oxidized, orburnt away, and resolved again into dead matter. It is truethat we have much more complicated apparatus for performingthese functions, but it does not follow that these give us muchreal superiority, except relatively to the more difficult conditionsof our existence. The gourmand who enjoys his dinnermay have no more pleasure in the act than the Amœba whichswallows a Diatom; and for all that the man knows of thesubsequent processes to which the food is subjected, his interiormight be a mass of jelly, with extemporised vacuoles,« 153 »like that of his humble fellow-animal. The clay is after allthe same, and there may be as much difficulty in the makingof a simple organism with varied powers, as a more complexframe for doing higher work.

In order that we may feel, a complicated apparatus ofnerves and brain cells has to be constructed and set to work;but the Protozoon, without any distinct brain, is all brain, andits sensation is simply direct. Thus vision in these creaturesis probably performed in a rough way by any part of theirtransparent bodies, and taste and smell are no doubt in thesame case. Whether they have any perception of sound asdistinct from the mere vibrations ascertained by touch, we donot know. Here, also, we are not far removed above the Protozoa,especially those of us to whom touch, seeing and hearingare direct acts, without any thought or knowledge of theapparatus employed. We might, so far, as well be Amœbas.As we rise higher we meet with more differences. Yet it isevident that our gelatinous fellow being can feel pain, dreaddanger, desire possessions, enjoy pleasure, and in a direct unconsciousway entertain many of the appetites and passionsthat affect ourselves. The wonder is that with so little oforganization it can do so much. Yet, perhaps, life can manifestitself in a broader and more intense way where there islittle organization, and a highly strung and complex organismis not so much a necessary condition of a higher life as a meremeans of better adapting it to its present surroundings.

A similar lesson is taught by the complexity of theirskeletons. We speak in a crude, unscientific way of theseanimals accumulating calcareous matter, and building upreefs of limestone. We must, however, bear in mind that theyare as dependent on their food for the materials of theirskeletons as we are, and that their crusts grow in the interiorof the sarcode just as our bones do within our bodies. Theprovision even for nourishing the interior of the skeleton by« 154 »tubuli and canals is in principle similar to that involved in thecanals, cells, and canalicules of bone. The Amœba, of course,knows neither more nor less of this than the average Englishman.It is altogether a matter of unconscious growth. Theprocess in the Protozoa strikes some minds, however, as themore wonderful of the two. It is, says an eminent modernphysiologist, a matter of "profound significance" that this"particle of jelly [the sarcode of a Foraminifer] is capable ofguiding physical forces in such a manner as to give rise tothese exquisite and almost mathematically arranged structures."Respecting the structures themselves there is no exaggerationin this. No arch or dome framed by human skill is moreperfect in beauty or in the realization of mechanical ideas thanthe tests of some Foraminifera, and none is so complete andwonderful in its internal structure. The particle of jelly, however,is a figure of speech. The body of the humblest Foraminiferis much more than this. It is an organism with diversparts, and it is endowed with the mysterious forces of life whichin it guide the physical forces, just as they do in building upphosphate of lime in our bones, or indeed, just as the will ofthe architect does in building a palace. The profound significancewhich this has, reaches beyond the domain of thephysical and vital, even to the spiritual. It clings to all ourconceptions of living things: "quite as much, for example, tothe evolution of an animal with all its parts from a one-celledgerm, as to the connection of brain cells with the manifestationsof intelligence." Viewed in this way, we may share withthe author of the sentence I have quoted his feeling of venerationin the presence of this great wonder of animal life, "burning,and not consumed," nay, building up, and that in manyand beautiful forms. We may realize it most of all in thepresence of the organism which was perhaps the first to manifeston our planet these marvellous powers. We must, however,here also, beware of that credulity which makes too many« 155 »thinkers limit their conceptions altogether to physical force inmatters of this kind The merely materialistic physiologist isreally in no better position than the savage who quails beforethe thunderstorm, or rejoices in the solar warmth, and seeingno force or power beyond, fancies himself in the immediatepresence of his God. In Eozoon we must discern not only amass of jelly but a being endowed with that higher vital forcewhich surpasses vegetable life, and also physical and chemicalforces; and in this animal energy we must see an emanationfrom a Will higher than our own, ruling vitality itself; andthis not merely to the end of constructing the skeleton of aProtozoon, but of elaborating all the wonderful developmentsof life that were to follow in succeeding ages, and with referenceto which the production and growth of this creaturewere initial steps. It is this mystery of design which reallyconstitutes the "profound significance" of the foraminiferalskeleton.

Another phenomenon of animality forced upon our noticeby the Protozoa is that of the conditions of life in animals notindividual, as we are, but aggregative and cumulative in indefinitemasses. What, for instance, the relations to eachother of the Polyps, growing together in a coral mass, or theseparate parts of a Sponge, or the separate lobes of a Foraminifer.In the case of the Polyps we may believe that thereis special sensation in the tentacles and oral opening of eachindividual, and that each may experience hunger when inwant, or satisfaction when it is filled with food, and that injuriesto one part of the mass may indirectly affect other parts,but that the nutrition of the whole mass may be as muchunfelt by the individual Polyps as the processes going on inour own liver are by us. So in the case of a large Sponge, orForaminifer, there may be some special sensation in individualcells, pseudopods, or segments, and the general sensation maybe very limited, while unconscious living powers pervade the« 156 »whole. In this matter of aggregation of animals we have thusvarious grades. The Foraminifers and Sponges present uswith the simplest of all, and that which most resembles theaggregation of buds in the plant. The Polyps and complexBryozoons present a higher and more specialized type; andthough the bilateral symmetry which obtains in the higheranimals is of a different nature, it still at least reminds us ofthat multiplication of similar parts which we see in the lowergrades of being. It is worthy of notice here that the loweranimals which show aggregative tendencies present but imperfectindications, or none at all, of bilateral symmetry.Their bodies, like those of plants, are for the most part builtup around a central axis, or they show tendencies to spiralmodes of growth.

It is this composite sort of life which is connected with themain geological function of the Foraminifer. While activesensation, appetite, and enjoyment pervade the pseudopodsand external sarcode of the mass, the hard skeleton commonto the whole is growing within; and in this way the calcareousmatter is gradually removed from the sea water, and built upin solid reefs, or in piles of loose foraminiferal shells. Thusit is the aggregative or common life, alike in Foraminifers asin Corals, that tends most powerfully to the accumulation ofcalcareous matter; and those creatures whose life is of thiscomplex character are best suited to be world builders, sincethe result of their growth is not merely a cemetery of theirosseous remains, but a huge communistic edifice, to whichmultitudes of lives have contributed, and in which successivegenerations take up their abode on the remains of their ancestors.This process, so potent in the progress of the earth'sgeological history, began, as far as we know, with Eozoon.

Whether, then, in questioning our proto-foraminifer, we havereference to the vital functions of its gelatinous sarcode, to thecomplexity and beauty of its calcareous test, or to its capacity« 157 »for effecting great material results through the union of individuals,we perceive that we have to do, not with a lowcondition of those powers which we designate life, but withtheir manifestation through the means of a simple organism;and this in a degree of perfection which we, from our point ofview, would have in the first instance supposed impossible.

If we imagine a world altogether destitute of life, we stillmight have geological formations in progress. Not only wouldvolcanoes belch forth their liquid lavas and their stones andashes, but the waves and currents of the ocean and the rainsand streams on the land, with the ceaseless decomposing actionof the carbonic acid of the atmosphere, would be piling upmud, sand, and pebbles in the sea. There might even besome formation of limestone taking place where springs chargedwith bicarbonate of lime were oozing out on the land or thebottom of the waters. But in such a world all the carbonwould be in the state of carbon dioxide, and all the limestonewould either be diffused in small quantities through variousrocks or in limited local beds, or in solution, perhaps aschloride of calcium, in the sea. Dr. Hunt has given chemicalgrounds for supposing that the most ancient seas were largelysupplied with this very soluble salt, instead of the chloride ofsodium, or common salt, which now prevails in the sea water.

Where in such a world would life be introduced? on theland or in the waters? All scientific probability would sayin the latter.[67] The ocean is now vastly more populous thanthe land. The waters alone afford the conditions necessaryat once for the most minute and the grandest organisms, atonce for the simplest and for others of the most complexcharacter. Especially do they afford the best conditions for« 158 »those animals which subsist in complex communities, andwhich aggregate large quantities of mineral matter in theirskeletons. So true is this that up to the present time all thespecies of Protozoa and of the animals most nearly allied tothem are aquatic. Even in the waters, however, plant life,though possibly in very simple forms, must precede theanimal.

Let humble plants, then, be introduced in the waters, andthey would at once begin to use the solar light for the purposeof decomposing carbonic acid, and forming carbon compoundswhich had not before existed, and which, independently ofvegetable life, would never have existed. At the same timelime and other mineral substances present in the sea waterwould be fixed in the tissues of these plants, either in a minutestate of division, as little grains or Coccoliths, or in more solidmasses like those of the Corallines and Nullipores. In thisway a beginning of limestone formation might be made, andquantities of carbonaceous and bituminous matter, resultingfrom the decay of vegetable substances might accumulate onthe sea bottom. Now arises the opportunity for animal life.The plants have collected stores of organic matter, and theirminute germs, along with microscopic species, are floatingeverywhere in the sea. The plant has fulfilled its function asfar as the waters are concerned, and now a place is preparedfor the animal. In what form shall it appear? Many of itshigher forms, those which depend upon animal food or on themore complex plants for subsistence, would obviously be unsuitable.Further, the sea water is still too much saturatedwith saline matter to be fit for the higher animals of the waters.Still further, there may be a residue of internal heat forbiddingcoolness, and that solution of free oxygen which is an essentialcondition of existence to the higher forms of life. Somethingmust be found suitable for this saline, imperfectly oxygenated,tepid sea. Something, too, is wanted that can aid in introducing« 159 »conditions more favourable to higher life in the future.Our experience of the modern world shows us that all theseconditions can be better fulfilled by the Protozoa than by anyother creatures. They can live now equally in those greatdepths of ocean where the conditions are most unfavourableto other forms of life, and in tepid unhealthy pools overstockedwith vegetable matter in a state of putridity. They form amost suitable basis for higher forms of life. They have remarkablepowers of removing mineral matters from the watersand of fixing them in solid forms. So, in the fitness of things,a gigantic Foraminifer is just what we need, and after it hasspread itself over the mud and rock of the primeval seas, andbuilt up extensive reefs therein, other animals may be introduced,capable of feeding on it, or of sheltering themselves inits stony masses, and thus we have the appropriate dawn ofanimal life.

But what are we to say of the cause of this new series offacts, so wonderfully superimposed upon the merely vegetableand mineral? Must it remain to us as an act of creation, orwas it derived from some pre-existing matter in which it hadbeen potentially present? Science fails to inform us, but conjectural"phylogeny" steps in and takes its place. Haeckel,the prophet of this new philosophy, waves his magic wand,and simple masses of sarcode spring from inorganic matter,and form diffused sheets of sea slime, from which are in timeseparated distinct amœboid and foraminiferal forms. Experience,however, gives us no facts whereon to build thissupposition, and it remains neither more nor less scientific orcertain than that old fancy of the Egyptians, which derivedanimals from the fertile mud of the Nile.

If we fail to learn anything of the origin of Eozoon, and ifits life processes are just as inscrutable as those of highercreatures, we can at least enquire as to its history in geologicaltime. In this respect we find, in the first place, that« 160 »the Protozoa have not had a monopoly in their profession ofaccumulators of calcareous rock.

Originated by Eozoon in the old Laurentian time, this processhas been proceeding throughout the geological ages; andwhile Protozoa, equally simple with the great prototype of therace, have been and are continuing its function, and producingnew limestones in every geological period, and so adding tothe volume of the successive formations, new workers of highergrades have been introduced, capable of enjoying higher formsof animal activity, and equally of labouring at the great taskof continent building; of existing, too, in seas less rich inmineral substances than those of the Eozoic time, and for thatvery reason better suited to higher and more skilled artists. Itis to be observed in connection with this, that as the work ofthe Foraminifers has thus been assumed by others, their sizeand importance have diminished, and the larger forms ofmore recent times have some of them been fain to build uptheir hard parts of cemented sand instead of limestone.

When the marvellous results of recent deep-sea dredgingswere first made known, and it was found that chalky foraminiferalearth is yet accumulating in the Atlantic, with spongesand sea urchins, resembling in many respects those whoseremains exist in the chalk, the fact was expressed by the statementthat we still live in the chalk period. Thus stated theconclusion is scarcely correct. We do not live in the chalkperiod, but the conditions of the chalk period still exist in thedeeper portions of the sea. We may say more than this. Tosome extent the conditions of the Laurentian period still existin the sea, except in so far as they have been removed by theaction of the Foraminifera and other limestone builders. Tothose who can realize the enormous lapse of time involved inthe geological history of the earth, this conveys an impressionalmost of eternity in the existence of this oldest of all thefamilies of the animal kingdom.

We are still more deeply impressed with this when we bringinto view the great physical changes which have occurred sincethe dawn of life. When we consider that the skeletons ofEozoon contribute to form the oldest hills of our continents;that they have been sealed up in solid marble, and that theyare associated with hard crystalline rocks contorted in themost fantastic manner; that these rocks have almost from thebeginning of geological time been undergoing waste to supplythe material of new formations; that they have witnessed innumerablesubsidences and elevations of the continents; andthat the greatest mountain chains of the earth have been builtup from the sea since Eozoon began to exist,—we acquire amost profound impression of the persistence of the lower formsof animal life, and know that mountains may be removed andcontinents swept away and replaced, before the least of thehumble gelatinous Protozoa can finally perish. Life may bea fleeting thing in the individual, but as handed down throughsuccessive generations of beings, and as a constant animatingpower in successive organisms, it appears, like its Creator,eternal.

This leads to another and very serious question. How longdid lineal descendants of Eozoon exist, and do they still exist?We may for the present consider this question apart from ideasof derivation and elevation into higher planes of existence.Eozoon as a species, and even as a genus, may cease to existwith the Eozoic age, and we have no evidence whatever thatany succeeding creatures are its modified descendants. As faras their structures inform us, they may as much claim to beoriginal creations as Eozoon itself. Still descendants of Eozoonmay have continued to exist, though we have not yet met withthem. I should not be surprised to hear of a veritable specimenbeing some day dredged alive in the Atlantic or thePacific. It is also to be observed that in animals so simple asthis many varieties may appear, widely different from the« 162 »original. In these the general form and habit of life are themost likely things to change, the minute structures much lessso. We need not, therefore, be surprised to find its descendantsdiminishing in size or altering in general form, while thecharacters of the fine tubulation and of the canal system wouldremain. We need not wonder if any sessile Foraminifer of theNummuline group should prove to be a descendant of Eozoon.It would be less likely that a Sponge or a Foraminifer of theRotaline type should originate from it. If one could onlysecure a succession of deep-sea limestones with Foraminifersextending all the way from the Laurentian to the present time,I can imagine nothing more interesting than to compare thewhole series, with the view of ascertaining the limits of descentwith variation, and the points where new forms are introduced.We have not yet such a series, but it may be obtained; and asthese creatures are eminently cosmopolitan, occurring overvastly wide areas of sea bottom, and are very variable, theywould afford a better test of theories of derivation than anythat can be obtained from the more locally distributed andless variable animals of higher grade. I was much struck withthis recently, in examining a series of Foraminifera fromthe Cretaceous of Manitoba, and comparing them with thevarietal forms of the same species in the interior of Nebraska,500 miles to the south, and with those of the English chalk andof the modern seas. In all these different times and places wehad the same species. In all they existed under so manyvarietal forms passing into each other, that in former timesevery species had been multiplied by naturalists into several.Yet, in all, the identical varietal forms were repeated with themost minute markings the same. Here were at once constancythe most remarkable, and variations the most extensive. If wedwell on the one to the exclusion of the other, we reach onlyone-sided conclusions, imperfect and unsatisfactory. By takingboth into connection we can alone realize the full significance« 163 »of the facts. We cannot yet obtain such series for all geologicaltime; but it may even now be worth while to enquire, What dowe know as to any modification in the case of the primevalForaminifers, whether with reference to the derivation fromthem of other Protozoa or of higher forms of life?

There is no link in geological fact to connect Eozoon withany of the Mollusks, Radiates, or Crustaceans of the succeedingCambrian. What may be discovered in the future we cannotconjecture; but at present these stand before us as distinctcreations. It would of course be more probable that Eozoonshould be the ancestor of some of the Foraminifera of thePrimordial age, but strangely enough it is very dissimilar fromall these, except Cryptozoum and some forms of Stromatopora;and here, as already stated, the evidence of minute structurefails to a great extent. Of actual facts, therefore, we havenone; and those evolutionists who have regarded the dawnanimal as an evidence in their favour have been obliged to haverecourse to supposition and assumption.

We may imagine Eozoon itself, however, to state its experienceas follows:—"I, Eozoon Canadense, being a creature oflow organization and intelligence, and of practical turn, am notheorist, but have a lively appreciation of such facts as I amable to perceive. I found myself growing upon the sea bottom,and know not whence I came. I grew and flourished for ages,and found no let or hindrance to my expansion, and abundanceof food was always floated to me without my having to go insearch of it. At length a change came. Certain creatureswith hard snouts and jaws began to prey on me. Whencethey came I know not; I cannot think that they came fromthe germs which I had dispersed so abundantly throughout theocean. Unfortunately, just at the same time lime became alittle less abundant in the waters, perhaps because of the greatdemands I myself had made, and thus it was not so easy asbefore to produce a thick supplemental skeleton for defence.« 164 »So I had to give way. I have done my best to avoid extinction;but it is clear that I must at length be overcome, andmust either disappear or subside into a humbler condition, andthat other creatures better provided for the new conditions ofthe world must take my place." In such terms we may supposethat this patriarch of the seas might tell his history, and mournhis destiny, though he might also congratulate himself on havingin an honest way done his duty and fulfilled his function inthe world, leaving it to other and perhaps wiser creatures todispute as to his origin and fate, while perhaps much lessperfectly fulfilling the ends of their own existence.

Thus our dawn animal has positively no story to tell as toits own introduction or its transmutation into other forms ofexistence. It leaves the mystery of creation where it was, butin connection with the subsequent history of life we can learnfrom it a little as to the laws which have governed the successionof animals in geological time. First, we may learn thatthe plan of creation has been progressive, that there has beenan advance from the few low and generalized types of theprimæval ocean to the more numerous, higher, and morespecialized types of more recent times. Secondly, we learn thatthe lower types, when first introduced, and before they weresubordinated to higher forms of life, existed in some of theirgrandest modifications as to form and complexity, and thatin succeeding ages, when higher types were replacing them,they were subjected to decay and degeneracy. Thirdly, welearn that while the species has a limited term of existence ingeological time, any large type of animal existence, like that ofthe Foraminifera or Sponges, for example, once introduced,continues and finds throughout all the vicissitudes of the earthsome appropriate residence. Fourthly, as to the mode of introductionof new types, or whether such creatures as Eozoonhad any direct connection with the subsequent introductionof Mollusks, Worms, or Crustaceans, it is altogether silent, nor« 165 »can it predict anything as to the order or manner of theirintroduction.

Had we been permitted to visit the Laurentian seas, and tostudy Eozoon and its contemporary Protozoa when alive, it isplain that we could not have foreseen or predicted from theconsideration of such organisms the future development of life.No amount of study of the prototypal Foraminifer could haveled us distinctly to the conception of even a Sponge or a Polyp,much less of any of the higher animals. Why is this? Theanswer is that the improvement into such higher types does nottake place by any change of the elementary sarcode, either inthose chemical, mechanical, or vital properties which we canstudy, but in the adding to it of new structures. In the Sponge,which is perhaps the nearest type of all, we have the movablepulsating cilium and true animal cellular tissue, and along withthis the spicular or fibrous skeleton, these structures leading toan entire change in the mode of life and subsistence. In thehigher types of animals it is the same. Even in the highest wehave white blood corpuscles and germinal matter, which, in sofar as we know, carry on no higher forms of life than those of anAmœba; but they are now made subordinate to other kinds oftissues, of great variety and complexity, which never have beenobserved to arise out of the growth of any Protozoon. Therewould be only a few conceivable inferences which the highestfinite intelligence could deduce as to the development of futureand higher animals. He might infer that the Foraminiferalsarcode, once introduced, might be the substratum or foundationof other but unknown tissues in the higher animals, andthat the Protozoon type might continue to subsist side by sidewith higher forms of living things, as they were successivelyintroduced. He might also infer that the elevation of theanimal kingdom would take place with reference to those newproperties of sensation and voluntary motion in which thehumblest animals diverge from the life of the plant.

It is important that these points should be clearly before ourminds, because there has been current of late among naturalistsa loose way of writing with reference to them, which seemsto have imposed on many who are not naturalists. It has beensaid, for example, that such an organism as Eozoon may includepotentially all the structures and functions of the higheranimals, and that it is possible that we might be able to inferor calculate all these with as much certainty as we can calculatean eclipse or any other physical phenomenon. Now, thereis not only no foundation in fact for these assertions, but it is,from our present standpoint, not conceivable that they can everbe realized. The laws of inorganic matter give no data whenceanyà priori deductions or calculations could be made as tothe structure and vital forces of the plant. The plant gives nodata from which we can calculate the functions of the animal.The Protozoon gives no data from which we can calculate thespecialties of the Mollusk, the Articulate, or the Vertebrate.Nor, unhappily, do the present conditions of life of themselvesgive us any sure grounds for predicting the new creations thatmay be in store for our old planet. Those who think to builda philosophy and even a religion on such data are meredreamers, and have no scientific basis for their dogmas. Theyare as blind guides as our primæval Protozoon himself wouldbe in matters whose real solution lies in the harmony of ourown higher and immaterial nature with the Being who is theAuthor of all life—the Father "from whom every family inheaven and earth is named."

References:—"Life's Dawn on Earth." London, 1885. Specimens
of Eozoon in the Peter Redpath Museum, Montreal, 1888.

THE APPARITION AND SUCCESSION OF ANIMAL FORMS.

DEDICATED TO THE MEMORY OF
THE EMINENT SWISS AND AMERICAN ZOOLOGIST

LOUIS AGASSIZ,

The Founder of the Modern School of American Biology,
and of

SIR RICHARD OWEN,

A Great and Philosophical Naturalist,
to whose Teaching I and very many Others owe our earliest
introduction to the Principle of Homology
in the Animal Kingdom.

Modern Ideas of Derivation—Development of AnimalForms in Time—Various Theories of Derivation—Historyof Organic Types—History of Organs—Testimonyof the Geological Record—Laws of theSuccession Development and Evolution—EvolutionistTheologians

CHAPTER VII.

Time was when naturalists were content to take nature asthey found it, without any over-curious inquiries as tothe origin of its several parts, or the changes of which theymight be susceptible. Geology first removed this pleasantstate of repose, by showing that all our present species hada beginning, and were preceded by others, and these againby others. Geologists were, however, too much occupied withthe facts of the succession to speculate on the ultimate causesof the appearance and disappearance of species, and it remainedfor zoologists and botanists, or as some prefer to callthemselves, biologists, to construct hypotheses or theories toaccount for the ascertained fact that successive dynasties ofspecies have succeeded each other in time. I do not proposein this paper so much to deal with the various doctrines as toderivation and development now current, as to ask the question,What do we actually know as to the origin and history oflife on our planet?

This great question, confessedly accompanied with manydifficulties and still waiting for its full solution, has points ofintense interest both for the Geologist and the Biologist."If," says the great founder of the uniformitarian School ofGeology, "the past duration of the earth be finite, then theaggregate of geological epochs, however numerous, must constitutea mere moment of the past, a mere infinitesimal portionof eternity." Yet to our limited vision, the origin of life fades« 170 »away in the almost illimitable depths of past time, and we areready to despair of ever reaching, by any process of discovery,to its first steps of progress. At what time did life begin? Inwhat form did dead matter first assume or receive thosemysterious functions of growth, reproduction and sensation?Only when we picture to ourselves an absolutely lifeless world,destitute of any germ of life or organization, can we realizethe magnitude of these questions, and perceive how necessaryit is to limit their scope if we would hope for any satisfactoryanswer.

We may here dismiss altogether that form in which thesequestions present themselves to the biologist, when he experimentsas to the evolution of living forms from dead liquids orsolids attacking the unsolved problem of spontaneous generation.Nor need we enter on the vast field of discussion as tomodern animals and plants opened up by Darwin and others.I shall confine myself altogether to that historical or palæontologicalaspect in which life presents itself when we study thefossil remains entombed in the sediments of the earth's crust,and which will enable me at least to show why some studentsof fossils hesitate to give in their adhesion to any of the currentnotions as to the origin of species. It will also be desirableto avoid, as far as possible, the use of the term "evolution,"as this has recently been employed in so many senses, whetherof development or causation, as to have become nearly uselessfor any scientific purpose; and that when I speak of creationof species, the term is to be understood not in the arbitrarysense forced on it by some modern writers, but as indicatingthe continuous introduction of new forms of life under definitelaws, but by a power not emanating from within themselves,nor from the inanimate nature surrounding them.[68]

If we were to follow the guidance of those curious analogieswhich present themselves when we consider the growth of theindividual plant or animal from the spore or the ovum, and thedevelopment of vegetable and animal life in geological time—analogieswhich, however, it must be borne in mind can haveno scientific value whatever, inasmuch as that similarity ofconditions which alone can give force to reasoning from analogyin matters of science, is wholly wanting—we should expectto find in the oldest rocks embryonic forms alone, but ofcourse embryonic forms suited to exist and reproduce themselvesindependently.[69]

I need not say to palæontologists that this is not what weactually find in the primordial rocks. I need but to remindthem of the early and remarkable development of such formsas the Trilobites, the Lingulidæ and the Pteropods, all of themhighly complex and specialized types, and remote from theembryonic stages of the groups to which they severally belong.In the case of the Trilobites, one need merely consider thebeautiful symmetry of their parts, both transversely and longitudinally,their division into distinct regions, the necessary complexityof their muscular and nervous systems, their highlycomplex visual organs, the superficial ornamentation and microscopicstructure of their crusts, their advanced position amongCrustaceans, indicated by their strong affinity with the Arachnidansor spiders and scorpions. (See figures prefixed.)

All these characters give them an aspect far from embryonic,while, as Barrande has pointed out, this advanced position ofthe group has its significance greatly strengthened by the factthat in early primordial times we have to deal not with onespecies, but with a vast and highly differentiated group, embracingforms of many and varied subordinate types. As we shallsee, these and other early animals may be regarded as ofgeneralized types, but not as embryonic. Here, then, meets usat the outset the fact that in as far as the great groups of annuloseand molluscous animals are concerned, we can trace theseback no farther than to a period in which they appear alreadyhighly advanced, much specialized and represented by manydiverse forms. Either, therefore, these great groups came in onthis high initial plane, or we have scarcely reached half wayback in the life-history of our planet.

We have, here, however, by this one consideration, attainedat once to two great and dominant laws regulating the historyof life. First, the law of continuity, whereby new formscome in successively, throughout geological time, though,as we shall see, with periods of greater or less frequency.Secondly, the law of specialization of types, whereby generalizedforms are succeeded by those more special, and this probablyconnected with the growing specialization of the inorganicworld. It is this second law which causes the parallelismbetween the history of successive species and that of theembryo.

We have already considered the claims which Eozoon andits contemporaries may urge to recognition, as beginnings oflife; but when we ascend from the Laurentian beds, we findourselves in a barren series of conglomerates, sandstones, andother rocks, indicating shore rather than sea conditions, andremarkably destitute of indications of life. These are theHuronian beds, and possibly other series associated with them.They have afforded spicules of sponges, casts of burrows of« 173 »worms, obscure forms, which may represent crustaceans ormollusks, markings of unknown origin, and some laminatedforms which may perhaps represent remains of Eozoon, thoughtheir structures are imperfectly preserved. These are sufficientto show that marine life continued in some forms, and to encouragethe hope that a rich pre-Cambrian fauna may yet bediscovered.

But let us leave for the present the somewhat isolated caseof Eozoon, and the few scattered forms of the Huronian, andgo on farther to the early Cambrian fauna. This is graphicallypresented to us in the sections in South Wales, as describedby Hicks. Here we find a nucleus of ancient rocks,supposed to be Laurentian, though in mineral character morenearly akin to the Huronian, but which have hitherto affordedno trace of fossils. Resting unconformably on these is aseries of slates and sandstones, regarded as Lower Cambrian,the Caerfai group of Hicks, and which are the earliest holdingorganic remains. The lowest bed which contains indicationsof life is a red shale near the base of the series, which holds afew organic remains. The species are aLingulella, worm burrowsand a Trilobite.[70] Supposing these to be all, it is remarkablethat we have no Protozoa or Corals or Echinoderms, andthat the types of Brachiopods and Crustaceans are of comparativelymodern affinities. Passing upward through 1,000 feetof barren sandstone and shale, we reach a zone in whichmany Trilobites of at least five genera are found, along withPteropods, Brachiopods and Sponges. Thus it is that lifecomes in at the base of the Cambrian in Wales, and it may beregarded as a fair specimen of the facts as they appear in theearlier fossiliferous beds succeeding the Laurentian. Takingthe first of these groups of fossils, we may recognise in theworms representatives of those that still haunt our shores, inthe Trilobite a Crustacean or Arachnoid of no mean grade.« 174 »TheLingulellæ, whether we regard them as molluscoids, or,with Professor Morse, as singularly specialized worms, representa peculiar and distinct type, handed down, through all thevicissitudes of the geological ages, to the present day. Hadthe Primordial life begun with species altogether inscrutableand unexampled in succeeding ages, this would no doubt havebeen mysterious; but next to this is the mystery of the oldestforms of life being also among the newest. One great factshines here with the clearness of noon-day. Whatever theorigin of these creatures, they represent families which haveendured till now in the struggle for existence without eitherelevation or degradation. Here, again, we may formulate anothercreative law. In every great group there are some formsmuch more capable of long continuance than others. Lingulaamong the Brachiopods is a marked instance.

But when, with Hicks, we surmount the mass of barren bedsunderlying these remains, which from its unfossiliferous characteris probably a somewhat rapid deposit of Arctic mud, likethat which in all geological time has constituted the rough fillingof our continental formations, and have suddenly sprungupon us many genera of Trilobites, including the fewest-jointedand most many-jointed, the smallest and the largest of theirrace, our astonishment must increase, till we recognise the factthat we are now in the presence of another great law of creation,which provides that every new type shall be rapidly extendedto the extreme limits of its power of adaptation.

That this is not merely local is evidenced by the researchesof Matthew and Walcott in the oldest Cambrian of America,where a similar succession occurs, but with this difference, thatin the wider area presented by the American continent we finda greater variety of forms of life. Walcott records up to 1892no less than 67 genera and 165 species in the oldest Cambrianof America. These include representatives of the Sponges,Hydroids, Corals, Echinoderms, Worms, Brachiopods, Bivalve« 175 »and Univalve Mollusks and Crustaceans, or in other words, allthe leading groups of invertebrate animals that we find in thesea at present. Of these the dominant group is the Crustaceans,including Trilobites, numbering one-third of the whole; andthese with the univalve Mollusks and the Brachiopods constitutethe majority, the other groups having comparatively few species.What a marvellous incoming of life is here! Walcott maywell say that on the theory of gradual development we mustsuppose that life existed at a period far before the Cambrian—asfar, indeed, as the Cambrian is before our own time. Butthis would mean that we know only half of the history of life;and perhaps it is more reasonable to suppose that when theconditions became favourable, it came in with a rush.

Before considering the other laws that may be inferred fromthese facts, however, let us in imagination transfer ourselvesback to the Primordial age, and suppose that we have in ourhands a living specimen of one of the larger Trilobites, recentlytaken from the sea, flapping vigorously its great tail, and full oflife and energy; an animal larger and heavier than the modernking-crab of our shores, furnished with all the complexity ofexternal parts for which the crustaceans are so remarkable, andno doubt with instincts and feelings and modes of action as pronouncedas those of its modern allies, and, if Woodward's viewsare correct, on a higher plane of rank than the king-crab itself,inasmuch as it is a composite type connecting Limuli withIsopods, and even with scorpions. We have obviously here,in the appearance of this great Crustacean or Arachnoid, a repetitionof the facts which we met with in Eozoon; but how vastthe interval between them in geological time, and in zoologicalrank! Standing in the presence of this testimony, I think itis only right to say that we possess no causal solution of theappearance of these early forms of life; but in tracing themand their successors upward through the succeeding ages, wemay hope at least to reach some expressions of the laws of« 176 »their succession, in possession of which we may return toattack the mystery of their origin.

First, it must strike every observer that there is a great samenessof plan throughout the whole history of marine invertebratelife. If we turn over the pages of an illustrated text-bookof geology, or examine the cases or drawers of a collection offossils, we shall find extending through every succeeding formation,representative forms of Crustaceans, Mollusks, Corals,etc., in such a manner as to indicate that in each successiveperiod there has been a reproduction of the same type withmodifications; and if the series is not continuous, this appearsto be due rather to abrupt physical changes; since sometimes,where two formations pass into each other, we find a gradualchange in the fossils by the dropping out and introduction ofspecies one by one. Thus, in the whole of the great PalæozoicPeriod, both in its Fauna and Flora, we have a continuity andsimilarity of a most marked character.

It is evident that there is presented to us in this similarityof the forms of successive faunas and floras, a phenomenonwhich deserves very careful sifting as to the question of identityor diversity of species. The data for its comprehension mustbe obtained by careful study of the series of closely alliedforms occurring in successive formations, and the great andundisturbed areas of the older rocks in America seem to givespecial facilities for this, which should be worked, not in thedirection of constituting new species for every slightly divergentform, but in striving to group these forms into largespecific types.[71]

There is nothing to preclude the supposition that some ofthe groups mentioned in the note are really specific types, with« 177 »numerous race modifications. My own provisional conclusion,based on the study of Palæozoic plants, is that the general lawwill be found to be the existence of distinct specific types, independentof each other, but liable in geological time to agreat many modifications, which have often been regarded asdistinct species.[72]

While this unity of successive faunæ at first sight presentsan appearance of hereditary succession, it loses much of thischaracter when we consider the number of new types introducedwithout apparent predecessors, the necessity that there shouldbe similarity of type in successive faunæ on any hypothesis ofa continuous plan; and above all, the fact that the recurrenceof representative species or races in large proportion markstimes of decadence rather than of expansion in the types towhich they belong. To turn to another period, this is verymanifest in that singular resemblance which obtains betweenthe modern mammals of South America and Australia, andtheir immediate fossil predecessors—the phenomenon beinghere manifestly that of decadence of large and abundantspecies into a few depauperated representatives. This will befound to be a very general law, elevation being accompaniedby the apparent abrupt appearance of new types and decadenceby the apparent continuation of old species, or modificationsof them.

This resemblance with difference in successive faunas alsoconnects itself very directly with the successive elevations anddepressions of our continental plateaus in geological time.Every great Palæozoic limestone, for example, indicates adepression with succeeding elevation. On each elevationmarine animals were driven back into the ocean, and on eachdepression swarmed in over the land, reinforced by newspecies, either then introduced, or derived by migration fromother localities. In like manner, on every depression, land« 178 »plants and animals were driven in upon insular areas, and onre-elevation, again spread themselves widely. Now I think itwill be found to be a law here that periods of expansion wereeminently those of introduction of new specific types, andperiods of contraction those of extinction, and also of continuanceof old types under new varietal forms.

It must also be noticed that all the leading types of invertebratelife were early introduced, that change within thesewas necessarily limited, and that elevation could take placemainly by the introduction of the vertebrate orders. So inplants, Cryptogams early attained their maximum as well asGymnosperms, and elevation occurred in the introduction ofPhænogams, and this not piecemeal, but as we shall see ina succeeding chapter, in great force at once.

We may further remark the simultaneous appearance of liketypes of life in one and the same geological period, over widelyseparated regions of the earth's surface. This strikes us especiallyin the comparatively simple and homogeneous life-dynastiesof the Palæozoic, when, for example, we find the sametypes of Silurian Graptolites, Trilobites and Brachiopods appearingsimultaneously in Australia, America and Europe.Perhaps in no department is it more impressive than in theintroduction of the Devonian and Carboniferous Ages of thatgrand cryptogamous and gymnospermous flora which rangesfrom Brazil to Spitzbergen, and from Australia to Scotland,accompanied in all by the same groups of marine invertebrates.Such facts may depend either on that long life of specifictypes which gives them ample time to spread to all possiblehabitats, before their extinction, or on some general law wherebythe conditions suitable to similar types of life emerge at onetime in all parts of the world. Both causes may be influential,as the one does not exclude the other, and there is reason tobelieve that both are natural facts. Should it be ultimatelyproved that species allied and representative, but distinct in« 179 »origin, come into being simultaneously everywhere, we shallarrive at one of the laws of creation, and one probably connectedwith the gradual change of the physical conditions ofthe world.

Another general truth, obvious from the facts which havebeen already collected, is the periodicity of introduction ofspecies. They come in by bursts or flood tides at particularpoints of time, while these great life waves are followed andpreceded by times of ebb in which little that is new is beingproduced. We labour in our investigation of this matterunder the disadvantage that the modern period is evidentlyone of the times of pause in the creative work. Had our timebeen that of the early Tertiary or early Mesozoic, our views asto the question of origin of species might have been very different.It is a striking fact, in illustration of this, that sincethe glacial age no new species of mammal, except, possibly, manhimself, can be proved to have originated on our continents,while a great number of large and conspicuous forms havedisappeared. It is possible that the proximate or secondarycauses of the ebb and flow of life production may be in part atleast physical, but other and more important efficient causesmay be behind these. In any case these undulations in thehistory of life are in harmony with much that we see in otherdepartments of nature.

It results from the above and the immediately precedingstatement, that specific and generic types enter on the stage ingreat force, and gradually taper off towards extinction. Theyshould so appear in the geological diagrams made to illustratethe succession of living beings. This applies even to thoseforms of life which come in with fewest species and under themost humble guise. What a remarkable swarming, for example,there must have been of Marsupial Mammals in theearly Mesozoic, and in the Coal formation the only knownPulmonate snails, five or six in number, belong to four generic« 180 »types, while the Myriapods and Amphibians alike appear in acrowd of generic forms.

I have already referred to the permanence of species ingeological time. We may now place this in connection withthe law of rapid origination and more or less continuoustransmission of varietal forms. A good illustration will beafforded by a group of species with which I am very familiar,that which came into our seas at the beginning of the Glacialage, and still exists. With regard to their permanence, it canbe affirmed that the shells now elevated in Wales to 1,200,and in Canada to 600 feet above the sea, and which lived beforethe last great revolution of our continents a period veryremote as compared with human history—differ in no tittlefrom their modern successors after hundreds or thousands ofgenerations. It can also be affirmed that the more variablespecies appear under precisely the same varietal forms then asnow, though these varieties have changed much in their localdistribution. The real import of these statements, which mightalso be made with regard to other groups, well known to palæontologists,is of so great significance that it can be realizedonly after we have thought of the vast time and numerouschanges through which these humble creatures have survived.I may call in evidence here a familiar New England animal,the common sand clam,Mya arenaria, and its relativeMyatruncata, the short sand clam, which now inhabit together allthe northern seas; for the Pacific specimens, from Japan andCalifornia, though differently named, are undoubtedly the same.Mya truncata appears in Europe in the Coralline Crag, andwas followed byM. arenaria in the Red Crag. Both shellsoccur in the Pleistocene of America, and their several varietalforms had already developed themselves in the Crag, and remainthe same to-day; so that these humble mollusks, littoralin their habits, and subjected to a great variety of conditions,have continued for a very long period to construct their shells« 181 »precisely as at present; while in many places, as on the LowerSt. Lawrence, we find them living together on the same banks,and yet preserving their distinctness.[73] Nor are there any indicationsof a transition between the two species. I mightmake similar statements with regard to the Astartes, Buccinumsand Tellinæ of the drift, and could illustrate them byextensive series of specimens from my own collections.

Another curious illustration is that presented by the Tertiaryand modern faunæ of some oceanic islands far separated fromthe continents. In Madeira and Porto Santo, for example,according to Lyell, we have fifty-six species of land shells inthe former, and forty-two in the latter, only twelve being commonto the two, though these islands are only thirty milesapart. Now in the Pliocene strata of Madeira and PortoSanto we find thirty-six species in the former, and thirty-five inthe latter, of which only eight per cent, are extinct, and yetonly eight are common to the two islands. Further, thereseem to be no transitional forms connecting the species, andof some of them the same varieties existed in the Pliocene asnow. The main difference in time is the extinction of somespecies and the introduction of others without known connectinglinks, and the fact that some species, plentiful in thePliocene, are rare now, andvice versâ. All these shells differfrom those of modern Europe, but some of them are allied toMiocene species of that continent. Here we have a case ofcontinued existence of the same forms, and in circumstanceswhich, the more we think of them, the more do they defy allour existing theories as to specific origins.

Perhaps some of the most remarkable facts in connectionwith the permanence of varietal forms of species are thosefurnished by that magnificent flora which burst in all itsmajesty on the American continent in the Cretaceous period,and still survives among us, even in some of its specific types.« 182 »I say survives; for we have but a remnant of its forms living,and comparatively little that is new has probably been addedsince. The confusion which has obtained as to the age ofthis flora, and its mistaken reference to the Miocene Tertiary,have arisen in part from the fact that this modern flora was inits earlier times contemporary with Cretaceous animals, andsurvived the gradual change from the animal life of the Cretaceousdown to that of the Eocene, and even of the Miocene.In collections of these plants, from what may be termed bedsof transition from the Cretaceous to the Tertiary, we find manyplants of modern species, or so closely related that they may bemere varietal forms. Some of these will be mentioned in thenext paper, and they show that modern plants, some of themsmall and insignificant, others of gigantic size, reach back to atime when the Mesozoic Dinosaurs were becoming extinct, andthe earliest Placental mammals being introduced. Shall wesay that these plants have propagated themselves unchangedfor half a million of years, or more?[74]

Take from the western Mesozoic a contrasting yet illustrativefact. In the lowest Cretaceous rocks of Queen Charlotte'sIsland, Mr. Richardson and Dr. G. M. Dawson find Ammonitesand allied Cephalopods similar in many respects to thosediscovered farther south by the California Survey, and Mr.Whiteaves finds that some of them are apparently not distinctfrom species described by the Palæontologists of the GeologicalSurvey of British India. On both sides of the Pacific theseshells lie entombed in solid rock, and the Pacific rolls between,as of yore. Yet these species, genera, and even families areall extinct why, no man can tell, while land plants that musthave come in while the survivors of these Cephalopods stilllived, reach down to the present. How mysterious is all this,« 183 »and how strongly does it show the independence in some senseof merely physical agencies on the part of the manifestationsof life!

We have naturally been occupied hitherto with the lowertribes of animals and with plant life, because these are predominantin the early ages of the earth. Let us turn now tothe history of vertebrate or back-boned animals, which presentssome peculiarities special to itself. Many years ago Pander [75]described and figured from the Cambro-Silurian of Russia, anumber of minute teeth, some conical and some comb-like,which he referred to fishes, and to that low form of the fishtype represented by the modern lampreys. Much doubt wasthrown on this determination, more especially as the teethseemed to be composed not of bone earth, but of carbonate oflime, and it was suggested that they may have belonged tomarine worms, or to the lingual ribbons of Gastropod mollusks.Some confirmatory evidence seems to have been suppliedby the discovery of great numbers of similar forms in theshales of the coal formation of Ohio, by the late Dr. Newberry.I have had an opportunity to examine these, and find that theyconsist of calcium phosphate,[76] or bone earth, and that theirmicroscopic structure is not dissimilar from that of the teethof some of the smaller sharks (Diplodus) found with them. Ihave therefore been inclined to believe that there may havealready been, even in the Cambrian or Lower Silurian seas,true fishes, related partly to the lampreys and partly to sharks;so that the history of the back-boned animals may have gonenearly as far back as that of their humbler relations. Thisconjecture has recently received further support from thediscovery in rocks of Lower Silurian age, in Colorado of averitable bone bed, rich in fragmentary remains of fishes.« 184 »They are unfortunately so comminuted as to resemble thedébris of the food of some larger animal; but in so far as I canjudge from specimens kindly given to me,[77] they resemble thebony coverings of some of the familiar fishes of the Devonian.Thus they would indicate, with Pander's and Rohan's specimens,already two distinct types of fishes as existing almost asearly as the higher invertebrates of the sea.

In the Silurian (Upper Silurian of Murchison) we have undoubtedevidence of the same kind, on both sides of theAtlantic, in teeth and spines of sharks, and the plates whichprotected the heads and bodies of the plate-covered fishes(Placo-ganoids). But it is in the Devonian that these typesappear to culminate, and we have added to them that remarkabletype of "lung fish," as the Germans call them, representedin our modern world only by the curious and exceptionalBurramunda of Australia, and the mud fishes of Africa andSouth America,[78] creatures which show, as do some of themailed fishes, or ganoids, of equally great age, the intermediatestages between a swimming bladder and a lung, and thus approachnearer to the air-breathing animals than any other fishes.

Many years ago, in "Acadian Geology," I referred to theprobability that the mailed and lung fishes of the Devonian andCarboniferous possessed air bladders so constructed as toenable them to breathe air, as is the case with their modernrepresentatives. In the modern species this, no doubt, enablesthem to haunt badly aërated waters, in swamps and sluggishstreams, and in some cases even to survive when the waterin which they live is dried up. In the Carboniferous andDevonian it may have served a similar purpose, fitting themto inhabit the lagoons and creeks of the coal swamps, thewater of which must often have been badly aërated. It makesagainst this that some sharks followed them into these waters,and the modern sharks have no swim-bladders. Possibly,however, the sharks habitually haunted the open sea, andonly made occasional raids on the dangerous waters tenantedby the ganoids. It is also true that only certain genera ofsharks are found to be represented in the carbonaceous shales,and they may have differed in this respect from the ordinaryforms of the order. It has been suggested that only a smallchange would be necessary to enable some of these lung fishesto become Batrachians, and no doubt this is the nearestapproach of the fish to the reptile; but we have not yet foundconnecting links sufficient to bridge over the whole distance.

The plate-bearing ganoids of the Silurian and Devonian, atone time supposed to be allied to Crustaceans, but whosedignity as "Forerunners of the back-boned animals" is nowgenerally admitted,[79] are clearly true fishes, and of somewhathigh rank, their strange bony armour being evidently a specialprotection against the attacks of contemporary sharks andgigantic crustaceans; and if we may judge by the Coloradospecimens, their existence dates back almost to the close of theCambrian, and they were probably contemporary with smallsharks; while as early as the Silurian and Devonian, if weregard the scaly ganoids as a distinct type, we have alreadyfour types of fishes, and these akin to those which in moderntime we must regard as the highest of their class.

One very little fish of the Devonian, of which specimenshave been kindly sent me by a friend in Scotland,[80] the Palæospondylus« 186 »of Traquair, may raise still higher hopes for the earlyvertebrates. It is a little creature, an inch to two inches inlength, destitute or nearly destitute of bony covering, having ahead which suggests the presence of external gills, large eyes,and even elongated nasal bones,[81] a long vertebral columncomposed of separate bony rings, more than fifty in number,with possible indications of ribs in front and distinct neuraland haemal processes behind. One cannot look at it withoutthe suggestion occurring of some of the smaller snake-likeBatrachians of the Carboniferous and Permian; and Ishould not be surprised if it should come to be regardedeither as a forerunner of the Batrachians or as a primitivetadpole.

However this may be, the upper part of the Devonian, thoughrich in fishes and plants, has afforded no higher vertebratesthan its lower parts, and in the lowest Carboniferous beds wesuddenly find ourselves in the presence of Batrachians withwell-developed limbs and characters which ally them to theLizards. True lizard-like reptiles appear in the Permian, andthen we enter on that marvellous reign of reptiles, in whichthis class assumed so many great and remarkable forms, andasserted itself in a manner of which the now degraded reptilianclass can afford no conception.

The mammals and birds make their first appearance quietlyin small and humble forms in the reign of reptiles, in whichthere was little place left for them by the latter; but themammals burst upon us in all their number and magnitude inthe Eocene and Miocene, in which quadrupedal mammalianlife may be said to have culminated in grandeur, variety, andgeographical distribution; far excelling in these respects thetime in which we live.

The development in time of the back-boned animals thusstands in some degree by itself; but it illustrates the same« 187 »laws of early generalised types, and sudden and wide introductionof new forms, which we have seen in the case of the invertebratesand the plants.

Such facts as those to which I have referred, and manyothers, which want of space prevents me from noticing, are inone respect eminently unsatisfactory, for they show us howdifficult must be any attempts to explain the origin and successionof life. For this reason they are quietly put aside orexplained away in most of the current hypotheses on the subject.But we must, as men of science, face these difficulties,and be content to search for facts and laws, even if they shouldprove fatal to preconceived views.

A group of new laws, indeed, here breaks upon us. (1)The great vitality and rapid extension and variation of newspecific types. (2) The law of spontaneous decay and mortalityof species in time. (3) The law of periodicity and ofsimultaneous appearance of many allied forms. (4) Theabrupt entrance and slow decay of groups of species. (5) Theextremely long duration of some species in time. (6) Thegrand march of new forms landwards, and upwards in rank.Such general truths deeply impress us at least with the conclusionthat we are tracing, not a fortuitous succession, but theaction of power working by law.

I have thus far said nothing of the bearing of the prevalentideas of descent with modification on this wonderful processionof life. None of these, of course, can be expected totake us back to the origin of living beings; but they also failto explain why so vast numbers of highly organized speciesstruggle into existence simultaneously in one age and disappearin another, why no continuous chain of succession in time canbe found gradually blending species into each other, and why,in the natural succession of things, degradation under theinfluence of external conditions and final extinction seem to belaws of organic existence. It is useless here to appeal to the« 188 »imperfection of the record, or to the movements or migrationsof species. The record is now, in many important parts, toocomplete, and the simultaneousness of the entrance of thefaunas and floras too certainly established, and moving speciesfrom place to place only evades the difficulty. The truth isthat such hypotheses are at present premature, and that werequire to have larger collections of facts. Independently ofthis, however, it appears to me that from a philosophical pointof view it is extremely probable that all theories of evolution, asat present applied to life, are fundamentally defective in beingtoo partial in their character; and perhaps I cannot better groupthe remainder of the facts to which I wish to refer than byusing them to illustrate this feature of most of our attempts atgeneralization on this subject.

First, then, these hypotheses are too partial, in their tendencyto refer numerous and complex phenomena to one cause, or toa few causes only, when all trustworthy analogy would indicatethat they must result from many concurrent forces and determinationsof force. We have all, no doubt, read those ingenious,not to say amusing, speculations in which some entomologistsand botanists have indulged with reference to the mutualrelations of flowers and suctorial insects. Geologically thefacts oblige us to begin with Cryptogamous plants and chewinginsects, and out of the desire of insects for non-existent honey,and the adaptations of plants to the requirements of non-existentsuctorial apparatus, we have to evolve the marvellouscomplexity of floral form and colouring, and the exquisitelydelicate apparatus of the mouths of haustellate insects. Now,when it is borne in mind that this theory implies a mental confusionon our part precisely similar to that which, in the departmentof mechanics, actuates the seekers for perpetual motion,that we have not the smallest tittle of evidence that the changesrequired have actually occurred in any one case, and that thethousands of other structures and relations of the plant and the« 189 »insect have to be worked out by a series of concurrent developmentsso complex and absolutely incalculable in the aggregate,that the cycles and epicycles of the Ptolemaic astronomy werechild's play in comparison, we need not wonder that the commonsense of mankind revolts against such fancies, and that weare accused of attempting to construct the universe by methodsthat would baffle Omnipotence itself, because they are simplyabsurd. In this aspect of them, indeed, such speculations arenecessarily futile, because no mind can grasp all the complexitiesof even any one case, and it is useless to follow out animaginary line of development which unexplained facts mustcontradict at every step. This is also, no doubt, the reasonwhy all recent attempts at constructing "Phylogenies" are sochangeable, and why no two experts can agree about almostany of them.

A second aspect in which such speculations are too partial,is in the unwarranted use which they make of analogy. It isnot unusual to find such analogies as that between the embryonicdevelopment of the individual animal and the successionof animals in geological time placed on a level with thatreasoning from analogy by which geologists apply moderncauses to explain geological formations. No claim could bemore unfounded. When the geologist studies ancient limestonesbuilt up of the remains of corals, and then applies thephenomena of modern coral reefs to explain their origin, hebrings the latter to bear on the former by an analogy which includesnot merely the apparent results, but the causes at work,and the conditions of their action, and it is on this that thevalidity of his comparison depends, in so far as it relates tosimilarity of mode of formation. But when we compare thedevelopment of an animal from an embryo cell with the progressof animals in time, though we have a curious analogy asto the steps of the process, the conditions and causes at workare known to be altogether dissimilar, and therefore we have no« 190 »evidence whatever as to identity of cause, and our reasoningbecomes at once the most transparent of fallacies. Further, wehave no right here to overlook the fact that the conditions ofthe embryo are determined by those of a previous adult, andthat no sooner does this hereditary potentiality produce a newadult animal, than the terrible external agencies of the physicalworld, in presence of which all life exists, begin to tell on theorganism, and after a struggle of longer or shorter duration itsuccumbs to death, and its substance returns into inorganicnature, a law from which even the longer life of the speciesdoes not seem to exempt it. All this is so plain and manifestthat it is extraordinary that evolutionists will continue to usesuch partial and imperfect arguments. Another illustrationmay be taken from that application of the doctrine of naturalselection to explain the introduction of species in geologicaltime, which is so elaborately discussed by Sir C. Lyell in thelast edition of his "Principles of Geology." The great geologistevidently leans strongly to the theory, and claims for it the"highest degree of probability," yet he perceives that there isa serious gap in it; since no modern fact has ever proved theorigin of a new species by modification. Such a gap, if itexisted in those grand analogies by which he explained geologicalformations through modern causes, would be admittedto be fatal.

A third illustration of the partial character of these hypothesesmay be taken from the use made of the theory deducedfrom modern physical discoveries, that life must be merely aproduct of the continuous operation of physical laws. Theassumption for it is nothing more that the phenomena of lifeare produced merely by some arrangement of physical forces,even if it be admitted to be true, gives only a partial explanationof the possible origin of life. It does not account for thefact that life, as a force, or combination of forces, is set inantagonism to all other forces. It does not account for the« 191 »marvellous connection of life with organization. It does notaccount for the determination and arrangement of forcesimplied in life. A very simple illustration may make thisplain. If the problem to be solved were the origin of themariner's compass, one might assert that it is wholly a physicalarrangement, both as to matter and force. Another mightassert that it involves mind and intelligence in addition. Insome sense both would be right. The properties of magneticforce and of iron or steel are purely physical, and it might evenbe within the bounds of possibility that somewhere in theuniverse a mass of natural lodestone may have been so balancedas to swing in harmony with the earth's magnetism. Yet wewould surely be regarded as very credulous if we could be inducedto believe that the mariner's compass has originated inthat way. This argument applies with a thousandfold greaterforce to the origin of life, which involves even in its simplestforms so many more adjustments of force and so much morecomplex machinery.

Fourthly, these hypotheses are partial, inasmuch as they failto account for the vastly varied and correlated interdependenciesof natural things and forces, and for the unity of planwhich pervades the whole. These can be explained only bytaking into the account another element from without. Evenwhen it professes to admit the existence of a God, the evolutionistreasoning of our day contents itself altogether with thephysical or visible universe, and leaves entirely out of sight thepower of the unseen and spiritual, as if this were somethingwith which science has nothing to do, but which belongs onlyto imagination or sentiment. So much has this been the case,that when recently a few physicists and naturalists have referredto the "Unseen Universe," they have seemed to be teachingnew and startling truths, though only reviving some of theoldest and most permanent ideas of our race. From the dawnof human thought it has been the conclusion alike of philosophers,« 192 »theologians, and the common sense of mankind, that theseen can be explained only by reference to the unseen, andthat any merely physical theory of the world is necessarilypartial. This, too, is the position of our sacred Scriptures, andis broadly stated in their opening verse, and indeed it lies alikeat the basis of all true religion and all sound philosophy, for itmust necessarily be that "the things that are seen are temporal,the things that are unseen, eternal." With reference to theprimal aggregation of energy in the visible universe, with referenceto the introduction of life, with reference to the soul ofman, with reference to the heavenly gifts of genius and prophecy,with reference to the introduction of the Saviour Himselfinto the world, and with reference to the spiritual gifts andgraces of God's people, all these spring, not from sporadic actsof intervention, but from the continuous action of God and theunseen world; and this, we must never forget, is the true idealof creation in Scripture and in sound theology. Only in suchexceptional and little influential philosophies as that of Democritus,and in the speculations of a few men carried off theirbalance by the brilliant physical discoveries of our age, hasthis necessarily partial and imperfect view been adopted. Never,indeed, was its imperfection more clear than in the light ofmodern science.

Geology, by tracing back all present things to their origin,was the first science to establish on a basis of observed factsthe necessity of a beginning and end of the world. But evenphysical science now teaches us that the visible universe is avast machine for the dissipation of energy; that the processesgoing on in it must have had a beginning in time, and that allthings tend to a final and helpless equilibrium. This necessityimplies an unseen power, an invisible universe, in which thevisible universe must have originated, and to which its energyis ever returning. The hiatus between the seen and the unseenmay be bridged over by the conceptions of atomic vortices of« 193 »force, and by the universal and continuous ether; but whetheror not, it has become clear that the conception of the unseen,as existing, has become necessary to our belief in the possibleexistence of the physical universe itself, even without takinglife into account.

It is in the domain of life, however, that this necessity becomesmost apparent; and it is in the plant that we firstclearly perceive a visible testimony to that unseen which is thecounterpart of the seen. Life in the plant opposes the outwardrush of force in our system, arrests a part of it on itsway, fixes it as potential energy, and thus, forming a mere eddy,so to speak, in the process of dissipation of energy, it accumulatesthat on which animal life and man himself may subsist,and assert for a time supremacy over the seen and temporal onbehalf of the unseen and eternal. I say, for a time, becauselife is, in the visible universe, as at present constituted, but atemporary exception, introduced from that unseen world whereit is no longer the exception but the eternal rule. In a stillhigher sense, then, than that in which matter and force testifyto a Creator, organization and life, whether in the plant, theanimal, or man, bear the same testimony, and exist as outpostsput forth in the succession of ages from that higher heaventhat surrounds the visible universe. In them, too, Almightypower is no doubt conditioned or limited by law; yet they bearmore distinctly upon them the impress of their Maker, and,while all explanations of the physical universe which refuse torecognise its spiritual and unseen origin must necessarily bepartial and in the end incomprehensible, this destiny falls morequickly and surely on the attempt to account for life and itssuccession on merely materialistic principles.

Here again, however, we must bear in mind that creation, asmaintained against such materialistic evolution, whether bytheology, philosophy, or Holy Scripture, is necessarily a continuous,nay, an eternal, influence, not an intervention of disconnected« 194 »acts. It is the true continuity, which includes andbinds together all other continuity.

It is here that natural science meets with theology, not as anantagonist, but as a friend and ally in its time of greatestneed; and I must here record my belief that neither men ofscience nor theologians have a right to separate what God inHoly Scripture has joined together, or to build up a wallbetween nature and religion, and write upon it, "no thoroughfare."The science that does this must be impotent to explainnature, and without hold on the higher sentiments of man.The theology that does this must sink into mere superstition.

In conclusion, can we formulate a few of the general laws,or perhaps I had better call them the general conclusions,respecting life, in which all Palæontologists may agree. Perhapsit is not possible to do this at present satisfactorily, butthe attempt may do no harm. We may, then, I think, makethe following affirmations:—

1. The existence of life and organization on the earth is noteternal, or even coeval with the beginning of the physical universe,but may possibly date from Laurentian or immediatelypre-Laurentian ages.

2. The introduction of new species of animals and plants hasbeen a continuous process, not necessarily in the sense ofderivation of one species from another, but in the higher senseof the continued operation of the cause or causes which introducedlife at first. This, as already stated, I take to be thetrue theological or Scriptural as well as scientific idea of whatwe ordinarily and somewhat loosely term creation.

3. Though thus continuous, the process has not been uniform;but periods of rapid production of species have alternatedwith others in which many disappeared and few wereintroduced. This may have been an effect of physical cyclesreacting on the progress of life.

4. Species, like individuals, have greater energy and vitality in« 195 »their younger stages, and rapidly assume all their varietal forms,and extend themselves as widely as external circumstances willpermit. Like individuals also, they have their periods of oldage and decay, though the life of some species has been ofenormous duration in comparison with that of others; thedifference appearing to be connected with degrees of adaptationto different conditions of life.

5. Many allied species, constituting groups of animals andplants, have made their appearance at once in various parts ofthe earth, and these groups have obeyed the same laws withthe individual and the species in culminating rapidly, and thenslowly diminishing, though a large group once introduced hasrarely disappeared altogether.

6. Groups of species, as genera and orders, do not usuallybegin with their highest or lowest forms, but with intermediateand generalized types, and they show a capacity for both elevationand degradation in their subsequent history.

7. The history of life presents a progress from the lower tothe higher, and from the simpler to the more complex, andfrom the more generalized to the more specialized. In thisprogress new types are introduced, and take the place of theolder ones, which sink to a relatively subordinate place, andbecome thus degraded. But the physical and organic changeshave been so correlated and adjusted that life has not onlyalways maintained its existence, but has been enabled toassume more complex forms, and thus older forms have beenmade to prepare the way for newer, so that there has been, onthe whole, a steady elevation culminating in man himself.Elevation and specialization have, however, been secured at theexpense of vital energy and range of adaptation, until the newelement of a rational and inventive nature was introduced onlyin the case of man.

8. In regard to the larger and more distinct types, wecannot find evidence that they have, in their introduction,« 196 »been preceded by similar forms connecting them with previousgroups; but there is reason to believe that many supposedrepresentative species in successive formations are really onlyraces or varieties.

9. In so far as we can trace their history, specific types arepermanent in their characters from their introduction to theirextinction, and their earlier varietal forms are similar to theirlater ones.

10. Palæontology furnishes no direct evidence, perhapsnever can furnish any, as to the actual transformation of onespecies into another, or as to the actual circumstances ofcreation of a species; but the drift of its testimony is to showthat species come inper saltum, rather than by any slow andgradual process.

11. The origin and history of life cannot, any more than theorigin and determination of matter and force, be explained onpurely material grounds, but involve the consideration of powerreferable to the unseen and spiritual world.

Different minds may state these principles in different ways,but I believe that in so far as palæontology is concerned, insubstance they must hold good, at least as steps to highertruths. And now allow me to say that we should be thankfulthat it is given to us to deal with so great questions, andthat in doing so, deep humiliation, earnest seeking for truth,patient collection of all facts, self-denying abstinence fromhasty generalizations, forbearance and generous estimation withregard to our fellow labourers, and reliance on that DivineSpirit which has breathed into us our intelligent life, and isthe source of all true wisdom, are the qualities which best becomeus.

But while the principles noted above may be said to beknown laws of the apparition of new forms of life, they donot reach to the secondary efficient causes of the introductionof new species. What these may ultimately prove to be, to« 197 »what extent they can be known by us, and to what extent theymay include processes of derivation, it is impossible now tosay. At present we must recognise in the prevailing theorieson the subject merely the natural tendency of the human mindto grasp the whole mass of the unknown under some grandgeneral hypothesis, which, though perhaps little else than afigure of speech, satisfies for the moment. We are dealingwith the origin of species precisely as the alchemists did withchemistry, and as the Plutonists and Neptunists did withgeology; but the hypotheses of to-day may be the parents ofinvestigations which will become real science to-morrow. Inthe meantime it is safe to affirm that whatever amount of truththere may be in the several hypotheses which have engagedour attention, there is a creative force above and beyond them,and to the threshold of which we shall inevitably be brought,after all their capabilities have been exhausted by rigid investigationof facts. It is also consolatory to know thatspecies, in so far as the Modern period, or any one past geologicalperiod may be concerned, are so fixed that for allpractical purposes they may be regarded as unchanging. Theyare to us what the planets in their orbits are to the astronomer,and speculations as to the origin of species are merely ournebular hypotheses as to the possible origin of worlds andsystems.

References:—Address as Vice-President of American Association atDetroit, 1875. "The Chain of Life in Geological Time," London,1879. Addresses to Natural History Society of Montreal, publishedinCanadian Naturalist, "Apparition of Animal Forms,"PrincetonReview.

THE GENESIS AND MIGRATIONS OF PLANTS.

DEDICATED TO THE MEMORY OF

DR. OSWALD HEER,

The Able and Successful Student of the later Floras
of the Northern Hemisphere.

Geological Periods as Related to Plants—Arctic Originof Floras—The Devonian Flora—Arctic Climatesof the Past—History of Some Modern Forms—Lawsof the Succession

CHAPTER VIII.

If, for convenience of reference, we divide the whole historyof the earth, from the time when a solid crust first formedon its surface and began to be ridged up into islands or mountainsin the primeval ocean, into four great periods, we shallfind that each can be characterized by some features in relationto the world of plants.

That Archean age, in which the oldest known beds of rockswere produced—rocks now greatly crumpled by the first movementsof the thin crust, and hardened and altered by heat andpressure has, it is true, little to tell us. But, as elsewherestated, even it has beds of Carbon in the form of Graphite—veritablealtered coal seams—which the analogy of later formationswould lead us to believe must have been accumulated bythe growth of plants. This growth is indeed the only knowncause capable of producing such effects. If we should everbe fortunate enough to find beds of the Laurentian series inan unaltered state, we may hope to know something of this oldflora. Nor need we be surprised if it should prove of highergrade and more noble development than we should at first sightanticipate. If there ever was a time when vegetation alonepossessed the earth, and when there were no animals to devouror destroy it, we might expect to find it in its first and bestestate, perhaps not comparable in variety and complexity ofparts with the flora of the modern world, but grand in itsluxuriance and majesty. Of such discoveries, however, we haveno certain indication at present.

If such a primeval flora as that above indicated ever existed,it must have perished utterly before the incoming of thenext great age of the world—that known as the Palæozoic,whose rocks are surpassingly rich in the remains of animals,especially those of the lower or invertebrate classes and thosethat inhabit the waters.

In the oldest Palæozoic rocks we find no plants certainlyterrestrial, but abundance of Algæ or seaweeds, and somegigantic members of the vegetable kingdom which seem tohave been trees, with structures more akin to those of aquaticthan to those of land plants.[82] At a somewhat early stage, however,in the rocks of this period, we discover a few undoubtedland plants.[83] These seem to be allied to the modern Clubmosses and to their humble relations, the pillworts [84] andother small plants of similar structure found in ponds andswamps. Some of them, indeed, appear to be intermediatebetween these groups. All these plants are Cryptogams, ordestitute of true flowers, but do not belong to the lowest formsof that type. Thus, so far as we know, plant life on the landbegan possibly with certain large trees of algoid structures, andmore certainly with the club mosses and pillworts and theirallies, and these last in the form of species not tree-like indimensions, but of very moderate size. The structures ofthese plants are already sufficiently well known to inform usthat the plan and functions of the root, stem and leaf, and ofspores and spore case were set up; and that the structures andfunctions of vegetable cells, fibres and some kinds of vesselswere perfected, and all the apparatus introduced necessary forthe fertilization and reproduction of plants of some degree ofcomplexity. At the same time, the peculiar structures of thehigher Algæ were brought to a pitch of perfection not surpassedif equalled in modern times, and which may have enabledplants so constructed to exist even on the land.

From these beginnings in the early Palæozoic, the progressof the vegetable kingdom went on, until, in the later parts ofthat great period, the Devonian and Carboniferous eras, itculminated in those magnificent forests which have left somany interesting remains, and which accumulated the materialsof our great beds of coal. In these the families of the Clubmosses, the Ferns and the Mare's-tails attained to a perfectionin structure and size altogether unexampled in the modernworld, and may be said to have overspread the earth almost tothe exclusion of other trees. Here, however, two new familiescome in of higher grade, and leading the way to the floweringplants. These are the Pines and their allies and the Cycads,and certain intermediate forms, neither Pines nor Cycads, butallied to both.[85] This wonderful flora, which we have now thematerials to reproduce in imagination almost in its entirety,decays and passes away in the Permian system, the last portionof the Palæozoic, and in entering into the third great period ofthe earth's history—the Mesozoic, we again find an almostentire change of vegetation. Here, however, we are able tounderstand something of the reasons of this. The Palæozoicfloras seem to have originated in the North, and propagatedthemselves southward till they replenished the earth, and theywere favoured by the existence at that time of vast swampyflats extending over great areas of the yet imperfectly elaboratedcontinents. The Mesozoic floras, on the other hand, seem tohave been of Southern or equatorial origin, and to have followedup the older vegetation as it decayed and disappeared,« 204 »or retreated in its old age to its northern home. There is, ofcourse, much in all this that we do not understand, but thegeneral fact seems certain.

The early Mesozoic is altogether peculiar. It shows a vastpredominance of Cycads, Pines and Ferns, to the exclusionboth of the gigantic Cryptogams of the Palæozoic and of theordinary exogenous trees of the modern time. It has a strange,weird aspect, and more resembles that of some warm islandsof the southern hemisphere at present, than anything elseknown to us. It is as if the flora of some southern island hadmigrated and invaded all parts of the world. The geographicaland climated conditions which permitted this must have been ofa character different from those both of earlier and later times.

As we approach to the termination of the Mesozoic, which,in regard to animal life, is the age of reptiles, a new andstrange development meets us. We find beds filled withleaves of broad-leaved plants similar to those of our modernwoods, and in most cases apparently belonging to the samegenera with plants now living, and this new type of vegetationpersists to the present, though with marked differencesof species in successive eras, as in the Middle and UpperCretaceous, and the Lower, Middle and Upper Kainozoic, orTertiary. It is noteworthy that while this new vegetation notonly altogether supersedes the great Cryptogamous forests ofthe Palæozoic, but replaces the Cycads of the immediatelypreceding eras, the Pines retain all their prominence andgrandeur, and even seem to excel in number of species, inbreadth of dispersion, and in magnitude of growth theirsuccessors in the present world.

While in the latter Cretaceous and Early Tertiary, thenorthern hemisphere at least seems to have enjoyed an exceptionallywarm climate, the later Tertiary introduces thatperiod of cold known as the Glacial age. While there is nodoubt that the intensity of this glaciation has been greatly« 205 »exaggerated by extreme glacialists, and while it is certain thatsome vegetation, and this not altogether of Arctic types, continuedto exist throughout this period, even in the now temperateregions of our continents, it is evident that a greatreduction of the exuberance of the flora occurred by theremoval of many species, and that the present flora of thenorthern hemisphere is inferior in variety and magnificenceto that of the Middle Tertiary, just as it is found that theMammalian fauna of our continents has since that time beenreduced both in the number and magnitude of its species.

If the reader has followed this general sketch, he will beprepared to appreciate some examples of a more detailedcharacter relating to the floras of different periods, and somediscussions of general points relating to the genesis and vicissitudesof the vegetable kingdom.

The origination of the more important floras which haveoccupied the northern hemisphere in geological times, not,as one might at first sight suppose, in the sunny climates ofthe South, but under the arctic skies, is a fact long known orsuspected. It is proved by the occurrence of fossil plants inGreenland, in Spitzbergen, and in Grinnell Land, under circumstanceswhich show that these were their primal homes.The fact bristles with physical difficulties, yet is fertile of themost interesting theoretical deductions, to reach which we maywell be content to wade through some intricate questions.Though not at all a new fact, its full significance seems only recentlyto have dawned on the minds of geologists, and withinrecent years it has produced a number of memoirs and addressesto learned societies, besides many less formal notices.[86]

The earliest suggestion on this subject known to the writeris that of my old and dear friend, Professor Asa Gray, in 1867,with reference to the probable northern source of the relatedfloras of North America and Eastern Asia. With the aid ofnew facts disclosed by Heer and Lesquereux, Gray returnedto the subject in 1872, and more fully developed this conclusionwith reference to the Tertiary floras,[87] and still later hefurther discussed these questions in an able lecture on "ForestGeography and Archæology."[88] In this he puts the case sowell and tersely that I may quote the following sentences as atext for what follows:—

"I can only say, at large, that the same species (of Tertiaryfossil plants) have been found all round the world; that therichest and most extensive finds are in Greenland; that theycomprise most of the sorts which I have spoken of, as Americantrees which once lived in Europe—Magnolias, Sassafras,Hickories, Gum-trees, our identical Southern Cypress (for allwe can see of difference), and especiallySequoias, not only thetwo which obviously answer to the two Big-trees now peculiarto California, but several others; that they equally comprisetrees now peculiar to Japan and China—three kinds of Gingko-trees,for instance, one of them not evidently distinguishablefrom the Japan species which alone survives; that we haveevidence, not merely of Pines and Maples, Poplars, Birches,Lindens, and whatever else characterize the temperate-zoneforests of our era, but also of particular species of these, solike those of our own time and country, that we may fairlyreckon them as the ancestors of several of ours. Longgenealogies always deal more or less in conjecture; but weappear to be within the limits of scientific inference when weannounce that our existing temperate trees came from thenorth, and within the bounds of high probability when we« 207 »claim not a few of them as the originals of present species.Remains of the same plants have been found fossil in ourtemperate region, as well as in Europe."

Between 1860 and 1870 the writer was engaged in workingout all that could be learned of the Devonian plants ofEastern America, the oldest known flora of any richness, andwhich consists almost exclusively of gigantic, and to usgrotesque, representatives of the Club mosses, Ferns, andMare's-tails, with some trees allied to the Cycads and Pines.In this pursuit nearly all the more important localities werevisited, and access was had to the large collections of ProfessorHall and Professor Newberry in New York and Ohio, as wellas to those of the Geological Survey of Canada, and to thosemade in the remarkable plant-bearing beds of St. John, NewBrunswick, by Messrs. Matthew and Hartt. In the progressof these researches, which developed an unexpectedly richassemblage of species, the northern origin of this old floraseemed to be established by its earlier culmination in thenorth-east, in connection with the growth of the Americanland to the southward, which took place after the great UpperSilurian subsidence, by elevations which began in the north,while those portions of the continent to the south-west stillremained under the sea.

When, in 1870, the labours of those ten years were broughtbefore the Royal Society of London, in the Bakerian Lectureof that year, and in a memoir illustrating no less than onehundred and twenty-five species of plants older than the greatCarboniferous system, these deductions were stated in connectionwith the conclusions of Hall, Logan, and Dana, as tothe distributions of sediment along the north-east side of theAmerican continent, and the anticipation was hazarded thatthe oldest Palæozoic floras would be discovered to the northof Newfoundland. Mention was also made of the apparentearlier and more copious birth of the Devonian flora in« 208 »America than in Europe, a fact which is itself connected withthe greater northward extension of this continent.

Unfortunately the memoir containing these results was notpublished by the Royal Society, and its publication wassecured in a less perfect form only in the reports of the GeologicalSurvey of Canada. The part of the memoir relatingto Canadian fossil plants, with a portion of the theoretical deductions,was published in a report issued in 1871.[89] In thisreport the following language was used:—

"In Eastern America, from the Carboniferous period onward,the centre of plant distribution has been the Appalachianchain. From this the plants and sediments extended westwardin times of elevation, and to this they receded in timesof depression. But this centre was non-existent before theDevonian period, and the centre of this must have been to thenorth-east, whence the great mass of older Appalachian sedimentwas derived. In the Carboniferous period there wasalso an eastward distribution from the Appalachians, andlinks of connection in the Atlantic bed between the floras ofEurope and America. In the Devonian such connection canhave been only far to the north-east. It is therefore in Newfoundland,Labrador, and Greenland that we are to look forthe oldest American flora, and in like manner on the border ofthe old Scandinavian nucleus for that of Europe."

"Again, it must have been the wide extension of the sea ofthe Corniferous limestone that gave the last blow to the remainingflora of the Lower Devonian: and the re-elevation inthe middle of that epoch brought in the Appalachian ridges asa new centre, and established a connection with Europe whichintroduced the Upper Devonian and Carboniferous floras.Lastly, from the comparative richness of the later Erian [90] flora« 209 »in Eastern America, especially in the St. John beds, it mightbe a fair inference that the north-eastern end of the Appalachianridge was the original birthplace or centre of creation ofwhat we may call the later Palæozoic flora, or a large part ofthat flora."

When my paper was written I had not seen the accountpublished by the able Swiss palæobotanist Heer, of the remarkableDevonian flora of Bear Island, near Spitzbergen.[91]From want of acquaintance with the older floras of Americaand Western Europe, Heer fell into the unfortunate error ofregarding the Bear Island plants as Lower Carboniferous, amistake which his great authority has tended to perpetuate,and which has even led to the still graver error of some Europeangeologists, who do not hesitate to regard as Carboniferousthe fossil plants of the American deposits from theHamilton to the Chemung groups inclusive, though these belongto formations underlying the oldest Carboniferous, andcharacterized by animal remains of unquestioned Devonianage. In 1872 I addressed a note to the Geological Society ofLondon on the subject of the so-called "Ursa stage" of Heer,showing that though it contained some forms not known at soearly a date in temperate Europe, it was clearly Devonian whentested by North American standards; but that in this highlatitude, in which, for reasons stated in the report above referredto, I believed the Devonian plants to have originated,there might be an intermixture of the two floras. But such amixed group should in that latitude be referred to a lowerhorizon than if found in temperate regions.

Between 1870 and 1873 my attention was turned to the twosub-floras intermediate between those of the Devonian and the« 210 »coal formation, the floras of the Lower Carboniferous (Sub-carboniferousof some American geologists) and the MillstoneGrit, and in a report upon these [92] similar deductions were expressed.It was stated that in Newfoundland and NorthernCape Breton the coal formation species come in at an earlypart of that period, and as we proceed southward they belongto progressively newer portions of the Carboniferous system.The same fact is observed in the coal beds of Scotland, ascompared with those of England, and it indicates that thecoal formation flora, like that of the Devonian, spread itselffrom the north, and this accords with the somewhat extensiveoccurrence of Lower Carboniferous rocks and fossils in theParry Islands and elsewhere in the Arctic regions.[93]

Passing over the comparatively poor flora of the earlierMesozoic, consisting largely of cycads, pines, and ferns, which,as we have seen, is probably of southern origin, and is as yetlittle known in the arctic, though represented, according toHeer, by the supposed Jurassic flora of Cape Boheman, wefind, especially at Komé and Atané in Greenland, an interestingoccurrence of those earliest precursors of the truly modernforms of plants which appear in the Cretaceous, the period ofthe English chalk, and of the New Jersey greensands. Thereare two plant groups of this age in Greenland, one, that ofKomé consists almost entirely of ferns, cycads, and pines, and isof decidedly Mesozoic aspect. This was regarded by Heer asLower Cretaceous. The other, that of Atané, holds remainsof many modern temperate genera, asPopulus,Myrica,Ficus,Sassafras, andMagnolia. This he regards as Middle Cretaceous.Above this is the Patoot series, with many exogenoustrees of modern genera, and representing the Upper Cretaceous.Resting upon these Upper Cretaceous beds, without« 211 »the intervention of any other formation,[94] are beds rich inplants of much more modern appearance, and referred byHeer to the Miocene period, a reference which appeared atthe time to be warranted by comparison with the Tertiaryplants of Europe, but, as we shall see, not with those ofAmerica. Still farther north this so-called Miocene assemblageof plants appears in Spitzbergen and Grinnell Land; butthere, owing to the predominance of trees allied to the spruces,it has a decidedly more boreal character than in Greenland, asmight be anticipated from its nearer approach to the pole.[95]

If now we turn to the Cretaceous and Tertiary floras ofWestern America, as described by Lesquereux, Newberry, andWard, we find in the lowest Cretaceous rocks known thereuntil very recently—those of the Dakota group, which maybe in the lower part of the Middle Cretaceous—a series ofplants [96] essentially similar to those of the Middle Cretaceousof Greenland. To these I have been able to add, through theresearches of Mr. Richardson and Dr. G. M. Dawson, a stillearlier flora, that of the Kootanie and Queen Charlotte Islandformations, as old as the Gault and Wealden. It wants thebroad-leaved plants of the Dakota, and consists mainly ofpines, cycads, and ferns; and only in its upper part containsa few forerunners of the exogens.[97] These plants occur in bedsindicating shallow sea conditions as prevalent in the interiorof America, causing, no doubt, a warm climate in the north.Overlying this plant-bearing formation we have an oceaniclimestone (the Niobrara), corresponding in many respects to« 212 »the European chalk, and containing similar microscopic organisms.This extends far north into the British territory,[98] indicatingfarther subsidence and the prevalence of a vast MediterraneanSea, filled with warm water from the equatorial currents,and not invaded by cold waters from the north. Thisis succeeded by Upper Cretaceous deposits of clay and sandstone,with marine remains, though very sparsely distributed;and these show that further subsidence or denudation in thenorth had opened a way for the arctic currents, producing afall of temperature at the close of the Cretaceous, and partiallyfilling up the Mediterranean of that period.

Of the flora of the Middle and Upper Cretaceous periods,which must have been very long, we know something in theinterior regions through the plants of Dunvegan and PeaceRiver;[99] and on the coast of British Columbia we have theremarkable Cretaceous coal field of Vancouver's Island, whichholds the remains of plants of modern genera, including speciesof fan palm, ginkgo, evergreen oak, tulip tree, and other formsproper to a warm temperature or subtropical climate. Theyprobably indicate a warmer climate as then prevalent on thePacific coast than in the interior, and in this respect correspondwith a meagre transition flora, intermediate between theCretaceous and Eocene or earliest Tertiary of the interior regions,and named by Lesquereux the Lower Lignitic.

Immediately above these Upper Cretaceous beds we havethe great Lignite Tertiary of the west—the Laramie group ofrecent American reports [100]—abounding in fossil plants, properto a temperate climate, at one time regarded as Miocene, butnow known to be Lower Eocene.[101] These beds, with their« 213 »characteristic plants, have been traced into the British territorynorth of the forty-ninth parallel, and it has been shown thattheir fossils are identical with those of the McKenzie RiverValley, described by Heer as Miocene, and probably also withthose of Alaska, referred to the same age.[102] Now this trulyEocene flora of the temperate and northern parts of Americahas so many species in common with that called Miocene inGreenland, that its identity can scarcely be doubted. Thesefacts have led me to doubt the Miocene age of the upperplant-bearing beds of Greenland, and more recently Mr. J.Starkie Gardner has shown from comparison with the Eoceneflora of England and other considerations, that they are reallyof that earlier date.[103]

In looking at these details, we might perhaps suppose thatno conditions of climate could permit the vegetation of theneighbourhood of Disco in Greenland to be identical withthat of Colorado and Missouri, at a time when little differenceof level existed in the two regions. Either the southern floramigrated north in consequence of a greater amelioration ofclimate, or the northern flora moved southward as the climatebecame colder. The same argument, as Gardner has ablyshown, applies to the similarity of the Tertiary plants of temperateEurope to those of Greenland. If Greenland requireda temperature of about 50°, as Heer calculates, to maintain its"Miocene" flora, the temperature of England must have beenat least 70°, and that of the south-western States still warmer.It is to be observed, however, that the geographical arrangements« 214 »of the American land in Cretaceous and early Eocenetimes, included the existence of a great inland sea of warmwater extending at some periods as far north as the latitude of55°, and that this must have tended to much equality of climaticalconditions.

We cannot certainly affirm anything respecting the originand migrations of these floras, but there are some probabilitieswhich deserve attention. The ferns and cycads of the so-calledLower Cretaceous of Greenland are nothing but acontinuation of the previous Jurassic flora. Now this wasestablished at an equally early date in the Queen CharlotteIslands,[104] and still earlier in Virginia.[105] The presumption is,therefore, that it came from the south. It has indeed thefacies of a southern hemisphere and insular flora; and probablyspread itself northward as far as Greenland at a timewhen the American land was long, narrow, and warm, andwhen the ocean currents were carrying tepid water far towardthe arctic regions. The flora which succeeds this in the sectionsat Atané and Patoot has no special affinities with thesouthern hemisphere, and is of a warm temperate and continentalcharacter. It is very similar in its general aspect tothat of the Dakota group farther to the south, and this isprobably Middle Cretaceous. This flora must have originatedeither somewhere in temperate America, or within the arcticcircle, and it must have replaced the older one by virtue ofincreasing subsidence and gradual change of climate. It musttherefore have been connected with the depression of the landwhich took place in the course of the Cretaceous. During thismovement it spread over all Western America, and as the landagain arose from the sea of the Niobrara chalk, it assumed anaspect more suited to a cool climate, or moved southward,« 215 »and finally abandoned the Arctic regions, perhaps continuingto exist on the Pacific coast, and in sheltered places in thenorth, till the warm inland seas of the Upper Cretaceous hadgiven place to the wide plains and land-locked brackish seas orfresh-water lakes of the Laramie period (Eocene). Thus thetrue Upper Cretaceous marks in the interior a cooler periodintervening between the Middle Cretaceous and the LowerEocene floras of Greenland.

This latter established itself in Greenland, and probably allaround the Arctic circle, in the mild period of the earliestEocene, and as the climate of the northern hemisphere becamegradually reduced from that time till the end of the Pliocene,it marched on over both continents to the southward, chasedbehind by the modern arctic flora, and eventually by the frostand snow of the Glacial age. This history may admit of correctionin details; but, so far as present knowledge extends, itis in the main not far from the truth.

Perhaps the first great question which it raises is that as tothe causes of the alternations of warm and cold climates in thenorth, apparently demanded by the vicissitudes of the vegetablekingdom. Here we may set aside the idea that in formertimes plants were suited to endure greater cold than at present.It is true that some of the fossil Greenland plants are of unknowngenera, and many are new species to us; but we areon the whole safe in affirming that they must have requiredconditions similar to those necessary to their modern representatives,except within such limits as we now find to hold insimilar cases among existing plants. Still we know that at thepresent time many species found in the equable climate ofEngland will not live in Canada, though species to all appearancesimilar in structure are natives of the latter. There isalso some reason to suppose that species, when new, may havegreater hardiness and adaptability than when in old age, andverging toward extinction. In any case, these facts can account« 216 »for but a small part of the phenomena, which require to be explainedby physical changes affecting the earth as a whole, orat least the northern hemisphere. Many theoretical viewshave been suggested on this subject, which will be found discussedelsewhere, and perhaps the most practical way to dealwith them here will be to refer to the actual conditions knownto have prevailed in connection with the introduction anddistribution of the principal floras which have succeeded eachother in geological history.

If we can assume that all the carbon now sealed up in limestonesand in coal was originally floating in the atmosphereas carbon dioxide, then we would have a cause which mightseriously have affected the earlier land floras—that, for instance,which may have existed in the Eozoic age, and those wellknown to us in the Palæozoic. Such an excess of carbonicacid would have required some difference of constitution inthe plants themselves; it would have afforded them a super-abundanceof wood-forming nutriment, and it would haveacted as an obstacle to the radiation of heat from the earth,almost equal to the glass roof of a greenhouse, thus constitutinga great corrective of changes of temperature. Under such circumstanceswe might expect a peculiar and exuberant vegetationin the earlier geological ages, though this would not applyto the later in any appreciable degree. In addition to thiswe know that the geographical arrangements of our continentswere suited to the production of a great uniformity of climate.Taking the American continent as the simpler, we know thatin this period there existed in the interior plateau between therudimentary eastern and western mountains a great inlandsea, so sheltered from the north that its waters contained hundredsof species of corals, growing with a luxuriance unsurpassedin the modern tropics. On the shores and islands ofsuch a sea we do not wonder that there should have been tree-fernsand gigantic lycopods. In the succeeding Carboniferous,« 217 »vast areas, both on the margins and in the interior of thecontinent, were occupied with swampy flats and lagoons, theatmosphere of which must have been loaded with vapour, andrich in compounds of carbon, though the temperature mayhave been lower than in the Devonian. There still remained,however, more especially in the west, a remnant of the oldinland sea, which must have greatly aided in carrying a warmtemperature to the north.

If now we pass to the succeeding Jurassic age, we find amore meagre and less widely distributed flora, correspondingto less favourable geographical and climatal conditions, whilein the Cretaceous and Eocene ages a return to the old conditionof a warm Mediterranean in continuation of the Gulf ofMexico gave those facilities for vegetable growth, whichcarried plants of the temperate zone as far north as Greenland.

It thus appears that those changes of physical geographyand of the ocean currents to which reference is so often madein these papers, apply to the question of the distribution ofplants in geological time.

These same causes may help us to deal with the peculiaritiesof the great Glacial age, which may have been rendered exceptionallysevere by the combination of several of the continentaland oceanic causes of refrigeration. We must notimagine, however, that the views of those extreme glacialists,who suppose continental ice caps reaching half way to theequator, are borne out by facts. In truth, the ice accumulatinground the pole must have been surrounded by water, andthere must have been tree-clad islands in the midst of the icyseas, even in the time of greatest refrigeration. This is provedby the fact that in the lower Leda clay of Eastern Canada,which belongs to the time of greatest submergence, and whosefossil shells show sea water almost at the freezing point, thereare leaves of poplars and other plants which must have beendrifted from neighbouring shores. Similar remains occur in« 218 »clays of similar origin in the basin of the great lakes and inthe West, and are not Arctic plants, but members of the NorthTemperate flora.[106] These have been called "interglacial," butthere is no evidence to prove that they are not truly glacial.Thus, while the arctic flora must have continued to exist withinthe Arctic circle in the Glacial age, we have evidence that thoseof the cold temperate and subarctic zones continued to existpretty far north. At the same time the warm temperate florawould be driven to the south, except where sustained in insularspots warmed by the equatorial currents. It would return northwardon the re-elevation of the land and the return of warmth.

If, however, our modern flora is thus one that has returnedfrom the south, this would account for its poverty in speciesas compared with those of the early Tertiary. Groups of plantsdescending from the north have been rich and varied. Returningfrom the south they are like the shattered remains ofa beaten army. This, at least, has been the case with such retreatingfloras as those of the Lower Carboniferous, the Permian,and the Jurassic, and possibly that of the Lower Eoceneof Europe.

The question of the supply of light to an Arctic flora ismuch less difficult than some have imagined. The longsummer day is in this respect a good substitute for a longerseason of growth, while a copious covering of winter snow notonly protects evergreen plants from those sudden alternationsof temperature which are more destructive than intense frost,and prevents the frost from penetrating to their roots, butby the ammonia which it absorbs preserves their greenness.According to Dr. Brown, the Danish ladies of Disco long agosolved this problem.[107] He informs us that they cultivate in« 219 »their houses most of our garden flowers, as roses, fuchsias, andgeraniums, showing that it is merely warmth, and not lightthat is required to enable a subtropical flora to thrive in Greenland.Even in Canada, which has a flora richer in some respectsthan that of temperate Europe, growth is effectuallyarrested by cold for nearly six months, and though there isample sunlight there is no vegetation. It is indeed not impossiblethat in the plans of the Creator the continuoussummer sun of the Arctic regions may have been made themeans for the introduction, or at least for the rapid growth andmultiplication, of new and more varied types of plants. It is amatter of familiar observation in Canada that our hardy gardenflowers attain to a greater luxuriance and intensity of colourin those more northern latitudes where they have the advantageof long and sunny summer days.

Much, of course, remains to be known of the history of theold floras whose fortunes I have endeavoured to sketch, andwhich seem to have been driven like shuttlecocks from northto south, and from south to north, especially on the Americancontinent, whose meridional extension seems to have given afield specially suited for such operations.

This great stretch of the western continent from north tosouth is also connected with the interesting fact that, whennew floras are entering from the Arctic regions, they appearearlier in America than in Europe; and that in times when theold floras are retreating from the south, old genera and specieslinger longer in America. Thus, in the Devonian and Cretaceousnew forms of those periods appear in America longbefore they are recognised in Europe, and in the modernepoch forms that would be regarded in Europe as Miocenestill exist. Much confusion in reasoning as to the geologicalages of the fossil flora has arisen from want of attention tothis circumstance.

What we have learned respecting this wonderful history has« 220 »served strangely to change some of our preconceived ideas.We must now be prepared to admit that an Eden might existeven in Spitsbergen, that there are possibilities in this oldearth of ours which its present condition does not reveal tous; that the present state of the world is by no means thebest possible in relation to climate and vegetation; that therehave been and might be again conditions which could convertthe ice-clad Arctic regions into blooming paradises, andwhich, at the same time, would moderate the fervent heat of thetropics. We are accustomed to say that nothing is impossiblewith God; but how little have we known of the gigantic possibilitieswhich lie hidden under some of the most common ofHis natural laws.

Yet these facts have been made the occasion of speculationsas to the spontaneous development of plants without anydirect creative intervention. It would, from this point of view,be a nice question to calculate how many revolutions of climatewould suffice to evolve the first land plant; what are thechances that such plant would be so dealt with by physicalchanges as to be preserved and nursed into a meagre flora likethat of the Upper Silurian or the Jurassic; how many transportationsto Greenland would suffice to promote such meagreflora into the rich and abundant forests of the Upper Cretaceous,and to people the earth with the exuberant vegetationof the early Tertiary. Such problems we may never be ableto solve. Probably they admit of no solution, unless we invokethe action of a creative mind, operating through long ages, andcorrelating with boundless power and wisdom all the energiesinherent in inorganic and organic nature. Even then we shallperhaps be able to comprehend only the means by which, afterspecific types have been created, they may, by the culture oftheir Maker, be "sported" into new varieties or sub-species,and thus fitted to exist under different conditions, or to occupyhigher places in the economy of nature.

Before venturing on such extreme speculations as some nowcurrent on questions of this kind, we would require to knowthe successive extinct floras as perfectly as those of the modernworld, and to be able to ascertain to what extent each speciescan change, either spontaneously or under the influence ofstruggle for existence, or expansion under favourable conditions,and under Arctic semi-annual days and nights, or the shorterdays of the tropics. Such knowledge, if ever acquired, it maytake ages of investigation to accumulate. In any case the subjectof this paper indicates one hopeful line of study withthe object of arriving at some comprehension of the laws ofcreation.

While the facts above slightly sketched impress us with thegrand progress of the vegetable kingdom in geological time,they equally show the persistence of vegetable forms as comparedwith that of the dead continental masses and the decayof some forms of life in favour of the introduction of others.

When we find in the glacial beds the leaves of trees stillliving in North America and Europe, and consider the vicissitudesof elevation and submergence of the land, and ofArctic and temperate climates which have occurred, we arestruck with the persistence of the weak things of life, as comparedwith the changeableness of rocks and mountains. Asuperficial observer might think the fern or the moss of agranite hill a frail and temporary thing as compared with solidand apparently everlasting rock. But just the reverse is thecase. The plant is usually older than the mountain. But theglacial age is a very recent thing. We have facts older thanthis. As hinted in a previous paper, in the Laramie claysassociated with the Lignite beds of North-western Canada—bedsof Lower Eocene or early Tertiary age—which were depositedbefore the Rocky Mountains or the Himalayas hadreared their great peaks and ridges, and at a time when thewhole geography of the northern hemisphere was different« 222 »from what it is at present—are remains of very frail and delicateplants which still live. I have shown that in these claysthere exist, side by side, the Sensitive Fern,Onoclea sensibilis,and one of the delicate rock ferns,Davallia tenuifolia.[108] Thefirst is still very abundant all over North America. The secondhas ceased to exist in North America, but still survives in thevalleys of the Himalayas. These two little plants, once probablyvery widely diffused over the northern hemisphere, havecontinued to exist through the millenniums separating theCretaceous from the present time, and in which the greaterpart of our continent was again and again under the sea, inwhich great mountain chains have been rolled up and sculpturedinto their present forms, and in which giant forms, both ofanimal and plant life, have begun, culminated and passedaway. Truly God hath chosen the weak things of the world toconfound those that are strong.

Other plants equally illustrate the decadence of importanttypes of vegetable life. In the beautiful family of the Magnoliasthere exists in America a most remarkable and elegant tree,whose trunk attains sometimes a diameter of 7 feet and aheight of 80 or 90 feet. Its broad deep green leaves aresingularly truncate at the end, as if artificially cut off, and inspring it puts forth a wealth of large and brilliant orange andyellow flowers, from which it obtains the name of Tulip tree.It is theLiriodendron tulipifera of botanists, and the solespecies of its genus. This Tulip tree has a history. Allthrough the Tertiary beds we find leaves referable to the genus,and belonging not to one species only, but to several, and aswe go back into the Cretaceous, the species seem to becomemore numerous. Many of them have smaller leaves than themodern species, others larger, and some have forms even morequaint than that of the existing Tulip tree. The oldest that Ihave seen in Canada is one from the Upper Cretaceous of« 223 »Port McNeil in the north of Vancouver Island, which is aslarge as that of the modern species, and very similar in form.Thus this beautiful vegetable type culminated long geologicalages ago, and was represented by many species, no doubt occupyinga prominent place in the forests of the northern hemisphere.To-day only a single species exists, in our warmer regions,to keep up the memory of this almost perished genus;but that species is one of our most beautiful trees.

The history of the Sequoias or giant Cypresses, of which twospecies now exist in limited areas in California, is still morestriking. These giant trees, monsters of the vegetable kingdom,are, strange to say, very limited in their geographicalrange. The greater of the two,Sequoia gigantea, the gianttreepar excellence, seems limited to a few groves in California.At first sight this strikes us as anomalous, especially as we findthat the tree will grow somewhat widely both in Europe andAmerica when its seeds are sown in suitable soil. The mysteryis solved when we learn that the two existing species are butsurvivors of a genus once diffused over the whole northernhemisphere, and represented by many species, constituting,in the Later Cretaceous and Eocene ages, vast and dark forestsextending over enormous areas of our continents, and formingmuch of the material of the thick and widely distributedLignite beds of North-western America. Thus the genus hashad its time of expansion and prevalence, and is now probablyverging on extinction, not because there are not suitablehabitats, but either because it is now old and moribund, orbecause other and newer forms have now a preference in theexisting conditions of existence.

The Plane trees, the Sassafras, the curious Ginkgo tree orfern-leaved yew of Japan, are cases of similar decadence ofgenera once represented by many species, while other trees, likethe Willows and Poplars, the Maples, the Birches, the Oaksand the Pines, though of old date, are still as abundant as« 224 »they ever were, and some genera would seem even to haveincreased in number of species, though on the whole the floraof our modern woods is much less rich than those of theMiocene and Eocene, or even than that of the Later Cretaceous.The early Tertiary periods were, as we know, times ofexuberant and gigantic animal life on the land, and it is in connectionwith this that the vegetable world seems to haveattained its greatest variety and luxuriance. Even that earlypost-glacial age in which primitive man seems first to havespread himself over our continents was one richer both inanimal and plant life than the present. The geographicalchanges which closed this period and inaugurated the modernera seem to have reduced not only the area of the continentsbut the variety of land life in a very remarkable manner. Thusour last lesson from the genesis and migrations of plants isthe humbling one that the present world is by no means thebest possible in so far as richness of vegetable and animal lifeis concerned.

Reference has been made to the utility of fossil plants asevidence of climate; but the subject deserves more detailednotice. I have often pondered on the nature of the climateevidenced by the floras of the Devonian and Carboniferous; butthe problem is a difficult one, not only because of the peculiarcharacter of the plants themselves, so unlike those of our time,but because of the probably different meteorological conditionsof the period. It is easy to see that a flora of tree-ferns, greatlycopods and pines is more akin to that of oceanic islands inwarm latitudes than anything else that we know. But theDevonian and Carboniferous plants did not flourish in oceanicislands, but for the most part on continental areas of considerabledimensions, though probably more flat and less elevatedthan those of the present day. They also grew, from Arcticlatitudes, almost, if not altogether, to the equator; and thoughthere are generic differences in the plants of these periods in« 225 »the southern hemisphere, yet these do not affect the generalfacies. There are, for example, characteristic Lepidodendroidsin the Devonian and Carboniferous of Brazil, Australia, andSouth Africa. If now we consider the plants a little more indetail, coniferous and taxine trees grow now in very differentlatitudes and climates. There is therefore nothing so veryremarkable in their occurrence. The great group of Cordaitesmay have been equally hardy; but it is noteworthy that theirgeographical distribution is more limited. In Europe, forexample, they are more characteristic in France than in GreatBritain. Ferns and Lycopods and Mare's-tails are also cosmopolitan,but the larger species belong to the warmer climates,and nowhere at present do they become so woody and so complexin structure as they were in the older geological periods.At the present day, however, they love moisture rather thanaridity, and uniformity of temperature rather than extremelight and heat. The natural inference would be that in theseolder periods geographical and other conditions must haveconspired to produce a uniform and moist climate over a largeportion of the continents. The geographical conditions ofthe Carboniferous age, and the distribution of animal life onthe sea and land, confirm the conclusion based on the flora.Further, if, as seems probable, there was a larger proportion ofcarbon dioxide in the atmosphere than at present, this wouldnot only directly affect the growth of plants, but would impederadiation, and so prevent escape of heat by that means,while the moisture exhaled from inland seas and lagoons andvastly extended swamps, would tend in the same direction.

It would, however, be a mistake to infer that there were notlocal differences of climate. I have elsewhere [109] advocated thetheory that the great ridge of boulders, the New Glasgow conglomerate,which forms one margin of the coal field of Picton,« 226 »in Nova Scotia, is an ice-formed ridge separating the area ofaccumulation of the great thirty-six feet seam from an outerarea in which aqueous conditions prevailed, and little coal wasformed. In this case, an ice-laden sea, carrying boulders onits floes and fields of ice, must have been a few miles distantfrom forests of Lepidodendra, Cordaites, and Sigillariæ, and theclimate must have been anything but warm, at least at certainseasons. Nor have we a right to infer that the growth of thecoal-plants was rapid. Stems, with woody axes and a thickbark, containing much fibrous and thick-walled cellular tissue,are not to be compared with modern succulent plants, especiallywhen we consider the sparse and rigid foliage of manyof them. Our conclusion should, therefore, be that geographicalconditions and the abundance of carbon dioxide in theatmosphere favoured a moist climate and uniform temperature,and that the flora was suited to these conditions.

As to the early Mesozoic flora, I have already suggested thatit must have been an invader from the south, for which theintervening Permian age had made way by destroying thePalæozoic flora. This was probably effected by great earth-movementschanging geographical conditions. But in theMesozoic the old conditions to some extent returned, and theCarboniferous plants being extinct, their places were taken bypines, lycopods, and ferns, whose previous home had been in theinsular regions of the tropics, and which, as climatal conditionsimproved, pushed their way to the Arctic circle. But, beingderivatives of warm regions, their vitality and capacity forvariation were not great, and they only locally and in favourableconditions became great coal producers. The new flora of theLater Cretaceous and the Tertiary, as previously stated, originatedin the Arctic, and marched southward.

These newer Cretaceous plants presented from the first thegeneric aspects of modern vegetation, and so enable us muchbetter to gauge their climatal conditions. In general, they do« 227 »not indicate tropical heat in the far north, but only that of thewarm temperate zone; but this in some portions of the periodcertainly extends to the middle of Greenland, unless, withoutany evidence, we suppose that the Cretaceous and lower Tertiaryplants differed in hardiness of constitution from their modernrepresentatives. They prove, however, considerable oscillationsof climate. Gardner, Nathorst and Reid have shown this inEurope, and that it extends from the almost tropical flora ofthe lower Eocene to the Arctic flora of the Pleistocene. InAmerica, owing, as Grey has suggested, to its great north andsouth extension, the changes were more regular and gradual.In the warmer periods of the Cretaceous, the flora as far northas 55° was similar to that of Georgia and Northern Florida atthe present day, while in the cooler period of the Laramie(Lower Eocene, or more probably Paleocene) it was not unlikethat of the Middle States. In the Pleistocene, the floraindicates a boreal temperature in the Glacial age. Thus thereare no very extreme contrasts, but the evident fact of a warmtemperate or subtropical climate extending very far north atthe same times when Greenland had a temperate climate. AsI have elsewhere shown,[110] discoveries in various parts of NorthAmerica are beginning to indicate the precise geographicalconditions accompanying the warmer and colder climates.

It would be wrong to leave this subject without noticingthat remarkable feature in the southward movement of thelater floras, to which I believe Prof. Gray was the first todirect attention. In those periods when a warm climate prevailedin the Arctic regions, the temperate flora must have been,like the modern Arctic flora, circumpolar. When obliged tomigrate to the south, it had to follow the lines of the continents,and so to divide into separate belts. Three of theseat present are the floras of Western Europe, Eastern Asia,and Eastern America, all of which have many representative« 228 »species. They are separated by oceans and by belts of landoccupied by plants which have not been obliged to migrate.Thus, while the flora of the Eastern United States resemblesthat of China and Japan, that of California and Oregon isdistinct from both, and represents a belt of old species retainedin place by the continued warmth of the Pacific shore, and thecontinuous extension of the American continent to the southaffording them means of retreat in the Glacial age. Were theplants of China and Eastern America enabled to return to theArctic, they would then reunite into one flora. Gray comparesthe process of their separation to the kind of selection whichmight be made by a botanical distributor who had the wholecollection placed in his hands, with instructions to give onespecies of each genus to Europe, to Eastern Asia, and toEastern America; and if there was only one species in agenus, or if one remained over, this was to be thrown into oneof the regions, with a certain preference in favour of Americaand Asia. This remarkable kind of geographical selectionopens a wide field not only for thought, but for experiment onthe actual relationship of the representative species. There isa similar field for comparison between the trees of Georgia inlatitude 30° to 35°, and the same species or their representativesas they existed in Cretaceous times in the latitudes of50° and 60°. The two floras, as I know from actual comparison,are very similar.

One word may be said here as to use of fossil plants indetermining geological time. In this I need only point tothe fact of my having defined in Canada three Devonianfloras, a Lower, Middle, and Upper, and that Mr. Whiteaves, inhis independent study of the fossil fishes, has vindicated myconclusions. There are also in Nova Scotia three distinctivesub-floras of the Lower, Middle, and Upper Carboniferous.[111] I« 229 »have verified these for the Devonian and Carboniferous of theUnited States, and to some extent also for those of Europe.To the same effect is the recognition of the Kootanie orLower Cretaceous, the Middle Cretaceous, Upper Cretaceous,Laramie and Miocene in Western Canada. These have in allcases corresponded with the indications of animal fossils [112] andof stratigraphy. Fossil plants have been less studied in thisconnection than fossil animals, but I have no hesitation inaffirming that, with reference to the broader changes of theearth's surface, any competent palæobotanist is perfectly safein trusting to the evidence of vegetable fossils.

It may be objected that such evidence will be affected by themigrations of plants, so that we cannot be certain that identicalspecies flourished in Greenland and in temperate America atthe same time. If such species originated in Greenland andmigrated southward, the specimens found at the south may bemuch newer than those in the north. This, no doubt, islocally true, but the migrations of plants, though slow, occupyless time than that of a great geological period. It may also beobjected that the flora of swamps, plains, and mountain topswould differ at any one period. This also is true, but the samedifficulty applies to animals of the deep sea, the shore, and theland; and these diversities of station have always to be takeninto account by the palæontologist.

References:—Report on the Erian or Devonian Plants of Canada,Montreal, 1871. Article in Princeton Review on Genesis andMigrations of Plants. "The Geological History of Plants," Londonand New York, 1888 and 1892. Papers on Fossil Plants of WesternCanada, 1883, and following volumes of Transactions of RoyalSociety of Canada.

Note.—Since writing the above, I have obtained access to Dall andHarris' "Neocene Correlation Papers," which throw some additional« 230 »light on the Cretaceous and Eocene Floras of Alaska, which, from its highnorthern latitude, affords a good parallel to Greenland. It would appearthat plant-beds occur in that territory at two horizons. One of these(Cape Beaufort), according to Lesquereux and Ward, holds species ofNeocomian Age, and apparently equivalent to the Kootanie of BritishColumbia and the Komé of Greenland. The other, which occurs atseveral localities (Elukak, Port Graham, etc.), has a flora evidently ofLaramie (Eocene) age, equivalent to the "Miocene" of Heer and Lesquereux,and to the Lignite Tertiary of Canada. The plants are accompaniedby lignite, and evidentlyin situ, and clearly prove harmony withGreenland and British Columbia in two of the periods of high Arctictemperature indicated above.

THE GROWTH OF COAL.

DEDICATED TO THE MEMORY OF

DR. SCHIMPER,

OF STRASBURG,

The Author of "La Flore du Monde Primitif," and
many other Contributions to Fossil Botany,
and of

DR. H. R. GOEPPERT,

whose Essay on the Structure and Formation of Coal
was One of my first Guides in its Study.

Questions of Growth and Driftage—Testimony of aBlock of Coal under the Microscope—DifferentKinds of Coal—Conditions Necessary to Accumulationin Situ—Coal Beds and their Accompaniments—Underclaysand Roofs—Vegetable Remains—Historyof Coal Groups—Summary of Evidence—Subsidenceof Coal Areas—Stigmaria and otherCoal Plants—Later Coal Accumulations—TheStory and Uses of Coal

CHAPTER IX.

My early boyhood was spent on the Coal formation rocksand in the vicinity of collieries; and among my firstnatural history collections, in a childish museum of manykinds of objects, were some impressions of fern leaves from theshales of the coal series. It came to pass in this way that theCarboniferous rocks were those which I first studied as anembryo geologist, and much of my later work has consisted incollecting and determining the plants of that ancient period, andin studying microscopic sections of coals and fossil woods accompanyingthem. For this reason, and because I have publishedso much on this subject, my first decision was to leaveit out of these Salient Points: but on second thoughts itseemed that this might be regarded as a dereliction of duty;more especially as some of the conclusions supposed to be thebest established on this subject have recently been called inquestion.

Had I been writing a few years ago, I might have referred tothe mode of formation of coal as one of the things most surelysettled and understood. The labours of many eminent geologists,microscopists and chemists in the old and the new worldshad shown that coal nearly always rests upon old soil-surfacespenetrated with roots, and that coal beds have in their roofserect trees, the remains of the last forests that grew upon them.Logan and the writer have illustrated this in the case of theseries of more than eighty successive coal beds exposed at the« 234 »South Joggins, and of the great thirty feet seam of the Pictoncoal series, whose innumerable laminæ have all been subjectedto careful scrutiny, and have shown unequivocal evidence ofland surfaces accompanying the deposition of the coal. Microscopicalexamination has proved that these coals are composedof the materials of the same trees whose roots are found in theunderclays, and their stems and leaves in the roof shales; thatmuch of the material of the coal has been partially subjected tosubaërial decay at the time of its accumulation; and that inthis, ordinary coal differs from bituminous shale, earthy bitumenand some kinds of cannel, which have been formed underwater; that the matter remaining as coal consists almost entirelyof epidermal tissues, which being suberose or corky in characterare highly carbonaceous, very durable and impermeableby water, and are, hence, the best fitted for the production ofpure coal; and finally, that the vegetation and the climatal andgeographical features of the coal period were eminently fittedto produce in the vast swamps of that period precisely theeffects observed. All these points and many others have beenthoroughly worked out for both European and American coalfields, and seemed to leave no doubt on the subject. Butseveral years ago certain microscopists observed in slices ofcoal, thin layers full of spore cases, a not unusual circumstance,since these were shed in vast abundance by the trees of thecoal forests, and because they contain suberose matter of thesame character with epidermal tissues generally. Immediatelywe were informed that all coal consists of spores, and this beingat once accepted by the unthinking, the results of the laboursof many years are thrown aside in favour of this crude andpartial theory. A little later, a German microscopist hasthought proper to describe coal as made up of minute algæ, andtries to reconcile this view with the appearances, devising at thesame time a new and formidable nomenclature of generic andspecific names, which would seem largely to represent mere« 235 »fragments of tissues. Still later, some local facts in a Frenchcoal field have induced an eminent observer of that country torevive the drift theory of coal, in opposition to that of growthin situ. Views of this kind have also recently been advancedin England by some of those younger men who would earn distinctionrather by overthrowing the work of their seniors thanby building on it. These writers base their conclusions on afew exceptional facts, as the occasional occurrence of seams ofcoal without distinct underlays, and the occurrence of claypartings showing aquatic conditions in the substance of thickcoals; and they fail to discern the broader facts which these exceptionsconfirm. Let us consider shortly the essential natureof coal, and some of the conditions necessary to its formation.

A block of the useful mineral which is so important an elementin national wealth, and so essential to the comfort of our winterhomes, may tell us much as to its history if properly interrogated,and what we cannot learn from it alone we may be taughtby studying it in the mine whence it is obtained, and in thecliffs and cuttings where the edges of the coaly beds and theiraccompaniments are exposed.

Our block of coal, if anthracite, is almost pure carbon. Ifbituminous coal, it contains also a certain amount of hydrogen,which in combination with carbon enables it to yield gas andcoal tar, and which causes it to burn with flame. If, again, weexamine some of the more imperfect and more recent coals, thebrown coals, so called, we shall find that in composition andtexture they are intermediate between coal proper and hardenedor compressed peat. Now such coaly rocks can, under thepresent constitution of nature, be produced only in one way,namely, by the accumulation of vegetable matter, for vegetationalone has the power of decomposing the carbonic acid of theatmosphere, and accumulating it as carbon. This we see inmodern times in the vegetable soil, in peaty beds, and in« 236 »vegetable muck accumulated in ponds and similar places.Such vegetable matter, once accumulated, requires only pressureand the changes which come of its own slow putrefaction to beconverted into coal.

But in order that it may accumulate at all, certain conditionsare necessary. The first of these includes the climatal and organicarrangements necessary for abundant vegetable growth.The second is the facility for the preservation of the vegetablematter, without decay or intermixture with earthy substances;and this, for a long time, till a great thickness of it accumulates.The third is its covering up by other deposits, so as to be compressedand excluded from air. It is evident that when we haveto consider the formation of a bed of coal several feet in thickness,and spread, perhaps, over hundreds of square miles, manythings must conduce to such a result, and the wonder is perhapsrather that such conditions should ever have been effectivelycombined. Yet this has occurred at different periods of geologicalhistory and in many places, and in some localities it hasbeen so repeated as to produce many beds of coal in succession.

Let us now question our block of coal as to its origin, supposingit to be a piece of ordinary bituminous coal, or still better,a specimen of one of the impure somewhat shaly coals whichone sometimes finds accidentally in the coal bin. In lookingat the edge of our specimen we observe that it has a "reed"or grain, which corresponds with the lamination or bedding ofthe seam of coal from which it came. Looking at this carefully,we shall see that there are many thin layers of bright shiningcoal, and the more of these usually the better the coal. Theselayers, in tracing them along, we observe often to thin out anddisappear. They are not very continuous. If our specimen isan impure coal, we will find that it readily splits along the surfacesof these layers, and that when so split, we can see that eachlayer of shining coal has certain markings, perhaps the flattened« 237 »ribs and scars of Sigillaria or other coal-formation trees onits surface. In other words, the layers of fine coal are usuallyflattened trunks and branches of trees, or perhaps rather of theimperishable and impermeable bark of such trees, the woodhaving perished. A few very thin layers of shining coal we mayalso find to consist of the large-ribbed leaves of the plant knownas Cordaites. This kind of coaly matter then usually representstrunks of trees which in a prostrate and flattened state mayconstitute more than half of the bulk of ordinary coal-formationcoal. Under the microscope this variety of coal shows littlestructure, and this usually the thickened cells of cortical tissue.Intervening between these layers we perceive lamina?, more orless thick and continuous, of what we may call dull coal, blackbut not shining; resembling, in fact, the appearance of cannelcoal. If we split the coal along one side of these layers, andexamine it in a strong light, we may see shreds of leaf stalksand occasionally even of fern leaves, or skeletons of these, showingthe veins, and many flattened disc-like bodies, spore casesand macrospores, shed by the plants which make up the coal.These layers represent what may be called compressedvegetable mould or muck, and this is by no means a smallconstituent of many coals. This portion of the coal is themost curious and interesting in microscopic slices, showing agreat variety of tissues and many spores and spore cases.Lastly, we find on the surface of the coal, when split parallel tothe bedding, a quantity of soft shining fibrous material, knownas mineral charcoal or mother coal, which in some varieties ofthe mineral is very abundant, in others much more rare. Thisis usually too soft and incoherent to be polished in thin slicesfor the microscope; but if boiled for a length of time in nitricacid, so as to separate all the mineral matter contained in it,the fibres sometimes become beautifully translucent and revealthe tissues of the wood of various kinds of Carboniferous trees,more especially of Calamites, Cordaites and Sigillariæ. Fibres« 238 »of mineral charcoal prepared in this way are often very beautifulmicroscopic objects under high powers; and this material ofthe coal is nothing else than little blocks of rotten wood andfibrous bark, broken up and scattered over the surface of theforming coal bed. All these materials, it must be observed, havebeen so compressed that the fragments of decayed wood havebeen flattened into films, the vegetable mould consolidated intoa stony mass, and trunks of great trees converted by enormouspressure into laminæ of shining coal, a tenth of an inch in thickness,so that the whole material has been reduced to perhapsone-hundredth of its original volume.

Restoring the mass in imagination to its original state, whatdo we find? A congeries of prostate trunks with their intersticesfilled with vegetable muck or mould, and occasional surfaceswhere rotten wood, disintegrated into fragments, was washedabout in local floods or rain storms, and thus thrown over thesurface. Lyell seems very nearly to have hit the mark whenhe regarded the conditions of the great dismal swamp ofVirginia as representing those of a nascent coal field. Wehave only to realize in the coal period the existence of a densevegetation very different from that of modern Virginia, of ahumid and mild climate, and of a vast extension of lowswampy plains, to restore the exact conditions of the coalswamps.

But how does this correspond with the facts observed inmines and sections? To the late Sir William Logan is due themerit of observing that in South Wales the underclays or bedsof indurated clay and earth underlying the coal seams areusually filled with the long cylindrical rootlets and branchingroots of a curious plant, very common in the coal formation,the Stigmaria. He afterwards showed that the same factoccurs in the very numerous coal beds exposed in the finesection cut by the tides of the Bay of Fundy, in the coal rocksof Nova Scotia. In that district I have myself followed up« 239 »his observations, examining in detail every one of eighty-oneCoal Groups, as I have called them, each consisting of atleast one bed of coal, large or small, with its accompaniments,and in many cases of several small seams with interveningclays or shales.[113] In nearly every case the Stigmaria "underclay"is distinctly recognisable, and often in a single coalgroup there are several small seams separated by underclayswith roots and rootlets. These underclays are veritable fossilsoils; sometimes bleached clays or sands, like the subsoils ofmodern swamps; sometimes loamy or sandy, or of the natureof hardened vegetable mould. They rarely contain any remainsof aquatic animals, or of animals of any kind, but are filledwith stigmaria roots and rootlets, and sometimes hold a fewprostrate stems of trees.[114] While the underclay is thus a fossilsoil, the roof or bed above the coal, usually of a shaly character,is full of remains of leaves and stems and fruits, andoften holds erect stumps, the remains of the last trees thatgrew in the swamp before it was finally covered up.

Some of the thinnest coals, and some beds so thin andimpure that they can scarcely be called coals at all, are themost instructive. Witness the following from my section ofthe South Joggins.

Coal Group 1, of Division 3, is the highest of the series. Itssection is as follows:—

"The roof holds abundance of fern leaves (Alethopteris« 240 »lonchitica). The coal is coarse and earthy, with much epidermaland bast tissue, spore cases, etc., vascular bundles of fernsand impressions of bark of Sigillaria and leaves of Cordaites.It may be considered as a compressed vegetable soil resting ona subsoil full of rootlets of Stigmaria." In this case the coal isan inch in thickness, but there are many beds where the coalis a mere film, and supports great erect stems of Sigillaria,sending downward their roots in the form of branchingStigmariæ into the underclay, thus proving that the Stigmariæof the underclays are the roots of the Sigillariæ of the coalsand their roofs.

Here is another example which may be called a coal group,and is No. 11 of the same division:

"Grey argillaceous shale, erect Calamites.
  Coal, 1 inch.
  Grey argillaceous underclay, Stigmaria, 1 ft. 6 in.
  Coal, 2 inches.
  Grey argillaceous underclay, Stigmaria, 4 in.
  Coal, 1 inch.
  Grey argillaceous underclay, Stigmaria.

"This is an alternation of thin, coarse coals with fossil soils.The roof shale contains erect Calamites, which seem to havebeen the last vegetation which grew on the surface of the uppercoal."

Such facts, with many minor varieties, extend through thewhole eighty-one coal groups of this remarkable section, asany one may see by referring to the paper and work cited inthe preceding note. It is possibly because in most coal fieldsthe smaller and commercially useless beds are so little open toobservation, that so crude ideas derived merely from imperfectaccess to the beds that are worked exist among geologists. Thefollowing summary of facts may perhaps serve to place theevidence as to the mode of accumulation of coal fairly beforethe reader:—

(1) The occurrence of Stigmaria under nearly every bed ofcoal proves, beyond question, that the material was accumulatedby growthin situ, while the character of the sedimentsintervening between the beds of coal proves with equal certaintythe abundant transport of mud and sand by water. Inother words, conditions similar to those of the swampy deltasof great rivers, or the swampy flats of the interiors of great continents,are implied.

(2) The true coal consists principally of the flattened barkof sigillaroid and other trees, intermixed with leaves of fernsandCordaites, and other herbaceousdébris, including vastnumbers of spores and spore cases, and with fragments ofdecayed wood constituting "mineral charcoal," all theirmaterials having manifestly alike grown and accumulated wherewe find them.

(3) The microscopical structure and chemical compositionof the beds of cannel coal and earthy bitumen, and of themore highly bituminous and carbonaceous shales, show themto have been of the nature of the fine vegetable mud whichaccumulates in the ponds and shallow lakes of modern swamps.These beds are always distinct from true subaërial coal.When such fine vegetable sediment is mixed, as is often thecase, with mud, it becomes similar to the bituminous limestoneand calcareo-bituminous shales of the coal measures.

(4) A few of the underclays which support beds of coalare of the nature of the vegetable mud above referred to; butthe greater part are argillo-arenaceous in composition, withlittle vegetable matter, and bleached by the drainage fromthem of water containing the products of vegetable decay.They are, in short, loamy or clay soils in the chemical conditionin which we find such soils under modern bogs, andmust have been sufficiently above water to admit of drainage.The absence, or small quantity of sulphides, and the occurrenceof carbonate of iron in connection with them, prove that« 242 »when they existed as soils, rain water, and not sea water, percolatedthem.

(5) The coal and the fossil trees present many evidences ofsubaërial conditions. Most of the erect and prostrate treeshad become hollow shells of bark before they were finallyimbedded, and their wood had broken into cubical pieces ofmineral charcoal. Land snails and galley worms (Xylobius)crept into them, and they became dens or traps for reptiles.Large quantities of mineral charcoal occur on the surfaces ofall the larger beds of coal. None of these appearances couldhave been produced by subaqueous action.

(6) Though the roots ofSigillaria bear some resemblanceto the rhizomes of certain aquatic plants, yet structurally theyhave much resemblance to the roots of Cycads, which thestems also resemble. Further, theSigillariæ grew on thesame soils which supported conifers,Lepidodendra,Cordaites,and ferns, plants which could not have grown in water. Again,with the exception, perhaps, of somePinnulariæ andAsterophyllites,and Rhizocarpean spores, there is a remarkableabsence from the coal measures of any form of properlyaquatic vegetation.

(7) The occasional occurrence of marine or brackish-wateranimals in the roofs of coal beds, or even in the coal itself,affords no evidence of subaqueous accumulation, since thesame thing occurs in the case of modern submarine forests.Such facts merely imply that portions of the areas of coalaccumulation were liable to inundation of a character sotemporary as not finally to close the process, as happened whenat last a roof shale was deposited by water over the coal.Cannel coals and bituminous shales holding mussel-like shells,fish scales, etc., imply the existence sometimes for long periodsof ponds, lakes or lagoons in the coal swamps, but ordinarycoal did not accumulate in these. It is in the cannels andsimilar subaqueous coals that the macrospores which I« 243 »attribute in great part to aquatic plants, allied to modernSalvinia, etc., are chiefly found.[115]

For these and other reasons, some of which are more fullystated in the papers referred to, while I admit that the areas ofcoal accumulation were frequently submerged, I must maintainthat the true coal is a subaërial accumulation by vegetablegrowth on soils wet and swampy, it is true, but not submerged.I would add the further consideration, already urged elsewhere,that in the case of the fossil forests associated with the coal, theconditions of submergence and silting-up which have preservedthe trees as fossils, must have been precisely thosewhich were fatal to their existence as living plants, a factsufficiently evident to us in the case of modern submarineforests, but often overlooked by the framers of theories of theaccumulation of coal.

It seems strange that the occasional inequalities of the floorsof the coal beds, the sand or gravel ridges which traverse them,the channels cut through the coal, the occurrence of patchesof sand, and the insertion of wedges of such material splittingthe beds, have been regarded by some able geologists asevidences of the aqueous origin of coal. In truth, theseappearances are of constant occurrence in modern swampsand marshes, more especially near their margins, or wherethey are exposed to the effects of ocean storms or river inundations.The lamination of the coal has also been adducedas a proof of aqueous deposition; but the miscroscope shows,as I have elsewhere pointed out, that this is entirely differentfrom aqueous lamination, and depends on the superposition ofsuccessive generations of more or less decayed trunks of treesand beds of leaves. The lamination in the truly aqueous cannelsand carbonaceous shales is of a very different character.

It is scarcely necessary to remark that in the above summary« 244 »I have had reference principally to my own observations in thecoal formation of Nova Scotia; but similar facts have beendetailed by many other observers in other districts.[116]

A curious point in connection with the origin of coal is thequestion how could vegetable matter be accumulated in sucha pure condition? There is less difficulty in regard to this ifwe consider the coal as a swamp accumulationin situ. It isin this way that the purest vegetable accumulations take placeat present, whereas in lakes and at the mouths of rivers vegetablematter is always mixed up with mud. Coal swamps,however, must have been liable to submergences or to temporaryinundations, and it is no doubt to these that we have toattribute the partings of argillaceous matter often found in coalbeds, as well as the occasional gulches cut into the coal andfilled with sand and lenticular masses of earthy matter. To asimilar cause we must also attribute the association of cannelwith ordinary coal. The cannel is really a pulpy, maceratemass of vegetable matter accumulated in still water, surroundedand perhaps filled with growing aquatic herbage. Hence it isin such beds that we find the greatest accumulations of macrospores,derived, probably, in great part from aquatic plants.Buckland long ago compared the matter of cannel to thesemi-fluid discharge of a bursting bog, and Alex. Agassiz hasmore recently shown that in times of flood the vegetable muckof the Everglades of Florida flows out in thick inky streams,and may form large beds of vegetable matter having thecharacter of the materials of cannel. It is evident that inswamps of so great extent as those of the coal formation, theremust have been shallow lakes and ponds, and wide sluggishstreams, forming areas for the accumulation of vegetabledébrisand this readily accounts for the association of ordinary bedsof coal with those of cannel, and with bituminous shales or« 245 »earthy bitumen, as well as for the occurrence of scales of fishand other aquatic animals in such beds. Lyell's interestingobservation of the submerged areas at New Madrid, keepingfree of Mississippi mud, because fringed with a filter of cane-brake,shows that the areas of coal accumulation might oftenbe inundated without earthy deposit, if, as seems probable,they were fringed with dense brakes of calamites, shelteringthem from the influx of muddy water. It seems also certainthat the water of the coal areas would be brown and ladenwith imperfect vegetable acids, like that of modern bogs, andsuch water has usually little tendency to deposit any mineralmatter, even in the pores of vegetable fragments. The onlyexception to this is one which also occurs in modern swamps,namely, the tendency to deposit iron, either as carbonate (ClayIronstone), or sulphide (Iron Pyrite), both of which areproducts of modern bogs, and equally characteristic of the coalswamps.

Where great accumulations of sediment are going on, as atthe mouths of modern rivers, there is a tendency to subsidenceof the area of the deposit, owing to its weight. This applies,perhaps, to a greater extent to coal areas. Thus the area of acoal swamp would ultimately sink so low as to be overflowed,and a roof shale would be deposited to bury up the bed ofcoal, and transmit it to future ages, chemically, and mechanicallychanged by pressure and by that slow decomposition whichgradually converts vegetable matter into carbon and hydrocarbons.The long continuance and great extent of these alternationsof growth and subsidence is perhaps the most extraordinaryfact of all. At the South Joggins, if we include the surfaceshaving erect trees with those having beds of coal, the processof growth of a forest or bog, and its burial by subsidence anddeposition must have been repeated about a hundred timesbefore the final burial of the whole under the thick sandstonesof the Upper Carboniferous and Permian.

Mention has been made of Sigillaria and other trees of thecoal formation period. These trees and others allied to them,of which there were many kinds, may be likened to giganticclub mosses, which they resembled in fruit and foliage, thoughvastly more complex in structure of stem and branch. Someof them, perhaps, were of much higher rank than any of themodern plants most nearly allied to them. One of their mostremarkable features was that of their roots—those Stigmariæ,to which so frequent reference has been made. They differedfrom modern roots, not only in some points of structure, butin their regular bifurcation, and in having huge root fibresarticulated to the roots, and arranged in a regular spiralmanner, like leaves. They radiate regularly from a single stem,and do not seem to have sent up buds or secondary stems.They thus differed from the botanical definition of a root, andalso from that of a rhizoma, or root stock; being, in short, aprimitive and generalized contrivance, suited to trees themselvesprimitive and generalized, and to special and peculiarcircumstances of growth. Some botanists have imagined thatthey were aquatic plants, growing at the bottom of lakes, buttheir mode of occurrence negatives this. I have elsewherestated this as follows:—[117]

"It is quite certain that Stigmariæ are not 'rhizomes whichfloated in water, or spread themselves out on the surface ofmud.' Whether rhizomes or not, they grew in the soil, or inthe upper layers of peaty deposits since changed into coal.The late Richard Brown and the writer have shown that theygrew in the underclays or fossil soils, and that their rootletsradiated in these soils in all directions.[118] In one of my papersI have figured a Stigmarian root penetrating through an erectSigillaria, and Logan, in his Report of 1845, had already« 247 »figured a similar example. The penetration of decaying stemsby the rootlets ofStigmaria is a fact well known to all whohave studied slices of Carboniferous plants,[119] whileStigmariæare often found creeping inside the bark of erect and prostratetrunks. Besides this, as I have shown in 'Acadian Geology,'in the section of 5,000 feet of coal measures at the SouthJoggins (including eighty-one distinct coal groups, and a largernumber of soils withStigmaria, or erect trees),Sigillaria andStigmaria occur together, and the latter nearly always eitherin argillaceous soils, or sands hardened into 'Gannister,' whichare often filled with roots or rootlets, or on the surfaces ofcoal beds. On the other hand, the numerous bituminouslimestones, and calcareous and other shales holding remainsof fishes, crustaceans, and bivalve shells do not containStigmariain situ—the only exceptions being two beds of bituminouslimestone, the upper parts of which have been convertedinto underclays. This section, and that of North Sydney—twoof the most complete and instructive in the world—haveafforded conclusive proof of this mode of growth ofSigillariaandStigmaria.

"The objection to calling the Stigmariæ roots and theirprocesses rootlets, appears to me a finical application of modernbotanical usages to times for which they do not hold. Wemight equally object to the application of the term roots tothose which spring from the earthed-up stems of Calamites,radiating as they do from nodes which, in the air, would producebranchlets. Grand' Eury's figures show abundant instancesof this. We might also object to the exogenous stemsdescribed by Williamson, which belong to cryptogamousplants; and, unlike anything modern, are made up exclusivelyof scalariform tissue. If the articulation and regular arrangementof those gigantic root hairs, the rootlets, or 'leaves' of« 248 »Stigmaria, are to be regarded as depriving them of the namewhich clearly describes their function, we may call them undergroundbranches, though, by so doing, we set at nought boththeir function and their mode of growth."

Dr. Williamson, in a recent paper, expresses the same viewin the following terms [120]:—"At that period (the Carboniferousage) no Angiosperms existed on the earth, and even theGymnosperms were very far from reaching their moderndevelopment. Under these circumstances the Cryptogamschiefly became the giant forest trees of that remote age. Tobecome such, they required an organization very differentin some respects from that of their degraded living representatives.Hence we must not appeal to these degenerate typesfor illustrations and explanations of structures no longerexisting. Still less must we turn to what we find in theAngiosperms, that wholly distinct race which has taken theplace of the primæval Cryptogams in our woods. The primevalgiants of the swampy forests had doubtless a morphologyassigned to them, adapted to the physical conditions by whichthey were surrounded; but if even their dwarfed and otherwisemodified descendants fail to throw light upon morphologicaldetails once so common, still less must we expect to obtainthat light from the living and wholly different floweringplants."

With the remarkable trees above referred to, there coëxisteda vast multitude of ferns, some arborescent, others herbaceous,tall, reed-like plants, the Calamites, allied to modern Mare's-tails,a very remarkable family of plants allied to modernCycads and Pines; the Cordaites, which seem to have grownplentifully in certain parts of the coal areas—probably thedrier parts, so that their remains sometimes constitute thegreater part of small seams of coal. There were also true pine-liketrees, though these would seem to have grown most abundantly« 249 »on the higher levels. Nor was strictly aquatic vegetationwanting. We find, both in the preceding Devonian and theCarboniferous, that the little aquatic plants now known asRhizocarps, and structurally allied to the Ferns—such plantsas the floating Salvinia, and the Pillworts of our swamps, werevastly abundant, and they may have filled and choked up withtheir exuberant growth many of the lakes and slow streams ofthe period, furnishing layers of cannel and "macrospore"coal, and earthly bitumen or Torbanite.

We have hitherto confined our attention to the great Carboniferousperiod, so called, as emphatically the age of coal;but this mineral, and allied forms of carbon, were producedboth before and after. Even in that old Laurentian age,which includes the oldest rocks that we know, formed whenthe first land had just risen out of the waters, there are thickbeds of graphite, or plumbago, chemically the same withanthracite coal, and which must have been produced by theagency of plants, whether terrestrial or aquatic. We may supposethat the plants of this remote age were of very humbletype as much lower than those of the coal formation as theseare lower than those of the present day; but if so, then, on theanalogy of the Carboniferous, they would be high and complexrepresentatives of those low types. But there is another andmore startling possibility; that the Laurentian may have beena period when vegetable life culminated on the earth, andexisted in its most complete and grandest forms in advance ofthe time when it was brought into subordination to the higherlife of the animal. In the meantime, the Laurentian rocks arein a state of so extreme metamorphism that they have affordedno certain indication of the forms or structures of the vegetationof the period.

We find indications of plant life through all the Palæozoicgroups succeeding the Laurentian; but it is not till we reachthe Devonian, the system immediately preceding the Carboniferous,« 250 »that we find an abundance of forms not essentiallydifferent from those of the Carboniferous, though similar indetails. Only a few and very small beds of coal were accumulatedin this age; but there was an immense abundance ofbituminous shale enriched with the macrospores of Rhizocarps.The Ohio black shale, which is said to extend its outcropacross that state with a breadth of ten to twenty miles, and athickness of 550 feet, is filled with macrospores of Protosalvinia,as is its continuation in Canada.

Above the great coal formation the Permian and Jurassiccontain beds of coal, though of limited extent, and formed inthe case of the two latter of very different plants from those ofthe Carboniferous. In the Cretaceous and Tertiary ages,after the abundant introduction of species of forest trees stillliving, coal making seems to have obtained a new impulse, sothat in China and the western part of America there are coalsof great extent and value, all made of plants of genera stillexisting. In the Cretaceous coal of Vancouver Island thereare remains of such modern trees as the Poplars, Magnolias,Palmettos, Sequoias, and a great variety of other genera stillliving in America. Out of the remains of these, under favouringconditions, quite as good coal as that of the coal formationhas been made, although the plants are so different. Thereis, indeed, reason to believe that those now rare trees, theSequoias, represented at the present time only by the big treesof California, and their companion, the redwood, were thenspread universally over the northern hemisphere, and formeddense forests on swampy flats which led to the accumulation ofcoal beds in which the trunks and leaves of the Sequoiasformed main ingredients, so that Sequoia and its allies in thislater age take the place of the Sigillariæ of the coal formation.Last of all, coal accumulation is still going on in the Evergladesof Florida, the dismal swamp of Virginia, and the peat-bogsof the more northern regions. So the vegetable kingdom« 251 »has, throughout its long history, been continually depriving theatmosphere of its carbon dioxide, and accumulating this inbeds of coal. In the earlier ages indeed, this would seem tous to have been its main use.

To the modern naturalist, vegetable life, with regard to itsuses, is the great accumulator of pabulum for the sustenanceof the higher forms of vital energy manifested in the animal.In the Palæozoic this consideration sinks in importance. Inthe Coal period we know few land animals, and these not vegetablefeeders, with the exception of some insects, millipedes,and snails. But the Carboniferous forests did not live in vain,if their only use was to store up the light and heat of thoseold summers in the form of coal, and to remove the excess ofcarbonic acid from the atmosphere. In the Devonian periodeven these utilities fail, for coal does not seem to have beenaccumulated to any great extent, though the abundant petroleumof the Devonian is, no doubt, due to the agency of aquaticvegetation. In addition to scorpions, a few insects are theonly known tenants of the Devonian land, and these are ofkinds whose lame probably lived in water, and were notdependent on land plants. We may have much yet to learnof the animal life of the Devonian; but for the present, thegreat plan of vegetable nature goes beyond our measures ofutility; and there remains only what is perhaps the mostwonderful and suggestive correlation of all, namely, that ourminds are able to trace in these perished organisms structuressimilar to those of modern plants, and thus to reproduce inimagination the forms and habits of growth of living thingswhich so long preceded us on the earth.

In another way Huxley has put the utilitarian aspect of thecase so admirably, that I cannot refrain from quoting his cleverapotheosis of nature in connection with the production of coal.

"Nature is never in a hurry, and seems to have had alwaysbefore her eyes the adage, 'Keep a thing long enough, and« 252 »you will find a use for it.' She has kept her beds of coal formillions of years without being able to find a use for them;she has sent them beneath the sea, and the sea beasts couldmake nothing of them; she had raised them up into dry land,and laid the black veins bare, and still for ages and ages therewas no living thing on the face of the earth that could see anysort of value in them; and it was only the other day, so tospeak, that she turned a new creature out of her workshop,who, by degrees, acquired sufficient wits to make a fire, andthen to discover that the black rock would burn.

"I suppose that nineteen hundred years ago, when JuliusCæsar was good enough to deal with Britain as we have dealtwith New Zealand, the primæval Briton, blue with cold andwoad, may have known that the strange black stone which hefound here and there in his wanderings would burn, and sohelp to warm his body and cook his food. Saxon, Dane, andNorman swarmed into the land. The English people grewinto a powerful nation; and Nature still waited for a returnfor the capital she had invested in ancient club mosses. Theeighteenth century arrived, and with it James Watt. Thebrain of that man was the spore out of which was developedthe steam engine, and all the prodigious trees and branchesof modern industry which have grown out of this. But coalis as much an essential of this growth and development ascarbonic acid is of a club moss. Wanting the coal, we couldnot have smelted the iron needed to make our engines; norhave worked our engines when we got them. But take awaythe engines, and the great towns of Yorkshire and Lancashirevanish like a dream. Manufactures give place to agricultureand pasture, and not ten men could live where now ten thousandare amply supported.

"Thus all this abundant wealth of money and of vivid lifeis Nature's investment in club mosses and the like so longago. But what becomes of the coal which is burnt in yielding« 253 »the interest? Heat comes out of it, light comes out of it, andif we could gather together all that goes up the chimney, andall that remains in the grate of a thoroughly burnt coal fire,we should find ourselves in possession of a quantity of carbonicacid, water, ammonia, and mineral matters exactly equal inweight to the coal. But these are the very matters with whichNature supplied the club mosses which made coal. She ispaid back principal and interest at the same time; and shestraightway invests the carbonic acid, the water, and theammonia in new forms of life, feeding with them the plantsthat now live. Thrifty Nature, surely! no prodigal, but themost notable of housekeepers."[121]

All this is true and well told; but who is "Nature," thisgoddess who, since the far-distant Carboniferous age, hasbeen planning for man? Is this not another name for thatAlmighty Maker who foresaw and arranged all things for Hispeople "before the foundation of the world."

References:—On Structures in Coal,Journal Geological Society ofLondon, xv., 1853. Contains results of microscopic study of NovaScotia coals. Conditions of Accumulation of Coal,Ibid., xxii.,1866. Contains South Joggins section. Spore-cases in Coal,Am.Journal of Science, 3rd series, vol. I, 1871. Rhizocarps in theDevonian,Bulletin Chicago Academy, vol. I, 1886. "AcadianGeology and Supplement," 3rd edition, 1891, Cumberland Coal Field."Geological History of Plants," chap, iv., London and New York,2nd edition, 1892.

THE OLDEST AIR-BREATHERS.

DEDICATED TO THE MEMORY OF
MY FRIEND AND EARLY PATRON AND GUIDE

SIR CHARLES LYELL,

To whom we are Indebted for so much
of the Scientific Basis of Modern Geology.

Earliest Discoveries—Footprints of Batrachians—Labyrinthodentsof the Carboniferous—Microsauriaof the Carboniferous—Other Types—Discoveriesin Erect Trees—Invertebrate Air-breathers,Land Snails, Millipedes, Insects, SpidersAnd Scorpions—General Conclusions

CHAPTER X.

Animal life had its beginning in the waters, and tothis day the waters are the chief habitat of animals,especially of the lower forms. If we divide the animal kingdominto great leading types, the lowest of these groups, theProtozoa, includes only aquatic forms; the next, that of thecoral animals and their allies, is also aquatic. So are all thespecies of the Sea Urchins and Star Fishes. Of the remaininggroups, the Mollusks, the Crustaceans, and the Worms aredominantly aquatic, only a small proportion being air-breathers.It is only in the two remaining groups, including the Insectsand Spiders on the one hand, and the Vertebrate animals onthe other, that we have terrestrial species in large proportion.

The same fact appears in geological time. The periodsrepresented by the older Palæozoic rocks have been termedages of invertebrates, and they might also be termed agesof aquatic animals. It is only gradually, and as it were withdifficulty, that animals living in the less congenial element ofair are introduced—at first a few scorpions and insects, later,land snails and amphibian reptiles, later still, the higher reptilesand the birds, and last of all the higher mammalia.

We need not wonder at this, for the conditions of life withreference to support, locomotion, and vicissitudes of temperatureare more complex and difficult in air, and require morecomplicated and perfect machinery for their maintenance.Thus it was that probably half of the whole history of our« 258 »earth had passed away before the land became the abodeof any large number and variety of animals; while it was onlyabout the same time that the development of the vegetablekingdom became so complete as to afford food and shelterfor air-breathers.

It is also worthy of note that it is only in comparativelyrecent times that we have been able to discover the oldestair-breathing animals, and geologists long believed that thetime when animals had existed on the land was even shorterthan it had actually been. This arose in part from the infrequencyand rarity of preservation of the remains of theearliest creatures of this kind, and perhaps partly from thefact that collectors were not looking for them.

That there was dry land, even in the Cambro-Silurianperiod, we know, and can even trace its former shores. InCanada our old Laurentian coast extends for more than athousand miles, from Labrador to Lake Superior, marking thesouthern border of the nucleus of the American continent inthe Cambrian and Cambro-Silurian periods. Along a greatpart of this ancient coast we have the sand flats of the PotsdamSandstone, affording very favourable conditions for the imbeddingof land animals, did these exist; still, notwithstandingthe zealous explorations of the Geological Survey, and of manyamateurs, no trace of an air-breather has been found. I havemyself followed the oldest Palæozoic beds up to their ancientlimits in some localities, and collected the shells which thewaves had dashed on the beach, and have seen under theCambro-Silurian beds the old pre-Cambrian rocks pitted andindented with weather marks, showing that this shore was thengradually subsiding; yet the record of the rocks was totallysilent as to the animals that may have trod the shore, or thetrees that may have waved over it. All that can be said isthat the sun shone, the rain fell, and the wind blew as it doesnow, and that the sea abounded in living creatures. The eyes« 259 »of Trilobites, the weathered Laurentian rocks, the wind ripplesin the Potsdam sandstone, the rich fossils of the limestones,testify to these things. The existence of such conditionswould lead us to hope that land animals may yet be found inthese older formations. On the other hand, the gradual failureof one form of life after another, as we descend in the geologicalseries, and the rarity of fishes and land plants in theSilurian rocks and their absence from the Cambrian, mightinduce us to believe that we have here reached the beginningof animal life, and have left far behind us those forms thatinhabit the land.

Even in the Carboniferous period, though land plantsabound, air-breathers are not numerous, and most of themhave only been recently recognised. We know, however,with certainty that the dark and luxuriant forests of the coalperiod were not destitute of animal life. Reptiles [122] creptunder their shade, land snails and millipedes fed on therank leaves and decaying vegetable matter, and insects flittedthrough the air of the sunnier spots. Great interest attachesto these creatures; perhaps the first-born species in some oftheir respective types, and certainly belonging to one of theoldest land faunas, and presenting prototypes of future formsequally interesting to the geologist and the zoologist.

It has happened to the writer of these pages to have hadsome share in the finding of several of these ancient animals.The coal formation of Nova Scotia, so full in its development,so rich in fossil remains, and so well exposed in coast cliffs,has afforded admirable opportunities for such discoveries,which have been so far improved that at least twenty-five outof the not very large number of known Carboniferous landanimals have been obtained from it.[123] The descriptions of« 260 »these creatures, found at various times and at various places,are scattered through papers ranging in date from 1844 to1891,[124] and are too fragmentary to give complete informationrespecting the structures of the animals, and their conditionsof existence.

It has often happened to geologists, as to other explorers ofnew regions, that footprints on the sand have guided them tothe inhabitants of unknown lands, and such footprints, proverbiallyperishable, may be so preserved by being filled upwith matter deposited in them as to endure for ever. This wemay see to-day in the tracks of sandpipers and marks of rain-dropspreserved in the layers of alluvial mud deposited by thetides of the Bay of Fundy, and which, if baked or hardenedby pressure, might become imperishable, like the inscriptionsof the old Chaldeans on their tablets of baked clay. Thefirst trace ever observed of reptiles in the Carboniferoussystem consisted of a series of small but well-marked footprintsfound by Sir W. E. Logan, in 1841, in the lower coalmeasures of Horton Bluff, in Nova Scotia; and as the authorsof most of our general works on geology have hitherto, in sofar as I am aware, failed to do justice to this discovery, I shallnotice it here in detail. In the year above mentioned, SirWilliam, then Mr. Logan, examined the coal fields of Pennsylvaniaand Nova Scotia, with the view of studying theirstructure, and extending the application of the discoveries asto beds with roots, or Stigmaria underclays, which he had madein the Welsh coal fields. On his return to England he reada paper on these subjects before the Geological Society ofLondon, in which he noticed the subject of reptilian footprintsat Horton Bluff. The specimen was exhibited at the meetingof the Society, and was, I believe, admitted, on the highauthority of Prof. Owen, to be probably reptilian. UnfortunatelySir William's paper appeared only in abstract in theTransactions; and in this abstract, though the footprints arementioned, no opinion is expressed as to their nature. SirWilliam's own opinion is thus stated in a letter to me, datedJune, 1843, when he was on his way to Canada, to commencethe survey which has since developed so astonishing a massof geological facts.

"Among the specimens which I carried from Horton Bluff,one is of very high interest. It exhibits the footprints of somereptilian animal. Owen has no doubt of the marks beinggenuine footprints. The rocks of Horton Bluff are below thegypsum of that neighbourhood; so that the specimen in question(if Lyell's views are correct [125]) comes from the very bottomof the coal series, or at any rate very low down in it, anddemonstrates the existence of reptiles at an earlier epoch thanhas hitherto been determined; none having been previouslyfound below the magnesian limestone, or, to give it Murchison'snew name, the 'Permian era.'"

This extract is of interest, not merely as an item of evidencein relation to the matter now in hand, but as a mark in theprogress of geological investigation. For the reasons abovestated, the important discovery thus made in 1841, and publishedin 1842, was overlooked; and the discovery of reptilianbones by Von Dechen, at Saarbruck, in 1844, and that offootprints by Dr. King in the same year, in Pennsylvania,« 262 »have been uniformly referred to as the first observations ofthis kind. Insects and Arachnidans, it may be observed, hadpreviously been discovered in the coal formation in Europe.

The original specimen of these footprints is still in thecollection of the Geological Survey of Canada, and a castwhich Logan kindly presented to me is exhibited in the PeterRedpath Museum of McGill University. It is a slab of dark-colouredsandstone, glazed with fine clay on the surface; andhaving a series of seven footprints in two rows, distant aboutthree inches; the distance of the impressions in each row beingthree or four inches, and the individual impressions about oneinch in length. They seem to have been made by the pointsof the toes, which must have been armed with strong andapparently blunt claws, and appear as if either the surface hadbeen somewhat firm, or the body of the animal had beenpartly water-borne. In one place only is there a distinct markof the whole foot, as if the animal had exerted an unusualpressure in turning or stopping suddenly. One pair of feet—thefore feet, I presume—appear to have had four toes touchingthe ground; the other pair show only three or four, and it isto be observed that the outer toe, as in the larger footprintsdiscovered by Dr. King, projects in the manner of a thumb,as in the cheirotherian tracks of the Trias. At a later dateanother series of footprints, possibly of the same animal, wasobtained at the same place by Prof. Elder, and is now in thePeter Redpath Museum. Each foot in this shows five toes,and it is remarkable that the animal was digitigrade and tooka long step for its size, indicating a somewhat high gradeof quadrupedal organization. No mark of the tail or bellyappears. The impressions are such as may have been madeby animals similar to some of those to be described in thesequel.

Shortly afterward, Dr. Harding, of Windsor, when examininga cargo of sandstone which had been landed at that place from« 263 »Parrsboro', found on one of the slabs a very distinct series offootprints, each with four toes, and a trace of the fifth. Dr.Harding's specimen is now in the museum of King's College,Windsor. Its impressions are more distinct, but not verydifferent otherwise from those above described, as found atHorton Bluff. The rocks at that place are probably of nearlythe same age with those of Parrsboro'. I afterward examinedthe place from which this slab had been quarried, and satisfiedmyself that the beds are Carboniferous, and probably LowerCarboniferous. They were ripple-marked and sun-cracked,and I thought I could detect some footprints, though moreobscure than those in Dr. Harding's slab. Similar footprintsare also stated to have been found by Dr. Gesner, at Parrsboro'.All of these were from the lowest beds of the Carboniferoussystem.

I have since observed several instances of such impressionsat the Joggins, at Horton, and near Windsor, showing thatthey are by no means rare, and that reptilian animals existedin no inconsiderable numbers throughout the coal field ofNova Scotia, and from the beginning to the end of the Carboniferousperiod. Most of these, when well preserved, shew fivetoes both on the anterior and posterior limb. On comparingthese earlier Carboniferous footprints with one another, it willbe observed that they are of similar general character, andmay have been made by one kind of animal, which must havehad the fore and hind feet nearly of equal size, and a digitigrademode of walking. Footprints of similar form are foundin the coal formation, as well as others of much larger size.The latter are of two kinds. One of these shows short hindfeet of digitigrade character and a long stride, in this resemblingthe smaller footprints of the Lower Carboniferous, whichare remarkable for the length of limb which they indicate bythe distance between the footprints. The other kind showslong hind feet, as if the whole heel were brought down to the« 264 »ground in a plantigrade manner. These have also the outertoe separated from the others, and sometimes provided witha long claw. The fore foot is sometimes smaller than thehind foot, and differently formed.[126] In these respects theyresemble the great Labyrinthodont Batrachians of the subsequentTrias. Their stride also is comparatively short, andthe rows of impressions wide apart, as if the body of theanimal had been broad, and its limbs short.

We have thus two types of quadrupedal footprints, to thefirst of which I have given the name Hylopus, and haverestricted the term Sauropus,[127] to the second. The firstapparently belongs to the usually small reptiles of the groupMicrosauria, which had a well-marked lizard-like form, withwell-developed limbs, and perhaps also to some of the smallerLabyrinthodonts, the second to the group ofLabyrinthodontia,which were often of large size and with stout and short limbsand plantigrade hind feet. There are also some small anduncertain tracks, which may have been made by newt-likeanimals with short feet, and a singular trail of large size, andwith a row of impressions at each side (Diplichnites),[128] which,if made by a vertebrate animal, would seem to indicate thatserpentiform shape which we know belonged to some CarboniferousBatrachians.

The bones of these animals, however, hitherto found inNova Scotia, may all have belonged to the two groups firstnamed, the Labyrinthodontia and Microsauria, and I shallproceed to give some examples of each of these.

In leaving the footprints, I may merely mention that theanimals which produced them may, in certain circumstances,have left distinct impressions only of three or four toes,« 265 »when they actually possessed five, while in other circumstancesall may have left marks; and that, when wading in deep mud,their footprints were altogether different from those made onhard sand or clay. In some instances the impressions mayhave been made by animals wading or swimming in water,while in others the rain marks and sun cracks afford evidencethat the surface was a subaërial one. They are chiefly interestingas indicating the wide diffusion and abundance of thecreatures producing them, and that they haunted tidal flatsand muddy shores, perhaps emerging from the water that theymight bask in the sun, or possibly searching for food amongthe rejectamenta of the sea, or of lagunes and estuaries.

The Labyrinthodonts of the Coal Period, BaphetesPlaniceps and Dendrerpeton Acadianum.

In the summer of 1851 I had occasion to spend a dayat the Albion Mines in the eastern part of Nova Scotia, andon arriving at the railway station in the afternoon, found myselfsomewhat too early for the train. By way of improvingthe time thus left on my hands, I betook myself to the examinationof a large pile of rubbish, consisting of shale andironstone from one of the pits, and in which I had previouslyfound scales and teeth of fishes. In the blocks of hard carbonaceousshale and earthy coal, of which the pile chieflyconsisted, scales, teeth and coprolites often appeared on theweathered ends and surfaces as whitish spots. In lookingfor these, I observed one of much greater size than usual onthe edge of a block, and on splitting it open, found a largeflattened skull, about six inches broad, the cranial bones ofwhich remained entire on one side of the mass, while the palateand teeth, in several fragments, came away with the other half.Carefully trimming the larger specimen, and gathering all thesmaller fragments, I packed them up as safely as possible, and« 266 »returned from my little excursion much richer than I hadhoped.

The specimen, on further examination, proved somewhatpuzzling. I supposed it to be, most probably, the head of alarge ganoid fish; but it seemed different from anything ofthis kind with which I could compare it; and at a distancefrom comparative anatomists, and without sufficient means ofdetermination, I dared not refer it to anything higher in theanimal scale. Hoping for further light, I packed it up withsome other specimens, and sent it to the Secretary of theGeological Society of London, with an explanatory note as toits geological position, and requesting that it might be submittedto some one versed in such fossils. For a year ortwo, however, it remained as quietly in the Society's collectionas if in its original bed in the coal mine, until attentionhaving been attracted to such remains by the discoveriesmade by Sir Charles Lyell and myself in 1852, at the SouthJoggins, and published in 1853,[129] the Secretary or President ofthe Society re-discovered the specimen, and handed it to SirRichard Owen, by whom it was described in December, 1853,[130]under the name ofBaphetes planiceps, which may be interpretedthe "flat-headed diving animal," in allusion to theflatness of the creature's skull, and the possibility that it mayhave been in the habit of diving.

The parts preserved in my specimen are the bones of theanterior and upper part of the skull in one fragment, andthe teeth and palatal bones in others. These parts werecarefully examined and described by Owen, and the detailswill be found in his papers referred to in the note. Wemay merely observe here that the form and arrangement ofthe bones showed batrachian affinities, that the surface of thecranium was sculptured in the manner of the group of« 267 »Labyrinthodonts, and that the teeth possessed the peculiarand complicated plication of the ivory and enamel seen increatures of this type. The whole of these characters areregarded as allying the animal with the great crocodilian frogsof the Trias of Europe, first known asCheirotherians, owingto the remarkable hand-like impressions of their feet, andafterwards asLabyrinthodonts, from the beautifully complicatedconvolutions of the ivory of their teeth.

Unfortunately the original specimen exhibited only thehead, and after much and frequent subsequent searching, theonly other bones found are a scapula, or shoulder bone, andone of the surface scales which served for protection, andwhich indicate at least that the creature possessed walkinglimbs and was armed with bony scales sculptured in thesame manner with the skull bones.

Of the general form and dimensions ofBaphetes, the factsat present known do not enable us to say much. Itsformidable teeth and strong maxillary bones show that it musthave devoured animals of considerable size, probably thefishes whose remains are found with it, or the smaller reptilesof the coal. It must, in short, have been crocodilian, ratherthan frog-like, in its mode of life; but whether, like theLabyrinthodonts, it had strong limbs and a short body, orlike the crocodiles, an elongated form and a powerfulnatatory tail, the remains do not decide. One of the limbsor a vertebra of the tail would settle this question, but neitherhas as yet been found. That there were large animals ofthe labyrinthodontal form in the coal period is proved bythe footprints discovered by Dr. King in Pennsylvania, whichmay have been produced by an animal of the type ofBaphetes,as well as by those ofSauropus unguifer from the Carboniferousof Nova Scotia, and which would very well suit ananimal of this size and probable form. On the other hand,that there were large swimming reptiles seems established« 268 »by the discovery of the vertebræ ofEosaurus Acadianus, atthe Joggins, by Marsh.[131] The locomotion ofBaphetes musthave been vigorous and rapid, but it may have been effectedboth on land and in water, and either by feet or tail, or both.A jawbone found at the Joggins in Nova Scotia, and towhich I have attached the nameBaphetes minor, may havebelonged to a second species. Great Batrachians allied toBaphetes, but different specifically or generically, have sincebeen found in the coal formations of Great Britain, the continentof Europe and the United States.

With the nature of the habitat of this formidable creaturewe are better acquainted. The area of the Albion Mines coalfield was somewhat exceptional in its character. It seems tohave been a bay or indentation in the Silurian land, separatedfrom the remainder of the coal field by a high shingle beach,now a bed of conglomerate. Owing to this circumstance,while in the other portions of the Nova Scotia coal field thebeds of coal are thin, and alternate with sandstones and shales,at the Albion Mines a vast thickness of almost unmixed vegetablematter has been deposited, constituting the "main seam"of thirty-eight feet thick, and the "deep seam," twenty-four feetthick, as well as still thicker beds of highly carbonaceousshale. But, though the area of the Albion coal measures wasthus separated, and preserved from marine incursions, it musthave been often submerged, and probably had connectionwith the sea, through rivers or channels cutting the enclosingbeach. Hence beds of earthy matter occur in it, containingremains of large fishes. One of the most important of theseis that known as the "Holing stone," a band of black highlycarbonaceous shale, coaly matter, and clay ironstone, occurringin the main seam, about five feet below its roof, and varyingin thickness from two inches to nearly two feet. It wasfrom this band that the rubbish heap in which I found the« 269 »skull ofBaphetes planiceps was derived. It is a laminated bed,sometimes hard and containing much ironstone, in otherplaces soft and shaly, but always black and carbonaceous,and often with layers of coarse coal, though with few fossilplants retaining their forms. It contains large round flatscales and flattened curved teeth, which I attribute to a fish ofthe genusRhizodus, resembling, if not identical with,R.lancifer, Newberry. With these are double-pointed shark-liketeeth, and long cylindrical spines of a species ofDiplodus,which I have namedD. acinaces.[132] There are also shells ofthe minuteSpirorbis, so common in the coal measures ofother parts of Nova Scotia, and abundance of fragments ofcoprolitic matter, or fossil excrement, sometimes containingbones and scales of fishes.

It is evident that the "Holing stone" indicates one ofthose periods in which the Albion coal area, or a large part ofit, was under water, probably fresh or brackish, as there are noproperly marine shells in this, or any of the other beds of thiscoal series. We may then imagine a large lake or lagune,loaded with trunks of trees and decaying vegetable matter,having in its shallow parts, and along its sides, dense brakes ofCalamites, and forests ofSigillaria,Lepidodendron, and othertrees of the period, extending far on every side as damp pestilentialswamps. In such a habitat, uninviting to us, but nodoubt suited toBaphetes, that creature crawled throughswamps and thickets, wallowed in flats of black mud, or swamand dived in search of its finny prey. It was, in so far as weknow, the monarch of these swamps, though there is, asalready stated, evidence of the existence of similar creatures ofthis type quite as large in other parts of the Nova Scotia coalfield. We must now notice a smaller animal belonging to thesame family of Labyrinthodonts.

The geology of Nova Scotia is largely indebted to the world-embracinglabours of Sir Charles Lyell. Though much hadpreviously been done by others, his personal explorations in1842, and his paper on the gypsiferous formation, published inthe following year, first gave form and shape to some of themore difficult features of the geology of the country, andbrought it into relation with that of other parts of the world.In geological investigation, as in many other things, patientplodding may accumulate large stores of fact, but the magicwand of genius is required to bring out the true value andsignificance of these stores of knowledge. It is scarcely toomuch to say that the exploration of a few weeks, and subsequentstudy of the subject by Sir Charles, with the impulseand guidance given to the labours of others, did as much forNova Scotia as might have been effected by years of laboriouswork under less competent heads.

Sir Charles naturally continued to take an interest in thegeology of Nova Scotia, and to entertain a desire to exploremore fully some of those magnificent coast sections which hehad but hastily examined; and when, in 1851, he had occasionto revisit the United States, he made an appointmentwith the writer of these pages to spend a few days in renewedexplorations of the cliffs of the South Joggins. The objectspecially in view was the thorough examination of the beds ofthe true coal measures, with reference to their containedfossils, and the conditions of accumulation of the coal; andthe results were given to the world in a joint paper on "Theremains of a reptile and a land shell discovered in the interiorof an erect tree in the coal measures of Nova Scotia," and inthe writer's paper on the "Coal Measures of the SouthJoggins";[133] while other important investigations grew out ofthe following up of these researches, and much matter in« 271 »relation to the vegetable fossils still remains to be worked up.It is with the more striking fact of the discovery of the remainsof a reptile in the coal measures that we have now to do.

The South Joggins Section is, among other things, remarkablefor the number of beds which contain remains of erecttrees imbeddedin situ: these trees are for the most partSigillariæ, those great-ribbed pillar-like trees which seem tohave been so characteristic of the forests of the coal formationflats and swamps, and so important contributors to the formationof coal. They vary in diameter from six inches to five feet.They have grown on underclays and wet soils, similar to thoseon which the coal was accumulated; and these having beensubmerged or buried by mud carried down by inundations,the trees, killed by the accumulations around their stems,have decayed, and their tops being broken off at the level ofthe mud or sand, the cylindrical cavities left open by the disappearanceof the wood, and preserved in their form by thegreater durability of the bark, have been filled with sand andclay. This, now hardened into stone, constitutes pillar-likecasts of the trees, which may often be seen exposed in thecliffs, and which, as these waste away, fall upon the beach.The sandstones enveloping these pillared trunks of the ancientSigillariæ of the coal, are laminated or bedded, and thelaminæ, when exposed, split apart with the weather, so that thetrees themselves become broken across; this being oftenaided by the arrangement of the matter within the trunks, inlayers more or less corresponding to those without. Thus oneof these fossil trees usually falls to the beach in a series ofdiscs, somewhat resembling the grindstones which are extensivelymanufactured on the coast. The surfaces of thesefragments often exhibit remains of plants which have beenwashed into the hollow trunks, and have been imbeddedthere; and in our explorations of the shore, we always carefullyscrutinized such specimens, both with the view of observing« 272 »whether they retained the superficial markings of Sigillariæ,and with reference to the fossils contained in them. It waswhile examining a pile of these "fossil grindstones" that wewere surprised by finding on one of them what seemed to befragments of bone. On careful search other bones appeared,and they had the aspect, not of remains of fishes, of whichmany species are found fossil in these coal measures, butrather of limb bones of a quadruped. The fallen pieces of thetree were carefully broken up, and other bones disengaged, andat length a jaw with teeth made its appearance. We felt quiteconfident, from the first, that these bones were reptilian; andthe whole, being carefully packed and labelled, were taken bySir Charles to the United States, and submitted to Prof. J.Wyman of Cambridge; who recognised their reptilian character,and prepared descriptive notes of the principal bones,which appeared to have belonged to two species. He alsoobserved among the fragments an object of different character,apparently a shell; which was recognised by Dr. Gould ofBoston, and afterward by M. Deshayes, as probably a land-snail,and has since been namedPupa vetusta.

The specimens were subsequently taken to London and reexaminedby Prof. Owen, who confirmed Wyman's inferences,added other characters to the description, and named thelarger and better preserved speciesDendrerpeton Acadianum,in allusion to its discovery in the interior of a tree, and to itsnative country of Acadia or Nova Scotia. It is necessary tostate in explanation of the fragmentary character of the remainsobtained, that in the decay of the animals imbedded in theerect trees at the Joggins, their skeletons have become disarticulated,and the portions scattered, either by falling into theinterstices of the vegetable fragments in the bottom of thehollow trunks, or by the water with which these may havesometimes been partly filled. We thus usually obtain onlyseparate bones; and though all of these are no doubt presentin each case, it is often impossible in breaking up the hardmatrix to recover more than a portion of them. The originaldescription by Owen was therefore based on somewhat imperfectmaterial, but additional specimens subsequently found havesupplemented it in such a manner as to enable us somewhatcompletely to restore in imagination the form of the animal,which, though much smaller thanBaphetes, agrees with it in itssculptured bones, in its bony armature, especially beneath, andin its plicated teeth.

In form,Dendrerpeton Acadianum was probably lizard-like;with a broad flat head, short stout limbs and an elongated tail;and having its skin, and more particularly that of the belly,protected by small bony plates closely overlapping each other,and arrangeden chevron, in oblique rows meeting on themesial line, where in front was a thoracic plate. It may haveattained the length of two feet. The form of the head is notunlike that ofBaphetes, but longer in proportion; and muchresembles that of the labyrinthodont reptiles of the Trias.The bones of the skull are sculptured as in Baphetes, but in asmaller pattern.

The fore limb of the adult animal, including the toes,must have been four or five inches in length, and is ofmassive proportions. The bones were hollow, and in the caseof the phalanges the bony walls were thin, so that they areoften crushed flat. The humerus, or arm bone, however, wasa strong bone, with thick walls and a cancellated structuretoward its extremities; still even these have sometimes yieldedto the great pressure to which they have been subjected. Thecavity of the interior of the limb bones is usually filled withcalc-spar stained with organic matter, but showing no structure;and the inner side of the bony wall is smooth withoutany indication of cartilaginous matter lining it.

The vertebræ, in the external aspect of their bodies, remindone of those of fishes, expanding toward the extremities, and« 274 »being deeply hollowed by conical cavities, which appear evento meet in the centre. There is, however, a large and flattenedneural spine. The vertebræ are usually much crushed, and itis almost impossible to disengage them from the stone. Theribs are long and curved, showing a reptilian style of chest.The posterior limb seems to have been not larger than theanterior, perhaps smaller. The tibia, or principal bone of thefore leg is much flattened at the extremity, as in some Labyrinthodonts,and the foot must have been broad, and probablysuited for swimming, or walking on soft mud, or both. Thatthe hind limb was adapted for walking is shown, not merelyby the form of the bones, but also by that of the pelvis.

The external scales are thin, oblique-rhomboidal or elongated-oval,marked with slight concentric lines, but otherwisesmooth, and having a thickened ridge or margin, in whichthey resemble those of Archegosaurus, and also those ofPholidogasterpisciformis, described by Huxley from the Edinburghcoal field,—an animal which indeed appears in most respectsto have a close affinity withDendrerpeton. The microscopicstructure of the scales is quite similar to that of the otherbones, and different from that of the scales of ganoid fishes, theshape of the cells being batrachian. For other particulars ofits structure reference may be made to the papers named atthe end of the chapter.

With respect to the affinities of the creature, I think it isobvious that it is most nearly related to the group of Lahyrinthodonts,and that it has the same singular mixture of batrachianand reptilian characters which distinguish these ancientanimals, and which give them the appearance of prototypes ofthe reptilian class. A second and smaller species of Dendrerpetonwas subsequently obtained at the Joggins, and othershave been found, more especially by Fritsch, in the Carboniferousand Permian of Europe.

This ancient inhabitant of the coal swamps of Nova Scotia« 275 »was, in short, as we often find to be the case with the earliestforms of life, the possessor of powers and structures not usually,in the modern world, combined in a single species. Itwas certainly not a fish, yet its bony scales and the form of itsvertebræ, and of its teeth, might, in the absence of other evidence,cause it to be mistaken for one. We call it a Batrachian,yet its dentition, the sculpturing of the bones of its skull,which were certainly no more external plates than the similarbones of a crocodile, its ribs, and the structure of its limbs,remind us of the higher reptiles; and we do not know that itever possessed gills, or passed through a larval or fish-likecondition. Still, in a great many important characters, itsstructures are undoubtedly batrachian. It stands, in short, inthe same position with theLepidodendra andSigillariæ underwhose shade it crept, which, though placed by palæobotanistsin alliance with certain modern groups of plants, manifestlydiffered from these in many of their characters, and occupieda different position in nature. In the coal period the distinctionsof physical and vital conditions were not well defined.Dry land and water, terrestrial and aquatic plants and animals,and lower and higher forms of animal and vegetable life, areconsequently not easily separated from each other. This isno doubt a state of things characteristic of the earlier stages ofthe earth's history, yet not necessarily so; for there are somereasons, derived from fossil plants, for believing that in thepreceding Devonian period there was less of this, and consequentlythat there may then have been a higher and morevaried animal life than in the coal period.[134]

The dentition ofDendrerpeton shows it to have been carnivorousin a high degree. It may have captured fishes andsmaller reptiles, either on land or in water, and very probablyfed on dead carcases as well. If, as seems likely, any of the« 276 »footprints referred to previously belong to this animal, itmust have frequented the shores, either in search of garbage,or on its way to and from the waters. The occurrence of itsremains in the stumps of Sigillaria, with land snails and millipedes,shows also that it crept in the shade of the woods insearch of food; and in noticing coprolitic matter, in a subsequentpage, I shall show that remains of excrementitioussubstances, probably of this species, contain fragments attributableto smaller reptiles, and other animals of the land.

All the bones ofDendrerpeton hitherto found, as well asthose of the smaller reptilian species hereafter described, havebeen obtained from the interior of erect Sigillariæ, and all ofthese in one of the many beds, which, at the Joggins, containsuch remains. The thick cellular inner bark of Sigillaria wasvery perishable; the slender woody axis was somewhat moredurable; but near the surface of the stem, in large trunks,there was a layer of elongated cells, or bast tissue, of considerabledurability, and the outer bark was exceedingly dense andindestructible.[135] Hence an erect tree, partly imbedded insediment, and subjected to the influence of the weather, becamea hollow shell of bark; in the bottom of which lay thedecaying remains of the woody axis, and shreds of the fibrousbark. In ordinary circumstances such hollow stems would bealmost immediately filled with silt and sand, deposited in thenumerous inundations and subsidences of the coal swamps.Where, however, they remained open for a considerable time,they would constitute a series of pitfalls, into which animalswalking on the surface might be precipitated; and being probablyoften partly covered by remains of prostrate trunks, orby vegetation growing around their mouths, they would beplaces of retreat and abode for land snails and such creatures.When the surface was again inundated or submerged, all suchanimals, with the remains of those which had fallen into thedeeper pits, would be imbedded in the sediment which wouldthen fill up the holes. These seem to have been the preciseconditions of the bed which has afforded all these remains.

The history of a bed containing reptiliferous erect treeswould thus be somewhat as follows:—

A forest or grove of the large-ribbed trees known asSigillariæ,was either submerged by subsidence, or, growing on lowground, was invaded with the muddy waters of an inundation,or successive inundations, so that the trunks were buried tothe depth of several feet. The projecting tops having beenremoved by subaërial decay, the buried stumps became hollow,while their hard outer bark remained intact. They thus becamehollow cylinders in a vertical position, and open at top.The surface having then become dry land, covered with vegetation,was haunted by small quadrupeds and other land animals,which from time to time fell into the open holes, in some casesnine feet deep, and could not extricate themselves. On theirdeath, and the decomposition of their soft parts, their bonesand other hard portions remained in the bottom of the treeintermixed with any vegetabledébris or soil washed in by rain,and which formed thin layers separating successive animaldeposits from each other. Finally, the area was again submergedor overflowed by water, bearing sand and mud. Thehollow trees were filled to the top, and their animal contentsthus sealed up. At length the material filling the trees was bypressure and the access of cementing matter hardened intostone, not infrequently harder than that of the containing beds,and the whole being tilted to an angle of 20°, and elevated intoland exposed to the action of the tides and waves, these singularcoffins present themselves as stony cylinders projecting fromthe cliff or reef, and can be extracted and their contentsstudied.

The singular combination of accidents above detailed was,« 278 »of course, of very rare occurrence, and in point of fact weknow only one set of beds at the South Joggins in which suchremains so preserved occur; nor is there, so far as I am aware,any other known instance elsewhere. Even in the beds inquestion only a portion of the trees, about fifteen in thirty,have afforded animal remains. We have, however, thus beenenabled to obtain specimens of a number of species whichwould probably otherwise have been unknown, being lesslikely than others to be preserved in properly aqueous deposits.Such discoveries, on the one hand impress us withthe imperfection of the geological record; on the other, theyshow us the singular provisions which have been made in thecourse of geological time for preserving the relics of the ancientworld, and which await the industry and skill of collectors todisclose their hidden treasures.

I may add that I believe all the trees, about thirty in number,which have become exposed in this bed since its discovery,have been ransacked for such remains; and that whilethe majority have afforded some reward for the labour, somehave been far more rich than others in their contents. It isalso to be observed that owing to the mode of accumulationof the mass filling the trees, the bones are usually found scatteredin every position, and those of different species intermingled;and that being often much more friable than thematrix, much labour is required for their development; whileafter all has been done, the result is a congeries of fragments.A few specimens only have been found, showing skeletonscomplete, or nearly so, and I shall endeavour to figure one ortwo of these by way of illustration in the present chapter.

The beds on a level with the top of the reptiliferous erecttrees are arenaceous sandstones, with numerous erectCalamites.I have searched the surfaces of these beds in vain forbones or footprints of the reptiles which must have traversedthem, and which, but for hollow erect trees," would apparentlyhave left no trace of their existence. On a surface of similarcharacter, sixty feet higher, and separated by three coals, withtheir accompaniments, and a very thick compact sandstone, Iobserved a series of footprints, which may be those ofDendrerpetonorHylonomus.

In the original reptiliferous tree discovered by Sir C. Lyelland the writer, at the Joggins, in 1851, there were, beside thebones ofDendrerpeton Acadianum, some small elongatedvertebræ, evidently of a different species. These were firstdetected by Prof. Wyman, in his examination of these specimens,and were figured, but not named, in the original noticeof the specimens. In a subsequent visit to the Joggins Iobtained from another erect stump many additional remains ofthese smaller reptiles, and, on careful comparison of the specimens,was induced to refer them to three species, all apparentlygenerically allied. I proposed for them the genericnameHylonomus, "forest dweller." They were described inthe Proceedings of the Geological Society for 1859, with illustrationsof the teeth and other characteristic parts.[136] The smallerspecies first described I namedH. Wymani; the next in size,that to which this article refers, and which was represented bya larger number of specimens, I adopted as a type of the genus,and dedicated to Sir Charles Lyell. The third and largest,represented only by a few fragments of a single skeleton, wasnamedH. aciedentatus. This I had subsequently to removeto a new genus,Smilerpeton.

Hylonomus Lyelli was an animal of small size. Its skull isabout an inch in length, and its whole body, including the tail,could not have been more than six or seven inches, long. Thebones appear to have been thin and easily separable; and even« 280 »when they remain together, are so much crushed as to renderthe shape of the skull not easily discernible. They are smoothon the outer surface to the naked eye; and under a lens showonly delicate, uneven striæ and minute dots. They are moredense and hard than those ofDendrerpeton, and the bone-cellsare more elongated in form. The bones of the snout wouldseem to have been somewhat elongated and narrow. A specimenin my possession shows the parietal and occipital bones,or the greater part of them, united and retaining their form.We learn from them that the brain case was rounded, and thatthere was a parietal foramen. There would seem also to havebeen two occipital condyles, as in modern Batrachians. Severalwell-preserved specimens of the maxillary and mandibularbones have been obtained. They are smooth, or nearly so,like those of the skull, and are furnished with numerous sharp,conical teeth, anchylosed to the jaw, in a partial grooveformed by the outer ridge of the bone. In the anterior part ofthe lower jaw there is a group of teeth larger than the others.The total number of teeth in each ramus of the lower jaw wasabout forty, and the number in each maxillary bone aboutthirty. The teeth are perfectly simple, hollow within, andwith very fine radiating tubes of ivory. The vertebras havethe bodies cylindrical or hour-glass shaped, covered with athin, hard, bony plate, and having within a cavity of the formof two cones, attached by the apices. This cavity was completelysurrounded by bone, as it is filled with stained calc-sparin the same manner as the cavities of the limb bones. It wasprobably occupied by cartilage. The vertebræ were apparentlybi-concave, and are furnished with upper and lateral processessimilar to those of small lacertian animals. The ribs are long,curved, and at the proximal end have a shoulder and neck.They are hollow, with thin hard bony walls. The anteriorlimb, judging from the fragment procured, seems to have beenslender, with long toes, four or possibly five in number. The« 281 »posterior limb was longer and stronger, and attached to apelvis so large and broad as to give the impression that thecreature enlarged considerably in size toward the posterior extremityof the body, and that it may have been in the habit ofsitting erect. The thigh bone is large and well-formed, with adistinct head and trochanter, and the lower extremity flattenedand moulded into two articulating surfaces for the tibia andfibula, the fragments of which show that they were muchshorter. The toes of the hind feet have been seen only indetached joints. They seem to have been thicker than thoseof the fore foot. Detached vertebræ, which seem to be caudal,have been found, and show that the tail was long and probablynot flattened. The limb bones are usually somewhat crushedand flattened, especially at their articular extremities, and thisseems to have led to the error of supposing that this flattenedform was their normal condition; there can be no doubt, however,that it is merely an effect of pressure. The limb bonespresent in cross section a wall of dense bone with elongated bone-cells,surrounding a cavity now filled with brown calc-spar, andoriginally occupied with cartilage or marrow. I desire to specifythe above points because I believe that most of the creaturesreferred by Fritsch, Credner, and other European naturaliststo the Microsauria are of inferior grade to Hylonomus, thoughadmitted to present points of approximation to the true reptiles.Woodward has recently described the remains of aMicrosaurian from the English coal formation. Nothing ismore remarkable in the skeleton of this creature than the contrastbetween the perfect and beautiful forms of its bones, andtheir imperfectly ossified condition, a circumstance which raisesthe question whether these specimens may not represent theyoung of some reptile of larger size.

The dermal covering of this animal is represented in part byoval bony scales, which are so constantly associated with itsbones that I can have no doubt that they belonged to it, being,« 282 »perhaps, the clothing of its lower or abdominal parts. But themost remarkable and unexpected feature of this little creaturewas the beautiful and ornate scaly covering of its back andsides. Modern Batrachians are characteristically naked, andthough we know that some fossil species had coverings belowof bony scales, these seemed rather to ally them with bonyfishes. One of the specimens of Hylonomus had associatedwith it a quantity of crumpled shining skin, black and carbonaceous,and which may perhaps have been tanned and sopreserved by the water filling the hollow tree impregnatedwith solution of tannin from the bark. This skin was coveredwith minute overlapping scales, which, under the microscope,showed the structure of horn rather than of bone. Besidesthese ordinary scales there were bony prominences, likethose of the horned frog, on the back and shoulders, and aspecies of epaulettes made of long horny bristles curved downward,and apparently placed at the edges of the shoulders.Besides these there were in front and at the side rows of pendantsor lappets, all no doubt ornamented with colouring,though now perfectly black. It may be asked what was theuse of the ornate covering, and perhaps the question raisesthat perplexing problem, of the use of beauty in a world wherethere were no animals with higher æsthetic faculties than thoseof Batrachians. Scudder suggests a somewhat prosaic use insupposing them to be an armour against the venomous scorpionswhich were the contemporaries of these little reptiles,and some of them almost as large in size. But the word "venomous"raises another question, for we only infer that thescorpions were venomous from modern analogy and traces ofan inflated joint at the end of the tail in some specimens. Wehave no absolute certainty that the subtle and complex organicpoison of the scorpion, and his beautiful injection syringe forplacing it under the skin, were perfected at this early time.Thus we have in the far back Carboniferous age a creature as« 283 »elaborately ornamented and protected as any of the modernlizards, and this, let it be observed, constitutes another and importantdeparture from that batrachian type to which theseanimals are supposed to conform. I may add here that subsequentlyportions of skin were found, which from their sizeprobably belonged toDendrerpeton, and that these also werescaly and had lappets, though they did not appear to have thehorny tubercles and fringes. It may be asked why suchadvanced characters should be found in Nova Scotia alone.The answer is that the circumstances of preservation in theerect trees were peculiar, and that only animals of purely terrestrialhabits could find access to them, whereas the remainsof reptiles found in the Carboniferous elsewhere are in aqueousbeds in which aquatic forms were more likely to be preserved,and in which all the soft parts were certain to perish.

It is evident from the remains thus described, that we haveinHylonomus Lyelli an animal of lacertian form, with largeand stout hind limbs, and somewhat smaller fore limbs, capableof walking and running on land; and though its vertebræwere imperfectly ossified externally, yet the outer walls weresufficiently strong, and their articulation sufficiently firm, tohave enabled the creature to erect itself on its hind legs, or toleap. They were certainly proportionately larger and muchmore firmly knit than those ofDendrerpeton. Further, theribs were long and much curved, and imply a respiration of ahigher character than that of modern Batrachians, and consequentlya more highly vitalized muscular system. If to thesestructural points we add the somewhat rounded skull, indicatinga large brain, we have before us a creature which, howeverpuzzling in its affinities when anatomically considered, is clearlynot to be ranked as low in the scale of creation as moderntailed Batrachians, or even as the frogs and toads. We mustadd to these also, as important points of difference, the bonyscales with which it was armed below, and the ornate apparatus« 284 »of horny appendages, with which it was clad above.These last, as described in the last section, show that this littleanimal was not a squalid, slimy dweller in mud, likeMenobranchusand its allies, but rather a beautiful and sprightlytenant of the coal-formation thickets, vying in brilliancy, andperhaps in colouring, with the insects which it pursued anddevoured. Remains of as many as eight or ten individualshave been obtained from three erect Sigillariæ, indicating thatthese creatures were quite abundant, as well as active and terrestrialin their mode of life.

With respect to the affinities of this species, I think it isabundantly manifest that it presents no close relationship withany reptile hitherto discovered in the Carboniferous system,except perhaps some of the smaller forms in the Permian ofEurope, with which Credner and Fritsch have compared it. Itis scarcely necessary to say that the characters above describedentirely remove this animal from the Labyrinthodonts. Equaldifficulties attend the attempt to place it in any other groupof recent or extinct Batrachians or proper reptiles. The structuresof the skull, and of some points in the vertebræ, certainlyresemble those of Batrachians; but, on the other hand, thewell-developed ribs, evidently adapted to enlarge the chest inrespiration, the pelvis, and the cutaneous covering, are unexampledin modern Batrachians, and assimilate the creatureto the true lizards. I have already, in my original descriptionof the animal in 1859, expressed my belief thatHylonomusmay have had lacertian affinities, but I do not desire to speaktoo positively in this matter;[137] and shall content myself withstating the following alternatives as to the probable relationsof these animals, (1) They may have been true reptiles of lowtype, and with batrachian tendencies. (2) They may havebeen representatives of a new family of Batrachians, exhibitingin some points lacertian affinities. (3) They may have« 285 »been the young of some larger reptile, too large and vigorousto be entrapped in the pitfalls presented by the hollow Sigillariastumps, and in its adult state losing the batrachian peculiaritiesapparent in the young. Whichever of these views wemay adopt, the fact remains, that in the structure of this curiouslittle creature we have peculiarities both batrachian andlacertian, in so far as our experience of modern animals isconcerned. It would, however, accord with observed facts inrelation to other groups of extinct animals, that the primitiveBatrachians of the coal period should embrace in their structurespoints in after times restricted to the true reptiles. Onthe other hand, it would equally accord with such facts thatthe first-born of Lacertians should lean towards a lower type, bywhich they may have been preceded. My present impressionis, that they may constitute a separate family or order, to whichI would give the name ofMicrosauria, and which may beregarded as allied, on the one hand, to certain of the humblerlizards, as the Gecko or Agama, and, on the other, to thetailed Batrachians.

It is likely thatHylonomus Lyelli was less aquatic in itshabits thanDendrerpeton, Its food consisted, apparently, ofinsects and similar creatures. The teeth would indicate this,and near its bones there are portions of coprolite, containingremains of insects and myriapods. It probably occasionallyfell a prey toDendrerpeton, as bones, which may have belongedeither to young individuals of this species or to its smallercongenerH. Wymani, are found in larger coprolites, whichmay be referred with probability toDendrerpeton Acadianum.This coprolitic matter, which is somewhat plentiful on some ofthe surfaces in the erect trees, also informs us that the imprisonedanimals may in some cases have continued to live forsome time, feeding on such animals as may have fallen intotheir place of confinement, which was destined also to betheir tomb. Some other points of interest appear on the« 286 »examination of this excrementitious matter. It contains muchcarbonate of lime, indicating that snails or other mollusksfurnished a considerable part of the food of the smaller reptiles.Some portions of it are filled with chitinous fragments,parts of millipedes or insects, but usually so broken up asscarcely to be distinguishable. One curious exception was apart of the head of an insect containing a portion of one of itseyes. The facets of this can be readily seen with the microscope,and are similar to those of modern cockroaches. About250 of these little eyes are discernible, and they must havebeen much more numerous. Two points are of interest here:First, the perfection of the compound eye for vision in air.It had long before, in the case of the Trilobites, been used forseeing under water. Secondly, the great age of the still ubiquitousand aggressive family of the cockroaches. In point offact the oldest known insect, the Protoblattina of the Silurian,is one of these creatures, and they are the most abundant insectsin the Carboniferous, so that if they now dispute with usthe possession of our food, they may at least put in the claimof prior occupancy of the world. In one mass a quantity ofthickish crust or shell appears, which under the microscopepresents a minutely tubular and laminated appearance. It mayhave belonged to some small crustacean or large scorpion onwhich aDendrerpeton may have been feeding before it fell intothe pit in which it was entombed.

In addition to the reptilian species above noticed, the erecttrees of Coal Mine Point have afforded several others. Thereis a second and smaller species of Dendrerpeton (D. Oweni)and other forms belonging to the group of Microsauria of whichHylonomus is the type. A second species of that genus (H.Wymani) has already been mentioned. A similar creature, butof larger size and with teeth of a wedge or chisel shape, hasbeen referred to a distinct genus,Smilerpeton. It seems tohave been rare, and the only skeleton found is very imperfect.Its teeth are of a form that may have served even forvegetable food, as their sharp edges must have had considerablecutting power. Another curious form of tooth appears in thegenusHylerpeton. It has the points worked into obliquegrooves separated by sharp edges, which must have greatlyaided in piercing tough integument. These creatures seem tohave been of stout and robust build, with large limbs. Stillanother generic type (Fritschia) is represented by a speciesnear to Hylonomus in several respects, and with long and beautifullyformed limb bones, but with the belly protected withrod-like bodies instead of scales. In this respect Hylerpetonis somewhat intermediate, having long and narrow scales onthe belly instead of the oval or roundish scales of Hylonomus.All these last-mentioned forms are Microsaurians, with simpleteeth and well-developed ribs and limbs, and smooth cranialbones. Two other species are represented by portions ofsingle skeletons too imperfect to allow them to be certainlydetermined.

I would emphasize here that the vertebrate animals foundin the erect trees are necessarily a selection from the mostexclusively terrestrial forms, and from the smaller species ofthese. The numerous newt-like and serpentiform species foundin the shales of the coal formation could not find access to thesepeculiar repositories, nor could the larger species of the Labyrinthodontsand their allies, even if they were in the habit ofoccasionally prowling in the forests in search of prey, and thiswould scarcely be likely, more especially as the waters musthave afforded to them much more abundant supplies of food.Of the numerous species figured by Fritsch, Cope and Huxley,only a few approach very near to the forms entrapped in theold hollow Sigillariæ, though several have characters half batrachianand half reptilian.

The coal formation rocks have afforded Land Snails, Millipedes,Spiders, Scorpions and Insects, so that all the greattypes of invertebrate life which up to this day can live on landalready had representatives in this ancient period. Some ofthem, indeed, we can trace further back, the land snails probablyto the Devonian, the Millipedes to the same period, andthe Scorpions and insects as far as the Silurian. No land vertebrateis yet known, older than the Lower Carboniferous, butthere is nothing known to us in physical condition, to precludethe existence of such creatures at least in the Devonian.

It would take us too far afield to attempt to notice the invertebrateland life of the Palæozoic in general. This has beendone in great detail by Dr. Scudder. I shall here limit myselfto the animals found in our erect trees, and merely touch incidentallyon such others as may be connected with them.

I have already mentioned the occurrence of a land-snail,a true pulmonate mollusk, in the first find by Lyell and myselfat Coal Mine Point, and this was the first animal of thiskind known in any rocks older than the Purbeck formation ofEngland. It is one of the groups of so-called Chrysalis-shells,scarcely distinguishable at first sight from some modern WestIndian species, and distinctly referable to the modern genusPupa. It was namedPupa vetusta, and a second and smallerspecies subsequently found was namedP. Bigsbyi, and a thirdof different form, and resembling the modern snails, bears thenameZonites priscus. The only other Palæozoic land mollusksknown at present are a few species found in the coalformation of Ohio, and a fragment supposed to indicate anotherspecies from the Devonian plant-beds of St. John's, NewBrunswick. This last is the oldest known evidence of pulmonatesnails. If we ask the precise relations of these creatures tomodern snails, it may be answered that of the two leading subdivisionsof the group of air-breathing snails (Pulmonifera), theOperculate, or those with a movable plate to close the mouthof the shell, and the Inoperculate, or those that are destituteof any such shelly lid or operculum to close the shell, the firsthas been traced no farther back than the Eocene. The secondor inoperculate division, includes some genera that are aquaticand some that are terrestrial. Of the aquatic genera no representativesare known in formations older than the Wealdenand Purbeck, and these only in Europe. The terrestrial group,or the family of theHelicidæ, which, singularly enough, is thatwhich diverges farthest from the ordinary gill-bearing Gasteropods,is the one which has been traced farthest back, andincludes the Palæozoic species. It is further remarkable thata very great gap exists in the geological history of this family.No species are known between the Carboniferous and the earlyTertiary, though in the intervening formations there are manyfresh-water and estuarine deposits in which such remainsmight be expected to occur. There is perhaps no reason todoubt the continuance of the Helicidæ through this long portionof geological time, though it is probable that during theinterval the family did not increase much in the numbers ofits species, more especially as it seems certain that it has itsculmination in the modern period, where it is represented byvery many and large species, which are dispersed over nearlyall parts of our continents.

I published in 1880, in theAmericanJournal of Science, a fragment ofwhat seemed to be a land-snail, fromthe Middle Erian plant-beds of St.John, New Brunswick (Strophia grandava,figured here), but have mentionedit with some doubt in the text. Mr. G.F. Matthew has, however, recentlycommunicated to the Royal Society ofCanada a second species, found by Mr.W. I. Wilson in the same beds, andwhich he namesPupa primava. It isaccompanied with a scorpion and amillipede. Thus the existence of LandSnails of the Pupa type in the Devonianmay be considered as established.

The mode of occurrence of the Palæozoic Pulmonifera inthe few localities where they have been found is characteristic.The earliest known species,Pupa vetusta, was found, asalready stated, in the material filling the once hollow stem ofa Sigillaria at the South Joggins in Nova Scotia, and manyadditional specimens have subsequently been obtained fromsimilar repositories in the same locality, where they are associatedwith bones of Batrachians and remains of Millipedes.Other specimens, and also the speciesZonites priscus, have« 290 »been found in a thin, shaly layer, containingdébris of plantsand crusts of Cyprids, and which was probably deposited atthe outlet of a small stream flowing through the coal-formationforest. The two species found in Illinois occur, according toBradley, in an underclay or fossil soil which may have beenthe bed of a pond or estuary, and subsequently became aforest subsoil. The Erian .species occurs in shales chargedwith remains of land plants, and which must consequentlyhave received abundant drainage from neighbouring land. Itis only in such deposits that remains of true land snails can beexpected to occur; though, had fresh-water or brackish waterPulmonates abounded in the Carboniferous age, their remainsshould have occurred in those bituminous and calcareo-bituminousshales which contain such vast quantities ofdébris ofCyprids, Lamellibranchs and fishes of the period, mixed withfossil plants.

The specimen first obtained in 1887 having been taken bySir Charles Lyell to the United States, and submitted to thelate Prof. Jeffries Wyman, the shell in question was recognisedby him and the late Dr. Gould, of Boston, as a land shell. Itwas subsequently examined by M. Deshayes and Mr. GwynJeffries, who concurred in this determination; and its microscopicstructure was described by the late Prof. Quekett, ofLondon, as similar to that of modern land shells. The singlespecimen obtained on this occasion was somewhat crushed,and did not show the aperture. Hence the hesitation as toits nature, and the delay in naming it, though it was figuredand described in the paper above cited in 1852. Betterspecimens showing the aperture were afterward obtained bythe writer, and it was named and described by him in his"Air-breathers of the Coal Period," in 1863. Owen, in his"Palæontology," subsequently proposed the generic nameDendropupa. This I have hesitated to accept, as expressinga generic distinction not warranted by the facts; but should« 291 »the shell be considered to require a generic or sub-genericdistinction, Owen's name should be adopted for it. Thereseems, however, nothing to prevent it from being placed inone of the modern sub-genera of simple-lipped Pupæ. Withregard to the form of its aperture, I may explain that somecurrency has been given to an incorrect representation of it,through defective specimens. In the case of delicate shellslike this, imbedded in a hard matrix, it is of course difficultto work out the aperture perfectly; and in my publishedfigure in the "Air-breathers," I had to restore somewhat thebroken specimens in my possession. This restoration, specimenssubsequently found have shown to be very exact.

As already stated, this shell seems closely allied to somemodern Pupæ. Perhaps the modern species which approachesmost nearly to it in form, markings and size, isMacrocheilusGossei from the West Indies, specimens of which were sent tome some years ago by Mr. Bland, of New York, with theremark that they must be very near to my Carboniferousspecies. Such edentulous species asPupa (Leucochila)fallaxof Eastern America very closely resemble it; and it was regardedby the late Dr. Carpenter as probably a near ally ofthose species which are placed by some European conchologistsin the genusPupilla.

Pupa vetusta has been found at three distinct levels in thecoal formation of the South Joggins. The lowest is the shaleabove referred to. The next, 1,217 feet higher, is that of theoriginal discovery. The third, 800 feet higher, is in an erectSigillaria holding no other remains. Thus, this shell has livedin the locality at least during the accumulation of 2,000 feetof beds, including a number of coals and erect forests, as wellas beds of bituminous shales and calcareo-bituminous shale,the growth of which must have been very slow.

In the lowest of these three horizons the shells are found,as already stated, in a thin bed of concretionary clay of dark« 292 »grey colour, though associated with reddish beds. It containsZonites priscus as well, though this is very rare, and there area few valves ofCythere and shells ofNaiadites as well ascarbonaceous fragments, fronds of ferns,Trigonocarpa, etc.ThePupæ are mostly adult, but many very young shells alsooccur, as well as fragments of broken shells. The bed isevidently a layer of mud deposited in a pond or creek, or atthe mouth of a small stream. In modern swamps multitudesof fresh-water shells occur in such places, and it is remarkablethat in this case the only Gasteropods are land shells, andthese very plentiful, though only in one bed about an inch inthickness. This would seem to imply an absence of fresh-waterPulmonifera. In the erectSigillariæ of the secondhorizon the shells occur either in a sandy matrix, more or lessdarkened with vegetable matter, or in a carbonaceous masscomposed mainly of vegetabledébris. Except when crushedor flattened, the shells in these repositories are usually filledwith brownish calcite. From this I infer that most of themwere alive when imbedded, or at least that they contained thebodies of the animals; and it is not improbable that theysheltered themselves in the hollow trees, as is the habit ofmany similar animals in modern forests. Their residence inthese trees, as well as the characters of their embryology, areillustrated by the occurrence of their mature ova. One ofthose, which I have considered worth figuring, has been brokenin such a way as to show the embryo shell.

They may also have formed part of the food of the reptiliananimals whose remains occur with them. In illustration ofthis I have elsewhere stated that I have found as many aseleven unbroken shells ofPhysa heterostropha in the stomachof a modernMenobranchus. I think it certain, however, thatboth the shells and the reptiles occurring in these trees musthave been strictly terrestrial in their habits, as they could nothave found admission to the erect trees unless the ground had« 293 »been sufficiently dry to allow several feet of the imbeddedhollow trunks to be free from water. In the highest of thethree horizons the shells occurred in an erect tree, but withoutany other fossils, and they had apparently been washed inalong with a greyish mud.[138]

If we exclude the allegedPalæorbis referred to below, allthe Palæozoic Pulmonifera hitherto found are American.Since, however, in the Carboniferous age, Batrachians, Arachnidans,Insects and Millipedes occur on both continents, it isnot unlikely that ere long European species of land snails willbe announced The species hitherto found in EasternAmerica are in every way strangely isolated. In the plantbeds of St. John, about 9,000 feet in thickness, and in thecoal formation of the South Joggins, more than 7,000 feet inthickness, no other Gasteropods occur, nor, I believe, do anyoccur in the beds holding land snails in Illinois. Nor, asalready stated, are any of the aquatic Pulmonifera known inthe Palæozoic. Thus, in so far as at present known, thesePalæozoic snails are separated not only from any predecessors,if there were any, or successors, but from any contemporaryanimals allied to them.

It is probable that the land snails of the Erian and Carboniferouswere neither numerous nor important members of thefaunas of those periods. Had other species existed in anyconsiderable numbers, there is no reason why they should nothave been found in the erect trees, or in those shales whichcontain land plants. More especially would the discovery ofany larger species, had they existed, been likely to haveoccurred. Further, what we know of the vegetation of thePalæozoic period would lead us to infer that it did not abound« 294 »in those succulent and nutritious leaves and fruits which aremost congenial to land snails. It is to be observed, however,that we know little as yet of the upland life of the Erian orCarboniferous. The animal life of the drier parts of the lowcountry is indeed as yet very little known; and but for therevelations in this respect of the erect trees in one bed in thecoal formation of Nova Scotia, our knowledge of the landsnails and Millipedes, and also of an eminently terrestrial groupof reptiles, theMicrosauria, would have been much moreimperfect than it is. We may hope for still further revelationsof this kind, and in the meantime it would be premature tospeculate as to the affinities of our little group of land snailswith animals either their contemporaries or belonging toearlier or later formations, except to note the fact of the littlechange of form or structure in this type of life in that vastinterval of time which separates the Erian period from thepresent day.

It may be proper to mention here the alleged Pulmoniferaof the genusPalæorbis described by some German naturalists.These I believe to be worm tubes of the genusSpirorbis, andin fact to be nothing else than the commonS. carbonarius orS. pusillus of the coal formation. The history of this errormay be stated thus. The eminent palæobotanists Germar,Goeppert and Geinitz have referred theSpirorbis, so commonin the Coal measures to the fungi, under the nameGyromyces,and in this they have been followed by other naturalists,though as long ago as 1868 I had shown that this littleorganism is not only a calcareous shell, attached by one sideto vegetable matters and shells of mollusks, but that it has themicroscopic structure characteristic of modern shells of thistype.[139] More recently Van Beneden, Cænius, and Goldenberg,perceiving that the fossil is really a calcareous shell, but« 295 »apparently unaware of the observations made in this countryby myself and Mr. Lesquereux, have held theSpirorbis to be apulmonate mollusk allied toPlanorbis, and have supposed thatits presence on fossil plants is confirmatory of this view,though the shells are attached by a flattened side to theseplants, and are also found attached to shells of bivalves of thegenusNaiadites. Mr. R. Etheridge, jun., of the GeologicalSurvey of Great Britain, has summed up the evidence as to thetrue nature of these probably brackish-water shells, and hasrevised and added to the species, in a series of articles in theGeological Magazine of London, vol. viii.

The erect trees of Coal Mine Point are rich in remains ofMillipedes. The first of these (Xylobius Sigillariæ), which wasthe first known Palæozoic Myriapod, was described by mefrom specimens found in a tree extracted in 1852, and this,with a number of other remains subsequently found, was afterwardsplaced in the hands of Dr. Scudder, who has recognisedin the material submitted to him eight species belonging tothree genera (Xylobius,Archiulus, andAmynilyspes). Theseanimals in all probability haunted these trees to feed on thedecaying wood and other vegetable matter, and were undoubtedlythemselves the prey of the Microsaurians. Thoughthese were the earliest known, their discovery was followed bythat of many other species in Europe and America, and someof them as old as the Devonian.[140]

The only other remains of Air-breathers found in the erecttrees belong to Scorpions, of which some fragments remain insuch a state as to make it probable that they have beenpartially devoured by the imprisoned reptiles. No remains ofany aquatic animals have been found in these trees. The« 296 »Scorpions are referred by Scudder to three species belongingto two genera.[141]

In the previous paper we have considered the mode ofaccumulation of Coal, and it may be useful here to note thelight thrown on this subject by the Air-breathers of the coalformation and their mode of occurrence.

In no part of the world are the coal measures betterdeveloped, or more fully exposed, than in the coast sections ofNova Scotia and Cape Breton; and in these, throughout theirwhole thickness, no indication has been found of any of themarine fossils of the Lower Carboniferous Limestone. Abundantremains of fishes occur, but these may have frequentedestuaries, streams and ponds, and the greater part of them aresmall ganoids which, like the modernLepidosteus andAmia,may have been specially fitted by their semi-reptilian respiration,for the impure waters of swampy districts. Bivalvemollusks also abound; but these are all of the kinds to whichI have given the generic nameNaiadites, and Mr. Salter thoseofAnthracomya andAnthracoptera. These shells are alldistinct from any known in the marine limestones. Their thinedentulous valves, their structure consisting of a wrinkledepidermis, a thin layer of prismatic shell and an inner layer ofimperfectly pearly shell, all remind us of the Anodons andUnios. A slight notch in front concurs with their mode ofoccurrence in rendering it probable that, like mussels inmodern estuaries, they attached themselves to floating orsunken timber. They are thus removed, both in structure andhabit, from truly marine species; and may have been fresh-wateror brackish-water mussels closely allied to modernUnios.

The crustaceans (Eurypterus,Diplostylus,Cyprids), and theworm shell (Spirorbis) found with them, are not necessarilymarine, though some of them belonged probably to brackishwater, and they have not yet been found in those carboniferousbeds deposited in the open sea. There is thus in the wholethickness of the middle coal measures of Nova Scotia aremarkable absence at least of open sea animals; and if, as isquite probable, the sea inundated at intervals the areas of coalaccumulation, the waters must have been shallow, and to agreat extent land-locked, so that brackish-water rather thanmarine animals inhabited them.

On the other hand, there are in these coal measuresabundant evidences of land surfaces; and subaërial decay ofvegetable matter in large quantity is proved by the occurrenceof the mineral charcoal of the coal itself, as I have elsewhereshown.[142] The erect trees which occur at so many levels alsoimply subaërial decay. A tree imbedded in sediment andremaining under water, could not decay so as to becomehollow and deposit the remains of its wood in the state ofmineral charcoal within the hollow bark. Yet this is the casewith the greater part of the erect Sigillariæ which occur atmore than twenty levels in the Joggins section. Nor couldsuch hollow trunks become repositories for millipedes, snailsand reptiles, if under water. On the other hand, if, as seemsnecessary to explain the character of the reptiliferous erecttrees, these remained dry, or nearly so, in the interior, thiswould imply not merely a soil out of water, but comparativelywell drained; as would indeed always be the case, when a flatresting on a sandy subsoil was raised several feet above thelevel of the water. Further, though the peculiar character ofthe roots ofSigillariæ andCalamites may lend some countenanceto the supposition that they could grow under water, or inwater-soaked soils, this will not apply to coniferous trees, to« 298 »ferns, and other plants, which are found under circumstanceswhich show that they grew with theSigillariæ.

In the coal measures of Nova Scotia, therefore, while marineconditions are absent, there are ample evidences of fresh-wateror brackish-water conditions, and of land surfaces, suitable forthe air-breathing animals of the period. Nor do I believe thatthe coal measures of Nova Scotia were exceptional in thisrespect. It is true that in Great Britain evidences of marinelife do occur in the coal measures; but not, so far as I amaware, in circumstances which justify the inference that thecoal is of marine origin. Alternations of marine and landremains, and even mixtures of these, are frequent in modernsubmarine forests. When we find, as at Fort Lawrence inNova Scotia, a modern forest rooted in upland soil forty feetbelow high-water mark,[143] and covered with mud containingliving Tellinas and Myas, we are not justified in inferring thatthis forest grew in the sea. We rather infer that subsidencehas occurred. In modern salt marshes it is not unusual tofind every little runnel or pool full of marine shell fish, while inthe higher parts of the marsh land plants are growing; andin such places the deposit formed must contain a mixture ofland plants and marine animals with salt grasses and herbage—thewholein situ.[144]

These considerations serve, I think, to explain all theapparently anomalous associations of coal plants with marinefossils; and I do not know any other arguments of apparentweight that can be adduced in favour of the marine or even« 299 »aquatic origin of coal, except such as are based on misconceptionsof the structure and mode of growth of sigillaroid treesand of the stratigraphical relations of the coal itself.[145] It is tobe observed, however, that while I must maintain the essentiallyterrestrial character of the ordinary coal and of its plants,I have elsewhere admitted that cannel coals and earthybitumen present evidences of subaquatic deposition; andhave also abundantly illustrated the facts that the coal plantsgrew on swampy flats, liable not only to river inundations, butalso to subsidence and submergence.[146] In the oscillation ofthese conditions it is evident thatSigillariæ and their contemporariesmust often have been placed in conditions unfavourableor fatal to them, and when their remains arepreserved to us in these conditions, we may form very incorrectinferences as to their mode of life. Further, it is to beobserved that the conditions of submergence and silting upwhich were favourable to the preservation of specimens ofSigillariæ as fossils, must have been precisely those which« 300 »were destructive to them as living plants; and on the contrary,that the conditions in which these forests may have flourishedfor centuries must have been those in which there was littlechance of their remains being preserved to us, in any othercondition at least than that of coal, which reveals only tocareful microscopic examination the circumstances, whetheraërial or aquatic, under which it was formed.

It is also noticeable that, in conditions such as those of thecoal formation, it would be likely that some plants would bespecially adapted to occupy newly emerged flats and placesliable to inundation and silting up. I believe that many of theSigillariæ, and still more eminently theCalamites, were suitableto such stations. There is direct evidence that the nutsnamed Trigonocarpa were drifted extensively by water oversubmerged flats of mud. ManyCardiocarpa were wingedseeds which may have drifted in the air. The Calamites may,like modernEquiseta, have produced spores with elaters capableof floating them in the wind. One of the thinner coalsat the Joggins is filled with spores or spore cases that seem tohave carried hairs on their surfaces, and may have been suitedto such a mode of dissemination. I have elsewhere proved [147]that at least some species ofCalamites were, by their mode ofgrowth, admirably fitted for growing amid accumulating sediment,and for promoting its accumulation.

The reptiles of the coal formation are probably the oldestknown to us, and possibly, though this we cannot affirm, thehighest products of creation in this period. Supposing, forthe moment, that they are the highest animals of their time,and, what is perhaps less likely, that those which we know are afair average of the rest, we have the curious fact that they areall carnivorous, and the greater part of them fitted to find foodin the water as well as on the land. The plant feeders of theperiod, on the land at least, are all invertebrates, as snails,« 301 »millipedes, and perhaps insects. The air-breathing vertebratesare not intended to consume the exuberant vegetable growth,but to check the increase of its animal enemies. Plant lifewould thus seem to have had in every way the advantage.The millipedes probably fed only on roots and decaying substances,the snails on the more juicy and succulent plantsgrowing in the shadow of the woods, and the great predominanceof the family of cockroaches among carboniferous insectspoints to similar conclusions as to that class. While, moreover,the vegetation of the coal swamps was most abundant, it wasnot, on the whole, of a character to lead us to suppose that itsupported many animals. Our knowledge of the flora of thecoal swamps is sufficiently complete to exclude from them anyabundance of the higher phænogamous plants. We knowlittle, it is true, of the flora of the uplands of the period; butwhen we speak of the coal-formation land, it is to the flats onlythat we refer. The foliage of the plants on these flats with theexception of that of the ferns, was harsh and meagre, and thereseem to have been no grasses or other nutritious herbaceousplants. These are wants of themselves likely to exclude manyof the higher forms of herbivorous life. On the other hand,there was a profusion of large nut-like seeds, which in a modernforest would probably have afforded subsistence to squirrelsand similar animals. The pith and thick soft bark of many ofthe trees must at certain seasons have contained much nutritivematter, while there was certainly sufficient material for allthose insects whose larvæ feed on living and dead timber, aswell as for the creatures that in turn prey on them. It is remarkablethat there seem to have been no vertebrate animalsfitted to avail themselves of these vast stores of food. Thequestion: "What may have fed on all this vegetation?" wasnever absent from my mind in all my explorations of the NovaScotia coal sections; but no trace of any creature other thanthose already mentioned has ever rewarded my search. In« 302 »Nova Scotia it would seem that a few snails, gally-worms, andinsects were the sole links of connection between the plantcreation and air-breathing vertebrates. Is this due to thepaucity of the fauna, or the imperfection of the record? Thefact that a few erect stumps have revealed nearly all the air-breathersyet found, argues strongly for the latter cause; butthere are some facts bearing on the other side.

A gally-worm, if, like its modern relatives, hiding in crevicesof wood in forests, was one of the least likely animals to befound in aqueous deposits. The erect trees gave it its almostsole chance of preservation.Pupa vetusta is a small species,and its shell very thin and fragile, while it probably lived amongthick vegetation. Further, the measures 2,000 feet thick,separating the lowest and highest beds in which it occurs, includetwenty-one coal seams, having an aggregate thickness ofabout twenty feet, three beds of bituminous limestone of animalorigin, and perhaps twenty beds holdingStigmariain situ, orerectSigillariæ andCalamites. The lapse of time implied bythis succession of beds, many of them necessarily of very slowdeposition, must be very great, though it would be mere guesswork to attempt to resolve it into years. Yet long though thisinterval must have been,Pupa vetusta lasted without one iotaof change through it all; and, more remarkable still, was notaccompanied by more than two other species of its family.Where so many specimens occur, and in situations so diverse,without any additional species, the inference is strong that noother of similar habits existed. If in any of those subtropicalislands, whose climate and productions somewhat resemblethose of the coal period, after searching in and about decayingtrees, and also on the bars upon which rivers and lakes driftedtheir burdens of shells, we should find only three species, butone of these in very great numbers, we would surely concludethat other species, if present, were very rare.

Again, footprints referable toDendrerpeton, or similar animals,« 303 »occur in the lower Carboniferous beds below the marine limestones,in the middle coal measures, and in the upper coalformation, separated by a thickness of beds which may beestimated at 15,000 feet, and certainly representing a vast lapseof time. Did we know the creature by these impressionsalone, we might infer its continued existence for all this greatlength of time; but when we also find its bones in the principalrepositories of reptile remains, and in company with theother creatures found with it, we satisfy ourselves that of themall it was the most likely to have left its trail in the mud flats.We thus have reason to conclude that it existed alone duringthis period, in so far as its especial kind of habitat was concerned;though there lived with it other reptiles, some ofwhich, haunting principally the woods, and others the water,were less likely to leave impressions of their footprints. Thesemay be but slight indications of truth, but they convey strongimpressions of the persistence of species, and also of the paucityof species belonging to these tribes at the time.

If we could affirm that the Air-breathers of the coal periodwere really the first species of their families, they might acquireadditional interest by their bearing on this question of originof species. We cannot affirm this; but it may be a harmlessand not uninstructive play of fancy to suppose for a momentthat they actually are so, and to inquire on this supposition asto the mode of their introduction. Looking at them from thispoint of view, we shall first be struck with the fact that theybelong to all of the three great leading types of animals whichinclude our modern Air-breathers the Vertebrates, the Arthropods,and the Mollusks. We have besides to consider in thisconnection that the breathing organs of an insect are air tubesopening laterally (tracheæ), those of a land snail merely amodification of the chamber which in marine species holds thegills, while those of the reptiles represent the air bladder of thefishes. Thus, in the three groups the breathing organs are« 304 »quite distinct in their nature and affinities. This at once excludesthe supposition that they can all have been derived fromeach other within the limits of the coal period. No transmutationistcan have the hardihood to assert the convertibility, byany direct method, of a snail into a millipede or an insect, orof either into a reptile. The plan of structure in these creaturesis not only different, but contrasted in its most essentialfeatures. It would be far more natural to suppose that theseanimals sprang from aquatic species of their respective types.We should then seek for the ancestors of the snail in aquaticGasteropods, for those of the millipede in worms or Crustaceans,and for those of the reptiles in the fishes of the period. Itwould be easy to build up an imaginary series of stages, onthe principle of natural selection, whereby these results mightbe effected; but the hypothesis would be destitute of any supportfrom fact, and would be beset by more difficulties than itremoves. Why should the result of the transformation ofwater-snails breathing by gills be aPupa ? Would it not muchmore likely be anAuricula or aLimnea ? It will not solvethis difficulty to say that the intermediate forms became extinct,and so are lost. On the contrary, they exist to this day,though they were not, in so far as we know, introduced soearly. But negative evidence must not be relied on; therecord is very imperfect, and such creatures may have existed,though unknown to us. It may be answered that they couldnot have existed in any considerable numbers, else some oftheir shells would have appeared in the coal-formation beds, sorich in crustaceans and bivalve mollusks. Further, the littlePupa remained unchanged during a very long time, and showsno tendency to resolve itself into anything higher, or to descendto anything lower, while in the lowest bed in which it occursit is associated with a round snail of quite different type.Here, if anywhere, in what appears to be the first introductionof air-breathing invertebrates, we should be able to find the« 305 »evidences of transition from the gills of the Prosobranchiateand the Crustacean to the air sac of the Pulmonate and thetracheæ of the millipede. It is also to be observed that manyother structural changes are involved, the aggregate of whichmakes a Pulmonate or a millipede different in every particularfrom its nearest allies among gill-bearing Gasteropods orCrustaceans.

It may be said, however, that the links of connection betweenthe coal reptiles and fishes are better established. Allthe known coal reptiles have leanings to the fishes in certaincharacters; and in some, as inArchegosaurus, these are veryclose. Still the interval to be bridged over is wide, and thedifferences are by no means those which we should expect.Were the problem given to convert a ganoid fish into anArchegosaurus orDendrerpeton, we should be disposed toretain unchanged such characters as would be suited to thenew habits of the creature, and to change only those directlyrelated to the objects in view. We should probably give littleattention to differences in the arrangement of skull bones, inthe parts of the vertebræ, in the external clothing, in the microscopicstructure of the bone, and other peculiarities for servingsimilar purposes by organs on a different plan, which are soconspicuous so soon as we pass from the fish to the Batrachian.It is not, in short, an improvement of the organs of the fish thatwe witness so much as the introduction of new organs.[148] Thefoot of the batrachian bears, perhaps, as close a relation to thefin of the fish as the screw of one steamship to the paddlewheel of another, or as the latter to a carriage wheel; and canbe just as rationally supposed to be not a new instrument, butthe old one changed. In this connection even a footprint inthe sand startles us as much as that of Friday did Robinson« 306 »Crusoe. We see five fingers and toes, and ask how thisnumerical arrangement started at once from fin rays of fishesall over the world; and how it has continued unchanged tillnow, when it forms the basis of our decimal arithmetic.

Again, our reptiles of the coal do not constitute a continuousseries, and belong to a great number of distinct genera andfamilies, nor is it possible that they can all, except at widelydifferent times, have originated from the same source. Iteither happened, for some unknown reason, that many kinds offishes put on the reptilian guise in the same period, or else thevast lapse of ages required for the production of a reptile froma fish must be indefinitely increased for the production of manydissimilar reptiles from each other; or, on the other hand, wemust suppose that the limit between the fish and reptile beingonce overpassed, a facility for comparatively rapid changesbecame the property of the latter. Either supposition would,I think, contradict such facts bearing on the subject as areknown to us.

We commenced with supposing that the reptiles of the Coalmight possibly be the first of their family, but it is evidentfrom the above considerations, that on the doctrine of naturalselection, the number and variety of reptiles in this periodwould imply that their predecessors in this form must haveexisted from a time as early as any in which even fishes areknown to exist; so that if we adopt any hypothesis of derivation,it would probably be necessary to have recourse to thatwhich supposes at particular periods a sudden and as yet unaccountabletransmutation of one form into another; a viewwhich, in its remoteness from anything included under ordinarynatural laws, does not materially differ from that currently receivedidea of creative intervention, with which, in so far asour coal reptiles can inform us, we are for the present satisfied.

There is one other point which strikes the naturalist in consideringthese animals, and which has a certain bearing on such« 307 »hypothesis. It is the combination of various grades of reptiliantypes in these ancient creatures. It has been well remarkedby Hugh Miller, and more fully by Agassiz, that this is characteristicof the first appearance of new groups of animals. Nowselection, as it acts in the hands of the breeder, tends tospecialization; and natural selection, if there is such a thing, issupposed to tend in the same direction. But when some distinctlynew form is to be introduced, an opposite tendencyseems to prevail, a sort of aggregation in one species of charactersafterward to be separated and manifested in distinctgroups of creatures. The introduction of such new types alsotends to degrade and deprive of their higher properties previouslyexisting groups of lower rank. It is easy to perceive inall this, law and order, in that higher sense in which theseterms express the will and plan of the Supreme Mind, but notin that lower sense in which they represent the insensateoperation of blind natural forces.

References:—"Air-breathers of the Coal Period." Montreal, 1886.Papers on Reptiles, etc., in South Joggins Coal Field,Journal ofGeological Society of London, vols. ix. x. xi. xvi. Remains of Animalsin Erect Trees in the Coal Formation of Nova Scotia,Trans.Royal Society, 1881. "Acadian Geology," fourth edition, 1891. Revisionof Land Snails of the Palæozoic Era,Am. Journal of Science,vol. xx., 1880. Supplementary Report to Royal Society of London,Proceedings, 1892. Notice of additional Reptilian Remains,GeologicalMagazine of London, 1891.

MARKINGS, FOOTPRINTS AND FUCOIDS.

DEDICATED TO THE MEMORY OF THE LATE

DR. J. J. BIGSBY, F.R.S.,

OF LONDON,

The painstaking and accurate Author
of the Thesaurus Siluricus and Devonico-Carboniferous,
a warm and kind Friend and Christian Gentleman
and one of the
Pioneers of Canadian Geology.

Reminiscences of Lyell's Work—Tidal Flats of theBay of Fundy—Rill Marks and Shrinkage Cracks—WormTrails and Burrows—The Paces of Limulus—FucoidsVersus Trails—Footprints of Vertebrates

CHAPTER XI.

I believe my attention was first directed to the markingsmade by animals on the surfaces of rocks, when travellingwith the late Sir Charles Lyell in Nova Scotia, in 1842. Henoticed with the greatest interest the trails of worms, insects,and various other creatures, and the footprints of birds on thesurface of the soft red tidal mud of the Bay of Fundy, andsubsequently published his notes on the various markings inthese deposits in his "Travels in North America," and in a paperpresented to the Geological Society of London. I well rememberhow, in walking along the edge of the muddy shore,he stopped to watch the efforts of a grasshopper that hadleaped into the soft ooze, and was painfully making a mostcomplicated trail in his effort to escape. Sir Charles remarkedthat if it had been so fortunate as to make thesestrange and complicated tracks on some old formation nowhardened into stone and buried in the earth, it might havegiven occasion to much learned discussion.

At a later period I found myself perplexed in the study offossil plants by the evident errors of many palæobotanists unacquaintedwith modern markings on shores, in referring allkinds of mere markings to the vegetable kingdom, and especiallyto the group of fucoids or seaweeds, which had becomea refuge for destitute objects not referable to other kinds offossils. It thus became necessary to collect and study theseobjects, as they existed in rocks of different ages, and to compare« 312 »them with the examples afforded by the modern beach;and perhaps no locality could have afforded better opportunitiesfor this than the immense tidal flats of the finest mud leftbare by the great tides of the Bay of Fundy in Nova Scotia.At a more recent period still, the subject has come into greatprominence in Europe, and if we are to gauge its importanceby the magnitude of the costly illustrated works devoted to itby Delgado, Saporta, Nathorst, and others, and the multitudeof scattered papers in scientific periodicals, we should regardit as one of the most salient points in Geology.[149]

It may be well further to introduce the subject by a fewextracts from Lyell's work above referred to.

"The sediment with which the waters are charged is extremelyfine, being derived from the destruction of cliffs of redsandstone and shale, belonging chiefly to the coal measures.On the borders of even the smallest estuaries communicatingwith a bay, in which the tides rise sixty feet and upwards,large areas are laid dry for nearly a fortnight between thespring and neap tides, and the mud is then baked in summerby a hot sun, so that it becomes solidified and traversed bycracks caused by shrinkage. Portions of the hardened mudmay then be taken up and removed without injury. On examiningthe edges of each slab we observe numerous layers,formed by successive tides, usually very thin, sometimes onlyone-tenth of an inch thick, of unequal thickness, however,because, according to Dr. Webster, the night tides rising afoot higher than the day tides throw down more sediment.When a shower of rain falls, the highest portion of the mud-coveredflat is usually too hard to receive any impressions;while that recently uncovered by the tide, near the water'sedge, is too soft. Between these areas a zone occurs almostas smooth and even as a looking-glass, on which every dropforms a cavity of circular or oval form; and if the shower be« 313 »transient, these pits retain their shape permanently, being driedby the sun, and being then too firm to be effaced by theaction of the succeeding tide, which deposits upon them a newlayer of mud. Hence we find, on splitting open a slab aninch or more thick, on the upper surface of which the marksof recent rain occur, that an inferior layer, deposited perhapsten or fourteen tides previously, exhibits on its under surfaceperfect casts of rain prints which stand out in relief, the mouldsof the same being seen in the layer below."

After mentioning that a continued shower of rain obliteratesthe more regular impressions, and produces merely a blisteredor uneven surface, and describing minutely the characteristicsof true rain marks in their most perfect state, Sir Charlesadds:—

"On some of the specimens the winding tubular tracks ofworms are seen, which have been bored just beneath thesurface. Sometimes the worms have dived beneath the surface,and then re-appeared. Occasionally the same mud istraversed by the footprints of birds (Tringa minuta), and ofmusk-rats, minks, dogs, sheep and cats. The leaves also ofthe elm, maple and oak trees have been scattered by thewinds over the soft mud, and having been buried under thedeposits of succeeding tides, are found on dividing the layers.When the leaves themselves are removed, very faithful impressions,not only of their outline, but of their minutest veins,are left imprinted on the clay."

This is a minor illustration of that application of recentcauses to explain ancient effects of which the great Englishgeologist was the apostle and advocate, and which he soadmirably practised in his own work. It is also an illustrationof the fact that things the most perishable and evanescentmay, when buried in the crust of the earth, become its mostdurable monuments. Footprints in the sand of the tidal shoreare in the ordinary course of events certain to be obliterated« 314 »by the next tide; but when carefully filled up by gently depositednew material, and hardened into stone, there is no limitto their duration.

Let us inquire how this may take place, and the tidal flatsof the Bay of Fundy and Basin of Minas may supply us withthe information desired. In the upper parts of the Bay ofFundy and its estuaries the rise and fall of tide, as is wellknown, are excessive. I quote the following description ofthe appearance they present from a work of earlier date:—

"The tide wave that sweeps to the north-east, along theAtlantic coast of the United States, entering the funnel-likemouth of the Bay of Fundy, becomes compressed and elevated,as the sides of the bay gradually approach each other, until inthe narrower parts the water runs at the rate of six or sevenmiles per hour, and the vertical rise of the tide amounts tosixty feet or more. In Cobequid and Chiegnecto Bays thesetides, to an unaccustomed spectator, have rather the aspect ofsome rare convulsion of nature than of an ordinary dailyphenomenon. At low tide wide flats of brown mud are seento extend for miles, as if the sea had altogether retired fromits bed; and the distant channel appears as a mere strip ofmuddy water. At the commencement of flood a slight rippleis seen to break over the edge of the flats. It rushes swiftlyforward, and, covering the lower flats almost instantaneously,gains rapidly on the higher swells of mud, which appear as ifthey were being dissolved in the turbid waters. At the sametime the torrent of red water enters all the channels, creeksand estuaries; surging, whirling, and foaming, and often havingin its front a white, breaking wave, or 'bore,' which runssteadily forward, meeting and swallowing up the remains ofthe ebb still trickling down the channels. The mud flats aresoon covered; and then, as the stranger sees the water gainingwith noiseless and steady rapidity on the steep sides of banksand cliffs, a sense of insecurity creeps over him, as if no limit« 315 »could be set to the advancing deluge. In a little time, however,he sees that the fiat, 'Hitherto shalt thou come, and nofarther,' has been issued to the great bay tide: its retreat commences,and the waters rush back as rapidly as they entered.

"The rising tide sweeps away the fine material from everyexposed bank and cliff, and becomes loaded with mud andextremely fine sand, which, as it stagnates at high water, itdeposits in a thin layer on the surface of the flats. This layer,which may vary in thickness from a quarter of an inch to aquarter of a line, is coarser and thicker at the outer edge ofthe flats than nearer the shore; and hence these flats, as wellas the marshes, are usually higher near the channels than attheir inner edge. From the same cause,—the more rapid depositionof the coarser sediment,—the lower side of each layeris arenaceous, and sometimes dotted over with films of mica,while the upper side is fine and slimy, and when dry has ashining and polished surface. The falling tide has little effecton these deposits, and hence the gradual growth of the flats,until they reach such a height that they can be overflowed onlyby the high spring tides. They then become natural or saltmarsh, covered with the coarse grasses andcarices which growin such places. So far the process is carried on by the handof nature; and before the colonization of Nova Scotia, therewere large tracts of this grassy alluvium to excite the wonderand delight of the first settlers on the shores of the Bay ofFundy. Man, however, carries the land-making processfarther; and by diking and draining, excludes the sea water,and produces a soil capable of yielding for an indefinite period,without manure, the most valuable cultivated grains andgrasses."

The mud of these great tidal flats is at the surface of a redcolour, and so fine that when the tide leaves it and its surfacebecomes dry, it shines in the sun as if polished. It is thuscapable of taking the finest impressions. When the tide is in,« 316 »numerous small fish of various species occupy the ground andmay leave marks of their fins and tails as they gambol or seektheir food. Shell fishes, worms, and Crustaceans scrambleover the same surface, or make burrows in it. As the tiderecedes flocks of sandpipers and crows follow it down, andleave an infinity of footprints, and even quadrupeds like thedomestic hog go far out at low water in search of food. It issaid that in some parts of the Bay the hogs are so assiduousin this pursuit that they even awake and go out on the flats inthe night tide, and that they have so learned to dread thedangers of the flood, that when in the darkness they hear thedull sound of the approaching bore, they squeal with fear andrush madly for the shore.

If we examine it minutely, we shall find that the tidal depositis laminated. The tidal water is red and muddy, andholds in suspension sediment of various degrees of coarseness.This, undergoes a certain process of levigation. In the firstrun of the flood the coarser material falls to the bottom. Asits force diminishes the finer material is deposited, and at fulltide, when the current has ceased, the finest of all settles,forming a delicate coat of the purest and most tenacious clay.Thus, if a block of the material is taken up and allowed todry, it tends to separate into thin laminæ, each of which representsa tide, and is somewhat sandy below, and passes intothe finest moulding clay above. The tracks and impressionspreserved are naturally made on the last or finest deposit, andfilled in with the coarser or more sandy of the next tide. Butthis may take place in different ways. Impressions madeunder water at flood tide, or on the surface left bare by theebb, may in favourable localities be sufficiently tenacious orfirm to resist the abrading action of the flood, and may thusbe covered and preserved by the next layer, and in this waythey may be seen on splitting up a block of the dried mud.But in shallow places and near the shore, where the deposit« 317 »has time to consolidate and become dried by the sun and airbefore the next tide, much better impressions are preserved;and lastly, on those parts of the shore which are reached onlyby the spring tides, the mud of the highest tide of course mayhave several days to harden before the next tide reaches it,and in this case it becomes cracked by an infinity of shrinkagecracks, which, when it is next covered with the tide, are filledwith new sediment. In this way is produced in great perfectionthat combination of footprints, or even of impressions ofrain, with casts of cracks, which is so often seen in the olderrocks. Where on the sides of channels or near the shore themud has a considerable slope, another and very curious effectresults. As the tide ebbs the water drains off the surface, oroozing out of the wet sand and mud, forms at the top of thebank minute grooves often no larger than fine threads. Thesecoalesce and form small channels, and these, again, larger ones,till at low tide the whole sloping surface is seen to be coveredwith a smooth and beautiful tracery resembling the rivers ona map, or the impressions of the trunks and branches of trees,or the fronds of gigantic seaweeds. These "rill marks," asthey have been called, are found in great abundance in thecoal formation and triassic sandstones and shales, and I amsorry to say, have often been named and described as Fucoids,and illustrated by sumptuous plates. Sometimes these impressionsare so fine as to resemble the venation of leaves,sometimes so large as to simulate trees, and I have even seenthem complicated with shrinkage cracks, the edges of whichwere minutely crenulated by little rills running into them fromthe surface.

It is further to be noticed that all these markings and impressionson tidal shores may, when covered by succeedingdeposits, appear either in intaglio or relief. On the uppersurface they are of course sunken, but on the lower surface ofthe bed deposited on them they are in relief. It often happens« 318 »also that these casts in relief are the best preserved. Thisarises from the fact that the original moulds or impressionsare usually made in clay, whereas the filling material is sandy,and the latter, infiltrated with calcareous or siliceous matter,may become a hard sandstone, while the clay may remain acomparatively soft shale. This tendency of casts rather thanof moulds to be preserved sometimes produces puzzling effects.A cylindrical or branching trail thus often assumes the appearanceof a stem, and any pits or marginal impressions assumethe form of projections or leaves, and thus a trail of a wormor Gastropod or a rill mark may easily simulate a plant. It isto be observed, however, that these prominent casts are onthe under side of the beds, that their material is continuouswith that of the beds to which they belong, and that they aredestitute of any carbonaceous matter. There are, however,cases where markings may be in relief, even on the uppersurfaces of beds. The following are illustrations of this. Justas a man walking in newly fallen snow compresses it under hisfeet, and if the snow be afterwards drifted away or meltedaway by the sun, the compressed part resists longest, and mayappear as a raised footmark, so tracks made on soft materialmay consolidate it so that if the soft mud be afterwards washedaway the tracks may remain projecting. Again, worms ejectearthy matter from their burrows, forming mounds, patches orraised ridges of various forms on the surface, and some animalsburrow immediately under the surface, pushing up the mudover them into a ridge, while others pile up over their bodiespellets of clay, forming an archway or tunnel as they go.Zeiller has shown that the mole cricket forms curious roofedtrails of this kind, and it seems certain that Crustaceans andmarine worms of different kinds execute similar works, andthat their roofed burrows, either entire or fallen in, producecurious imitations of branches of plants.

The great and multiform army of the sea worms is indeed« 319 »the most prolific source of markings on sea-formed rocks.Sometimes they cover very large surfaces of these, or penetratethe beds as perforations, with tortuous furrows, or holes perfectlysimple, or marked with little striæ made by bristles orminute feet, sometimes with a fringe of little footmarks aeach side, sometimes with transverse furrows indicating thejoints of the animal's body. Multitudes of these markingshave been described and named either as plants or as worm-tracks.Again, these creatures execute subterranean burrows,sometimes vertical, sometimes tortuous. These are oftenmere cylindrical holes afterwards filled with sand, but sometimesthey have been lined with a membranous tube, or withthe rejectamenta of the food of the animals, or with littlefragments of organic matter cemented together. Sometimesthey open on the surface as simple apertures, but again theymay be surrounded with heaps of castings, sometimes spiralin form, or with dumps of sand produced in their excavation,and which may assume various forms, according to circumstances.Sometimes the aperture is double, so that they seemto be in pairs. Sometimes, for the convenience of the animal,the aperture is widened into the form of a funnel, and sometimesthe creature, by extending its body and drawing it in,surrounds its burrow with a series of radiating tracks simulatingthe form of a starfish or sea anemone, or of the divergingbranches of a plant.

Creatures of higher grade, provided with jointed limbs,naturally make their actions known in more complicated ways.Some years ago I had the pleasure of spending a few weeksat the favourite sea-side resort of Orchard Beach on the NewEngland coast, and there made my first acquaintance with thatvery ancient and curious creature the Limulus, or Horse-shoeCrab, or King-crab, as it is sometimes called. Orchard Beachis, I presume, near its northern range on our coast, and thespecimens seen were not very large in size, though by no means« 320 »rare, and not infrequently cast on shore in storms. But thebest facilities for studying their habits were found in a marshat no great distance from the hotel, where there were numerouschannels, ditches and little ponds filled with sea water at hightide. In these were multitudes of young Limuli, varying froman inch to three or four inches in breadth, and though manywere dead or merely cast shells, it was easy to take youngspecimens with a landing net. A number of these were secured,and I made it my business for some time to study theirhabits and mode of life, and especially the tracks which theymade in sand or mud.

The King-crab, viewed from above, consists of three parts.The anterior shield or carapace is semi-circular in form, withtwo spines or projecting points at the angles, raised in themiddle and sloping down to a smooth or moderately sharpedge in front. The eyes are set like windows in this shield.Two large ones at the sides, which are compound eyes consistingof numerous ocelli or little eyes, and two microscopicones in front, at the base of a little spine, which are simple.The second or abdominal part is also in one piece, somewhatquadrate in form, with ridges and serratures at the sides armedwith spines, and which may be said to simulate the separatejoints into which the abdomen of an ordinary Crustacean isdivided. The third part is a long tail spine, triangular in crosssection, sharply pointed, and so jointed to the posterior endof the abdomen that it can be freely moved in any directionas a bayonet-like weapon of defence. When unable to escapefrom an enemy it is the habit of the creature to double itselfup by bending the abdomen against the carapace, and erectingthe sharp spine. Thus, with fixed bayonet it awaits attack,like the kneeling soldier in front of a square.

Below this upper shield, which is thin and papery in theyoung, somewhat horny in the adult, are the numerous limbsof the creature, with which we are at present most concerned.« 321 »Under the carapace are several pairs of jointed limbs differingin size and form. The two anterior are small and peculiarlyformed claws, used apparently in manipulating the food. Thefour next are larger in size, and are walking feet, each furnishedwith two sharp points which form a pincer for holding. Thelast pair is much larger and stronger than any of the others, andarmed not only with a pair of pincers, but with four blunt nail-likepoints. Under the abdomen are flat swimming feet, as theyhave been called, each composed of a broad plate notched anddivided in the middle. When at rest these lie flat on eachother, but they can be flapped back and forth at the will of theanimal.

Let us now see what use the creature can make of thesenumerous and varied pedal appendages, and for distinctness'sake we shall call the anterior set thoracic and the posteriorabdominal. When placed in shallow water on fine sand itwalked slowly forward, and its tracks then consisted of anumber of punctures on the sand in two lines. If, however, thewater was very shallow or the sand very soft or inclined upwardthe two edges of the carapace touched the bottom, making aslight furrow at each side; and if the tail was trailed on thebottom, this made a third or central furrow. When climbing aslope, or when placed at the edge of the water, it adoptedanother mode of locomotion, pushing with great force with itstwo posterior limbs, and thus moving forward by jerks. Itthen made four deep marks with the toes of each hind limb,and more or less interrupted marks with the edges of the carapaceand the tail. In these circumstances the marks were almostexactly like those of some forms of the Protichnites of thePotsdam sandstone. When in sufficiently deep-water and desirousto escape, it flapped its abdominal feet, and then swamor glided close to the bottom. In this case, when moving nearthe soft bottom, it produced a series of transverse ridges andfurrows like small ripple marks, with a slight ridge in the middle,« 322 »and sometimes, when the edges of the carapace touched thebottom, with lateral furrows. In this way the animals wereable to swim with some ease and rapidity, and on one occasionI observed an individual, confined in a tub of water, raise itselffrom the bottom and swim around the tub at the surface insearch of a way of escape. Lastly, the young Limuli were fondof hiding themselves by burrowing in the sand. They did thisby pushing the anterior rounded end of the carapace under thesand, and then vigorously shovelling out the material from belowwith their feet, so that they gradually sank under the surface,and the sand flowed in upon them till they were entirely covered.If carefully removed from the hollow they had made, this wasfound to be ovoid or hoof shaped in form and bilobed, not unlikethe curious hollows (Rusophycus Grenvillensis of Billings)which I have supposed to be burrows of Trilobites.

I thus found that the common King-crab could produce aconsiderable variety of tracks and burrows comparable withthose which have been named Protichnites, Climactichnites,Bilobites, Cruziana, Rusichnites, etc.; and that the kind ofmarkings depended partly on the differences of gait in theanimal, and partly on the circumstances in which it was placed;so that different kinds of tracks do not always prove diversityin the animals producing them.

The interest of this investigation as applied to Limulus isincreased by the fact that this creature is the near ally ofTrilobites, Eurypterids and other Crustaceans which wereabundant in the earlier geological ages, and whose footprintsare probably among the most common we find on the rocks.

Lastly, on this part of the subject, it is to be observed thatmany other marine animals, both crustaceans and worms, makeimpressions resembling in general character those of Limulus.In addition to those already mentioned, Nathorst and Bureauhave shown that various kinds of shrimps and lobster-likeCrustaceans, when swimming rapidly by successive strokes ofthe tail, make double furrows with transverse ridges resemblingthose of Bilobites, and there are even some mollusks which bythe undulations of the foot or the hook-like action of its anteriorpart, can make similar trails. A question arises here asto the value of such things as fossils. This depends on the factthat many creatures have left their marks on the rocks whenstill soft on the sea bottom, of which we have no other indications,and it also depends on our ability to understand theimport of these unconscious hieroglyphics. They will certainlybe of little use to us so long as we persist in regarding them asvegetable forms, and until we have very carefully studied allkinds of modern markings.[150] Nor does it seem of much use toassign to them specific names. The same trail often changesfrom one so-called species, or even genus, to another in tracingit along, and the same animal may in different circumstancesmake very different kinds of tracks. There will eventually,perhaps, arise some general kind of nomenclature for thesemarkings under a separate sub-science of Ichnology or the doctrineof Footprints.

I have said nothing of true Algæ or seaweeds, of which thereare many fossil species known to us by their forms, and alsoby the carbonaceous or pyritous matter, or discharge of colourfrom the matrix, which furnishes evidence of the presenceof organic material; nor of the marks and trails left by seaweedsand land plants drifting in currents, some of which arevery curious and fantastic; nor of those singular trails referredto the arms of cuttle-fishes and the fins of fishes, or to seajellies and starfishes. These might form materials for atreatise. My object here is merely to indicate the mode ofdealing with such things, and the kind of information to bederived from them.

When we come to the consideration of actual footprints of« 324 »vertebrate animals having limbs, the information we can obtainis of a far more definite character. This has already been referredto in treating of the first Air-breathers in a previouschapter. One very curious example we may close with. It isthat of the celebrated "bird tracks" of the sandstone quarriesin the Trias of Connecticut and Massachusetts. These tracks,of immense size, as much as eighteen inches in length, and soarranged as to indicate the stride of a long-legged biped, werenaturally referred to gigantic birds, allied to modern waders.But when it was found that some of them showed a centralfurrow indicating a long tail trailing behind, this conclusion wasshaken, and when in tracing them along, places were foundwhere the animal had sat down on its haunches and the end ofits tail, and had brought down to the ground a pair of small forefeet with four or five fingers, it was discovered that we had todeal with biped reptiles; and when the tracks were correlatedwith the bones of the extinct reptiles known as Dinosaurs, wefound ourselves in the presence of a group of the most strangeand portentous reptilian forms that the earth has ever known.Marsh has been enabled, by nearly perfect skeletons of someallied reptilian bipeds found in the West, to reproduce themin their exact forms and proportions, so that we can realize inimagination their aspect, their gait, and their gigantic proportions.Examples of this putting together of footprints andosseous remains of vertebrate animals are not rare in thehistory of geology, and show us how the monsters of theancient world, equally with their human successors, could leave"footprints on the sands of time."

The Dinosaurs which have left their footprints on the sandstonesof Connecticut and Massachusetts are, however, greatlymore numerous than those known to us by osseous remains.Thus footprints have the further use of filling up the imperfectionsof our geological record, or at least of pointing out gapswhich but for them we might not have suspected. The remarkable« 325 »inferences of Matthew already referred to, respectingcuttle-fishes in the Cambrian period, constitute a case in point.Footprints of Batrachians in the Carboniferous rocks were knownbefore their bones. The strange hand-like tracks in the Triaswere known before we knew the Labyrinthodon that producedthem. We are still ignorant of the animals whose tracks in theold Potsdam sandstones we name Protichnites.

References:—On Rusichnites (a form of Bilobite),Canadian Naturalist,1864. On Footprints of Limulus compared with Protichnites, etc.Ibid. On Footprints and Impressions of Aquatic Animals and ImitativeMarkings,Amer. Journal of Science, 1873. On Burrows andTracks of Invertebrate Animals,Quarterly Journal of GeologicalSociety, 1890. On Footprints of Carboniferous Batrachians. "AcadianGeology," "Air-breathers of the Coal Period," etc.

PRE-DETERMINATION IN NATURE.

DEDICATED TO THE MEMORY OF

ELKANAH BILLINGS,

First Palæontologist of
the Geological Survey of Canada,
who laid the Foundations of our Knowledge
of the Invertebrate Fossils of Canada.

Fixity of Laws and Properties of Energy and Matter—Permanenceof Continents and Oceans—ThePermanent and the Changeable—Permanence ofAnimal and Vegetable Forms and Structures—Principlesof Construction in the Parts of Trilobites—Inthe Skeletons of Sponges—In EarlyVertebrates—In Plants Laws of Fixity andDiversity

CHAPTER XII.

The natural prejudice of persons not acquainted withgeology is that in the world all things continue as theywere from the beginning. But a little observation and experiencedispels this delusion, and perhaps replaces it with anopposite error. When our minds have been familiarized withthe continuous processes by which vaporous nebulæ may bedifferentiated into distinct planets, and these may be slowlycooled from an incandescent state till their surfaces becomeresolved into areas of land and water; and still more, whenwe contemplate the grand procession of forms of life from theearliest animals and plants to man and his contemporaries, webecome converts to the doctrine that all things are in a perpetualflux, and that every succeeding day sees them differentfrom what they were the day before. In this state of mind thescientific student is apt to overlook the fact that there aremany things which remain the same through all the ages, orwhich, once settled, admit of no change. I do not here referto those fundamental properties of matter and forces and lawsof nature which form the basis of uniformitarianism in geology,but to determinations and arrangements which might easilyhave been quite different from what they are, but which, oncesettled, seem to remain for ever.

We have already considered the great fact that the nucleiand ribs of the continental masses were laid down as foundationsin the earliest periods, and have been built upon by determinate« 330 »additions, more especially upon their edges and theirhollows, so that while there has been a constant process ofremoval of material from the higher parts of the land, anddeposition in the sea, and while there have been periodicalelevations and subsidences, the great areas of land and waterhave remained substantially the same, and the main lines ofelevation and folding have conformed to the directions originallyfixed. Thus, in regard to the dry land itself, there hasbeen fixity, on the one hand, and mutation on the other, of amost paradoxical aspect, till we understand something of thegreat law of constant change united with perennial fixity innature. From want of attention to this, the permanence ofcontinents is still a debated question, and it is difficult formany to understand how the frequent dips of the continentalplateaus and margins under the sea, and their re-elevation,often along with portions of the shallower sea bottom, can beconsistent with a general permanence of the position of thecontinents and of the corresponding ocean abysses; yet, whenthis is properly understood, it becomes plain that the unionof fixity with changes of level has been a main cause of thecontinuity and changes of organic beings. Only the submergenceof inland plateaus under shallow and warm waterscould have given scope for the introduction of new marinefaunas, and only re-elevation could have permitted the greatestextension of plants and animals of the land. Thus, the continuityof life with continual advance has depended on thepermanent existence of continental and oceanic areas; andthe continents that remain to us with all their diversity ofelevation and outline, their varied productions, both mineraland organic, and their life, which is a select remainder of allthat went before, have been produced and furnished by asuccession of changes, modified by the most conservativeretention of general arrangements and forms.

It is evident, however, that it is not merely permanence we« 331 »have to deal with here, but permanence of position along withchange of elevation; and this modified by the fact that therehave always been mountain ridges, internal plateaus, and marginalareas affected in various ways by the vertical movementof the land. Further, the elevation and subsidence of the landhave not always been uniform, but often differential, while everymovement has tended to produce modifications of ocean currentsand of atmospheric conditions. The whole subject, moreespecially in its relations to life, thus becomes very complicated,and it is perhaps in consequence of partial and imperfect viewson these points that so much diversity of opinion has arisen.For example, it is evident that we can gain nothing by addingto the continents those submerged margins delineated byMurray in theChallenger reports, and which have in periods ofcontinental elevation themselves formed portions of the land.Nor do we establish a case in favour of perished oceanic continentsby the argument that they are needed to furnish thematerials of marginal mountains which are due to the continuoussweeping of arctic material to the south by currents, aswe see in the coast of North America to-day. Nor do we invalidatethe permanence of the continents by the bridges ofland, islands, and shallow water at various times thrown acrossthe Atlantic. The distribution of Cambrian Trilobites, as illustratedby Matthew,[151] seems to show a bridge of this kind in thenorth in very early times, and similar evidence is furnished bythe animals and plants of the Devonian and Carboniferous,and by the sea animals and plants of the later Tertiary andmodern. Gardener has postulated a southern bridge in theregion of the West Indies for the migrations of plants, andGregory has adduced the evidence of those conservative andslow-moving creatures, the sea urchins, in favour of similar connectionin the West Indian region at two distinct periods oftime (the Lower Cretaceous and the Miocene Tertiary). But« 332 »bridges do not involve want of permanence in their termini.Because an engineer has bridged the Firth of Forth, it does notfollow that the banks of this inlet did not exist before thebridge was built; and if the bridge were to perish, the evidencethat trains had once passed that way would not justify thebelief that the bed of the Firth had been dry land, and theareas north and south of it depressed. The more we considerthis question the more we see that the permanence, growthand sculpture of the continents are parts of a great continuousand far-reaching plan. This view is strengthened rather thanotherwise, when we consider the probable manner in which theenormous weight of the continents is sustained above thewaters. We may attribute this, on the one hand, to rigidity andlateral arching and compression, or, on the other, to what maybe termed flotation of the lighter parts of the crust; and thereseems to be little doubt that both of these principles have beenemployed in constructing the "pillars which support the earth."It is evident, however, that an arch thrown over the internalabyss of the earth, or a portion of its crust so lightened as to bepressed upward by its heavier surroundings, must, when onceestablished, have become a permanent feature of the earth'sfoundations, not to be disturbed without calamitous consequencesto its inhabitants.

It is the part of the philosophical naturalist to bring togetherthese apparent contrarieties of mutation and permanence; bothof which are included, each in its proper place, in the greatplan of nature. It is therefore my purpose in the presentchapter to direct attention to some of the terminal points orfixed arrangements that we meet with in the course of thegeological history, and even in its earlier parts, and more particularlyin reference to the organic world. This, which is initself constantly changing, has been placed under necessity toadhere to certain determinations fixed of old, and whichregulate its forms and possibilities down to our own time.

The argument, as we have seen in a previous chapter, for theanimal nature of Eozoon depends on our assuming certainparts of this fixity. We suppose that then as now calciumcarbonate had been selected as the material for the skeletonsof such creatures; that then, as now, minute tubuli and largecanals were necessary to enable the soft animal matter to permeateand pass through the skeleton, and that the protoplasmicanimal matter of these far back geological periods had thesame vital properties of contraction and extension, digestion, etc.,that it has to-day. Could any one prove that these determinationsof vital and other forces had not been established, or thatliving protoplasmic matter, with all its wonderful properties,had not been constructed in the Laurentian period, the existenceof this ancient animal would be impossible. Yet howmuch is implied in all this, and though nothing is more unstablechemically or vitally than protoplasm, if it were introducedin the Laurentian, it has continued practically unchangedup to the present time.

If we pass on to the undoubted and varied life of theCambrian period, we shall find that multitudes of things whichmight have been otherwise were already settled in a way thathas required no change.

In the oldest Trilobites the whole of the mechanical conditionsof an external articulated skeleton had been finallysettled. The material chitinous or partly calcareous, its microscopicstructure, fitted to combine lightness and strength withfacility for rapid growth, the subdivision of its several rings, soas to form a protective armour and a mobile skeleton, thearrangement of its spines for defence without interfering withlocomotion, the contrivance of hinge joints arranged in differentplanes in the limbs, all these were already in full perfection,and just as they are found to-day in the skeleton of a king-crabor any other Crustacean. They have, it is true, beenmodified into a vast number of subordinate forms and uses,« 334 »but the general principles and main structures all stand. Iwas much struck with this recently in studying a remarkablespecimen now in the National Museum at Washington. It isa large species of Asaphus; the same genus which gave to thelate Mr. Billings the limbs of a Trilobite, the first ever described;but in the Washington specimen they are remarkablyperfect. Each limb presents a series of joints resemblingthose of the tarsus of an insect, each joint being of conicalform with the narrow proximal end articulated to the enlargeddistal end of the previous one, so as to give great facility ofmovement and accommodation for delicate muscular bands.This tells us of muscular fibre and tendon fitted for flexingand extending these numerous joints, of motor nerves to workthat marvellous contractile power of the striated muscle,whose mode of action is still an insoluble mystery, yet onepractically solved in the remote Cambrian age for the benefitof these humble inhabitants of the sea. If we could imaginethat the inventive power to perfect such machinery was presentin the brains of these old Crustaceans or Arachnidans, wemight wish that some of them had survived to instruct us inmatters which baffle our research.

It is long since the compound eyes of these Trilobites, asillustrated by Burmeister, gave Buckland the opportunity toinfer that the laws of light and of vision were the same fromthe first as now. But what does this imply? Not only thatthe light of the sun penetrating to the depths of the Cambriansea, was regulated by the same laws as to-day, but that a seriesof cameras was perfected to receive the light as reflected fromobjects, to picture the appearance of these objects on a retinalscreen as sensitive as the film of the photographer, and therebyto produce true perceptions of vision in the sensorium of theseancient animals. I have before me a fragment of the eye of aTrilobite (Phacops), in which may be seen the little radiatingtubes provided for the several ocelli of the compound eye, just« 335 »as we see in the modern Limulus; and each of these ocelli musthave been a perfect photographic camera, and more than this,since absolutely automatic, and probably having the power torepresent colour as well as light and shade. We know also,from the recent experiments of an Austrian physiologist on theeyes of insects, that such compound eyes are so constructedas to present a single picture, just as we can see the wholelandscape in looking through the many little panes of a cottagewindow. In our own time the king-crab and lobster no doubtsee just as their predecessors did millions of years ago, and withprecisely similar instruments.

But the eyes of the modern Crustaceans have to competewith eyes of a dissimilar type, constructed on the same generaloptical principles, but quite different in detail. These are thesimple or single eyes of the cuttle-fishes and the true fishes.The same rivalry existed in the oldest seas, when the competitionof Crustaceans and cuttles was just as keen as now.Though the eyes of the latter have not been preserved, or atleast have not yet been found, we have a right to infer that thecuttles of the Cambrian and Silurian seas must have been ableto see as well as their Crustacean foes and competitors. If so,the other type of eye must have been perfected for aquaticvision as early as the compound type. In any case we knowthat a little later, in the Carboniferous period, we have evidencethat the eyes of fishes conformed to those of their modern successors.I have myself described [152] a carboniferous fish (Palæoniscus)from the bituminous shales of Albert County, NewBrunswick, in which the hard globular lens of the eye had beensufficiently firm and durable to retain its form, and to be replacedby calcite, showing even that like the lens of the eye ofa modern fish it had been constructed of concentric laminæ.In the Carboniferous period also, both types of eye, the compoundand the single, experienced the further modifications« 336 »necessary to fit them for vision in air, the compound eye ininsects, the simple eye in Batrachians.[153] The original photographiccameras, strange though this may appear to us, wereintended for use under water; but at a very early time they wereadapted to work in air.

But we must bear in mind that this early solving of advancedproblems in mechanics, optics and physiology was in favour ofCrustaceans and cuttles, which were lords of creation in theirtime. There were in those early days humbler creatures whosestructures also present wonderful contrivances.

I have already referred, in the chapter on imperfection of thegeological record, to the fossil sponges which have been foundin so great number and perfection in some of the oldest rocksof Canada, and which have for the first time enabled us toappreciate the forms and structures of the wonderful silicioussponges which preceded those with which the dredgings of theChallenger have made us familiar in the modern seas. Humblesarcodous animals, without distinct muscular or nervoussystem or external senses, the sponges have at least to live andgrow, and to that end they must already, in the dawn of life onour planet,[154] have perfected those arrangements of ciliated cellsin chambers and canals which the microscope shows us drivingcurrents of water through the modern sponges, and therebybringing to them the materials of food and means of respiration.It is true we know as little as the sponges themselves ofthemodus operandi of those perpetually waving threads whichwe call cilia or flagella, yet they must have existed with all theirpowers even before the Cambrian period.[155]

The sponge, in order to support its delicate protoplasmicstructures, must have a skeleton. In modern times we findthese creatures depositing corneous or horny fibres, as in thecommon washing sponges, or forming complex and beautifulstructures of needles, or threads of silica or calcite, and theyseem from the first to have been able to avail themselves ofall these different materials. The oldest species that we knowhad silicious or calcareous skeletons, though some of themmust also have had a certain amount, at least, of the ordinaryspongy or corneous fibres. But the most astonishing featurein what remains of their skeletons, flattened out as they are onthe surfaces of dark slaty rock, is the manner in which theyworked up so refractory a material as silica into fibres like spunglass rods and crosses, and built these up into beautiful basket-likeforms, globular, cylindrical or conical. It was necessarythat they should fix themselves on the soft muddy bottomson which they grew, and to this end they produced slendersilicious fibres or anchoring rods, which, fine though they were,had the form of hollow tubes. Sometimes a single rod sufficed,but in this case it had a cross-like anchor affixed to its lowerend, to give it stability. Sometimes there were several simplerods, and then they were skilfully braced by spreading themapart at the ends, and by flattening their extremities intoblades. Sometimes four rods joined in a loop at the end gavethe required support. Some larger species wound together manythreads like a wire rope, and even added to this flanges like thethread of a screw, anticipating the principle of the modernscrew pile.

The body of the sponge must be hollow within, and musthave a large aperture or opening for the discharge of water, andsmaller pores for its admission. Various general forms wereadopted for this. Some were globular, or oval, or pear-shaped;others cylindrical, concave, or mitre-shaped. To give form andstrength to these shapes there were sometimes vertical and« 338 »transverse rods soldered together. In other cases there were four-rayedor six-rayed needles of silica, with their points attachedso as to form a beautiful lattice-work, with its meshes eithersquare or lozenge-shaped. For protection sharp needles werearranged likechevaux de frize at the sides and apertures, andthese last were sometimes covered with a hood or grating ofneedles, to exclude intruders from the interior cavity. Otherspecies, however, like some in the modern seas, seemed to despisethese niceties, and contented themselves with long straightneedles placed in bundles, or radiating from a centre, and thussupporting and protecting their soft and sensitive protoplasm.

Curiously enough, these old sponges did not avail themselvesof the natural cystallization of silica, which, left to itself,would have formed six-rayed stars, with the rays at angles ofsixty degrees, or six-sided plates, rods, or pyramids. Theyadopted another and peculiar form of the mineral, known ascolloidal silica, and being thus relieved from any need to beguided by its crystalline form, treated it as we do glass, andshaped it into cylindrical tubes, round needles and stars orcrosses, with the rays at right angles to each other.

The sponges whose skeletons are thus constructed, and whichanticipated so many mechanical contrivances long afterwardsdevised by man, belonged to a group of silicious sponges(Hexaclinellidæ) which is still extant, and represented bymany rare and beautiful species of the deep sea, which arethe ornaments of our museums, and of which the beautifulEupleectella or Venus flower-basket, from the Philippine Islands,and the glass-rope sponge (Hyalonema), from Japan, areexamples. But contemporary with these there was anothergroup (Lithistidæ), constructing skeletons of carbonate of lime,and which preferred, instead of the regular mechanical structuresof the others, a kind of rustic work, made up of irregularfibres, very beautiful and strong, but as a matter of pattern andtaste standing quite by itself. If there were any sponges with« 339 »altogether soft and spongy skeletons in these old times, theirremains do not seem to have been preserved.

Here, it will be observed, are a great variety of vital andmechanical contrivances devised in the very early history of theearth, settled for all time, and handed down without improvement,and with little change, to our later day. They are indeedvastly more wonderful than the above general account can show;for to go into the details of structure of any one of the specieswould develop a multitude of minor complexities and nicetieswhich no one not specially a student of these animals couldappreciate.

These are not solitary cases. The student of fossils meetswith them at every turn; and if he possesses the taste andimagination of a true naturalist, cannot fail to be impressed withthem.

To turn to a later but very ancient period, what can be moreastonishing than those first air-breathing vertebrates of theCoal formation referred to in a previous chapter, with all theirspecial arrangements for an aërial habitat? I have mentionedtheir footprints, and when we see the quarrymen split open aslab of sandstone and expose a series of great plantigrade tracks,not unlike those of a human foot, with the five toes well-developed,we are almost as much astonished as Crusoe was whenhe saw the footprints on the sand. Crusoe inferred the presenceof another man in his island; we infer the earliest appearanceof an air-breathing vertebrate and the pre-human determinationof the form and number of parts of the human foot and hand,to appear in the world long ages afterward. We see also thatalready that decimal system of notation which we have foundedon the counting of our ten fingers was settled in the frameworkof most unmathematical Batrachians. It has approved itself eversince as the typical and most perfect number of parts for suchorgans.

If sceptically inclined, we may ask, Why five rather than« 340 »four or six? In the case of man we see that individuals whohave lost one finger have the use of the hand impaired, whilethe few who happen to have six do not seem to be the better.How it was with the old Batrachians we do not know; but it iscertain that if we could have amputated the claw-bearing littletoe ofSauropus unguifer, or the reflexed little toe ofCheirotherium,we should have much injured their locomotive power.

The vegetable kingdom is full of similar examples of the earlysettlement of great questions. Perhaps nothing is more marvellousthan the power of the green cells of the leaf as workersof those complex and inimitable chemical changes whereby outof the water, carbon dioxide and ammonia of the soil and theatmosphere, the living vegetable cell, with the aid of solarenergy, elaborates all the varied organic compounds producedby the vegetable kingdom. Yet this seems all to have beensettled and perfected in the old Silurian period, long before anykind of plant now living was on the earth. Perhaps in someform it existed even in the Laurentian age, and was instrumentalin laying up its great beds of carbon. So all that isessential in plant reproduction, whether in that simpler form inwhich a one-celled spore is the reproductive organ, or in thatmore complex form in which an embryo plant is formed in theseed, with a store of nourishment laid up for its sustenance.

These arrangements were obviously as perfect in the greatclub mosses and pines of the Devonian and Carboniferous asthey have ever been since, and we have specimens so preservedas to show their minute parts just as well as in recent plants.The microscope also shows us that the contrivances for thickeningand strengthening the woody fibres and trunk of the stemby bars or interrupted linings of ligneous matter, so as to givestrength and at the same time permit transudation of sap, wereall perfected, down to their minutest details, in the oldest landplants. It is true that flowers with gay petals and some of the« 341 »more complicated kinds of fruit are later inventions, but theadditions in these consist mainly of accessories. The essentialsof vegetable reproduction were as well provided for from thefirst.

The same principle applies to many of the leading forms andtypes of life, considered as genera or species. While some ofthese are of recent introduction, others have continued almostunchanged from the remotest ages. Such creatures as theLingulæ, some of the Crustaceans and of the Mollusks, thePolyzoa and some Corals have remained with scarcely anychange throughout geological time, while others have disappeared,and have been replaced by new types.

We began this chapter with a consideration of the permanenceof continental areas, and may close with a referenceto the same great fact in connection with the continuity of life.Whether with some we attach more importance to the supportof the continents by lateral pressure and rigidity, or with othersto what may be termed flotation, by virtue of their less density,as compared with that of the lower parts of the earth; therecan be little doubt that both principles have been applied, andthat both admit of some vertical movement. Thus the stabilityof the continents is one of position rather than height, andtheir internal plateaus as well as their partially submergedmarginal slopes have undergone great and unequal elevationsand depressions, causing most important geographical changes.Among these are the formation of connecting bridges of shoals,islands, or low land, connecting the continental masses atdifferent periods, and permitting migrations of shallow-wateranimals and even of denizens of the land. The facts adducedin previous pages are sufficient to show connections across thenorth of the Atlantic at intervals reaching from the Cambrianto the Modern.

The conclusion of the whole matter is that there is a fixityand unchangeableness in determinations and arrangements of« 342 »force just as much as in natural laws; and that while God hasmade everything beautiful in its time He has also made everythingbeautiful and useful in some sense for all time. With allthis, while the great principles and modes of operation remainunchanged, there is ample scope for development, modificationand adaptation to new ends, without deviation from essentialproperties and characters. It is a wise and thoughtful philosophywhich can distinguish what is fixed and unchangeable from thatwhich is fluctuating and capable of development. Until thisdistinction is fully understood, we may expect one-sided viewsand faulty generalizations in our attempts to understandnature.

References:—"The Chain of Life in Geological Times." London. NewSpecies of Fossil Sponges from the Quebec Group at Little Metis.Trans. Royal Society of Canada, 1889. Fossil Fishes from the LowerCarboniferous of New Brunswick.Canadian Naturalist, "AcadianGeology," 1855, and later editions to 1892. London and Montreal."The Story of the Earth," 1872 and later editions to 1891. London.

THE GREAT ICE AGE.

DEDICATED TO THE MEMORY OF
MY LATE FRIEND

DAVID MILNE HOME, LL.D., F.R.S.E., ETC.,

An eminent and judicious Advocate of sound and
moderate Views respecting the Glacial Age.

Exaggerated Ideas—The St. Lawrence Valley—ModernIce Action in the St. Lawrence—Coast Ice—TheIcebergs of Belle-Isle—Mt. Blanc and its Glaciers—Effectsof Glaciers—Possible Extension ofGlaciers—Facts of Glaciation in Canada—CordilleranGlacier, Laurentide Glacier, AppalachianGlacier—Submerged Valleys and Plains—DoubleSubmergence and Intermediate Partial Elevation—InterglacialPeriods—Questions as to AlternateGlaciation of Northern and Southern Hemispheres

CHAPTER XIII.

Scientific superstitions, understanding by this namethe reception of hypotheses of prominent men, and usingthese as fetishes to be worshipped and to be employed inmiraculous works, are scarcely less common in our time thansuperstitions of another kind were in darker ages. One ofthese which has been dominant for a long time in geology,and has scarcely yet run its course, is that of the Great IceAge, with its accompaniments of Continental Glaciers andPolar Ice Cap. The cause of this it is not difficult todiscern. The covering of till, gravel and travelled boulderswhich encumbers the surface of the northern hemispherefrom the Arctic regions more than half way to the equator,had long been a puzzle to geologists, and this was increasedrather than diminished when the doctrine of appeal to recentcauses on the principle of uniformity became current. It wasseen that it was necessary to invoke the action of ice in someform to account for these deposits, and it was at the sametime perceived that there was much evidence to prove thatbetween the warm climate of the early Tertiary and the moresubdued mildness of the modern time there had interveneda period of unusual and extreme cold. In this state ofaffairs attention was attracted to the Alpine glaciers. Theirmovement, their erosion of surfaces, their heaping up ofmoraines bearing some resemblance to the widely extendedboulder deposits, their former greater extension, as indicated« 346 »by old moraines at lower levels than those in process offormation, were noted. Here was a modern cause capable ofexplaining all the phenomena. Men's minds were taken bystorm, and as always happens in the case of new and importantdiscoveries, the agency of glaciers was pushed at oncefar beyond the possibilities of their action under any knownphysical or climatal laws. This exaggerated idea of theaction of land ice in the form of glaciers is not yet exploded,more especially in the United States, where official sanctionhas been given to it by the Geological Survey, and where ithas been introduced even into school and college text-books.It affords also a telling bit of scientific sensationalism, whichcan scarcely be resisted by a certain class of popular writers.America has also afforded greater facilities for extreme theoriesof this kind, owing to the wide and uninterrupted distributionof glacial deposits, and the more simple and less brokencharacter of its great internal plateau, while the influenceof great leading minds, like those of the elder Agassiz and ofDana, naturally held sway over the younger geologists. FortunatelyCanada, which possesses the larger and more northernhalf of the North American continent; though numericallyinferior, and therefore overborne in the discussion, has, inthe main, remained steadfast to facts rather than to specioustheories, and has been confirmed in this position by theclearer testimony of nature in a region where many of thefeatures of the glacial age still persist.[156]

The writer of these pages has, ever since the publication ofthe first edition of his "Acadian Geology,"[157] steadily resistedthe more extreme views of glaciation, and has opposed thesouthward progress of the great continental glacier. Though,figuratively speaking, overborne and pressed back in the« 347 »course of its extension, he has now, like those primitive menwho are imagined in the post-glacial age to have followed upthe retreat of the ice, the pleasure of seeing the once formidablecontinental glacier broken up into great local glacierson the mountain ranges separated by intervening areas ofsubmergence.

The questions relating to this subject are too numerous andvaried for treatment here. The question of the causes of thegreat lowering of temperature in the glacial age I shall leavefor consideration in the next chapter, and merely state herethat I believe changes of distribution of sea and land and ofocean currents are sufficient to account for all the refrigerationof which there is good evidence. I content myself with acomparison of the glacial phenomena of Mont Blanc and ofthe Gulf of St. Lawrence from my own observation,[158] and somegeneral deductions as to glacier possibilities.

A scientific voyager carries with him a species of questioningpeculiar to himself. Not content with vacantly gazingat the sea, scrutinizing his fellow passengers, noting thechanges of the weather and the length of the day's run, herecognises in the sea one of the great features of the earth,and questions it daily as to its present and its past Thepresent features of the sea include much of surpassing interest,but the questions which relate to its origin and early historyare still more attractive. Some of these questions are likelyto interest a voyager from Canada entering the Atlantic byone of its greatest tributaries, the St. Lawrence.

In doing so, we approach the ocean not at a right angle,but along a line only slightly inclined to its western side, andwe find ourselves in a broad estuary or trough, having on itsnorth-western side rugged hills of old crystalline rocks, theLaurentian, ridged up in great folds or earth waves parallelto the river. On the south-east or right-hand side we have« 348 »a lower barrier of earth waves composed of sedimentary rockssomewhat later in date, but still geologically very ancient. Weare thus introduced to a remarkable feature of the west sideof the North Atlantic, namely, that its border is made up ofvery old rocks folded into mountain ridges thrown up at anancient period, and approximately parallel to the coast. TheLower St. Lawrence occupies a furrow between two of theseridges.

Here, however, a more modern feature attracts our attention.The sides of the bounding hills are cut in a succession ofterraces, rising one above another from the level of the seato a height of 500 feet or more, capped with long ranges ofthe white houses and barns of the Canadian habitants, andfurnishing level lines for the "concession roads" which runalong the coast. These terraces are really old sea marginsindicating the stages of the elevation of the land out of thesea immediately before the modern period. On these terraces,and in the clays and sands which form the plateaus extendingin some places in front of them, are sea shells of thesame kinds with those now living in the Gulf of St. Lawrence,and occasionally we find bones of whales which have beenstranded on the old beaches.

These terraces are, of course, indications of change of levelin very modern times. They show that in what we call thePleistocene age the land was lower than at present, and weshall find that in the Lower St. Lawrence there is evidenceof a depression extending to over 1,000 feet, carrying thesea far up the valley, so that sea shells are found in the claysas far up as Kingston and Ottawa, and stranded skeletonsof whales as far west as Smith's Falls, in Ontario.

If we examine the shores more minutely, we shall find allalong the south coast a belt of boulders which are often asmuch as eight to ten feet in diameter, and consist largelyof rocks found only in the hills of the northern coast, more« 349 »than thirty miles distant, from which they must have beendrifted to their present position. This boulder belt, whichextends from the lowest tide mark about fifty feet or moreupward, is sometimes piled in ridges and sometimes flattenedout into a rude pavement. It is a product of the modernfield ice, which, attaining a great thickness in winter, hasboulders frozen into its bottom, and floating up and downwith the tide, deposits these on the shore. At Little Metis,two hundred miles below Quebec, where I have a summerresidence, I have from year to year cleared a passage throughthe boulder belt for bathing and for launching boats, andnearly every spring I find that boulders have been thrown intothe cleared space by the ice, while one can notice from yearto year differences in the position of very large boulders.

If we pass inland from the shore belt of boulders, we shallfind similar appearances on the inland terraces at variousheights, up to at least 400 feet. These are inland boulderbelts belonging to old shores now elevated. Like the modernboulder belt these inland belts and patches consist partly ofLaurentian rocks from the North Shore, partly of sandstonesand conglomerates in place near to their present sites. Insome places the stones are smaller than those of the presentbeach, in other places of gigantic size. These boulders lienot only on the bare rock striated in places with ice groovespointing to the north-north-east; but on the old till or boulderclay, which also abounds with boulders, and which is moreancient than the superficial boulder drift. Locally we findhere and there masses of fossiliferous limestone which musthave been derived from the high ground to the south of theSt. Lawrence, and which have been borne northward eitherby drift ice or by local glaciers.

If now we study the polished and scored surfaces of rocksin the St. Lawrence valley and the bounding hills, we shallfind that while the former testify to a great movement of« 350 »ice and boulders up the river from the north-east, the lattershow evident signs of the movement of local glaciers downthe valleys of the Laurentide hills to the south, and on thecontinuation of the Appalachians south of the river similarevidence of the movement of land ice to the north. Thuswe have evidence of the combined action of local glaciers andfloating ice. To add to all this, we can find on the flat topsof the hard sandstone boulders on the beach the scratchesmade by the ice of last winter, often in the same north-easterlydirection with those of the Pleistocene time.

In addition to the ice formed in winter in the St. Lawrenceitself, the snow-clad hills of Greenland send down to the seagreat glaciers, which in the bays and fiords of that inhospitableregion form at their extremities huge cliffs of everlasting ice,and annually "calve," as the seamen say, or give off a greatprogeny of ice islands, which, slowly drifted to the southwardby the arctic current, pass along the American coast, diffusinga cold and bleak atmosphere, until they melt in the warmwaters of the Gulf Stream. Many of these bergs enter theStraits of Belle-Isle, for the Arctic current clings closely tothe coast, and a part of it seems to be deflected into theGulf of St. Lawrence through this passage, carrying with itmany large bergs. The voyager passing through this straitin clear weather may see numbers of these ice islands glisteningin snowy whiteness, or showing deep green cliffs andpinnacles—sometimes with layers of earthy matter and stones,or dotted with numerous sea birds, which rest upon themwhen gorged with the food afforded by shoals of fish andothers marine animals which haunt these cold seas. In earlysummer the bergs are massive in form, often with flat tops,but as the summer advances they become eroded by the sunand warm winds, till they present the most grotesque formsof rude towers and spires rising from broad foundations littleelevated above the water.

Mr. Vaughan, late superintendent of the Lighthouse atBelle-Isle, has kept a register of icebergs for several years. Hestates that for ten which enter the straits, fifty drift to thesouthward, and that most of those which enter pass inward onthe north side of the island, drift toward the western end ofthe straits, and then pass out on the south side of the island, sothat the straits seem to be merely a sort of eddy in the courseof the bergs. The number in the straits varies much in differentseasons of the year. The greatest number are seen inspring, especially in May and June; and toward autumn andin the winter very few remain. Those which remain untilautumn are reduced to mere skeletons; but if they surviveuntil winter, they again grow in dimensions, owing to the accumulationsupon them of snow and new ice. Those that wesaw early in July were large and massive in their proportions.The few that remained when we returned in September weresmaller in size, and cut into fantastic and toppling pinnacles.Vaughan records that on the 30th of May, 1858, he counted inthe Straits of Belle-Isle 496 bergs, the least of them sixty feetin height, some of them half a mile long and 200 feet high.Only one-eighth of the volume of floating ice appears abovewater, and many of these great bergs may thus touch theground in a depth of thirty fathoms or more, so that if we imaginefour hundred of them moving up and down under the influenceof the current, oscillating slowly with the motion of thesea, and grinding on the rocks and stone-covered bottom at alldepths from the centre of the channel, we may form some conceptionof the effects of these huge polishers of the sea floor.

Of the bergs which pass outside of the straits, many groundon the banks off Belle-Isle. Vaughan has seen a hundred largebergs aground at one time on the banks, and they ground onvarious parts of the banks of Newfoundland, and all along thecoast of that island. As they are borne by the deep-seatedcold current, and are scarcely at all affected by the wind, they« 352 »move somewhat uniformly in a direction from north-east tosouth-west, and when they touch the bottom, the striation orgrooving which they produce must be in that direction.

In passing through the straits in July, I have seen greatnumbers of bergs, some low and flat-topped, with perpendicularsides, others convex or roof-shaped, like great tents pitched onthe sea; others rounded in outline or rising into towers andpinnacles. Most of them were of a pure dead white, like loafsugar, shaded with pale bluish green in the great rents andrecent fractures. One of them seemed as if it had groundedand then overturned, presenting a flat and scored surfacecovered with sand and earthy matter.

At present we wish to regard the icebergs of Belle-Isle intheir character of geological agents. Viewed in this aspect,they are in the first place parts of the cosmical arrangementsfor equalizing temperature, and for dispersing the great accumulationsof ice in the Arctic regions, which might otherwiseunsettle the climatic and even the static equilibrium of ourglobe, as they are believed by some imaginative physicists andgeologists to have done in the so-called glacial period. If theice islands in the Atlantic, like lumps of ice in a pitcher ofwater, chill our climate in spring, they are at the same timeagents in preventing a still more serious secular chilling whichmight result from the growth without limit of the Arctic snowand ice. They are also constantly employed in wearing downthe Arctic land, and aided by the great northern current fromDavis's Straits, in scattering stones, boulders and sand overthe banks along the American coast. Incidentally to thiswork, they smooth and level the higher parts of the sea bottom,and mark it with furrows and striæ indicative of the directionof their own motion.

When we examine a chart of the American coast, and observethe deep channel and hollow submarine valleys of the Arcticcurrent, and the sandbanks which extend parallel to this« 353 »channel from the great bank of Newfoundland to Cape Cod,we cannot avoid the conclusion that the Arctic current andits ice have great power both of excavation and deposition.On the one hand, deep hollows are cut out where the currentflows over the bottom, and on the other, great banks are heapedup where the ice thaws and the force of the current is abated.I have been much struck with the worn and abraded appearanceof stones and dead shells taken up from the banks off theAmerican coast, and am convinced that an erosive power comparableto that of a river carrying sand over its bed, and materiallyaided by the grinding action of ice, is constantly in actionunder the waters of the Arctic current.[159] The unequal pressureresulting from this deposition and abrasion is not improbablyconnected with the slight earthquakes experienced inEastern America, and also with the slow depression of thecoast; and if we go back to that earliest of all geologicalperiods when the Laurentian rocks of Sir Wm. Logan, constitutingthe Labrador coast and the Laurentide Hills, were aloneabove water, we may even attribute in no small degree to theArctic current of that old time the heaping up of those thousandsof feet of deposits which now constitute the great rangeof the Alleghany and Appalachian mountains, and form thebreast bone of the American continent. In those ancienttimes also large stones were floated southward, and enter intothe composition of very old conglomerates.

But such large speculations might soon carry us far fromBelle-Isle, and to bring us back to the American coast and tothe domain of common things, we may note that a vast varietyof marine life exists in the cold waters of the Arctic current,and that this is one of the reasons of the great and valuablefisheries of Labrador, Newfoundland and Nova Scotia, regionsin which the sea thus becomes the harvest field of much of thehuman population. On the Arctic current and its ice alsofloats to the southward the game of the sealers of St. John andthe whalers of Gaspé.

We may now proceed to connect these statements as to thedistribution of icebergs, with the glaciated condition of ourcontinents, with the remarkable fact that the same effects nowproduced by the ice and the Arctic current in the Strait ofBelle-Isle and the deep-current channel off the American coast,are visible all over the North American and European landnorth of forty degrees of latitude, and that there is evidencethat the St. Lawrence valley itself was once a gigantic Belle-Isle,in which thousands of bergs worked perhaps for thousandsof years, grinding and striating its rocks, cutting out itsdeeper parts, and heaping up in it quantities of northerndébris.Out of this fact of the so-called glaciated condition of the surfaceof our continents has, however, arisen one of the greatcontroversies of modern geology. While all admit the actionof ice in distributing and arranging the materials which constitutethe last coating which has been laid upon the surface ofour continents, some maintain that land glaciers have donethe work, others, that sea-borne ice has been the main agentemployed. As in some other controversies, the truth seems tolie between the extremes. Glaciers are slow, inactive, andlimited in their sphere. Floating ice is locomotive and far-travelled,extending its action to great distances from itssources. So far, the advantages are in favour of the flotation.But the work which the glacier does is done thoroughly, and,« 355 »time and facilities being given, it may be done over wide areas.Again, the iceberg is the child of the glacier, and therefore theagency of the one is indirectly that of the other. Thus, in anyview we must plough with both of these geological oxen, andthe controversy becomes like that old one of the Neptunistsand Plutonists, which has been settled by admitting both waterand heat to have been instrumental in the formation of rocks.

In the midst of these controversies a geologist resident inGreat Britain or Canada should have some certain doctrine asto the question whether at that period, geologically recent,which we call the Pleistocene period, the land was raised to agreat height above the sea, and covered like Greenland with amantle of perpetual ice, or whether it was, like the strait ofBelle-Isle and the banks of Newfoundland, under water, andannually ground over by icebergs, or whether, as now seemsmore probable, it was in part composed of elevated ridgescovered with snow and sending down glaciers, and partly depressedunder the level of ice-laden straits and seas.

A great advocate of the glacier* theory has said that we cannotproperly appreciate his view without exploring thoroughlythe present glaciers of Greenland and ascertaining their effects.This I have not had opportunity to do, but I have endeavouredto do the next best thing by passing as rapidly as possible fromthe icebergs of Belle-Isle to the glaciers of Mont Blanc, and byasking the question whether Canada was in the Pleistoceneperiod like the present Belle-Isle or the present Mont Blanc,or whether it partook of the character of both? and taking advantageof these two most salient points in order to elicit areply.

Transporting ourselves, then, to the monarch of the Alps, letus suppose we stand upon the Flegere, a spur of the mountainsfronting Mont Blanc, and commanding a view of the entiregroup. From this point the western end of the range presentsthe rounded summit of Mont Blanc proper, flanked by the« 356 »lower eminences of the Dome and Aiguille de Gouté, whichrise from a broad and uneven plateau ofnevé or hard snow,sending down to the plain two great glaciers or streams of ice,the Bossons and Tacony glaciers. Eastward of Mont Blancthenevé or snow plateau is penetrated by a series of sharppoints of rock or aiguilles, which stretch along in a row ofserried peaks, and then give place to a deep notch, throughwhich flows the greatest of all the glaciers of this side of MontBlanc, the celebrated Mer de Glace, directly in front of ourstandpoint. To the left of this is another mass of aiguilles,culminating in the Aiguille Verte. This second group ofneedles descends into the long and narrow Glacier of Argentiere,and beyond this we see in the distance the Glacier andAiguille de Tour. As seen from this point, it is evident thatthe whole system of the Mont Blanc glaciers originates in avast mantle of snow capping the ridge of the chain, and extendingabout twenty miles in length, with a breadth of about fivemiles. This mass of snow being above the limits of perpetualfrost, would go on increasing from year to year, except so faras it might be diminished by the fall of avalanches from itssides, were it not that its plasticity is sufficient to enable thefrozen mass to glide slowly down the valleys, changing in itsprogress into an icy stream, which, descending to the plain,melts at its base and discharges itself in a torrent of whitemuddy water. The Mont Blanc chain sends forth about adozen of large glaciers of this kind, besides many smaller ones.Crossing the valley of Chamouni, and ascending the Montanvertto a height of about 6,000 feet, let us look more particularlyat one of these glaciers, the Mer de Glace. It is a longvalley with steep sides, about half a mile wide, and filled withice, which presents a general level or slightly inclined surface,traversed with innumerable transverse cracks or crevasses,penetrating apparently to the bottom of the glacier, and withslippery sloping edges of moist ice threatening at every step to« 357 »plunge the traveller into the depths below. Still the treacheroussurface is daily crossed by parties of travellers, apparentlywithout any accident. The whole of the ice is moving steadilyalong the slope on which it rests, at the rate of eight to teninches daily—the rate of motion is less in winter and greater insummer; and farther down, where the glacier goes by the nameof the Glacier du Bois, and descends a steeper slope, its rapidityis greater; and at the same time by the opening of immensecrevasses its surface projects in fantastic ridges and pinnacles.The movements and changes in the ice of these glaciers are intruth very remarkable, and show a mobility and plasticitywhich at first sight we should not have been prepared toexpect in a solid like ice.[160] The crevasses become open orclosed, curved upwards or downwards, perpendicular or inclined,according to the surface upon which the glacier is moving,and the whole mass is crushed upward or flattens out, itsparticles evidently moving on each other with much the sameresult as would take place in a mass of thick mud similarlymoving. On the surface of the ice there are a few bouldersand many stones, and in places these accumulate in longirregular bands indicating the lines of junction of the minor icestreams coming in from above to join the main glacier. At thesides are two great mounds of rubbish, much higher than thepresent surface of the glacier. They are called the lateralmoraines, and consist of boulders, stones, gravel and sand,confusedly intermingled, and for the most part retaining theirsharp angles. This mass of rubbish is moved downward bythe glacier, and with the stones constituting the central moraine,« 358 »is discharged at the lower end, accumulating there in the massof detritus known as the terminal moraine.

Glaciers have been termed rivers of ice; but there is onerespect in which they differ remarkably from rivers. They arebroad above and narrow below, or rather, their width abovecorresponds to the drainage area of a river. This is well seenin a map of the Mer de Glace. From its termination in theGlacier du Bois to the top of the Mer de Glace proper, a distanceof about three and a half miles, its breadth does not exceedhalf a mile, but above this point it spreads out into threegreat glaciers, the Geant, the Du Chaud, and the Talefre, theaggregate width of which is six or seven miles. The snow andice of a large interior table-land or series of wide valleys arethus emptied into one narrow ravine, and pour their wholeaccumulations through the Mer de Glace. Leaving, however,the many interesting phenomena connected with the motion ofglaciers, and which have been so well interpreted by Saussure,Agassiz, Forbes, Hopkins, Tyndall, and others, we may considertheir effects on the mountain valleys in which theyoperate.

1. They carry quantities ofdébris from the hill tops andmountain valleys downward into the plains. From every peak,cliff and ridge the frost and thaw are constantly looseningstones and other matters which are swept by avalanches to thesurface of the glacier, and constitute lateral moraines. Whentwo or more glaciers unite into one, these become medialmoraines, and at length are spread over and through the wholemass of the ice. Eventually all this material, including stonesof immense size, as well as fine sand and mud, is deposited inthe terminal moraine, or carried off by the streams.

2. They are mills for grinding and triturating rock. Thepieces of rock in the moraine are, in the course of their movement,crushed against one another and the sides of the valley,and are cracked and ground as if in a crushing mill. Further« 359 »the stones on the surface of the glacier are ever falling intocrevasses, and thus reach the bottom of the ice, where they arefurther ground one against another and the floor of rock. Inthe movement of the glacier these stones seem in some casesto come again to the surface, and their remains are finally dischargedin the terminal moraine, which is the waste-heap ofthis great mill: The fine material which has been produced,the flour of the mill, so to speak, becomes diffused in the waterwhich is constantly flowing from beneath the glacier, and forthis reason all the streams flowing from glaciers are turbid withwhitish sand and mud.

The Arve, which drains the glaciers of the north side ofMont Blanc, carries its burden of mud into the Rhone, whichsweeps it, with the similar material of many other Alpinestreams, into the Mediterranean, to aid in filling up the bottomof that sea, whose blue waters it discolours for miles from theshore, and to increase its own ever-enlarging delta, whichencroaches on the sea at the rate of about half a mile percentury. The upper waters of the Rhone, laden with similarmaterial, are filling up the Lake of Geneva; and the greatdeposit of "loess" in the alluvial plain of the Rhine, aboutwhich Gaul and German have contended since the dawn ofEuropean history, is of similar origin. The mass of materialwhich has thus been carried off from the Alps, would suffice tobuild up a great mountain chain. Thus, by the action of iceand water—

Many observers who have commented on these facts havetaken it for granted that the mud thus sent off from glaciers,and which is so much greater in amount than the matterremaining in their moraines, must be ground from the bottomof the glacier valleys, and hence have attributed to these« 360 »glaciers great power of cutting out and deepening their valleys.But this is evidently an error, just as it would be an error tosuppose the flour of a grist mill ground out of the mill stones.Glaciers, it is true, groove and striate and polish the rocks overwhich they move, and especially those of projecting points andslight elevations in their beds; but the material which theygrind up is principally derived from the exposed frost-bittenrocks above them, and the rocky floor under the glacier ismerely the nether mill stone against which those loose stonesare crushed. The glaciers, in short, can scarcely be regardedas cutting agents at all, in so far as the sides and bottoms oftheir beds are concerned, and in the valleys which the oldglaciers have abandoned, it is evident that the torrents whichhave succeeded them have far greater cutting power.

The glaciers have their periods of advance and of recession.A series of wet and cool summers causes them to advance andencroach on the plains, pushing before them their moraines,and even forests and human habitations. In dry and warmsummers they shrink and recede. Such changes seem to haveoccurred in bygone times on a gigantic scale. All the valleysbelow the present glaciers present traces of former glacieraction. Even the Jura mountains seem at one time to havehad glaciers. Large blocks from the Alps have been carriedacross the intervening valley and lodged at great heights, on theslopes of the Jura, leading the majority of the Swiss andItalian geologists to believe that even this great valley and thebasin of Lake Leman were once filled with glacier ice. But,unless we can suppose that the Alps were then vastly higherthan at present, this seems scarcely to be physically possible,and it seems more likely that the conditions were just thereverse of those supposed, namely, that the low land was submerged,and that the valley of Lake Leman was a strait likeBelle-Isle, traversed by powerful currents and receiving icebergsfrom both Jurassic and Alpine glaciers, and probably« 361 »from farther north. One or other supposition is required toaccount for the appearances, which may be explained on eitherview. The European hills may have been higher and colder,and changes of level elsewhere may have combined with this togive a cold climate with moisture; or a great submergencemay have left the hills as islands, and may have so reduced thetemperature by the influx of arctic currents and ice, as toenable the Alpine glaciers to descend to the level of the sea.Now, we have evidence of such submergence in the beds ofsea-shells and travelled boulders scattered over Europe, whilewe also have evidence of contemporaneous glaciers, in theirtraces on the hills of Wales and Scotland and elsewhere, wherethey do not now occur.

I have long maintained that in America all the observedfacts imply a climate no colder than that which would haveresulted from the subsidence which we know to have occurredin the temperate latitudes in the Pleistocene period, andthough I would not desire to speak so positively about Europe,I confess to a strong impression that the same is the case there,and that the casing of glacier ice imagined by many geologists,as well as the various hypotheses which have been devised toaccount for it, and to avoid the mechanical, meteorological, andastronomical difficulties attending it, are alike gratuitous andchimerical, as not being at all required to account for observedfacts, and being contradictory, when carefully considered, toknown physical laws as well as geological phenomena.[161]

Carrying with me a knowledge of the phenomena of theglacial drift as they exist in North America, and of the modernice drift on its shores, I was continually asking myself thequestion To what extent do the phenomena of glacier driftand erosion resemble these? and standing on the moraine ofthe Bosson glacier, which struck me as more like boulder clay« 362 »than anything else I saw in the Alps, with the exception ofsome recent avalanches, I jotted down what appeared to meto be the most important points of difference. They standthus:—

1. Glaciers heap up theirdébris in abrupt ridges. Floatingice sometimes does this, but more usually spreads its load in amore or less uniform sheet.[162]

2. The material of moraines is all local. Floating ice carriesits deposits often to great distances from their sources.

3. The stones carried by glaciers are mostly angular, exceptwhere they have been acted on by torrents. Those moved byfloating ice are more often rounded, being acted on by thewaves and by the abrading action of sand drifted by currents.

4. In the marine glacial deposits mud is mixed with stonesand boulders. In the case of land glaciers, most of this mudis carried off by streams and deposited elsewhere.

5. The deposits from floating ice may contain marine shells.Those of glaciers cannot, except where, as in Greenland andSpitzbergen, glaciers push their moraines out into the sea.

6. It is of the nature of glaciers to flow in the deepestravines they can find, and such ravines drain the ice of extensiveareas of mountain land. Floating ice, on the contrary, actswith greatest ease on flat surfaces or slight elevations in the seabottom.

7. Glaciers must descend slopes and must be backed bylarge supplies of perennial snow. Floating ice acts independently,and being water-borne may work up slopes and onlevel surfaces.

8. Glaciers striate the sides and bottoms of their ravinesvery unequally, acting with great force and effect only onthose places where their weight impinges most heavily. Floating« 363 »ice, on the contrary, being carried by constant currents andover comparatively flat surfaces, must striate and grind moreregularly over large areas, and with less reference to localinequalities of surface.

9. The direction of the striæ and grooves produced byglaciers depends on the direction of valleys. That of floatingice, on the contrary, depends upon the direction of marinecurrents, which is not determined by the outline of the surface,but is influenced by the large and wide depressions of the seabottom.

10. When subsidence of the land is in progress, floatingice may carry boulders from lower to higher levels. Glacierscannot do this under any circumstances, though in their progressthey may leave blocks perched on the tops of peaks andridges.

I believe that in all these points of difference the boulderclay and drift on the lower lands of Canada and other parts ofNorth America, correspond rather with the action of floatingice than of land ice; though certainly with glaciers on such landas existed at the different stages of the submergence, and theseglaciers drifting stones and earthy matter in different directionsfrom higher land toward the sea. More especially is this thecase in the character of the striated surfaces, the bedded distributionof the deposits, the transport of material up thenatural slope, the presence of marine shells, and the mechanicaland chemical characters of the boulder clay. In short, thosewho regard the Canadian boulder clay as a glacier deposit, canonly do so by overlooking essential points of difference betweenit and modern accumulations of this kind.

I would wish it here to be distinctly understood, that I donot doubt that at the time of the greatest Pleistocene submergenceof Eastern America, at which time I believe the greaterpart of the boulder clay was formed, and the more importantstriation effected, the higher hills then standing as islands would« 364 »be capped with perpetual snow, and through a great part of theyear surrounded with heavy field and barrier ice, and that inthose hills there might be glaciers of greater or less extent.Further, it should be understood that I regard the boulderclays of the St. Lawrence valley as of different ages, rangingfrom those of the early Pleistocene to that now forming in theGulf of St. Lawrence; and that during these periods greatchanges of level occurred. Further, that this boulder clayshows in every place where I have been able to examine it,evidence of subaqueous accumulation, in the presence ofmarine shells or in the unweathered state of the rocks andminerals enclosed in it; conditions which, in my view, precludeany reference of it to glacier action, except possibly in somecases to that of glaciers stretching from the land over the marginof the sea, and forming under water a deposit equivalentin character to thebone glaciare of the bottom of the Swissglaciers. But such a deposit must have been local, and wouldnot be easily distinguishable from the marine boulder clay. Itis of some interest to compare Canadian deposits with those ofScotland,[163] which in character and relations so closely resemblethose of Canada; but I confess several of the facts lead me toinfer that much of what has been regarded as of subaërialorigin in that country must really be marine, though whetherdeposited by icebergs or by the fronts of glaciers terminatingin the sea, I do not pretend to determine.[164] It must, however,be observed that the antecedent probability of a glaciated conditionis much greater in the case of Scotland than in that ofCanada, from the high northern latitude of the former, itshilly and maritime character, and the fact that its present« 365 »exemption from glaciers is due to what may be termed exceptionaland accidental geographical conditions; more especiallyto the distribution of the waters of the Gulf Stream, whichmight be changed by a comparatively small subsidence in CentralAmerica. To assume the former existence of glaciers in acountry in north latitude 56°, and with its highest hills, underthe present exceptionally favourable conditions, snow-cappedduring most of the year, is a very different thing from assuminga covering of continental ice over wide plains more than tendegrees farther south, and in which, even under very unfavourablegeographical accidents, no snow can endure the summersun, even in mountains several thousand feet high. Were theplains of North America submerged and invaded by the coldarctic currents, the Gulf Stream being at the same time turnedinto the Pacific, the temperature of the remaining NorthAmerican land would be greatly diminished; but under thesecircumstances the climate of Scotland would necessarily bereduced to the same condition with that of South Greenlandor Northern Labrador. As we know such a submergence ofAmerica to have occurred in the Pleistocene period, it does notseem necessary to have recourse to any other cause for eitherside of the Atlantic. It would, however, be a very interestingpoint to determine, whether in the Pleistocene period thegreatest submergence of America coincided with the greatestsubmergence of Europe, or otherwise. It is quite possiblethat more accurate information on this point might removesome present difficulties. I think it much to be desired thatthe many able observers now engaged on the Pleistocene ofEurope, would at least keep before their minds the probableeffects of the geographical conditions above referred to, andinquire whether a due consideration of these would not allowthem to dispense altogether with the somewhat extravaganttheories of glaciation now agitated.

The preceding pages give the substance of my conclusions« 366 »of twenty-four years ago. I give those of to-day from a paperof 1891,[165] relating to Eastern Canada only:—

These conclusions have, in my judgment, been confirmed,and their bearing extended, more especially by the researchesof Mr. Chalmers, who has shown in the most convincing waythat glaciers proceeding from local centres along with sea-borneice, may have been the agents in glaciating surfaces and transportingboulders in Nova Scotia and New Brunswick. Takenin connection with the observations of Dr. Dawson and Mr.McConnell in the Cordillera region of the west, and those ofDr. Bell, Dr. Ells, Mr. Low, and others in the Laurentiancountry north of the St. Lawrence, and in the Province ofQuebec, we may now be said to know that there was not, evenat the height of the glacial refrigeration of America, a continentalice sheet, but rather several distinct centres of ice action,—onein the Cordillera of the West, one on the LaurentianV-shaped axis, and one on the Appalachians, with subordinatecentres on isolated masses like the Adirondacks, and at certainperiods even on minor hills like those of Nova Scotia. Itwould further seem that, in the west at least, elevation of themountain ridges coincided with depression of the plains. InNewfoundland also, it would appear from the observations ofCaptain Kerr, with which those of Mr. Murray are in harmony,[166]though they have been differently interpreted, that thegathering ground of ice was in the interior of the island, andthat glaciers moved thence to the coasts, but principally to theeast coast, as was natural from the conformation of the landand the greater supply of moisture from the Atlantic.

The labours of Murray in Newfoundland, of Matthew,Chalmers, Bailey, and others, in Nova Scotia and New Brunswick,have considerably enlarged our knowledge of Pleistocenefossils, showing, however, that the marine fauna is the same« 367 »with that of the beds of like age in the St. Lawrence valley, andwith the existing fauna of the Labrador coast and colder portionsof the Gulf and River St. Lawrence, as ascertained byPrickard, Whiteaves, and the writer. It would seem thatthroughout this region, the 60 feet and the 600 feet terraceswere the most important with reference to these marineremains, and that their chief repository is in the Upper LedaClay, a marine deposit intermediate between the Lower andUpper boulder drift, and corresponding to the interglacial bedsof the interior of America.

In this district, and the eastern part of North Americagenerally, it is, I think, universally admitted that the laterPliocene period was one of continental elevation, and probablyof temperate climate. The evidence of this is too well knownto require re-statement here. It is also evident, from the raisedbeaches holding marine shells, extending to elevations of 600feet, and from drift boulders reaching to a far greater height,that extensive submergence occurred in the middle and laterPleistocene. This was the age of the beds I have named theLeda clays andSaxicava sands, found at heights of 600 feetabove the sea in the St. Lawrence valley, nearly as far west asLake Ontario.

It is reasonable to conclude that the till or boulder clay,under the Leda clay, belongs to the earliest period of probablygradual subsidence, accompanied with a severe climate,and with snow and glaciers on all the higher grounds, sendingglaciated stones into the sea. This deduction agrees with themarine shells, polyzoa, and cirripedes found in the boulderdeposits on the lower St. Lawrence, with the unoxidized characterof the mass, which proves subaqueous deposition, with thefact that it contains soft boulders, which would have crumbledif exposed to the air, with its limitation to the lower levels and« 368 »absence on the hillsides, and with the prevalent direction ofstriation and boulder drift from the north-east.[167]

All these indications coincide with the conditions of themodern boulder drift on the lower St. Lawrence and in theArctic regions, where the great belts and ridges of bouldersaccumulated by the coast ice would, if the coast were sinking,climb upward and be filled in with mud, forming a continuoussheet of boulder deposit similar to that which has accumulatedand is accumulating on the shores of Smith's Sound and elsewherein the Arctic, and which, like the older boulder clay, isknown to contain both marine shells and driftwood.[168]

The conditions of the deposit of "till" diminished in intensityas the subsidence continued. The gathering ground of localglaciers was lessened, the ice was no longer limited to narrowsounds, but had a wider scope, as well as a freer drift to thesouthward, and the climate seems to have been improved.The clays deposited had few boulders and many marine shells,and to the west and north there were land-producing plantsakin to those of the temperate regions; and in places onlyslightly elevated above the water, peaty deposits accumulated.The shells of the Leda clay indicate depths of less than 100fathoms. The numerous Foraminifera, so far as have beenobserved, belong to this range, and I have never seen in thisclay the assemblage of foraminiferal forms now dredged from200 to 300 fathoms in the Gulf of St. Lawrence.

I infer that the subsidence of the Leda clay period and ofthe interglacial beds of Ontario belongs to the time of the seabeaches from 450 to 600 feet in height, which are so markedand extensive as to indicate a period of repose. In this period« 369 »there were marine conditions in the lower and middle St.Lawrence and in the Ottawa valley, and swamps and lakes onthe upper Ottawa and the western end of Lake Ontario. It isquite probable, nay, certain, that during this interglacial periodre-elevation had set in, since the upper Leda clay and theSaxicava sand indicate shallowing water, and during this re-elevationthe plant-covered surface would extend to lower levels.

This, however, must have been followed by a second subsidence,since the water-worn gravels and loose, far-travelledboulders of the later drift rose to heights never reached by thetill or the Leda clay, and attained to the tops of the highesthills of the St. Lawrence valley, 1,200 feet in height, and elsewhereto still greater elevations. This second boulder driftmust have been wholly marine, and probably not of longduration. It shows no evidence of colder climate than thatnow prevalent, nor of extensive glaciers on the mountains;and it was followed by a paroxysmal elevation in successivestages till the land attained even more than its present height,as subsidence is known to have been proceeding in moderntimes.

I am quite aware that the above sequence and the causesassumed are somewhat different from those held by manygeologists with reference to regions south of Canada; but musthold that they are the only rational conclusions which can bepropounded with reference to the facts observed from theparallel of 45° to the Arctic Ocean.

My own observations have been chiefly in the eastern partof North America. My son, Dr. G. M. Dawson, has muchmore ably and thoroughly explored those of the west; andafter describing the immense Cordilleran ice mass which extendedfor a length of 1,200 miles along the mountains ofBritish Columbia and discharged large glaciers to the north, aswell as to the west and south, and stating his reasons forbelieving in that differential elevation and depression which« 370 »caused the greatest height of the mountains to coincide withthe greatest depression of the plains, andvice versâ, and showingthe Cordilleran glacier must have been separated by awater area from that of the Laurentide hills on the east, thusconcludes:—

"It is now distinctly known, as the result of work doneunder the auspices of the Geological Survey of Canada, andmore particularly of observations by the writer and his colleagues,Messrs. McConnell and Tyrrell, that the extrememargins of the western and eastern glaciated areas of thecontinent barely overlap, and then only to a very limitedextent, while the two great centres of dispersion were entirelydistinct. For numerous reasons which cannot be here enteredinto, the writer does not consider it probable, or even possible,that the great confluent glacier of the north-eastern part of thecontinent extended at any time far into the area of the greatplains; but erratics and drift derived from this ice mass did soextend, and are found between the 49th and 50th parallels,stranded on the surface of moraines produced by the largelocal glaciers of the Rocky Mountains. Recognising, however,the essential separateness of the western and eastern confluentice masses, and the fact that it is no longer appropriate to designateone of these the "continental glacier," the writer venturesto propose that the easternmer de glace may appropriately benamed the greatLaurentide glacier, while its western fellow isknown as the "Cordilleran glacier." It may be added thatthere is good evidence to show that both the Laurentide andCordilleran glaciers discharged into open water to the north."

These conclusions, based on a large induction of factsapplying to a very large area of the North American Continent,coincide with my own observations in the east, and with theinferences deducible from the present condition of Greenlandand Arctic America.

When extreme glacialists point to Greenland and ask us to« 371 »believe that in the Glacial age the whole continent of NorthAmerica, as far south as the latitude of 40°, was covered with acontinuous glacier, having a wide front, and thousands of feetthick, we may well ask, first, what evidence there is that Greenlandor even the Antarctic continent is at present in such acondition; and, secondly, whether there exists a possibilitythat the interior of a great continent could ever receive so largean amount of precipitation as that required. So far as presentknowledge exists, it is certain that the meteorologist and thephysicist must answer both questions in the negative. In short,perpetual snow and glaciers must be local, and cannot be continental,because of the vast amount of evaporation and condensationrequired. These can only be possible where comparativelyWarm seas supply moisture to cold and elevated land,and this supply cannot, in the nature of things, penetrate farinland. The actual condition of interior Asia and interiorAmerica in the higher northern latitudes affords positive proofof this. In a state of partial submergence of our northerncontinents, we can readily imagine glaciation by the combinedaction of local glaciers and great ice floes; but in whateverway the phenomena of the boulder clay and of the so-called"terminal moraines" are to be accounted for, the theory of acontinuous continental glacier must be given up.

The great interior plain of western Canada, between theLaurentian axis on the east and the Rocky Mountains on thewest, is seven hundred miles in breadth, and is covered withglacial drift, presenting one of the greatest examples of thisdeposit in the world. Proceeding eastward from the base ofthe Rocky Mountains, the surface, at first more than 4,000feet above the sea level, descends by successive steps to 2,500feet, and is based on Cretaceous and Laramie rocks, coveredwith boulder clay and sand, in some places from one hundredto two hundred feet in depth, and filling up pre-existing hollows,though itself sometimes piled into ridges. Near the Rocky« 372 »Mountains the bottom of the drift consists of gravel notglaciated. This extends to about one hundred miles east ofthe mountains, and must have been swept by water out of theirvalleys. The boulder clay resting on this deposit is largelymade up of localdébris, in so far as its paste is concerned. Itcontains many glaciated boulders and stones from the Laurentianregion to the east, and also smaller pebbles from theRocky Mountains, so that at the time of its formation theremust have been driftage of large stones for seven hundredmiles or more from the east, and of smaller stones from a lessdistance on the west. The former kind of material extends tothe base of the mountains, and to a height of more than 4,000feet. One boulder is mentioned as being 42 × 40 × 20 feet indimensions. The highest Laurentian boulders seen were at anelevation of 4,660 feet on the base of the Rocky Mountains.The boulder clay, when thick, can be seen to be rudely stratified,and at one place includes beds of laminated clay withcompressed peat, similar to the forest beds described byWorthen and Andrews in Illinois, and the so-called interglacialbeds described by Hinde on Lake Ontario. The leaf beds onthe Ottawa river, and the drift trunks found in the boulderclay of Manitoba, belong to the same category, and indicatein the midst of the Glacial period many forest oases far tothe north, having a temperate rather than an arctic flora. Inthe valleys of the Rocky Mountains opening on these plainsthere are evidences of large local glaciers now extinct, andsimilar evidences exist on the Laurentian highlands on the east.A recent paper of Dr. G. M. Dawson on the Palæography of theRocky Mountains illustrates in a most convincing manner thechanges which have occurred in the Cordillera of NorthAmerica, and the differential elevation and depression whichhave affected its climate in the later geological periods.[169]

Perhaps the most remarkable feature of the western drift region« 373 »is that immense series of ridges of drift piled against an escarpmentof Laramie and Cretaceous rocks, at an elevation of about2,500 feet, and known as the "Missouri Coteau." It is in someplaces 30 miles broad and 180 feet in height above the plainat its foot, and extends north and south for a great distance:being, in fact, the northern extension of those great ridges ofdrift which have been traced south of the great lakes, andthrough Pennsylvania and New Jersey, and which figure on thegeological maps as the edge of the continental glacier—anexplanation obviously inapplicable in those western regionswhere they attain their greatest development. It is plain thatin the north it marks the western limit of the deep-water of aglacial sea, which at some periods extended much fartherwest, perhaps with a greater proportionate depression in goingwestward, and on which heavy ice from the Laurentian districtson the east was wafted south-westward by the arcticcurrents, while lighter ice from the Rocky Mountains wasbeing borne eastward from these mountains by the prevailingwesterly winds. We thus have in the west, on a very widescale, the same phenomena of varying submergence, cold currents,great ice floes and local glaciers producing icebergs, towhich I have attributed the boulder clay and upper boulderdrift of eastern Canada. In short, we arrive at the conclusionthat there never has been a continental glacier, properly socalled, but that in the extreme Glacial period there have beengreat centres of snow and glacial action, in the Cordillera ofthe west, in the Laurentian plateau of the north, and in thenorthern Appalachians, and the Adirondacks, while the lowerlands have been either submerged, or enjoying a climate habitableby hardy animals and plants.

The till or boulder clay has been called a "ground moraine,"but there are really no Alpine moraines at all corresponding toit. On the other hand, it is more or less stratified, often restson soft materials which glaciers would have swept away, sometimes« 374 »contains marine shells, or passes into marine clays in itshorizontal extension, and invariably in its embedded bouldersand its paste, shows an unoxidized condition, which could nothave existed if it had been a subaërial deposit. When theCanadian till is excavated and exposed to the air, it assumes abrown colour, owing to oxidation of its iron, and many of itsstones and boulders break up and disintegrate under the actionof air and frost. These are unequivocal signs of a subaqueousdeposit. Here and there we find associated with it, and especiallynear the bottom and at the top, indications of powerfulwater action, as if of land torrents acting at particularelevations of the land, or heavy surf and ice action on coasts,and the attempts to explain these by glacial streams have beenfar from successful. A singular objection sometimes raisedagainst the subaqueous origin of the till is its general want ofmarine remains; but this is by no means universal, and it iswell known that coarse conglomerates of all ages are generallydestitute of fossils, except in their pebbles, and it is further tobe observed that the conditions of an ice-laden sea are notthose most favourable for the extension of marine life, and thatthe period of time covered by the glacial age must have beenshort, compared with that represented by some of the olderformations.

It follows from all this that the great "continental moraine,"which the United States Geological Survey has now "delineatedfor several thousand miles extending from the Atlantic to thePacific," cannot be a glacier moraine, but must be, like itsgreat continuation northward, the Missouri coteau, a marginof sea drift, and that we must explain the whole of the driftof the American continent by the supposition, first, of a periodof elevation of the hills and subsidence of the valleys in whichthere were great accumulations of snow on the Western Cordillera;the Laurentian axis, and the Appalachians and Adirondacksradiating in every direction from these points, while« 375 »minor areas of radiation may have temporarily existed onsmaller elevations: that this was followed by a period of moreequal level, in which parts of the low grounds were clothedwith a temperate flora, the "Interglacial period" so called,succeeded by a second great depression, in which the high levelboulders of the second boulder drift were wafted to great distancesby floating ice.

The late Prof. Alexander Winchell, a man who did nothesitate to express his convictions, thus bears similar testimony:—"Therehas been no continental glacier. There hasbeen no uniform southerly movement of glacier masses.There has been no persistent declivity as asine qua non, downwhich glacier movements have taken place. The continuity ofthe supposed continental glacier was interrupted in the regionsof the dry and treeless plains of the west; and in the interiorand Pacific belts of the continent within the United States,ancient glaciation was restricted to the elevated slopes."[170] Hemight have added that the St. Lawrence valley was submergedand received the ends of Appalachian and Adirondack glacierson the south-east, and those of Laurentide glaciers on thenorth-west.

My friend Prof. Claypole, who, however, has some hesitation,fearing, I presume, to be cast out of the synagogue for heresy,ventures to say,[171] "We deduce from the facts and argumentsstated above, that all the observations of glacial action in thenorthern hemisphere are explicable by assuming the existenceof enormous and confluent [172] glacier-systems in and about thehigh lands of Europe, Asia, and America, which high lands became,therefore, glacial radiants, and shed their load of ice in alldirections over the lower adjacent ground, along the lines of« 376 »easiest flow; that this theory does no violence to the analogyof the existing order of things, requiring merely an enlargementof actual glaciers by the intensification of actual conditions :that abundant evidence can be obtained, as, for example, fromSwitzerland, that the present glacier system of the earth wasonce of sufficient magnitude to produce all the observedphenomena; that the most important glacial radiants in thenorthern hemisphere were, in North America, the districtround Hudson Bay, New England and the Adirondacks, withcertain areas in the western Cordilleras, and in Europe theNorwegian Dovrefelds and the Alps, Asia apparently possessingnone of commensurate importance; that it satisfactorilyexplains, also, the previously puzzling absence of glacial actionover the great plain of Siberia, the coldest portion of thenorthern temperate zone; that the belief in a vast polar ice cap,thousands of feet thick, covering the whole Arctic region, andextending almost continuously down to low latitudes, is an assumptiondoing violence to observed physical facts and toprobability, that it is not required to account for the phenomena,and is, in fact, contradictory to some of them."

In Europe there is equally good evidence of the existence ofhuge glaciers on the Scandinavian mountains and the Alps,and of lesser accumulations of ice on the hills, as, for instance,those of the British Islands; but the Scandinavian bouldersscattered over the plains of Great Britain must have beenwater-borne.[173]

In connection with these extracts I would observe that thewriter, and those with whom he has acted in this matter, havenever held that icebergs alone, or fields of ice alone, have producedthe Pleistocene deposits. Their contention has beenthat the period was one in which glaciers, icebergs, and field« 377 »ice acted together, and along with aqueous agencies, in producingthe complicated formations of this remarkable age. Theyhave, however, objected strenuously to the sole employment ofone agent to the exclusion of others, and to attributing to thatagent powers and extension which obviously could not belongto it, under the known laws which regulate the movement ofglaciers by the force of gravity, and the precipitation ofmoisture in the form of snow on mountains and plateaus.These laws show that the movement of glaciers over levelsurfaces, or against the slope of the ground, and their movingstones otherwise than down slopes, are physical impossibilities,and that the accumulation of snow to form glaciers can takeplace only on elevated and cold land, supplied with largequantities of vapour from neighbouring water. Such accumulationcan under no imaginable conditions take place in theinterior plains and table lands of great continents.

Applying these laws and conclusions to the whole northernhemisphere, we learn that the conditions to produce a glacialperiod are the diversion of the warm currents from the northernseas, the submergence of land in the temperate regions, andits invasion by cold Arctic water, and great condensation ofsnow on the higher lands. Whether this condensation has atendency finally to rectify the state of affairs, by pressing downthe mountains and elevating the plains, we do not know, but Ishould imagine that it has not; for the high lands will, in thecase supposed, be lightened by denudation, while the plainswill be burdened with a great weight of deposit. Perhaps weshould rather look to this as the agency for depressing and submergingthe plains and elevating the hills, and suppose someother and more general pressure proceeding from the great seabasins, to effect the re-elevation of the plains.

These questions suggest that of the date of the Glacial period.This subject has recently been discussed by Prestwich andothers, with the result that there is no purely geological ground« 378 »for referring the Glacial age to a period so remote as that advocatedby Croll on astronomical grounds. Claypole has recentlydiscussed the matter at some length, and in a temperate spirit.[174]He takes the rate of erosion of the Niagara gorge as a measure,and shows that the Falls of St. Anthony, as described by Winchell,and all the other falls and river gorges in North America,give similar estimates, which are confirmed by the evidences oflake ridges, of the rate of erosion, and of the conditions ofanimal and plant life. The whole go to show that the culminationof the Glacial age may have occurred less than 10,000years ago. He further shows that the differential elevation ofLakes Erie and Ontario, the greater ease with which the rivercould cut the lower part of its ravine, the probability thatthe part of the gorge between the whirlpool and the fall wasnot cut, but only cleaned out in modern times, and the possiblegreater flow of water in the early modern period, all tend toshorten the time required, and that, as Prestwich has inferredfrom other data, and the writer also in various papers, some ofthem of old date, the so-called post-glacial period, that of themelting away of the ice, may come within 8,000 to 10,000years of our own time. Probably the first of these figures isthe nearest to the truth,[175] so that, geologically considered, theGlacial age is very recent.

Still another question of great cosmic interest relates to thepossible alternation of glacial conditions in the northern andsouthern hemispheres. There is evidence of drift in the southernpart of South America, similar to that in the north; but wasit deposited at the same time? If we could be sure that it wasnot, many difficulties would be removed. The southern hemisphere« 379 »is at present emphatically the ocean hemisphere; thenorthern, the land hemisphere. Perhaps these conditions maybe capable of being reversed, in which case the periods of depressionin the south may have corresponded with those ofelevation in the north. One thing which we know is, thatthere is a polar ice ring, not an ice cap, for we do not knowwhat is within its edges at the South Pole, about 2,000 miles indiameter, and this in the only circumstances in which it canexist, namely, surrounded by a vast ocean furnishing it withabundant aqueous vapour. We also know that from this icering radiate glaciers, carryingdébris, with which the sea bottomis strown half way to the equator. If continents were elevatedout of the Southern Ocean, we should probably have on theirsurfaces glacial deposits more widespread and continuous thanany remaining on the continents of the northern hemisphere, andlike some of them thinning out to a terminal edge or border,instead of a terminal moraine like that of a glacier.[176] Thus wemay say with some truth that the southern hemisphere is nowpassing through one phase of the Glacial period.

I have often thought that in the southern hemisphere thecondition of Kerguelen Island and Heard Island, as describedin the reports of theChallenger,[177] must very nearly represent thestate of some mountain ranges and peaks in North Americain the Glacial age. Heard Island, in S. latitude 53° 2′, is amountain peak 6,000 feet high, and 25 miles in length. Itsends down large glaciers to the sea. In its larger neighbour,Kerguelen, the glaciers do not reach the sea; but there is evidencethat at one time they did. It is still more curious that,in Kerguelen the modern ice overlies late tertiary deposits,holding remains of large trees, indicating a more continentalcondition and mild climate at no very remote period.« 380 »The glaciers of Heard Island and Kerguelen have, no doubt,been carrying down moraine material into the sea, and this iscertainly done on a still greater scale by those of the Antarcticcontinent. This sends off bergs which fill the whole oceansouth of 60°, and float much farther north. Some of them havebeen seen 2,000 feet long and 200 high, and though most ofthe boulders they contain are necessarily concealed, yet massesof rock, supposed to weigh many tons, have been seen onthem. The whole sea bottom off this continent, as far southas 64°, consists of blue mud, with boulders and pebbles, someof them glaciated, and farther north there is, as far as 47degrees of latitude, a considerable percentage of drift material,and this sometimes in depths of 1,950 fathoms. It is evidentthat, if large areas of the southern hemisphere were elevatedinto land, we should have phenomena to deal with not muchunlike those of North America at present.

Perhaps no discussion carries with it more of warning togeologists to exercise caution in framing theories than this ofthe great ice age; and if the collapse of extreme views onthis subject shall have the effect of inducing geologists to keepwithin the limits of well-ascertained facts and sound induction,to adhere to the Lyellian doctrine of modern causes to explainancient phenomena, and to bear in mind that most greateffects involve not one cause, but many co-operating causes, itmay lead to consequences beneficial to science; and so, emergingfrom the cold shadows of the continental glacier, we mayfind ourselves in the sunshine of truth.

References:—"Acadian Geology," 1st ed., 1855; 4th ed., 1892. Icebergsof Belle-Isle, and Glaciers of Mont Blanc,Canadian Naturalist,1865. "Notes on Pleistocene of Canada," Montreal, 1871. Papers atvarious dates in theCanadian Naturalist andCanadian Record ofScience. "The Ice Age in Canada," Montreal, 1893. Canadian Pleistocene,London Geological Magazine, March, 1883. Flora of thePleistocene,Bulletin of Geological Society of America, vol. i., 1890,p. 311, Dawson and Penhallow.

CAUSES OF CLIMATAL CHANGE.

DEDICATED TO

DR. T. STERRY HUNT, F.R.S.,

Whose Work in
the Chemical and Cosmical Relations of Geology
is beyond all Praise,
and is destined to command
in the Future
even greater Acceptance than in the Past.

Various Theories as to Changes of Climate—TheAstronomical Theory of Croll—The GeographicalTheory of Lyell—Objections of a GeologicalCharacter to the Former—Testimony of Geologyand Physical Geography in Favour of the Latter

CHAPTER XIV.

The subject of this chapter is one which has been in disputeever since I began to read anything on geology,nearly sixty years ago. It ought to have been settled, but upto to-day one finds in geological works and papers—especiallythose relating to the Glacial age—the most divergent views;and in the writings of men not geologists, it is not unusual tofind exploded theories gravely stated as established facts ofscience. The subject is one which I cannot hope to makeinteresting, but if the reader will wade through a short chapter,he will be able to find some of the data on which statements onthis subject in other papers of this series are based.

Mr. Searles V. Wood, in an able summary of the possiblecauses of the succession of cold and warm climates in thenorthern hemisphere, enumerates no fewer than seven theorieswhich have met with more or less acceptance, and he mighthave added an eighth. These are:—

(4) The effect of the precession of the equinoxes, along withchanges of the eccentricity of the earth's orbit.

(6) Differences in the temperature of portions of space passedthrough by the earth.

(7) Differences in the distribution of land and water in connectionwith the flow of oceanic currents.

(8) Variations in the properties of the atmosphere withreference to its capacity for allowing the radiation of heat.

Something may be said in favour of all these alleged causes;but as efficient in any important degree in producing the coldand warm climates of the Tertiary period, the greater numberof them may be dismissed as incapable of effecting such results,or as altogether uncertain with reference to the fact of theirown occurrence.

(1) That the earth and the sun have diminished in heatduring geological time seems probable; but physical and geologicalfacts alike render it certain that this influence could haveproduced no appreciable effect, even in the times of theearliest animals and plants, and certainly not in the case ofTertiary floras or faunas.

(2) The obliquity of the ecliptic is not believed by astronomersto have changed to any great degree, and its effect wouldbe merely a somewhat different distribution of heat in differentperiods of the year.

(3) Independently of astronomical objections, there is goodgeological evidence that the poles of the earth must have beennearly in their present places from the dawn of life until now.From the Laurentian upward, those organic limestones whichmark the areas where warm and shallow equatorial water wasspreading over submerged continents, are so disposed as toprove the permanence of the poles. In like manner all thegreat foldings of the crust of the earth have followed lineswhich are parts of great circles tangent to the existing polarcircles. So, also, from the Cambrian age the great drift ofsediment from the north has followed the line of the existingArctic currents from the north-east to the south-west, throwingitself, for example, along the line of the Appalachian uplifts inEastern America, and against the ridge of the Cordilleras inthe west.

(4) The effects of change of eccentricity and precession havebeen so ably urged by Croll, and recently by Ball, and have sostrongly influenced the minds of those who are not workinggeologists, that they deserve a more detailed notice.

(5) The heat of the sun is known to be variable, and theeleven years' period of sun spots has recently attracted muchattention as producing appreciable effects on the seasons.There may possibly be longer cycles of solar energy; or thesun may be liable, like some variable stars, to paroxysms of increasedenergy. Such changes are possible, but we have noevidence of their occurrence, and they could not account forperiods of refrigeration of limited duration like the Glacialage.

(6) It has been supposed that the earth may have at differenttimes traversed more or less heated zones of space,giving alternations of warm and cold temperature. No suchdifferences in space are, however, known, nor does there seemany good ground for imagining their existence.

(7) The differences in the form and elevation of our continents,and in the consequent distribution of surfaces of differentabsorbent and radiating power, and of the oceanic currents, areknown causes of climatal change, and have been referred to inthese papers as competent to account for many, at least, of thephenomena.

(8) Reference has already been made, in connection with thedistribution of plants, to the possibility that the primevalatmosphere was richer in carbon than that of more moderntimes, and that this might operate to produce diminution ofradiation, and consequent uniformity of temperature; but thiscause could not have been efficient in the later geologicalperiods.

There may thus be said to remain two theories of thoseenumerated by Wood, to which more detailed consideration maybe given, namely, numbers four and seven, which may be named« 386 »respectively those of Croll and Lyell, or the astronomical andgeographical theories.

The late Mr. Croll has, in his valuable work "Climate andTime," and in various memoirs, brought forward an ingeniousastronomical theory to account for changes of climate. Thistheory, as stated by himself, is that when the eccentricity ofthe earth's orbit is at a high value, and the northern wintersolstice is in perihelion, agencies are brought into operationwhich make the south-east trade winds stronger than the north-east,and compel them to blow over upon the northern hemisphereas far as the Tropic of Cancer. The result is that allthe great equatorial currents of the ocean are impelled into thenorthern hemisphere, which thus, in consequence of the immenseaccumulation of warm water, has its temperature raised,so that ice and snow must, to a great extent, disappear from theArctic regions. In the prevalence of the converse conditionsthe Arctic zone becomes clad in ice, and the southern has itstemperature raised.

At the same time, according to Croll's calculations, the accumulationof ice on either pole would tend, by shifting theearth's centre of gravity, to raise the level of the ocean andsubmerge the land on the colder hemisphere. Thus a submergenceof land would coincide with a cold condition, andemergence with increasing warmth. Facts already referred to,however, show that this has not always been the case, but thatin many cases submergence was accompanied with the influxof warm equatorial waters and a raised temperature, this apparentlydepending on the question of local distribution ofland and water; and this, in its turn, being regulated not alwaysby mere shifting of the centre of gravity, but by foldings occasionedby contraction, by equatorial subsidences resulting fromthe retardation of the earth's rotation, and by the excess ofmaterial abstracted by ice and frost from the Arctic regions, anddrifted southward along the lines of arctic currents. This drifting« 387 »must in all geological times have greatly exceeded, as itcertainly does at present, the denudation caused by atmosphericaction at the equator, and must have tended to increase thedisposition to equatorial collapse occasioned by retardation ofrotation.[178]

While such considerations as those above referred to tend toreduce the practical importance of Mr. Croll's theory, on theother hand they tend to remove one of the greatest objectionsagainst it—namely, that founded on the necessity of supposingthat glacial periods recur with astronomical regularity in geologicaltime. They cannot do so if dependent on other causesinherent in the earth itself, and producing important movementsof its crust.

Sir Robert Ball has in a recent work very ingeniously improvedthis theory by showing that Croll was mistaken inassigning equal amounts of heat to the earth, as a whole, inthe periods of greater and less eccentricity. This would tendto augment the effect of astronomical revolutions as causes ofdifference of temperature; but has no bearing on the moreserious geological objections to the theory in question.

A fatal objection, however, to Croll's theory, the force ofwhich has been greatly increased by recent discoveries, is thatthe astronomical causes which he adduces would place theclose of the last Glacial period at least 80,000 years ago, whereasit is now certainly known from geological facts that the closeof the last Glacial period cannot be older than about an eighthor a tenth of that time. This difficulty seems to have causedthe greater number of geologists, specially acquainted with thelater geological periods, to regard this theory as quite inapplicableto the facts.

We are thus obliged to fall back upon the old Lyellian theoryof geographical changes, with such modifications as recent discoverieshave rendered necessary. Taking this as our guide,we reach at once the important conclusion that the movementsand distribution of animals and plants, however dependent onclimate, altitude and depth, have, when regarded in connectionwith geological time, been primarily determined by those greatmovements of the crust of the earth which have establishedour islands, continents and ocean depths. These geographicalchanges have also in connection with animal and vegetablegrowth, deposition of sediments and volcanic ejections, fixedeven the stations, soils and exposures of plants and animals.Thus, subject to those great astronomical laws which regulatethe temperature of our planet as a whole, our attention may berestricted to the factors of physical geography itself. Wemust, however, carry with us the idea that though the greatcontinents and the ocean depths may have been fixed throughoutgeological time, their relative elevations, and consequentlytheir limits, have varied to a great extent, and are constantlychanging.

We must also remember that something more than merecold is necessary to produce a glacial period. It has sometimesbeen assumed that the tendency of an exceptionally cold winterwould necessarily be to accumulate so great a quantity of snowand ice, that these could not be removed in the short thoughwarm summer, and so would go on accumulating from year toyear. Actual experience and observation do not confirm thissupposition. In those parts of North America which have along and severe winter, the amount of snow deposited is not inproportion to the lowness of the temperature, but, on the contrary,the greatest precipitation of snow takes place near thesouthern margin of a cold area, and the snow disappears withgreat rapidity when the spring warmth sets in. Nor is there, ashas been imagined, any tendency to the production of fogs and« 389 »mists which have been invoked as agencies to shield the snowfrom the sun. In North America the melting snow is ordinarilycarried off as liquid water, or as invisible vapour, and the sky isusually clear when the snow is melting in spring. It is onlywhen warm and moist winds are exceptionally thrown upon thesnow-covered land that clouds are produced; and when this isthe case, the warm rain that ensues promotes the melting of thesnow. Thus there is no possibility of continued accumulationsof snow on the lower parts of our continents, under any imaginableconditions of climate. It is only on elevated lands in highlatitudes and near the ocean, like Greenland and the Antarcticcontinent, that such permanent snow-clad conditions can occur,except on mountain tops. Wallace and Wœickoff [179] very properlymaintain, in connection with these facts, that permanentice and snow cannot under any ordinary circumstances exist inlow lands, and that high land and great precipitation are necessaryconditions of glaciers. The former, however, attachesrather too much importance to snow and ice as cooling agents;for though it is true that they absorb a large amount of heat inpassing from the solid to the liquid state, yet the quantity ofsnow or ice to be melted in spring is so small in comparisonwith the vast and continuous pouring of solar heat on the surface,that a very short time suffices for the liquefaction of a deepcovering of snow. The testimony of Siberian travellers provesthis, and the same fact is a matter of ordinary observation inNorth America.

Setting aside, then, these assumptions, which proceed fromincorrect or insufficient information, we may now refer to a considerationof the utmost importance, and which Mr. Croll himself,though he adduces it only in aid of the astronomical theoryof glacial periods, has treated in so masterly a manner, as« 390 »really to give it the first place as an efficient cause. This is thevarying distribution of ocean currents, in connection with thedifferences in the elevation and distribution of land. The greatequatorial current, produced by the action of the solar heat onthe atmosphere and the water, along with the earth's rotation,is thrown, by opposing continental shores, northward into theAtlantic and Pacific in the Gulf Stream and Japan current,giving us a hot-water apparatus which effectually raises the temperatureof the whole northern hemisphere, and especially ofthe western sides of the continents. Mr. Croll imagined thatif his astronomical causes could, to ever so small an extent, intensifythe action of these currents, or their determination tothe north, we should have a period of warmth, while a similaradvantage given to the southern hemisphere would produce aglacial age in the north. But this requires us to assume whatought to be proved; namely, that the position of aphelion, andthe increase or decrease of eccentricity, would actually so swingthe equatorial current to the north or south. It further requiresus to assume—and this is the most important defect of thetheory—that no change occurs in the distribution of landand water; because any important change of this kind mightobviously exert a dominant influence on the currents. Let ustake two examples in illustration of this.

At the present time the warm water thrown into the NorthAtlantic, co-operating with the prevalent westerly winds, notonly increases the temperature of its whole waters, but gives anexceptionally mild climate to western Europe. Still the countervailinginfluence of the Arctic currents and the Greenland ice,is sufficient to permit numerous icebergs to remain unmelted onthe coast of Labrador and Newfoundland throughout the summer.Some of the bergs which creep down to the mouth ofthe Strait of Belle-Isle, in the latitude of the south of England,actually remain unmelted till the snows of a succeeding winterfall upon them. Now let us suppose that a subsidence of land« 391 »in tropical America were to allow the equatorial current to passthrough into the Pacific. The effect would at once be to reducethe temperature of Norway and Britain to that of Greenlandand Labrador at present, while the latter countries wouldthemselves become colder. The northern ice, drifting downinto the Atlantic, would not, as now, be melted rapidly by thewarm water which it meets in the Gulf Stream. Much largerquantities of it would remain undissolved in summer, and thusan accumulation of permanent ice would take place, along theAmerican coast at first, but probably at length even on theEuropean side. This would still further chill the atmosphere,glaciers would be established on all the mountains of temperateEurope and America, the summer would be kept cold bymelting ice and snow, and at length all eastern America andEurope might become uninhabitable, except by Arctic animalsand plants, as far south as perhaps 40° of north latitude. Thiswould be simply a return of the glacial age. I have assumedonly one geographical change; but other and more complexchanges of subsidence and elevation might take place, witheffects on climate still more decisive.[180]

We may suppose an opposite case. The high plateau ofGreenland might subside, or be reduced in height, and theopening of Baffin's Bay might be closed. At the same timethe interior plain of America might be depressed, so that, aswe know to have been the case in the Cretaceous period, thewarm waters of the Mexican gulf might circulate as far north asthe basins of the present great American lakes. In these circumstancesthere would be an immense diminution of thesources of floating ice, and a correspondingly vast increase inthe surface of warm water. The effects would be to enable a« 392 »temperate flora to subsist in Greenland, and to bring all thepresent temperate regions of Europe and America into a conditionof subtropical verdure.

It is only necessary to add that we actually know thatchanges not dissimilar from those above sketched have reallyoccurred in comparatively recent geological times, to enable usto perceive that we can dispense with all other causes of changeof climate, though admitting that some of them may have occupieda secondary place. This will give us, in dealing with thedistribution of life, the great advantage of not being tied up todefinite astronomical cycles of glaciation, which do not wellagree with the geological facts, and of correlating elevation andsubsidence of the land with changes of climate affecting livingbeings. It will, however, be necessary, as Wallace well insists,that we shall hold to a certain fixity of the continents in theirposition, notwithstanding the submergences and emergenceswhich they have experienced.

Sir Charles Lyell, more than forty years ago, published inhis "Principles of Geology" two imaginary maps, which illustratethe extreme effects of various distribution of land and water.In one, all the continental masses are grouped around theequator. In the other they are all placed around the poles,leaving an open equatorial ocean. In the one case the wholeof the land and its inhabitants would enjoy a perpetual summer,and scarcely any ice could exist in the sea. In the other, thewhole of the land would be subjected to an Arctic climate, andit would give off immense quantities of ice to cool the ocean.Sir Charles remarks on the present apparently capricious distributionof land and water, the greater part being in the northernhemisphere, and, in this, placed in a very unequal manner.But Lyell did not suppose that any such distribution as thatrepresented in his maps had actually occurred, though thissupposition has been sometimes attributed to him. He merelyput what he regarded as an extreme case to illustrate what« 393 »might occur under conditions less exaggerated. Sir Charles,like all other thoughtful geologists, was well aware of the generalfixity of the areas of the continents, though with greatmodifications in the matter of submergences and of land conditions.The union, indeed, of these two great principles offixity and diversity of the continents lies at the foundation oftheoretical geology.

We can now more precisely indicate this than was possiblewhen Lyell produced his "Principles," and can reproduce theconditions of our continents in even the more ancient periodsof their history. An example of this may be given from theAmerican continent, which is more simple in its arrangementsthan the double continent of Eurasia. Take, for instance, theearly Devonian or Erian period, in which the magnificent floraof that age, the earliest certainly known to us, made its appearance.Imagine the whole interior plain of North Americasubmerged, so that the continent is reduced to two strips onthe east and west, connected by a belt of Laurentian land onthe north. In the great mediterranean sea thus produced,the tepid water of the equatorial current was circulated, and itswarmed with corals, of which we know no less than 150 species,and with other forms of life appropriate to warm seas. On theislands and coasts of this sea was introduced the Erian flora,appearing first in the north, and with that vitality and colonizingpower of which, as Hooker has well shown, the Scandinavianflora is the best modern type, spreading itself to the south. Avery similar distribution of land and water in the Cretaceousage gave a warm and equable climate in those portions of NorthAmerica not submerged, and coincided with the appearance ofthe multitude of broad-leaved trees of modern types which appearedin the middle Cretaceous, and prepared the way forthe mammalian life of the Eocene.

We have in America ancient periods of cold as well as ofwarmth. I have elsewhere referred to the boulder conglomerates« 394 »of the Huronian, of the early Lower Silurian, and of theMillstone grit period of the Carboniferous; but I have not venturedto affirm that either of these periods was comparable inits cold with the later glacial age, still less with that imaginaryage of continental glaciation, assumed by the more extremetheorists. We know that these ancient conglomerates wereproduced by floating ice, and this at periods when in areas notvery remote, temperate floras and faunas could flourish. Theglacial periods of our old continent occurred in times when thesurface of the submerged land was opened up to the northerncurrents drifting over it mud and sand and stones, and renderingnugatory, in so far, at least, as the bottom of the sea wasconcerned, the effects of the superficial warm streams. Someof these beds are also peculiar to the eastern margin of thecontinent, and indicate ice drift along the Atlantic coast muchas at present, while conditions of greater warmth existed in theinterior. Even in the more recent glacial age, while the mountainswere covered with snow, and the low lands submergedunder a sea laden with ice, there were interior tracts in somewhathigh latitudes of America in which hardy forest trees andherbaceous plants flourished abundantly, and these were by nomeans exceptional "interglacial" periods. Thus we can provethat from the remote Huronian period to the Tertiary, theAmerican land occupied the same position as at present, andthat its changes were merely changes of relative level, as comparedwith the sea; but which so influenced the ocean currentsas to cause great vicissitudes of climate.

Uniformitarian geologists have recently been taunted with awillingness to assume great and frequent elevations and submergencesof continents, as if this were contrary to theirprinciple. But rational uniformitarianism allows us to use anycause of whose operation in the past there is good geologicalevidence, and Lyell himself was perfectly aware of this.

While no geologists can fail to appreciate the evidence of« 395 »the power of geographical change in affecting climatal change,and the fact that such change has occurred at various geologicalperiods, there are some, and especially those who takeextreme views as to the latest period of cold climate, whodoubt its sufficiency to account for all the phenomena observed.It is instructive, however, to notice that some ofthe ablest of these, in default of other probable causes, aredriven to fall back either on agencies of a wholly improbablecharacter, or to give up the problem as insoluble. Two recentexamples of this deserve citation.

The late Dr. Newmayr, of Vienna, a veteran physical geographer,in an able discussion of the climates of past ages,one of his last scientific papers, has fallen back on the hypothesisof a change in the position of the poles.[181] His failureto account for ancient climates by other causes evidently,however, depends on an inadequate conception of the effectsof geographical changes, along with serious misconceptionsas to the distribution of plants and the characters of vegetationat different periods. These points we shall have todiscuss in subsequent pages.

In an address before the American Association, in 1886,Dr. Chamberlain, one of the ablest American authorities onthe Glacial period, makes the following remarks as to thecauses of the Pleistocene cold:—

"If we turn to the broader speculations respecting theorigin of the Glacial epoch, we find our wealth little increased.We have on hand practically the same old stock of hypotheses,all badly damaged by the deluge of recent facts. The earliertheory of northern elevation has been rendered practicallyvalueless; and the various astronomical hypotheses seem tobe the worse for the increased knowledge of the distributionof the ancient ice sheet. Even the ingenious theory of Croll« 396 »becomes increasingly unsatisfactory as the phenomena aredeveloped into fuller appreciation. The more we considerthe asymmetry of the ice distribution in latitude and longitude,and its disparity in elevation, the more difficult it becomesto explain the phenomena upon any astronomical basis. Ifwe were at liberty to disregard the considerations forced uponus by physicists and astronomers, and permit ourselves simplyto follow freely the apparent leadings of the phenomena, itappears at this hour as though we should be led upon an oldand forbidden trail,—the hypothesis of a wandering pole. Itis admitted that there is avera causa in elevations and depressionsof the earth's crust, but it is held inadequate. Itis admitted that the apparent changes of latitude shown bythe determinations of European and American observatoriesare remarkable, but their trustworthiness is challenged. Werethere no barriers against free hypotheses in this direction,glacial phenomena could apparently find adequate explanation;but debarred—as we doubtless should consider ourselves tobe at present—from this resource, our hypotheses remaininharmonious with the facts, and the riddle remains unsolved."

It should be observed here that the unsolved "riddle" isthat of a continental ice sheet. This, as we have already seen,is probably insoluble in any way, but fortunately needs nosolution, being merely imaginary. If we adopt a moderateview as to the actual conditions of the Pleistocene, the geographicaltheory will be found quite sufficient to account forthe facts.

Let it be observed here also, in connection with the abovethoughtful and frank avowal of one of the ablest of Americanglacialists, that the geographical theory provides for that"asymmetry "'or irregular distribution of glacial deposits towhich he refers; since, at every stage of continental elevationand depression, there must have been local changes of circumstances;and the same inequality of temperature in identical« 397 »latitudes which we observe at present must have existed, probablyin a greater degree, in the Glacial age.

The sufficiency of the Lyellian theory to account for thefacts, in so far as plants are concerned, may, indeed, beinferred from the course of the isothermal lines at present.The south end of Greenland is on the latitude of Christiania,in Norway, on the one hand, and of Fort Liard, in the PeaceRiver region, on the other; and while Greenland is clad inice and snow, wheat and other grains, and the ordinary treesof temperate climates, grow at the latter places. It is evident,therefore, that only exceptionally unfavourable circumstancesprevent the Greenland area from still possessing a temperateflora, and these unfavourable circumstances possibly tell evenon the localities with which we have compared it. Further,the mouth of the McKenzie River is in the same latitudewith Disco, near which are some of the most celebratedlocalities of fossil Cretaceous and Tertiary plants. Yet themouth of the McKenzie River enjoys a much more favourableclimate, and has a much more abundant flora than Disco.If North Greenland were submerged, and low land reachingto the south terminated at Disco, and if from any cause eitherthe cold currents of Baffin's Bay were arrested, or additionalwarm water thrown into the North Atlantic by the GulfStream, there is nothing to prevent a mean temperature of45° Fahrenheit from prevailing at Disco; and the estimateordinarily formed of the requirements of its extinct floras is50°, which is probably above, rather than below, the actualtemperature required.

We thus know that the present distribution of land andwater greatly influences climate, more especially by affectingthat of the ocean currents and of the winds, and by thedifferent action of land as compared with water in the receptionand radiation of heat. The present distribution of landgives a large predominance to the Arctic and sub-Arctic regions,« 398 »as compared with the equatorial and with the Antarctic; andwe might readily imagine other distributions that would givevery different results. But this is not an imaginary case, forwe can to some extent restore, on geological grounds, theancient geography of large regions, and can show that it hasbeen very different from that prevailing at present. Weknow also that, while the forms and positions of the greatcontinents have been fixed from a very early date, they haveexperienced many great submergences and re-elevations, andthat these have occurred in somewhat regular sequence, asevidenced by the cyclical alternations of organic limestonesand earthy sediments in the successive great geological periods,each of which, as may be seen in any geological text-book,presents a dip of the continental plateaus, with subsequentelevation, as if the land was subject to a series of regularpulsations.[182]

Finally, the Lyellian theory tends to abate the tendency toimagine portentous and impossible climatal changes; and itinclines geologists to give more attention to the connectionof palæogeography with changes in the life history of theearth.

References:—"Acadian Geology," 1st ed., 1855; 4th ed., 1892. Icebergsof Belle-Isle, and Glaciers of Mont Blanc,Canadian Naturalist,1865. "Notes on Pleistocene of Canada," Montreal, 1871. Papersat various dates in theCanadian Naturalist andCanadian Record ofScience. "The Ice Age in Canada," Montreal, 1892. CanadianPleistocene,London Geological Magazine, March, 1883. Flora ofthe Pleistocene, Dawson and Penhallow.Bulletin of GeologicalSociety of America, vol. i., 1890, p. 311.

THE DISTRIBUTION OF ANIMALS AND PLANTSAS RELATED TO GEOGRAPHICAL AND GEOLOGICALCHANGES.

DEDICATED TO THE MEMORY OF MY LATE FRIEND,

MR. GWYN JEFFRIES,

who so ably investigated the Distribution
of Oceanic Molluska,
more especially in the North Atlantic.

Changes of Climate and of Land and Water withReference to Distribution of Life—Regions ofthe Continents—Insular Faunas and Floras—TheirHistory Applications to Geology and toMan—Geological Time—Theories of IntroductionAnd Migration

CHAPTER XV.

THE DISTRIBUTION OF ANIMALS AND PLANTSAS RELATED TO GEOGRAPHICAL ANDGEOLOGICAL CHANGES.

All are now agreed that to explain the extraordinary andoften apparently anomalous distribution of animals andplants over the surface of the earth, and the occurrence oflike forms in very distant localities, and even on islandsseparated by vast stretches of ocean from one another andfrom the continents, we must invoke the aid of geology. Wemust have reference to those changes of climate and of elevationwhich have occurred in the more recent periods of theearth's history, and must carry with us the idea, at first notapparently very reasonable, that living beings have existedmuch longer than many of the lands which they inhabit,or at least than the present state of those lands in referenceto isolation or continental connection. To what extent wemay further require to call in the aid of varietal or specificmodification to explain the facts, may be more doubtful; andI think we shall find that a larger acquaintance with geologicaltruths would enable us to dispense with the aid of hypothesesof evolution, at least in so far as the local establishment ofnew generic and specific types is concerned.

One of the most remarkable and startling results of geologicalinvestigation, and one which must be accepted as anestablished fact, independently of all theoretical explanations,is that the earth has experienced enormous revolutions of« 402 »climate within comparatively late periods, and since the dateof the introduction of many existing species of animals andplants. To this great truth, in some of its bearings, I haveendeavoured to direct attention in the previous articles. Inthe present case it will be necessary to consider these vicissitudesin their more general aspects, and with some referenceto their effects on the distribution of living beings.

The modern or human period of geology, that in whichman and his contemporaries are certainly known to haveinhabited the earth, was immediately preceded by an age ofclimatal refrigeration known as the Glacial or Ice age. Thiswas further characterized not only by a prevalence of cold,unexampled so far as known either before or since, but byimmense changes of the relative levels of sea and land,amounting, in some cases, at least, to several thousands offeet. The occurrence of these changes is clearly proved bythe undoubted traces of the action of ice, whether land ice orfloating ice, on all parts of our continents, half way to theequator, and by the occurrence of sea terraces and modernmarine shells at high levels on mountains and table-lands.Perhaps we scarcely realize as we should the stupendouscharacter of the changes involved in the driftage of heavy iceover our continents as far south as the latitude of 40°, in thedeposit of boulders on hills several thousands of feet in height,and in the occurrence of shells of species still living in thesea, in beds raised to more than twelve hundred feet aboveits present level. Yet such changes must have occurred inthe latest geological period immediately preceding that inwhich we live. Proceeding farther back in geological time,we find the still more extraordinary fact that in the middle andearlier Tertiary the northern hemisphere enjoyed a climateso much more mild than that which now prevails, that plantsat present confined to temperate latitudes could flourish in« 403 »Greenland and Spitzbergen.[183] The age in which we live isthus one of mediocrity, attaining neither to the Arctic rigour ofthe later Pleistocene, nor to the universal mildness of thepreceding Miocene.

The causes of these changes of climate we have discussedelsewhere. It remains for us now to consider the actualcondition of our present continents, and the bearing of pastconditions on the distribution of their living inhabitants.

In speaking of continents and islands, it may be as well toremark at the outset that all the land existing, or whichprobably has at any time existed, consists of islands greator small. It is all surrounded by the ocean. Two of thegreater masses of land are, however, sufficiently extensive tobe regarded as continents, and from their very extent andconsequent permanence may be considered as the more specialhomes of the living beings of the land. Two other portionsof land, Australia and the Antarctic polar continent, may beregarded either as smaller continents or large islands, butpartake of insular rather than continental characters in theiranimals and plants. All the other portions of land are properlyislands; but while these islands, and more especiallythose in mid-ocean, cannot be regarded as the original homesof many forms of life, we shall find that they have a specialinterest as the shelters and refuges of numerous very ancientand now decaying species.

The two great continents of America and Eurasia have beenthe most permanent portions of the land throughout geologicaltime, some parts of them having always been above water,probably from the Laurentian age downward, though at varioustimes they have been reduced to little more than groups ofislands. On them, and more especially in their more northern« 404 »parts, in which the long continuance of daylight in summerseems in warm periods to have been peculiarly favourable tothe introduction of new vegetable and animal forms, and to thegiving to them that vigour necessary for active colonization,have originated the greater number of the inhabitants of theland.

Regarded as portions of the earth's crust, the continents areareas in which the lateral thrust, caused by the secular contractionof the interior of the earth and unequal settlement ofthe crust, has ridged up and folded the rocks, producingmountain chains. This process began in the earliest geologicalperiods, and has been repeated at long intervals, the originallines of folding guiding those formed in each new thrust proceedingfrom the broad oceanic areas. Along the ridges thusproduced, and in the narrower spaces between them, thegreater part of the sediment carried by water was laid down,thus producing plateaus in connection with the mountain-chains,while the weight of new sediments and the removal ofmatter from other areas by denudation, have been constantlyproducing local depression and elevation. The tendency ofthe ocean to be thrown toward the poles by the retardation ofthe earth's rotation, alternating with great collapses of thecrust at the equator proceeding from the same cause, alongwith the secular cooling, have produced alternate submergenceand emergence of these plateaus. This has beenfurther complicated by the constant tendency of the Arctic andAntarctic currents, aided by ice, to drift solid materials, set freeby the vast denuding action of frost, from the polar to thetemperate regions, and by the further tendency of animal lifeto heap up calcareous accumulations under the warm waters ofthe tropical regions. All these changes, as already stated, haveconspired to modify the directions of the great oceanic currents,and to produce vicissitudes of climate under whichanimals and plants have been subjected in geological time to« 405 »those migrations, extinctions, and renovations of which theirfossil remains and present distribution afford evidence.

Still, it is true that throughout the whole of these greatmutations, since the beginning of geological history, thereseems never to have been any time when the ocean so regainedits dominion as to produce a total extinction of land life;still less was there any time when the necessary conditions ofall the various forms of marine life failed to be found; norwas there any climatal change so extreme as to banish anyof the leading forms of life from the earth. To geologists it isnot necessary to say that the conclusions sketched above arethose that have been reached as the results of long andlaborious investigation, and which have been illustrated andestablished by Lyell, Dana, Wallace,[184] and many other writers.[185]Let us now place beside them some facts as to the presentdistribution of life, and of the agencies which influence it.

Just as political geography sometimes presents boundariesnot in accordance with the physical structure of countries, sothe distribution of animals and plants shows many peculiarand unexpected features. Hence naturalists have divided thecontinents into what Sclater has called zoological regions,which are, so to speak, the great empires of animal life, divisibleoften by less prominent boundaries into provinces. In vegetablelife similar boundaries may be drawn, more or less coincidentwith the zoological divisions. Zoologically, NorthAmerica and Greenland may be regarded as one great region,the Nearctic, or new Arctic, the prefix not indicating that theanimals are newer than those of the old world, which is by nomeans the case. South America constitutes another region« 406 »the Neotropical. If now we turn to the greater Eurasian continent,with its two prolongations to the south in Africa andAustralia, we shall find the whole northern portion, from theAtlantic to the Pacific, constituting one vast region of animallife, the Palearctic, which also includes Iceland and a stripacross North Africa. Africa itself, with Madagascar, whoseallegiance is, however, only partial, constitutes the Ethiopianregion. India, Burmah, the south of China, and certainAsiatic islands form the Oriental region. Australia, NewGuinea, and the Polynesian islands constitute the Australianregion. All of these regions may in a geological point ofview be considered as portions of old and permanent continentalmasses, which, though with movements of elevation anddepression, have continued to exist for vast periods. Some ofthem, however, seem to have enjoyed greater immunity fromcauses of change than others, and present, accordingly, animalsand plants having, geologically speaking, an antique aspect incomparison. In this sense the Australian province may be regardedas the oldest of all in the facies of its animal forms,since creatures exist there of genera and families which havevery long ago become extinct everywhere else. Next in age tothis should rank the Neotropical or South American region,which, like Australia, presents many low and archaic forms ofanimal life. The Ethiopian region stands next to it in this, theOriental and Nearctic next, and last and most modern in itsaspect is the great Palearctic region, to which man himself belongs,and the animals and plants of which vindicate their claimsto youth by that aggressive and colonizing character alreadyreferred to, and which has enabled them to spread themselveswidely over the other regions, even independently of the influenceof man. On the other hand, the animals and plantsof the Australian and South American regions show no suchcolonizing tendency, and can scarcely maintain themselvesagainst those of other regions when introduced among them.« 407 »Thus we have at once in these continental regions a great andsuggestive example of the connection of geographical and geologicaldistribution, the details of which are of the deepest interest,and have not yet been fully worked out. One greatprinciple is, however, sufficiently established; namely, thatthe northern regions have been the birthplace of new forms ofland life, whence they have extended themselves to the south,while the comparative isolation and equable climate of theSouth American and Australian regions have enabled them toshelter and retain the old moribund tribes.

Those smaller portions of land separated from the continentalmasses, the islands properly so called, present, asmight be expected, many peculiar features. Wallace dividesthem into two classes, though he admits that these pass intoeach other. Continental islands are those in the vicinity ofcontinents. They consist of ancient as well as modern rockformations, and contain animals which indicate a formercontinental connection. Some of these are separated fromthe nearest mainland only by shallow seas or straits, and maybe assumed to have become islands only in recent geologicaltimes. Others are divided from the nearest continent by verydeep-water, so that they have probably been longer severedfrom the mainland. These contain more peculiar assemblagesof animals and plants than the islands of the former class.Oceanic islands are more remote from the continents. Theyconsist mostly of rocks belonging to the modern geologicalperiods, and contain no animals of those classes which canmigrate only by land. Such islands may be assumed neverto have been connected with any continent. The study ofthe indigenous population of these various classes of islandsaffords many curious and interesting results, which Wallacehas collected with vast industry and care, and which, on thewhole, he explains in a judicious manner and in accordancewith the facts of geology. When, however, he maintains that« 408 »evolution of the Darwinian type is "the key to distribution,"he departs widely from any basis of scientific fact. This becomesapparent when we consider the following results, whichappear everywhere in the discussion of the various insularfaunas and floras:—(1) None of these islands, however remote,can be affirmed to have been peopled by the spontaneousevolution of the higher animals or plants from lower forms.Their population is in every case not autochthonous, but derived.(2) Even in those which are most distant from thecontinents, and may be supposed to have been colonized invery ancient times, there is no evidence of any very importantmodification of their inhabitants. (3) While the facts pointto the origin of most forms of terrestrial life in the Palearcticand Nearctic regions, they afford no information as to themanner or cause of their origination. In short, so far is evolutionfrom being a key to distribution, that the whole questionwould become much more simple if this element were omittedaltogether. A few examples may be useful to illustrate this, aswell as the actual explanation of the phenomena afforded bylegitimate science.

The Azores are situated in a warm temperate latitudeabout 900 miles west of Portugal, and separated from it by asea 2,500 fathoms in depth. The islands themselves are almostwholly volcanic, and the oldest rocks known in them areof late Miocene age. There is no probability that these islandshave ever been connected with Europe or Africa, nor is thereat present any certainty that they have been joined to oneanother, or have formed part of any larger insular tract. Inthese islands there is only one indigenous mammal, a bat,which is identical with a European species, and no doubtreached the islands by flight. There is no indigenous reptile,amphibian, or fresh-water fish. Of birds there are, exclusiveof waterfowl, which may be regarded as visitors, twenty-twoland birds; but of these, four are regarded as merely accidental« 409 »stragglers, so that only eighteen are permanent residents. Ofthese birds fifteen are common European or African species,which must have flown to the islands, or have been driftedthither in storms. Of the remaining three, two are found alsoin Madeira and the Canaries, and therefore may reasonablybe supposed to have been derived from Africa. One only isregarded as peculiar to the Azores, and this is a bullfinch, sonearly related to the European bullfinch that it may be regardedas merely a local variety. Wallace accounts for these facts bysupposing that the Azores were depopulated by the cold of theGlacial age, and that all these birds have arrived since thattime. There is, however, little probability in such a supposition.He further supposes that fresh supplies of stray birdsfrom the mainland, arriving from time to time, have kept upthe identity of the species. Instead of evolution assisting him,he has thus somewhat to strain the facts to agree with thathypothesis. Similar explanations are given for the still moreremarkable fact that the land plants of the Azores are almostwholly identical with European and African forms. The insectsand the land snails are, however, held to indicate theevolution of a certain number of new specific forms on theislands. The beetles number no less than 212 species, thoughnearly half of them are supposed to have been introduced byman. Of the whole number 175 are European, 19 are foundin Madeira and the Canaries, 3 are American. Fourteenremain to be accounted for, though most of these are closelyallied to European and other species; but a few are quite distinctfrom any elsewhere known. Wallace, however, very trulyremarks that our knowledge of the continental beetles is notcomplete; that the species in question are small and obscure;that they may be survivors of the Glacial period, and may thusrepresent species now extinct on the mainland; and that forthese reasons it may not be irrational to suppose that thesepeculiar insects either still inhabit, or did once inhabit, some« 410 »part of the continents, and may be portions of "ancient andwidespread groups," once widely diffused, but now restrictedto a few insular spots. Among the land snails, if anywhere,we should find evidence either of autochthonous evolution orof specific change. These animals have existed on the earthsince the Carboniferous period, and, notwithstanding theirproverbial slowness and sedentary habits, they have contrivedto colonize every habitable spot of land on the globe—that is,unless in some of these places they have originatedde novo.In the Azores there are sixty-nine species of land snails, ofwhich no less than thirty-two, or nearly one-half, are peculiar,though nearly all are closely allied to European types. What,then, is the origin of these thirty-two species, admitting for thesake of argument that they are really distinct, and not merelyvarietal forms, though it is well known that in this group speciesare often unduly multiplied. Three suppositions are possible,(1) These snails may have originated in the islands themselves,either by creation or evolution from lower forms; say, from seasnails. (2) They may have been modified from modern continentalspecies. (3) They may be unmodified descendantsof species of Miocene or Pliocene age now existing on thecontinents only as fossils. As the islands appear to have existedsince Miocene times, it is no more improbable thatspecies of that or the Pliocene age should have found theirway to them than that modern species should; and as weknow only a fraction of the Tertiary species of Europe orAfrica, it is not likely that we shall be able to identify all ofthese early visitors. Unfortunately no Miocene or Pliocenedeposits holding remains of land snails are known in theAzores themselves, so that this kind of evidence fails us. InMadeira and Porto Santo, however, where there are numerousmodern snails, there are Pliocene beds holding remains of theseanimals. In Madeira there are, according to Lyell, 36 Pliocenespecies, and in Porto Santo 35, and of these only eight« 411 »are extinct. Thus we can prove that many of the peculiarspecies of these islands have remained unchanged since Pliocenetimes. While differing from modern European shells,several of these species are very near to European Miocenespecies. Thus we seem to have evidence in the Madeiragroup, not of modification, but of unchanged survival of Tertiaryspecies long since extinct in Europe. May we not inferthat the same was the case in the Azores? These results arecertainly very striking when we consider how long the Azoresmust have existed as islands, how very rarely animals, and especiallypairs of animals, must have reached them, and howcomplete has been the isolation of these animals, and howpeculiar the conditions to which they have been subjected intheir island retreat.

Other oceanic islands present great varieties of conditions,but leading to similar conclusions. Some, as the Bermudas,seem to have been settled in very modern times with animalsand plants nearly all identical with those of neighbouring countries,though even here it would appear that there are someindigenous species which would indicate a greater age or moreextended lands, now submerged.[186] Others, like St. Helena,are occupied apparently with old settlers, which may have cometo them in early Tertiary, or even in Secondary periods, whichhave long since become extinct on the continents, and whosenearest analogues are now widely scattered over the world.Islands are therefore places of survival of old species—specialpreserves for forms of life lost to the continents. One of themost curious of these is Celebes, which seems to be a survivingfragment of Miocene Asia, which, though so near to that continent,has been sufficiently isolated to preserve its old population« 412 »during all the vast lapse of time between the middleTertiary and the present period. This is a fact which givesto the oceanic islands the greatest geological interest, andinduces us to look into their actual fauna and flora for therepresentatives of species known on the mainland only asfossils. It is thus that we look to the marsupials of Australiaas the nearest analogues of those of the Jurassic of Europe,and that we find in the strange Barramunda (ceratodus) of itsrivers the only survivor of a group of fishes once widely distributed,but which has long since perished elsewhere.

Perhaps one of the most interesting examples of this isfurnished by the Galapagos Islands, an example the more remarkablethat no one who has read in Darwin's fascinating"Journal" the description of these islands, can have failed toperceive that the peculiarities of this strange Archipelago musthave been prominent among the facts which first planted inhis mind the germ of that theory of the origin of species whichhas since grown to such gigantic dimensions. It is curiousalso to reflect that had the bearing of geological history on thefacts of distribution been as well known forty years ago as it isnow, the reasoning of the great naturalist on this and similarcases might have taken an entirely different direction.

The Galapagos are placed exactly on the equator, and thereforeout of reach of even the suspicion of having been visitedby the glacial cold, though from their isolation in the ocean,and the effects of the currents flowing along the Americancoast, their climate is not extremely hot. They are 600 mileswest of South America, and the separating ocean is in someparts 3,000 fathoms deep. The largest of the islands is 75miles in length, and some of the hills attain an elevation ofabout 4,000 feet, so that there are considerable varieties ofstation and climate. So far as is known they are wholly volcanic,and they may be regarded as the summits of submergedmountains not unlike in structure to the Andes of the mainland.« 413 »Their exact geological age is unknown, but there is noimprobability in supposing that they may have existed withmore or less of extension since the Secondary or Mesozoicperiod. In any case their fauna is in some respects a survivalof that age. Lyell has truly remarked, "In the fauna of theGalapagos Islands we have a state of things very analogous tothat of the Secondary period."

Like other oceanic islands, the Galapagos have no indigenousmammals, with the doubtful exception of a South Americanmouse; but, unlike most others, they are rich in reptiles. Atthe head of these stand several species of gigantic tortoises.This group of animals, so far as known, commenced its existencein the Eocene Tertiary; and in this and the Mioceneperiod still more gigantic species existed on the continents. Ithas been supposed that at some such early date they reachedthe Galapagos from South America. Another group of Galapaganreptiles, perhaps still more remarkable, is that of iguana-likelizards of the genusAmblyrhyncus, which are vegetablefeeders,—one of them browsing on marine weeds. They recallthe great iguana-like reptiles of the European Wealden, andstand remote from all modern types. There are also snakes oftwo species, but these are South American forms, and mayhave drifted to the islands in comparatively recent times onfloating trees. The birds are a curious assemblage. A few arecommon American species, like the rice bird. Others arequaint and peculiar creatures, allied to South American birds,but probably representing forms long since extinct on thecontinent. The bird fauna, as Wallace remarks, indicates thatsome of these animals are old residents, others more recentarrivals; and it is probable that they have arrived at varioustimes since the early Tertiary. He assumes that the earlierarrivals have been modified in the islands "into a variety ofdistinct types"; but the only evidence of this is that some ofthe species are closely related to each other. It is more likely« 414 »that they represent to our modern eyes the unmodified descendantsof continental birds of the early Tertiary. Darwin remarksthat they are remarkably sombre in colouring for equatorialbirds; but perhaps their ancestors came from a coolerclimate, and have not been able to don a tropical garb; orperhaps they belong to a far-back age, when the vegetable kingdomalso was less rich in colouring than it is at present, andthe birds were in harmony with it. This, indeed, seems stillto be the character of the Galapagos plants, which Darwinsays have "a wretched, weedy appearance," without gay flowers,though later visitors have expressed a more favourable opinion.

These plants are in themselves very remarkable, for they arelargely peculiar species, and are in many cases confined to particularislands, having apparently been unable to cross from oneisland to another, though in some way able to reach the group.The explanation is that they resemble North American plants,and came to the Galapagos at a time when a wide strait separatedNorth and South America, allowing the equatorial currentto pass through, and drift plants to the Galapagos, wherethey have been imprisoned ever since. This was probably inMiocene times, and when we know more of the Miocene floraof the southern part of North America we may hope to recoversome of the ancestors of the Galapagos plants. In the meantimetheir probable origin and antiquity, as stated by Wallace,render unnecessary any hypothesis of modification.

Before leaving this subject, it is proper to observe that onthe continents themselves there are many remarkable cases ofisolation of species, which help us better to understand theconditions of insular areas. The "variable hare" of theScottish highlands, and of the extreme north of Europe, appearsagain in the Alps, the Pyrenees, and the Caucasus, being inthese mountains separated by a thousand miles of apparentlyimpassable country from its northern haunts. It no doubt extendeditself over the intervening plains at a time when Europe« 415 »was colder than at present. Another curious case is that of themarsh-tit of Europe. This little bird is found throughout south-westernEurope. It reappears in China, but is not knownanywhere between. In Siberia and northern Europe thereis, however, a species or distinct race which connects theseisolated patches. In this case, if the Siberian species is trulydistinct, we have a remarkable case of isolation and of thepermanence of identical characters for a long time; for in thatcase this bird must be a survivor of the Pliocene or Miocenetime. On the other hand, if, as is perhaps more likely, themarsh-tit is only a local variety of the Siberian species, we havean illustration of the local recurrence of this form when theconditions are favourable, even though separated by a greatspace and long time.

The study of fossils gives us the true meaning of such facts,and causes us to cease to wonder at any case of local repetitionof species, however widely separated. The "big trees" ofCalifornia constitute a remarkable example. There are atpresent two very distinct species of these trees, both foundonly in limited areas of the western part of North America.Fossil trees of the same genus (Sequoia) occur as far back asthe Cretaceous age; but in this age ten or more species areknown. Nor are they confined to America, but occur invarious parts of the Eurasian continent as well. Two of theLower Cretaceous species are so near to the two modern onesthat even an unbeliever in evolution may suppose them to bepossible ancestors; the remaining eight are distinct, but someof them intermediate in their characters. In the Tertiaryperiod, intervening between the Cretaceous and the modern,fourteen species ofSequoia are believed to have been recognised,and they appear to have existed abundantly all over thenorthern hemisphere. Thus we know that these remarkableCalifornian giants are the last remnant of a once widely distributedgenus, originating, as far as known, in the Cretaceous age.« 416 »Now had a grove ofSequoias, however small, survived anywherein Europe or Asia, and had we no knowledge of thefossil forms, we might have been quite at a loss to account fortheir peculiar distribution. The fossil remains of the Tertiaryrocks, both animal and vegetable, present us with many instancesof this kind.

The discussion of the distribution of animals and plants,when carried on in the light of geology, raises many interestingquestions as to time, which we have already glanced at, butwhich deserve a little more attention. As to the vast durationof geological time all geologists are agreed. It is, however,now well understood that science sets certain limits to the timeat our disposal. Edward Forbes humorously defined a geologistto be "an amiable enthusiast who is content if allowed toappropriate as much as he pleases of that which other menvalue least, namely, past time "; but now even the geologistis obliged to be content with a limited quantity of this commodity.

The well-known estimate of Lord Kelvin gave one hundredmillions of years as the probable time necessary for the changeof the earth from the condition of a molten mass to that whichwe now see. On this estimate we might fairly have assumedfifty millions of years as covering the time from the Laurentianage to the modern period. The great physicist has, however,after allowing us thus much credit in the bank of time, "suddenlyput up the shutters and declared a dividend of less thanfour shillings in the pound."[187] In other words, he has reducedthe time at our disposal to twenty millions of years. Otherphysicists, reasoning on the constitution of the sun, agreewith this latter estimate, and affirm that "twenty millions ofyears ago the earth was enveloped in the fiery atmosphere ofthe sun."[188] Geology itself has attempted an independent calculation« 417 »based on the wearing down of our continents, whichappears to proceed at the rate of about a foot in four or fivethousand years, and on the time required to deposit the sedimentsof the several geological formations, estimated at about70,000 feet in thickness. These calculations would give us,say, eighty-six millions of years since the earth began to havea solid crust, which would, like Lord Kelvin's earlier estimate,give us nearly fifty millions of years for the geological timesince the introduction of life. The details of the several estimatesmade it would be tedious and unprofitable to enter into,but I may state as my own conclusion, that the modern rates ofdenudation and deposit must be taken as far below the average,and that perhaps the estimate stated by Wallace on data suppliedby Houghton, namely, twenty-eight millions, may be notfar from the truth, though perhaps admitting of considerableabatement.

This reduced estimate of geological time would still givescope enough for the distribution of animals and plants, butit will scarcely give that required by certain prevalent theoriesof evolution. When Darwin says, "If the theory (of naturalselection) be true, it is indisputable that before the lowest Cambrianstratum was deposited long periods elapsed, as long as,or probably far longer than, the whole interval from the Cambrianto the present day," he makes a demand which geologycannot supply; for independently of our ignorance of anyformations or fossils, except those included in the Archæan,to represent this vast succession of life, the time requiredwould push us back into a molten state of the planet. Thisdifficulty is akin to that which meets us with reference to theintroduction of many and highly specialized mammals in theEocene, or of the forests of modern type in the Cretaceous.To account for the origin of these by slow and gradual evolutionrequires us to push these forms of life so far back intoformations which afford no trace of them, but, on the contrary,« 418 »contain other creatures that appear to be exclusive of them,that our faith in the theory fails. The only theory of evolutionwhich seems to meet this difficulty is that advanced byMivart, Leconte, and Saporta, of "critical periods," or periodsof rapid introduction of new species alternating with othersof comparative inaction. This would much better accordwith the apparently rapid introduction of many new forms oflife over wide regions at the same period. It would alsoapproach somewhat near, in its manner of stating the problemto be solved, to the theory of "creation by law" as held bythe Duke of Argyll, or to what may be regarded as "mediatecreation," proceeding in a regular and definite manner, butunder laws and forces as yet very imperfectly known, throughoutgeological time.

It seems singular, in view of the facts of palæontology, thatevolutionists of the Darwinian school are so wedded to theidea of one introduction only of each form of life, and itssubsequent division by variation into different species, as itprogressively spreads itself over the globe, or is subjected todifferent external conditions. It is evident that a little furtherand very natural extension of their hypothesis would enablethem to get rid of many difficulties of time and space. Forexample, certain Millipedes and Batrachians are first known inthe coal formation, and this not in one locality only, but indifferent and widely separated regions. If they took beginningin one place, and spread themselves gradually overthe world, this must have required a vast lapse of time—morethan we can suppose probable. But if, in the coal-formationage, a worm could anywhere change into a Millipede, or a fishinto a Batrachian, why might this not have occurred in manyplaces at once? Again, if the oldest known land snails occurin the coal formation, and we find no more specimens till amuch later period, why is it necessary to suppose that thesecreatures existed in the intervening time, and that the later« 419 »species are the descendants of the earlier? Might not theprocess have been repeated again and again, so as to giveanimals of this kind to widely separated areas and successiveperiods without the slow and precarious methods of continuousevolution and migration? This apparent inconsistency strikesone constantly in the study of discussions of the theory ofderivation in connection with geographical and geological distribution.We constantly find the believers in derivationlaboriously devising expedients for the migration of animalsand plants to the most unlikely places, when it would seemthat they might just as well have originated in those places bydirect evolution from lower forms. Those who believe in aseparate centre of creation for each species must of courseinvoke all geological and geographical possibilities for thedispersion of animals and plants; but surely the evolutionist,if he has faith in his theory, might take a more easy andobvious method, especially when in any case he is under thenecessity of demanding a great lapse of time. That he doesnot adopt this method perhaps implies a latent suspicionthat he must not repeat his miracle too often. He also perceivesthat if repeated and unlimited evolution of similarforms had actually occurred, there could have remained littlespecific distinctness, and the present rarity of connecting linkswould not have occurred. Further, a new difficulty wouldhave sprung up in the geographical and geological relations ofspecies and genera, which would then have assumed too muchof the aspect of a preconceived plan. It is only fair to awell-known and somewhat extreme European evolutionist,Karl Vogt, to state that he launches boldly into the ocean ofmultiple evolution, not fearing to hold that identical speciesof mollusks have been separately evolved in separate Swisslakes, and that the horse has been separately evolved inAmerica and in Europe, in the former along a line beginningwith Eohippus, and in the latter along an entirely separate line,« 420 »commencing withPalæotherium. The serious complicationsresulting from such admissions are evident, but Vogt deservescredit for faith and consistency beyond those of his teachers.

With reference to the actual distribution of species, thequestion of time becomes most important when applied tothe Glacial period, since it is obvious that much of the presentdistribution must have been caused, or greatly modified,by that event. The astronomical theory would place theclose of the Glacial age as far back as 70,000 or 80,000 yearsago. But we have already seen in the chapter on that periodthat geological facts bring its close to only from 10,000 to7,000 years before our time. If we adopt the shorter estimatesafforded by these facts, it will follow that the submergencesand emergences of land in the Glacial ages were morerapid than has hitherto been supposed, and that this wouldreact on our estimate of time by giving facilities for morerapid denudation and deposition. Such results would greatlyshorten the duration assignable to the human period. Theywould render it less remarkable that no new species of animalsseem to have been introduced since the Glacial age, that manyinsular faunas belong to far earlier times, and that no changeseven leading to the production of well-marked varieties haveoccurred in the post-glacial or modern age.

In conclusion, does all this array of fact and reasoningbring us any nearer to the comprehension of that "mystery ofmysteries," the origin and succession of life? It certainly doesnot enable us to point to any species, and to say precisely here,at this time and thus it orginated. If we adopt the theoryof evolution, the facts seem to restrict us to that form of itwhich admits paroxysmal or intermittent introduction ofspecies, depending on the concurrence of conditions favourableto the action of the power, whatever it may be, which producesnew organisms. Nor is there anything in the facts ofdistribution to invalidate the belief in creation, according to« 421 »definite laws, if that really differs in its nature from certainforms of the hypothesis of evolution. We have also learnedthat, time being given, animals and plants manifest wonderfulpowers of migration, that they can vary within considerablelimits without ceasing to be practically the same species, andthat under certain conditions they can endure far longer insome places than in others. We also see evidence that it isnot on limited islands, but on the continents, that land animalsand plants have originated, and that swarms of new andvigorous species have issued from the more northern regionsin successive periods of favourable Arctic climate. The lastof these new swarms or "centres of creation," that withwhich man himself is more closely connected, belongs to thePalearctic region. We have already seen that in every geologicalperiod, when the submerged continental plateaus werepervaded by the warm equatorial waters, multitudes of newmarine species appear. In times when, on the contrary, thecolder Arctic currents poured over these submerged surfaces,carrying mud and stones, great extinction took place, butcertain northern forms of life swarmed abundantly, and whenelevation took place, marine species became extinct or wereforced to migrate. Everywhere and at all times multiplicationof species was promoted by facilities for expansion. The greatlimestones of our continents, full of corals and shells of newspecies, belong to times when the ocean spread itself over thecontinental plateaus, affording wide, untenanted areas ofwarm and shallow water. The introduction of new faunasand floras on the land belongs to times when vast supplies offood for plants and animals and favourable conditions ofexistence were afforded by the emergence of new landspossessing fertile soils and abundantly supplied with light,heat, and moisture. Thus geological and geographical factsconcur with ordinary observation and experience in referenceto varietal forms, in testifying that it is not mere struggle for« 422 »existence, but facilities for easy existence and rapid extension,that afford the conditions necessary for new and advancedforms of life. These considerations do not, of course, reachto the first cause of the introduction of species, nor even tothe precise mode in which this may have acted in any particularcase: but perhaps we cannot fully attain to this by anyprocess of inductive inquiry. The study of geographical distribution,'therefore, does not enable us to solve the questionof the origin of specific types, but, on the contrary, points tomarvellous capacities for migration and a wonderful tenacityof life in species. In these respects, however, it is a studyfull of interest, and in nothing more so than in the evidencewhich it affords of the practically infinite provisions made forthe peopling of every spot of land or sea with creatures fittedto flourish and enjoy life therein, and to carry on the greatand progressive plan of the Creator.

References:—Continental and Island Life,Princeton Review, July, 1881.Address to American Association, 1883. Papers and Addresses toNatural History Society,Canadian Naturalist, Montreal. "TheStory of the Earth and Man," 1st ed., 1873, 9th ed., London,1887.

ALPINE AND ARCTIC PLANTS IN CONNECTIONWITH GEOLOGICAL HISTORY

DEDICATED TO THE MEMORY OF

DR. ASA GRAY,

THE GREATEST AND MOST PHILOSOPHICAL EXPONENT
OF AMERICAN BOTANY.

A Botanico-Geological Excursion in the WhiteMountains—Distribution and Migrations of AlpinePlants—Relations to the Later GeologicalChanges—Bearing on the Vegetation of EarlierTimes

CHAPTER XVI.

The group of the White Mountains is the culminating pointof the northern division of the great Appalachian range, extendingfrom Tennessee to Gaspé in a south-west and north-eastdirection, and constituting the breast bone of the North Americancontinent. This great ridge or succession of ridges hasits highest peaks near its southern extremity, in the BlackMountains; but these are little higher than their northernrivals, which at least hold the undisputed distinction of beingthe highest hills in north-eastern America. As Guyot [189] haswell remarked, the White Mountains do not occur in the generalline of the chain, but rather on its eastern side. The centralpoint of the range, represented by the Green Mountains andtheir continuation, describes a great curve from Gaspé to thevalley of the Hudson, and opposite the middle of the concaveside of this curved line towers the almost isolated group of theWhite Hills. On the other side is the narrow valley of LakeChamplain, and beyond this the great isolated mass of the AdirondackMountains, nearly approaching in the altitude of theirhighest peaks, and greatly exceeding in their geological age, theopposite White Mountain group. The Appalachian range isthus, in this part of its course, supported on either side by outliershigher than itself. The dense grouping of mountains inthis region is due to the resistance offered by the old Adirondack« 426 »mass to the westward thrust of the Atlantic and the subsequentpiling up against this mass of the ridges of palæozoicsediments. Southward of this the Atlantic thrust has driventhese ridges back in a great bend to the westward.

My present purpose is not to give a general geographical orgeological sketch of the White Mountains, but to direct attentionto the vegetation which clothes their summits, and itsrelation to the history of the mountains themselves. For thispurpose I may first shortly describe the appearances presentedin ascending the highest of them, Mount Washington, andthen turn to the special points to which these notes relate.

In approaching Mount Washington by the Grand TrunkRailway, the traveller has ascended from the valley of the St.Lawrence to a height of 802 feet at the Alpine House at Gorham.Thence, in a distance of about eight miles along thebank of the Peabody River, to the Glen House, he ascends tothe elevation of 1,632 feet above the sea; and it is here, or immediatelyopposite the Glen House, that the actual ascentbegins. The distance from the Peabody River, opposite thehotel, to the summit is nine miles, and in this distance we ascend4,656 feet, the total height being 6,288 feet above thesea.[190] Formerly only a bridle path led up this ascent; but nowaccess can be had to the summit by carriage roads and by rail.

These royal roads to the summit are, however, too democraticfor the taste of some visitors, who mourn the olden daysof ponies, guides and adventures; and though they give anexcellent view of the geological structure of the mountain, theydo not afford a good opportunity for the study of the alpineflora, which is one of the chief attractions of Mount Washington.For this reason, though I availed myself of the new road forgaining a general idea of the features of the group, I determinedto ascend by Tuckerman's Ravine, a great chasm in the mountainside, named in honour of the indefatigable botanist of the« 427 »North American lichens.[191] I was aided in this by the kindnessof a gentleman of Boston, well acquainted with these hills, andpassionately fond of their scenery.[192] Our party, in addition tothis gentleman and myself, consisted of two ladies, two children,and two experienced guides, whose services were of the utmostimportance, not only in indicating the path, but in removingwindfalls and other obstructions, and in assisting members ofthe party over difficult and dangerous places.

We followed the carriage road for two miles, and then struckoff to the left by a bridle path that seemed not to have beenused for several years the gentlemen and guides on foot, theladies and children mounted on the sure-footed ponies used inthese ascents. Our path wound around a spur of the mountain,over rocky and uneven ground, much of the rock being micaslate, with beautiful cruciform crystals of andalusite, whichseemed larger and finer here than in any other part of themountain which I visited. At first the vegetation was notmaterially different from that of the lower grounds, but as wegradually ascended we entered the "evergreen zone," and passedthrough dense thickets of small spruces and firs, the groundbeneath which was carpeted with moss, and studded with animmense profusion of the delicate little mountain wood sorrel(Oxalis acetosella), a characteristic plant of wooded hills onboth sides of the Atlantic, and which I had not before seen insuch profusion since I had roamed on the hills of LochaberLake in Nova Scotia. Other herbaceous plants were rare, exceptferns and club mosses; but we picked up an aster (A.acuminatus), a golden rod (Solidago thyrsoidea), and the verypretty tway blade (Listera cordata), a species [193] very widely distributedthroughout British America.

In ascending the mountain directly, the spruces of this zonegradually degenerate, until they present the appearance of littlegnarled bushes, flat on top and closely matted together, so thatexcept where paths have been cut, it is almost impossible topenetrate among them. Finally, they lie flat on the ground,and become so small that, as Lyell remarks, the reindeer mossmay be seen to overtop the spruces. This dwarfing of thespruces and firs is the effect of adverse circumstances, and oftheir struggle to extend their range toward the summit. Yearby year they stretch forth their roots and branches, bendingthemselves to the ground, clinging to the bare rocks, and availingthemselves of every chasm and fissure that may cover theiradvance; but the conditions of the case are against them. Iftheir front advances in summer, it is driven back in winter, andif in a succession of mild seasons they are able to gain a littleground, less favourable seasons recur, and wither or destroy theholders of their advanced positions. For thousands of yearsthe spruces and firs have striven in this hopeless escalade, butabout 4,000 feet above the sea seems to be the limit of theiradvance, and unless the climate shall change, or these treesacquire a new plasticity of constitution, the genusAbies cannever displace the hardier alpine inhabitants above, and plantits standard on the summit of Mount Washington.

I was struck by the similarity of this dwarfing of the upperedges of the spruce woods, to that which I have often observedon the exposed northern coasts of Cape Breton and PrinceEdward Island, where the woods often gradually diminish inheight toward the beach or the edge of a cliff, till the externalrow of plants clings closely to the soil, or rises above it only afew inches. The causes are the same, but the appearance ismore marked on the mountain than on the coast. It is in miniaturea picture of the gradual dwarfing of vegetation in the greatbarren grounds of Arctic America.

On the path which we followed, before we reached the upper« 429 »limit of trees, we arrived at the base of a stupendous cliff,forming the termination of a promontory or spur of the mountain,separating Tuckerman's Ravine from another deep depressionknown as the Great Gulf. From the top of thisprecipice poured a little cascade, that lost itself in spray longbefore it touched the tops of the trees below. The view at thisplace was the most impressive that it was my fortune to see inthese hills.

Opposite the mouth of the Great Gulf, and I suppose at aheight of about 3,000 feet, is a little pond known as HermitLake. It is nearly circular, and appears to be retained by aridge of stones and gravel, perhaps an old moraine or sea beach.On its margin piped a solitary sandpiper, a few dragon fliesflitted over its surface, and tadpoles in the bottom indicatedthat some species of frog dwells in its waters. High overhead,and skirting the edges of the precipices, soared an eagle,intent, no doubt, on the hares that frequent the thickets ofthe ravines.

Before we reached Hermit Lake we had been obliged toleave our horses, and now we turned aside to the left and enteredTuckerman's ravine, where there is no path, but merely the bedof a brook, whose cold clear water tumbles in a succession ofcascades over huge polished masses of white gneiss, while onboth sides of it the bottom of the ravine is occupied by denseand almost impenetrable thickets of the mountain alder (Alnusviridis).

Tuckerman's Ravine has been formed originally either by asubsidence of a portion of the mountain side, or by the actionof the sea. It is, like most of the ravines and "gulfs" of thesehills, a deep cut or depression bounded by precipitous sidesand terminating at the top in a similarly precipitous manner.It must at one period have been in part filled with boulder clay,steep banks of which still remain in places on its sides; andextensive landslips have occurred, by which portions of the limiting« 430 »cliffs have been thrown toward the centre of the valley, inlarge piles of angular blocks of gneiss and mica slate, in thespaces between which grow gnarled birches and spruces thatmust be used as ladders and bridges whereby to scramble fromblock to block, by every one who would cross or ascend one ofthese rivers of stones. These "gulfs" of the White Mountainsare similar to the "cirques" of the Alps, and various explanationshave been given of their origin. To me they have alwaysappeared to be of the same nature with the "chines" or bayswith precipitous ends seen on rocky coasts, and which are producedby the action of the surf on the softer beds or veins ofrock. They testify to the raging of the waves for long agesagainst the sides of what are now lofty mountains. This, weknow, must have occurred in the great Pleistocene submergence;but in mountains so old as those now in question, it may havein part been effected in previous periods.

At the head of the ravine we paused to rest, to admire thewild prospect presented by the ravine and its precipitous sides,and to collect the numerous plants that flower on the surroundingslopes and precipices. Here, on the 19th of August, wereseveral large patches of snow, one of them about a hundredyards in length. From the precipice at the head of the ravinepoured hundreds of little rills, and several of them collectinginto a brook, had excavated in the largest mass of snow a longtunnel or cavern with an arched and groined roof. Under thefront of this we took our mid-day meal, with the hot Augustsun pouring its rays in front of us, and icy water gurgling amongthe stones at our feet. Around the margin of the snow thevegetation presented precisely the same appearances whichare seen in the low country in March and April, when thesnow banks have just disappeared—the old grass bleachedand whitened, and many perennial plants sending up blanchedshoots which had not yet experienced the influence of thesunlight.

The vegetation at the head of this ravine and on the precipicesthat overhang it, presents a remarkable mixture of lowlandand mountain species. The head of the ravine is not so highas the limit of trees already stated, but its steep sides riseabruptly to a plateau of 5,000 feet in height, intervening betweenMount Washington and Mount Munro, and on which are thedark ponds or tarns known as the Lakes of the Clouds, formingthe sources of the Amonoosook river, which flows in the oppositedirection. From this plateau many alpine plants stretch downwardinto the ravine, while lowland plants, availing themselvesof the shelter and moisture of thiscul-de-sac, climb boldlyupward almost to the higher plateau. Other species again occurhere, which are found neither on the exposed alpine summitsand ridges, nor in the low country. Conspicuous among thehardy climbers are two coarse and poisonous weeds of the rivervalleys, that look like intruders into the company of the moredwarfish alpine plants;—the cow parsnip (Heracleum lanatum)and the white hellebore (Veratrum viride). Both of these plantswere seen struggling up through the ground at the margin of thesnow, and climbing up moist hollows almost to the tops of theprecipices. Some specimens of the latter were crowded withthe infant caterpillars of a mountain butterfly or moth. Lessconspicuous, and better suited to the surrounding vegetation,were the bluets (Oldenlandia cœrulea), now in blossom here, asthey had been months before in the low country, the dwarfcornel (Cornus Canadensis) and the twin-flower (Linnæa borealis),the latter reaching quite to the plateau of the lake of theClouds, and entering into undisputed companionship with thetruly alpine plants, though it is also found at Gorham, 4,000feet lower.

Of the plants which seemed to be confined, or nearly so, tothe upper part of the ravine, one of the most interesting wasthe northern painted cup (Castelleia septentrionalis), a plantwhich abounds on the coast of Labrador, and extends thence« 432 »through all Arctic North America to the Rocky Mountains,and is perhaps identical with theC. Sibirica of Northern Asiaand theC. pallida of Northern Europe. Large beds of it werecovered with their pale yellow blossoms on the precipitousbanks overhanging the head of the ravine. With the paintedcup, and here alone, was another beautiful species of a verydifferent order, the northern green orchis (Platanthera hyperborea),a plant which occurs, though rarely, in Canada, but ismore abundant to the northward. Here also occurred Peck'sgeum (G. radiatum, var.),Arnica mollis, and several other interestingplants.

Of the alpine plants which descend into the ravine, the mostinteresting was the Greenland sand-wort (Arenaria (Alsine)Grænlandica) which was blooming abundantly, with its clustersof delicate white flowers, on the very summit of the mountain,and could be found here and there by the side of the brook inthe bottom of the ravine.

Clambering by a steep and dangerous path up the right sideof the ravine, we reach almost at once the limit, beyondwhich the ordinary flora of New England can extend no longer,and are in the presence of a new group of plants comparable withthose of Labrador and Greenland. Here, on the plateau of theLake of the Clouds, the traveller who has ascended the giddyprecipices overhanging Tuckerman's Ravine is glad to pause, thathe may contemplate the features of the new region which hehas reached. We have left the snow behind us, except a smallpatch which lingers on the shady side of Mount Munro; forit is only in the ravines into which it has drifted a hundredfeet deep or more, that it can withstand the summer heat untilAugust. We stand on a dreary waste of hard angular blocks ofmica slate and gneiss that lie in rude ridges, as if they had beenroughly raked up by Titans, who might have been trying to pileMonro upon Washington, but which seem to be merely theremains of the original outcropping edges of the rocks broken up« 433 »by the frost, but not disturbed or rounded by water.[194] Behindus is the deep trench-like ravine out of which we have climbed;on the left hand a long row of secondary summits stretchingout from Mount Washington to the south-westward, and designatedby the names of a series of American statesmen. In frontthis range descends abruptly in great wooded spurs or buttressesto the valley of the Amonoosook, which shines in silveryspots through the trees far below. On our right hand towersthe peak of Mount Washington, still more than a thousand feetabove us, and covered with angular blocks, as if it were a pileof fragments rather than a solid rock. These stones all aroundand up to the summit of the mountain, are tinted pale green bythe map lichen (Lecidea geographica), which tinges in the sameway the alpine summits of European mountains. Between theblocks and on their sheltered sides nestle the alpine floweringplants, of which twenty species or more may be collected onthis shoulder of the mountain, and some of which extend themselvesto the very summit, whereAlsine Grœnlandica and thelittle tufts of deep green leaves ofDiapensia Lapponica with afew Carices seem to luxuriate. Animal life accompanies theseplants to the summit, near which I saw a family of the snowbird, evidently summer residents here, instead of seeking thefar north for a breeding place, as is the habit of the species, anda number of insects, conspicuous among which was a brownbutterfly of the genusHipparchia. Shortly before sundown,when the thermometer at the summit house was fast settlingtoward the freezing point, a number of swallows were hawkingfor flies at a great height above the highest peak. To what« 434 »species they belonged I could not ascertain. Possibly the cliffswallows find breeding places in the sides of the ravines,and rise over the hill top to bask in the sunbeams, after themountain has thrown its shadows over their homes.

To return to the Alpine flora which is peculiar to the peaksof these mountains—are the species comprising it autochthonesoriginating on these hill tops, and confined to them, or are theyplants occurring elsewhere, and if so, where? and how andwhen did they migrate to their present abodes? These arequestions which must occur to every one interested in geology,botany, or physical geography.

Not one of the Alpine plants of Mount Washington is peculiarto the place. Nearly all of them are distinct from the plants ofthe neighbouring lowlands, but they occur on other hills of NewEngland and New York, and on the distant coasts of Labradorand Greenland, and some of them are distributed over theArctic regions of Europe, Asia and America. In short, theyare stragglers from that Arctic flora which encompasses thenorth polar region, and extends in promontories and islandsalong the high cold mountain summits far to the southward.

Some of the humble flowerless plants of these hills are ofnearly world-wide distribution. I have already noticed the palegreen map lichen which tints the rocks of the Pyrenees, theAlps, and the Scottish Highlands; and the curious ring lichen(Parmelia centrifuga) paints its conspicuous rings and arcs ofcircles alike on Mount Washington and the Scottish hills. Alittle club moss (Lycopodium selago) is not only widely distributedover the northern hemisphere, but Hooker has recognisedit in the Antarctic regions. Not long ago we unrolled inMontreal an Egyptian mummy, preserved in the oldest style ofembalming, and found that, to preserve the odour of the spices,quantities of a lichen (Evernia furfuracea) had been wrappedaround the body, and have no doubt been imported into Egyptfrom Lebanon, or the hills of Macedonia, for such uses. Yet« 435 »the specimens from this old mummy were at once recognisedby Professor Tuckerman as identical with this species as itoccurs on the White Hills and on Katahdin, in Maine. Thesefacts are, however, easily explicable in comparison with thosethat relate to the flowering plants.

The spores of lichens and mosses float lighter than the lightestdown in the air, and may be wafted over land and sea, anddropped everywhere to grow where conditions may be favourable.We can form an idea of this from the fact that the volcanicdust, consisting of shreds of pumice, etc., thrown up bythe eruption of Krakatoa, in 1883, was wafted, in a day or two,round the globe, and remained suspended for months in theatmosphere. The spores of many cryptogamous plants areeven lighter than volcanic dust. Had the Egyptian embalmerused some of the first created specimens ofEvernia furfuracea,it might easily, within the three thousand years or so since hiswork was done, have floated round the world and establisheditself on the White Hills. But, as we shall see, neither the timenor means would suffice for the flowering plants. The onlyavailable present agency for the transmission of these would bein the crops or the plumage of the migratory birds; and whenwe consider how few of these, on their migrations from thenorth, could ever alight on these hills, and the rarity of theircarrying seeds in a state fit to vegetate, and further, that few ofthese plants produce fruits edible by birds, or seeds likely toattach themselves to their feathers, the chances become infinitelysmall of their transmission in this way. The most profitablecourse of investigation in this and most other cases ofapparently unaccountable geographical distribution, is to inquireas to the past geological conditions of the region, and howthese may have affected the migrations of plants.

The earlier geological history of these mountains far antedatesour existing vegetation. It belongs, in the first instance,to the Archæan and early Palæozoic period, in which the« 436 »materials of these mountains were accumulating, as beds of clayand gravel, in the sea bottom. These were buried under greatdepths of newer deposits, and were folded and crumpled bylateral pressure, baked and metamorphosed into their presentcrystalline condition.[195] Again heaved above the sea level, theywere hewn by the action of the waves to some degree into theirpresent forms, and constituted part of the nucleus of theAmerican continent in the later Tertiary period, when they wereprobably higher than now. They were again, with all the surroundingland, depressed under the sea in the Pleistoceneperiod, and in the Post-glacial or modern, slowly upheavedagain to their present height. These last changes are those thatconcern their present flora, and their relations to it are wellstated by Sir C. Lyell in the following passages from his interestingaccount of his ascent of Mount Washington in 1840.

"If we attempt to speculate on the manner in which thepeculiar species of plants now established on the highest summitsof the White Mountains were enabled to reach thoseisolated spots, while none of them are met with in the lowerlands around, or for a great distance to the north, we shall findourselves trying to solve a philosophical problem which requiresthe aid, not of botany alone, but of geology, or a knowledge ofthe geographical changes which immediately preceded thepresent state of the earth's surface. We have to explain howan Arctic flora, consisting of plants specifically identical withthose which inhabit lands bordering the sea in the extremenorth of America, Europe and Asia, could get to the top ofMount Washington. Now geology teaches us that the speciesliving at present on the earth are older than many parts of ourexisting continents; that is to say, they were created before alarge portion of the existing mountains, valleys, plains, lakes,« 437 »rivers, and seas were formed. That such must be the case inregard to Sicily I announced my conviction in 1833, after firstreturning from that country; and a similar conclusion is noless obvious to any naturalist who has studied the structure ofNorth America, and observed the wide area occupied by themodern or glacial deposits, in which marine shells of living butnorthern species are entombed. It is clear that a great portionof Canada, and the country surrounding the great lakes, wassubmerged beneath the ocean when recent species of molluskaflourished, of which the fossil remains occur about 500 feetabove the level of the sea at Montreal. Lake Champlain was agulf or strait of the sea at that period, large areas in Maine wereunder water, and the White Mountains must then have constitutedan island or group of islands. Yet, as this period is somodern in the earth's history as to belong to the epoch of theexisting marine fauna, it is fair to infer that the Arctic flora, nowcontemporary with this, was then also established on the globe.

"A careful study of the present distribution of animals andplants over the globe has led nearly all the best naturalists tothe opinion that each species had its origin in a single birthplace,and spread gradually from its original centre to all accessiblespots fit for its habitation, by means of the powers ofmigration given to it from the first. If we adopt this view, orthe doctrine of specific centres, there is no difficulty in comprehendinghow theCryptogamous plants of Siberia, Lapland,Greenland and Labrador scaled the heights of Mount Washington,because the sporules of the fungi, lichens and mosses maybe wafted through the air for indefinite distances, like smoke;and, in fact, heavier particles are actually known to have beencarried for thousands of miles by the wind. But the cause ofthe occurrence of Arctic plants of thePhænogamous class onthe top of the New Hampshire Mountains, specifically identicalwith those of remote polar regions, is by no means so obvious.They could not in the present condition of the earth effect a« 438 »passage over the intervening lowlands, because the extremeheat of summer and cold of winter would be fatal to them.We must suppose, therefore, that originally they extended theirrange in the same way as the plants now inhabiting Arctic andAntarctic lands disseminate themselves. The innumerableislands in the polar seas are tenanted by the same species ofplants, some of which are conveyed as seeds by animals overthe ice, when the sea is frozen in winter, or by birds; while astill larger number are transported by floating icebergs and fieldice, on which soil containing the seeds of plants may be carriedin a single year for hundreds of miles. A great body of geologicalevidence has now been brought together to show thatthis machinery for scattering plants, as well as for carryingerratic blocks southward, and polishing and grooving the floorof the ancient ocean, extended in the western hemisphere tolower latitudes than that of the White Mountains. When theselast still constituted islands, in a sea chilled by the melting offloating ice, we may assume that they were covered entirely bya flora like that now confined to the uppermost or treelessregion of the mountains, except in such portions of the periodas were sufficiently cold to clothe their summits permanently insnow. As the continent grew by the slow upheaval of the land,and the islands gained in height, and the climate around thesehills grew milder, the Arctic plants would retreat to higherzones, and finally occupy an elevated area, which probably hadbeen, at first, or in the Glacial period, always covered with perpetualsnow. Meanwhile the newly formed plains around thebase of the mountain, to which northern species of plants couldnot spread, would be occupied by others migrating from thesouth, and perhaps by many trees, shrubs, and plants, then firstcreated, and remaining to this day peculiar to North America."

The time to which the above views of Sir. C. Lyell wouldrefer the migration of the White Mountain flora, is historically,very remote. The changes of level which have submerged the« 439 »American continent and re-elevated its land have occupied longperiods. Whether, with Lyell, we measure these periods bythe recession of the Falls of Niagara, or by the growth of thealluvial plain of the Mississippi; or, with Agassiz, by the extensionof the peninsula of Florida, or endeavour to estimate thetime required for the abrasion and deposition of the great massof clay that fills the valley of the St. Lawrence, and allowingfor the reductions of the antiquity of the Glacial period arisingfrom recent observations and calculations, we cannot supposethat less than 8,000 or 10,000 years have elapsed since theAlpine plants of the White Mountains were cut off from allconnection with their Arctic relatives. Their reign upon themountain tops not only antedates all human dynasties, butprobably reaches beyond the creation of man himself, and manyof his contemporaries.

Positive evidence of the existence of some of these plantsduring a large portion of this lapse of time has actually beenpreserved in the Pleistocene deposits of Canada. At Green'sCreek, on the Ottawa, in nodules in the clay containing marineshells, and coeval with the Leda clay of Montreal, there arenumerous remains of plants that have been embedded in thisclay at a time when the Ottawa valley was a bay or estuary, andwhen the Adirondack Mountains of New York and the mountainsof New England were two rocky islands, separated fromeach other and from the mainland on the north by wide armsof the sea. The plants found in these nodules all appear to beof modern species. Several of these plants are found on theWhite Mountains, and they are all northern or boreal, butscarcely Arctic, belonging as they do to the southern margin ofthe Arctic land species. I have no doubt that further examinationof these deposits will lead to the discovery of additionalexamples. This fact, proving as it does the existence of thesespecies at the period in which the theory of Lyell and Forbesrequires them to have migrated, is in itself strong corroborative« 440 »evidence. We can say that some of these species were waitingon the shores of the north, ready to be drifted to the insularspots to the south-west, and that their seeds were actually beingwashed out to sea by the streams which emptied themselvesinto the then estuary of the Ottawa.

Another aspect of the inquiry is that which relates to thereduction of temperature, which might be consequent on thegreat depression of the land which we know to have existedat the close of the Tertiary period, a fact on which I haveinsisted in former papers on the Pleistocene deposits ofCanada.[196] A very clever writer on the subject of geographicaldistribution [197] has pictured the case of a subsiding continent,with the fauna and flora of its lowlands becoming graduallyconcentrated on the spots which had previously been Alpinesummits, but now reduced to low and temperate islands. Buthe has left out of view the fact, that if land still existed in massin the Arctic regions, and if the subsidence was that of land intemperate regions, and if the remaining islands were encompassedwith cold and ice-laden currents, then, on the principleslong ago so well stated by Sir C. Lyell, these islands mighthave a mean temperature far below that of the former plains,and might, in consequence, be suitable only to such an Alpineflora as that which they had previously borne.

Now this is precisely what seems to have occurred in thePleistocene period. The Arctic land remained in great mass,detaching into the sea annual crops of icebergs and fields ofcoast ice, which have strewed all the northern hemisphere withboulders: the temperate regions were submerged, except a fewinsular spots. These are the very conditions required for alow mean temperature, both in the sea and on the land, andthese geographical conditions correspond precisely with thefacts as indicated by the fossil animals and plants of the« 441 »period. We must bear in mind, however, that under certaincontingencies the high mountain summits might have beenclad in snow and ice, like Greenland, and the Alpine plantsmight have been able to live only on their margins.

Further, it would be easy to show that the Alpine plants ofMount Washington would thrive under such conditions asthose supposed, at the sea level; a low and equable temperature,with a moist atmosphere, being that which they mostdesire, and their greatest enemy being the dry parching heat ofthe plains of the temperate regions. Those of them, such asPotentilla tridentata andAlsine Grœnlandica, which occur inlow ground within the limits of the United States, are foundunder shaded woods, in damp ravines, or on the moist sea-coast;and as we follow the coasts northward, we find theseplants, on these and on neighbouring islands, in lower latitudesthan those in which they occur inland. This is well seen inNorthern New Brunswick and in the south shore of the St.Lawrence, where several northern species occur in shady andmoist localities. I have, for example, collectedCornus Suecicaand the Alpine birch in such places. When the summer mistsroll around the summit of Mount Washington, it is in everyrespect the precise counterpart of an islet anywhere on thecoast of America, from Cape Breton to the Arctic seas, andwhen winter wraps everything in a mantle of snow, all theselands are in like manner under the same conditions. So, inthe Pleistocene period, though the islets of the WhiteMountains may have experienced a less degree of winter cold,they must have had very nearly the same summer temperatureas now; and as this is the season of growth for our Alpine andArctic plants, it is its character that determines the suitablenessof the locality to them.

Those stupendous vicissitudes of land and water which havechanged the aspect of continents, and swept into destructionraces of gigantic quadrupeds, have dealt gently with these« 442 »Alpine plants, which long ages ago looked out upon a waste ofice-laden waters that had engulfed the Pliocene land with allits inhabitants, as securely as they now look down upon thepleasant valleys of New England. It is curious, too, that thehumbler tenants of the sea have shared a similar exemption.In the clay banks of the Saco, on the shores of Lake Champlain,and mixed with the remains of these very plants in thevalley of the Ottawa, are shells that now live in the Gulf of St.Lawrence and on the coast of Maine, intermixed with otherspecies that are now found only in a few bays of the Arcticseas. Just as in the Post-pliocene clays of the Ottawa, the remainsof northern plants are found in the same nodule withthose ofLeda glacialis, so now similar associations maybe takingplace on the coasts at the mouth of the Great Fish River.Truly, in nature as in grace, God hath chosen the weak thingsof the world to confound those that are mighty, and has left inthe earth's geological history, monuments of His respect andregard for the humblest of His works.

It is interesting to notice here that Greenland, at the presenttime, presents conditions as to vegetation which may, in somerespects, correspond to those of the White Mountains in Pleistocenetimes. Its flora, though altogether Arctic, contains 386species, none of which are peculiar to it, but many of themrange quite round the Polar circle. Of those that are not sogenerally distributed, some, more especially on the west coast,are common to Greenland and Arctic America. Others, and alarger number, more especially on the east coast, are commonto Greenland, Iceland and Norway, between which and Greenlandthere may have been a closer land connection than now,in Pliocene and Post-glacial times.

We look in vain among the Alpine plants, so long isolated inthese mountains, for any evidence of decided change in specificcharacters. The Alpine plants, for ages separated from theirArctic brethren, are true to their kinds, and show little tendency« 443 »to vary, and none to adapt themselves to new forms inthe sunny plains below. This is especially noteworthy onMount Washington and the neighbouring peaks, because thesoil of these is the same with that of the valleys. Several ofthe plants peculiar to these hills, as the black crowberry(Empetrum nigrum), for instance, even when other conditionsare favourable, shun rich calcareous soils, and affect those ofgranitic origin. In many cases the difference in soil is a sufficientreason for the non-occurrence of such plants, except oncertain hills. At Murray Bay, and on the shores of LakeSuperior, the plant above named occurs only on the Laurentiangneiss. In Nova Scotia, its relative,Corema Conradi, isconfined to the granite barrens of the south coast. Many suchplants skirt the whole Laurentian range from Labrador to LakeSuperior, but refuse to extend themselves over the calcareousplains of Canada. But in the White Hills the soil of theriver alluvium is the same micaceous sand that fills the crevicesof the rocks in the mountains, and hence there is no obstruction,in so far as soil is concerned, to the diffusion of plantsupward and downward in the hills. In like manner there isevery possible condition as to moisture and dryness, sunshineand shade, in both localities. These circumstances are of allothers the most favourable to such variation as these plantsare capable of undergoing. The case is the same with thatwhich Hugh Miller so strongly puts in relation to the speciesof algæ that occur at different distances below high water markon the coast of Scotland, each species there attaining a certainlimit, and then, instead of changing to suit the new conditions,giving place to another. So it is on Mount Washington; andthis, whether we regard the lowland plants that climb to a certainheight, and there stop, the plants that are common to thebase and summit, or the plants that are confined to the latter.

I have already referred to the evident struggle of the sprucesand firs, and the plants associated with them, to ascend the« 444 »mountain, and the same remark applies to all the plants thatone after another cease to appear at various heights from thelower valleys. One by one they become stunted and depauperated,and then cease, without any semblance of an attemptto vary into new and hardier forms. And this must have beenproceeding, be it observed, from all those thousands of yearsthat have elapsed since the elevation of the mountains out ofthe glacial seas. It is to be observed, also, that the new plantsthat occur in ascending, often belong to different genera andfamilies from those left behind, not to closely allied species;and in the few cases in which this last kind of change occurs,there is no graduation into intermediate forms. For instance,Solidago thyrsoidea andS. virga-aurea [198] occur around the baseof the mountain, and for some distance up its sides. At theheight of four to five thousand feet the latter only remains,and this in a dwarfish condition. This corresponds to its distributionelsewhere, for, according to Richardson, it occurs inlat. 55° to 65° in Arctic America, and according to Hooker, it isfound in the Rocky Mountains, while it also occurs in the hillsof Scotland, and very abundantly in some parts of Norway.In the White MountainsS. thrysoidea prevails toward the base,S. virga-aurea toward the summit; and at the top of Tuckerman'sravine I found the former of these golden rods in blossom,within a few hundred feet of the latter, each preservingits distinctive peculiarities. Much has lately been said of theappearance of specific diversity that results from the breakingup of the continuity of the geographical areas of plants bygeological changes; but here we probably have the converse ofthis. The mountain species is no doubt a part of the olderArctic flora, the other perhaps belong to a more modern flora,and they have met on the sides of the White Hills.

Some hardy species climb from the plains to heights of5,000 feet or more, with scarcely even the usual change ofbeing depauperated, and then suddenly disappear. This isvery noteworthy in the case of two woodland plants, the dwarfcornel or pigeon-berry (Cornus Canadensis), and the twin-flower(Linnæa borealis). The former of these is a plant mostwidely distributed over northern America, and probably belongsto that newer flora which overspread the continent afterits re-elevation. In August this plant in the woods around thebase of Mount Washington is loaded with its red berries. Atan elevation of four to five thousand feet it may be found inbloom; above this a few plants appear, destitute of flowers,dwarfish in aspect, and nipped by cold, and then the speciesdisappears. No doubt the birds that feed on its little drupeshave carried it up the mountain, and have sown it a littlefarther up than the limit of its probable reproductiveness.The beautiful littleLinnæa is a still more widely distributedplant; for it occurs on the hills of northern Europe, and isfound across the whole breadth of the American continentfrom Nova Scotia to the Columbia River. It is almost beyondquestion a member of the old Arctic flora which colonized theislands of the Pleistocene sea, and 'has descended from themon all sides as the land became elevated. This plant alsoclimbs Mount Washington to a height of 5,000 feet, and presentsprecisely the same characters on the top as at the bottom,only losing a little in the length of its stem. Specimens bearingblossoms, and quite in the same stage of growth, may becollected at the same time on the highest shoulders of MountWashington, and on the flats at Gorham. TheLinnæa in thisis true to its designation. For, as if it belonged to it to supportthe reputation of the great systematist after whom it isnamed, it preserves its specific characters with scarcely a tittleof change throughout all its great range. One cannot see thishardy little survivor of the Glacial period, so unchanging yet so« 446 »gentle, so modest yet so adventurous, so wide in its migrationsyet so choice in the selection of the mossy nooks which itadorns with its pendant bells, and renders fragrant with itsdelicious perfume, without praying that we might, in these daysof petty distinctions and narrow views, be favoured with moresuch minds as that of the great Swede, to combine the littledetails of the knowledge of natural history into grand views ofthe unity of nature.

Another plant which, being less dependent on shade andshelter than theLinnæa, mounts still higher, is the cowberryor foxberry (Vaccinium vitis-Idæa). This, also, is both Europeanand American, and is probably a survivor of the Pleistoceneperiod. It still occurs in at least one locality in thelow country of Massachusetts, and on the coast of Maine. Itis found along the granitic coast of Nova Scotia, and extendsthence northward to the Arctic circle, being found at GreatBear Lake and at Unalaska. This, too, is a most unchangingspecies, and the same statement may be made respecting thecloudberry (Rubus Chamæmorus), the black crowberry (Empetrumnigrum), the Labrador tea (Ledum latifolium), thethree-toothed cinquefoil (Potentilla tridentata), which growson the coast of Nova Scotia, and is found in the nodules ofthe Ottawa clay, the same in every detail as on Mount Washington,the bog bilberry (Vaccinium uliginosum), and thedwarf bilberry (V. cæspitosum). Several of these, too, it will beobserved, are berry-bearing plants, whose seeds must be depositedin all kinds of localities by birds. Yet they neveroccur in the warm plains, nor do they show much tendencyto vary in the distant and somewhat dissimilar places in whichthey occur. In the case of most of these species, the mostcareful comparison of specimens from Mount Washingtonwith those from Labrador, shows no tittle of difference. Whenwe consider the vast length of time during which such specieshave existed, and the multiplied vicissitudes through which« 447 »they have passed, one is tempted to believe that it is thetendency of the "struggle for existence" to confirm and renderpermanent the characters of species rather than to modifythem.

Of the more specially Arctic plants which have held theirground unchanged on Mount Washington, the following aresome of the principal.Diapensia Lapponica, in beautiful deepgreen tufts, ascends quite to the summit. It occurs also in theAdirondack Mountains, on Mount Katahdin, in Maine, and onthe summit of Mount Albert, Gaspé (Macoun). It is foundin Labrador, and, according to Hooker, extends north toWhale Island, in the Arctic seas; but it is not found west ofthe Great Fish River. It occurs also on the mountains ofLapland, and is described as the hardiest plant of that bleakregion.Arenaria (Alsine)Grænlandica, the Greenland sand-wort,adorns with its clusters of white flowers every sandycrevice in the rocks of the very summit of Mount Washington,and is trodden under foot like grass by the hundreds of carelesssightseers that haunt that peak in summer; though Ishould add, that not a few of them carry off little tufts as amemento of the mountains, along with the fragments of micawhich appear to form the ordinary keepsakes of unscientificvisitors. It is a most frail and delicate plant, seemingly altogetherunsuited to the dangerous pre-eminence which it seeks,yet it loves the bare, unsheltered mountain peaks, and when itoccurs in the more sheltered ravines, has only its stems a littlelonger and more slender. It occurs on the AdirondackMountains and on Katahdin, where, if I may judge fromspecimens kindly sent to me by Prof. Goodale, it attains tosmaller dimensions than on Mount Washington, on the Catskills,and at one place on the sea coast of Maine. I have notseen it in Nova Scotia, but it ranges north to Greenland.

Another of the truly Arctic plants is the alpine azalea (Loiseleuriaprocumbens), a densely tufted mountain shrub, with« 448 »hard glossy leaves, that look as if constructed to brave extremesthardships. It is found on the mountains of Norway,at the height of 3,550 feet on the Scottish hills, according toWatson, and according to Fuchs, at the height of 7,000 feet inthe milder climate of the Venetian Alps. In America it isfound in Newfoundland, in Labrador, at 4,000 feet on MountAlbert, Gaspé,[199] and in the barren grounds from lat. 65 to theextreme Arctic islands. Gray does not mention its occurrenceelsewhere in the United States than the summits of the WhiteMountains. A member of the same family of the heaths, theyew-leaved phyllodoce (P. taxifolia), presents a still moresingular distribution. It is found on all the higher mountainsof New England and New York, and occurs also on the mountainsof Scotland and Scandinavia, but its only known stationin northern America is, according to Hooker, in Labrador.As many as nine or ten of the Alpine plants of the WhiteMountains belong to the order of the Heaths (Ericaceæ).Another example from this order isRhododendron Lapponicum,a northern European species, as its name indicates, and scatteredover all the high mountains of New England and NewYork, occurring also in Labrador, on the Arctic sea coasts, andthe northern part of the Rocky Mountains, and at 4,000 feeton Mount Albert, Gaspé (Macoun).

It would be tedious to refer in detail to more of these plants,but I must notice two herbaceous species belonging to differentfamilies, but resembling each other in size and habit theAlpine epilobium (E. alpinum oralsinefolium), and the Alpinespeedwell (Veronica alpina). Both are in the United Statesconfined to the highest mountain tops. Both occur as alpinenorthern plants in Europe, being found on the Alps, on theScottish Highlands, and in Scandinavia. Both are found inLabrador and on the Rocky Mountains, and the Veronica extends« 449 »as far as Greenland. The Alpine epilobium is one of thefew White Mountain plants that have attained the bad eminenceof being regarded as doubtful species. Gray notes asthe typical form, that with obtuse and nearly entire leaves, andas a variety, that with acute and slightly toothed leaves, whichsome other botanists seem to regard as distinct specifically.Thus we find that this little plant has been induced to assumea suspicious degree of variability; yet it is strange that bothspecies or varieties are found growing together, as if the littlepeculiarities in the form of the leaves were matters of indifference,and not induced by any dire necessities in the strugglefor life. Facts of this kind are curious, and not easily explainedunder the supposition either of specific unity or diversity. Forwhy should this plant vary without necessity? and why shouldtwo species so much alike be created for the same locality?Perhaps these two species or varieties, wandering from fardistant points of origin, have met here fortuitously, while thelines of migration have been cut off by geological changes; andyet the points of difference are too constant to be removed,even after the reason for them has disappeared. If this couldbe proved, it would afford a strong reason for believing theexistence of a real specific diversity in these plants.

I have said nothing of the grasses and sedges of these mountains;but one of them deserves a special notice. It is theAlpine herd's grass (Phleum alpinum), a humble relation of ourcommon herd's grass. This plant not only occurs on theWhite Mountains, in Arctic America, in the Canadian Mountains,from the summit of Mount Albert, in Gaspé, to themountains of British Columbia, and on the hills of Scotlandand Scandinavia, but has been found on the Mexican Cordilleraand at the Straits of Magellan. The seeds of this grassmay perhaps be specially suited for transportation by water, aswell as by land. It is observed in Nova Scotia that when thewide flats of mud deposited by the tides of the Bay of Fundy,« 450 »are dyked in from the sea, they soon become covered withgrasses and carices, the seeds of which are supposed to bewashed down by streams and mingled with the marine silt;and fragments of grasses abound in the Post-tertiary clays ofthe Ottawa.

It seems almost ridiculous thus to connect the persistence ofthe form of a little plant with the subsidence and elevation ofwhole continents, and the lapse of enormous periods of time.Yet the Power which preserves unchanged from generation togeneration the humblest animal or plant, is the same with thatwhich causes the permanence of the great laws of physicalnature, and the continued revolutions of the earth and all itscompanion spheres. A little leaf, entombed ages on ages agoin the Pleistocene clays of Canada, preserves in all its minutestfeatures the precise type of that of the same species as it nowlives, after all the prodigious geological changes that haveintervened. An Arctic and Alpine plant that has survived allthese changes maintains, in its now isolated and far removedstations, all its specific characters unchanged. The flora of amountain top is precisely what it must have been when it wasan island in the glacial seas. These facts relate not to hardcrystalline rocks that remain unaltered from age to age, but tolittle delicate organisms that have many thousands of timesdied and been renewed in the lapse of time. They show usthat what we call a species represents a decision of the unchangingcreative will, and that the group of qualities whichconstitutes our idea of the species goes on from generation togeneration animating new organisms constructed out of differentparticles of matter. The individual dies, but the specieslives, and will live until the Power that has decreed its creationshall have decreed its extinction; or until, in the slow processof physical change depending on another section of His laws,it shall have been excluded from the possibility of existenceanywhere on the surface of the earth, unless we suppose with« 451 »modern evolutionists that there is a possibility of these plantsso changing their characters that in the lapse of ages they mightappear to us to be distinct specific types. The fact, however,that the Arctic species have migrated around the whole Arcticcircle, and have advanced southward and retreated to the north,again and again, without changing their constitutions or forms,augurs for them at least a remarkable fixity as well as continuity.

While the huge ribs of mother earth that project into mountainsummits, and the grand and majestic movement of thecreative processes by which they have been formed, speak tous of the majesty of Him to whom the sea belongs, and whosehand formed the dry land, the continuance of these little plantspreaches the same lessons of humble faith in the Divine promisesand laws, which our Lord drew from the lilies of thefield.

It is suggestive, in connection with the antiquity and migrationsof these plants, to consider the differences in this respectof some closely allied species of the same genera. Of theblueberries that grow on the White Mountains, one species,Vaccinium uliginosum, is found in Behring's Straits andvery widely in Arctic and boreal America,[200] also in northernEurope.V. cæspitosum has a wide northern range in America,but is not European.V. Pennsylvanicum andV. Canadense,from their geographical distribution, do not seem tobelong to the Arctic flora at all, but to be of more southernorigin. The two bearberries (Arctostaphylos uva-ursi andalpina) occur together on the White Hills, and on the Scottishand Scandinavian mountains; but the former is a plant ofmuch wider and more southern distribution in America thanthe latter. Two of the dwarf willows of the White Mountains(Salix repens andS. herbacea) are European as well as« 452 »American, butS. uva-ursi seems to be confined to America.Rubus triflorus, the dwarf raspberry, andR. chamæmorus, thecloud berry, climb about equally high on Mount Washington;but the former is exclusively American, and ranges pretty farsouthward, while the latter extends no farther south than thenorthern coast of Maine, and is distributed all around theArctic regions of the Old and New Worlds. It is to beobserved, however, that the former can thrive on rich andcalcareous soils, while the latter loves those that are barrenand granitic; but it is nevertheless probable thatR. triflorusbelongs to a later and more local flora. Similar reasons wouldinduce the belief that the American dwarf cornel or pigeon-berry(Cornus Canadensis), whose distribution is solely American,and not properly Arctic, is of later origin than theC.Suecica,[201] which occurs in northern America locally, and is extensivelydistributed in northern Europe.

I can but glance at such points as these; but they raise greatquestions which are to be worked out, not merely by the patientcollection of facts, but by a style of scientific thought verymuch above those which, on the one hand, escape such problemsby the supposition of multiplied centres of creation, oron the other, render their solution worthless by confoundingraces due to external disturbing causes with species originallydistinct. Difficulties of various kinds are easily evaded byeither of these extreme views; but with the fact before him ofspecific diversity and its manifestly long continuance, on theone hand, and the remarkable migrations of some species onthe other, the true naturalist must be content to work out theproblems presented to him with the data afforded by the actualobservation of nature, following carefully the threads of guidance« 453 »thus indicated, not rudely breaking them by too hastygeneralizations.

But it is time to leave the scientific teachings of our littleAlpine friends, and to inquire if they can teach anything to theheart as well as to the head.

The mountains themselves, heaving their huge sides to theheavens, speak of forces in comparison with which all humanpower is nothing; and we can scarcely look upon them in theirmajesty without a psalm of praise rising up within us to Himwho made the sea, and from whose hands the dry land tookits form. As we ascend them, and as our vision ranges moreand more widely over the tops of wooded hills, along thecourses of streams, over cultivated valleys, and to the shoresof the blue sea itself, our mental vision widens too. We thinkthat the great roots of these hills run beneath a whole continent,that their tops look down on the wide St. Lawrenceplain, on the beautiful valleys of New England, and on therice fields of the sunny south. We are reminded of the brotherhoodof man, which overleaps all artificial boundaries, andshould cause us to pray that throughout their whole extentthese hills may rise amidst a happy, a free, and a God-fearingpeople.

Our Alpine plants have still higher lessons to teach. Theyare fitting emblems of that little flock, scattered everywhere,yet one in heart, and in all lands having their true citizenshipin heaven. They tell us that it is the humble who are nearestGod, and they ask why we should doubt the guardian care ofthe Father who cares for them. They witness, too, of the lowlyand hidden ones who may inhabit the barren and lowly spotsof earth, yet are special subjects of God's love, as they shouldbe of ours. We may thus read in the Alpine plants truths thatbeget deeper faith in God, and closer brotherhood with Hispeople.

The history of these plants has also a strange significance.« 454 »It might have been written of them, "Though the dry land beremoved out of its place, and the mountains cast into the midstof the sea, yet the Lord will not forsake the work of Hishands"; for this has been literally their history. In this theyhold forth an omen of hope to the people of God in that oncehappy land through which these hills extend, and who nowmourn the evil times on which they have fallen. The mountainplants may teach them that though the floods of strifeshould rise even to the tops of the hills, and leave but scatteredislets to mark the place of a united land, their rock is sure, andtheir prayers will prevail.[202] The power that has waked the stormis after all their Father's hand. For years a cry has risen highabove these hills: the cry of the bondman who has reaped thefields and received no hire. That cry is sure to be heard inheaven, whatever other prayers may go unanswered. An apostletells us that it enters directly into the ears of the God ofSabaoth, and is potent to call down the day of slaughter onthe proud ones of earth. The prayer of the slave has beenanswered; and the tempest is abroad, sweeping away hisoppressors and their abettors. Yet God rules in all this, andthose whom He has chosen will be spared, even like the hardyplants of the hill tops, to look again on a renewed and smilingland, from which many monsters and shapes of dread have forever passed away.

But last of all, the Alpine flowers have a lesson that shouldcome near to all of us individually. They tell us how wellnatural law is observed, as compared with moral. Obeying withunchanging fidelity the law of their creation, they have meeklyborne the cold and storms of thousands of winters, yet havethankfully expanded their bosoms to the returning sun of everysummer, and have not once forgot to open their tiny buds, andbring forth flowers and fruit, doing thus their little part to the« 455 »glory of their Maker and ours. How would the moral wastesof earth rejoice and be glad, did the sunshine of God's dailyfavours evoke a similar response from every human heart!

References:—Paper on Destruction and Renewal of Forests in NorthAmerica,Edinburgh Philosophical Journal, 1847-8. Alpine andArctic Plants,Canadian Naturalist, 1862. "The Geological Historyof Plants," International Scientific Series, 2nd edition, 1891. "ThePleistocene Flora of Canada," Dawson and Penhallow,BulletinAmerican Geological Society, 1890. Papers on Pleistocene Climateof Canada,Canadian Naturalist, 1857 to 1890.

EARLY MAN.

DEDICATED TO THE MEMORY OF THE LATE

SIR DANIEL WILSON, LL.D., F.R.S.E.,

a dear and valued Friend,
and one of the most eminent and judicious Students of
Pre-historic Man both in Europe and America.

Summary of the Story of Early Man—Classificationof Tertiary Time—Probabilities as to the Introductionof Man—The Anthropic Age As Distinguishedfrom the Pleistocene—Its Division intoPalanthropic and Neanthropic—Sketches of PalanthropicMan and His Immediate Successors

CHAPTER XVII.

The science of the earth has its culmination and terminusin man; and at this, the most advanced of our salientpoints, as we look back on the long process of the developmentof the earth, we may well ask, Was the end worthy of themeans? We may well have doubts as to an affirmativeanswer if we do not consider that the means were perfect,each in its own time, and that man, the final link in the chainof life, is that which alone takes hold of the unseen andeternal. He alone can comprehend the great plan, and appreciateits reason and design. Without his agency in this respectnature would have been a riddle without any solution—acolumn without a capital, a tree without fruit. Besides this,even science may be able to perceive that man may be notmerely the legatee of all the ages that lie behind, but the heirof the eternity that lies before, the only earthly being thathas implanted in him the germ and instinct of immortality.

Whatever view we may take of these questions, it is of interestto us to know, if possible, how and when this chief cornerstone was placed upon the edifice of nature, and what are theprecise relations of man to the later geological ages, as well asto the present order of nature, of which he is at once a part,and its ruler and head. Let us put this first in the form of anarrative based on geological facts only, and then considersome of its details and relations to history.

The Glacial age had passed away. The lower land, in greatpart a bare expanse of mud, sand, and gravel, had risen from« 460 »the icy ocean in which it had been submerged, and most of themountain tops had lost their covering of perennial snow andice. The climate was ameliorated, and the sun again shonewarmly on the desolate earth. Gradually the new land becameoverspread with a rich vegetation, and was occupied by manylarge animals. There were species of elephant, rhinoceros,hippopotamus, horse, bison, ox and deer, multiplying till theplains and river valleys were filled with their herds, in spite ofthe fact that they were followed by formidable carnivorousbeasts fitted to prey on them. At this time, somewhere in thewarm temperate zone, in an oasis or island of fertility, appeareda new thing on the earth, a man and woman walking erect inthe forest glades, bathing in the waters, gathering and tastingevery edible fruit, watching with curious and inquiring eyesthe various animals around them, and giving them nameswhich might eventually serve not merely to designate theirkinds, but to express actions and emotions as well. When,where, and how did this new departure, fraught with so manypossibilities, occur—introducing as it did the dexterous fingersand inventive mind of Man upon the scene? The last ofthese questions science is still unable to answer, and thoughwe may frame many hypotheses, they all remain destitute ofcertain proof in so far as natural science is concerned. Wecan here only fall back on the old traditional and historicalmonuments of our race, and believe that man, the child ofGod, and with God-like intellect, will, and consciousness, wasplaced by his Maker in an Edenic region, and commissioned tomultiply and replenish the earth. The when and where of hisintroduction, and his early history when introduced, are moreopen to scientific investigation.

That man was originally frugivorous, his whole structuretestifies. That he originated in some favourable climate andfertile land is equally certain, and that his surroundings musthave been of such a nature as to give him immunity from the« 461 »attacks of formidable beasts of prey, also goes without saying.These are all necessary conditions of the successful introductionof such a creature as man, and theories which supposehim to have originated in a cold climate, to struggle at oncewith the difficulties and dangers of such a position, are, from ascientific point of view, incredible.

But man was introduced into a wide and varied world, morewide and varied than that possessed by his modern descendants.The earliest men that we certainly know inhabited outcontinents in the second Continental age of the KainozoicPeriod, when, as we know from ample geological evidence, theland of the northern hemisphere was much more extensivethan at present, with a mild climate, and a rich flora and fauna.If he was ambitious to leave the oasis of his origin the waywas open to him, but at the expense of becoming a toiler, aninventor, and a feeder on animal food, more especially when heshould penetrate into the colder climates. The details of allthis, as they actually occurred, are not within the range of scientificinvestigation, for these early men must have left few, if any,monuments; but we can imagine some of them. Man's handswere capable of other uses than the mere gathering of fruit.His mind was not an instinctive machine, like that of loweranimals, but an imaginative and inventive intellect, capable ofadapting objects to new uses peculiar to himself. A fallenbranch would enable him to obtain the fruits that hung higherthan his hands could reach, a pebble would enable him tobreak a nut too hard for his teeth. He could easily weave afew twigs into a rough basket to carry the fruit he had gatheredto the cave or shelter, or spreading tree, or rough hut thatserved him for a home; and when he had found courage tosnatch a brand from some tree, ignited by lightning, or by thefriction of dry branches, and to kindle a fire for himself, he hadfairly entered on that path of invention and discovery whichhas enabled him to achieve so many conquests over nature.

Our imagination may carry us yet a little farther with referenceto his fortunes. If he needed any weapon to repel aggressiveenemies, a stick or club would serve his purpose, or perhaps astone thrown from his hand. Soon, however, he might learnfrom the pain caused by the sharp flints that lay in his path thecutting power of an edge, and, armed with a flint chip heldin the hand, or fitted into a piece of wood, he would becomean artificer of many things useful and pleasing. As he wanderedinto more severe climates, where vegetable food couldnot be obtained throughout the year, and as he observed thehabits of beasts and birds of prey, he would learn to bea hunter and a fisherman, and to cook animal food; and withthis would come new habits, wants and materials, as well as amore active and energetic mode of life. He would also haveto make new weapons and implements, axes, darts, harpoons,and scrapers for skins, and bodkins or needles to make skingarments. He would use chipped flint where this could beprocured, and failing this, splintered and rubbed slate, and forsome uses, bone and antler. Much ingenuity would be usedin shaping these materials, and in the working of bone, antlerand wood, ornament would begin to be studied. In the meantimethe hunter, though his weapons improved, would becomea ruder and more migratory man, and in anger, or in the desireto gain some coveted object, might begin to use his weaponsagainst his brother man. In some more favoured localities,however, he might attain to a more settled life; and he, or morelikely the woman his helpmate, might contrive to tame somespecies of animals, and to begin some culture of the soil.

It was probably in this early time that metals first attractedthe attention of men. The ages of stone, bronze, andiron believed in by some archæologists, are more or lessmythical to the geologist, who knows that these things dependmore on locality and on natural products than on stages ofculture. The analogy of America teaches us that the use of« 463 »different metals may be contemporaneous, provided that theycan be obtained in a native state. At the time of the discoveryof America the Esquimaux were using native iron,which, though rare in most parts of the world, is not uncommonin some rocks of Greenland. The people of the regionof the great lakes, and of the valleys of the Mississippi andOhio, were using native copper from Lake Superior for similarpurposes. Gold was apparently the only metal among thenatives of Central America. The people of Peru had inventedbronze, or had brought the knowledge of it with them frombeyond the sea. Thus the Peruvians were in the bronze age,the Mexicans and Mound builders in the copper age, and theEsquimaux in the iron age, while at the same time thegreater part of the aboriginal tribes were at one and the sametime in the ages of chipped and polished stone and in theseages what have been called palæolithic and neolothic weaponswere contemporaneous, the former being most usually unfinishedexamples of the latter, or extemporized tools roughly made inemergencies.[203] How long this had lasted, or how long it wouldhave continued, had not Europeans introduced from abroad aniron age, we do not know. It was probably the same in otherparts of the world, in pre-historic times. In any case, the discoveryof native metals must have occurred very early. Mensearching in the beds of streams for suitable pebbles to formhammers and other implements, would find nuggets of goldand copper, and the properties of these, so different from thoseof other pebbles, would at once attract attention, and lead touseful applications. Native iron is of rarer occurrence, but incertain localities would also be found.[204] It must have been« 464 »experiments on these ores, which resemble the native metals incolour, lustre and weight, that led to the first attempts at smeltingmetals, and these must have occurred at a very earlyperiod. Yet for ages the metals must have been extremelyscarce, and we know that in comparatively modern times civilizednations like the Egyptians were using flint flakes after theyhad domesticated many animals, had become skilful agriculturistsand artisans, and had executed great architectural works.

Probably all these ends had been to some extent, and insome localities, attained in the earliest human period, whenman was contemporary with many large animals now extinct.But a serious change was to occur in human prospects.There is the best geological evidence that in the northernhemisphere the mild climate of the earlier Post-glacial periodrelapsed into comparative coldness, though not so extreme asthat of the preceding Glacial age. Hill tops, long denuded ofthe snow and ice of the Glacial period, were again covered, andcold winters sealed up the lakes and rivers, and covered theground with wintry snows of long continuance, and with thiscame a change in animal life and in human habits. The oldsouthern elephant (E. antiquus), the southern rhinoceros (E.leptorhinus), and the river hippopotamus (H. major), whichhad been contemporaries, in Europe at least, of primitive man,retired from the advancing cold, and ultimately perished,while their places were taken by the hairy mammoth (E.primigenius), the woolly rhinoceros (R. tichorhinus), the reindeer,and even the musk ox. Now began a fierce struggle forexistence in the more northern districts inhabited by man astruggle in which only the hardier and ruder races could survive,except, perhaps, in some of the more genial portions ofthe warm temperate zone. Men had to become almost whollycarnivorous, and had to contend with powerful and fierceanimals. Tribe contended with tribe for the possession of themost productive and sheltered habitats. Thus the struggle« 465 »with nature became aggravated by that between man and man.Violence disturbed the progress of civilization, and favouredthe increase and power of the rudest tribes, while the more delicatelyorganized and finer types of humanity, if they continuedto exist in some favoured spots, were in constant danger ofbeing exterminated by their fiercer and stronger contemporaries.

In mercy to humanity, this state of things was terminatedby a great physical revolution, the last great subsidence of thecontinents—that Post-glacial flood, which must have sweptaway the greater part of men, and many species of great beasts,and left only a few survivors to re-people the world, just as themammoth and other gigantic animals had to give place tosmaller and feebler creatures. In these vicissitudes it seemeddetermined, with reference to man, that the more gigantic andformidable races should perish, and that one of the finer typesshould survive to re-people the world.

The age of which we have been writing the history, is thatwhich has been fitly named the Anthropic, in that earlier partof it preceding the great diluvial catastrophe, which has fixeditself in all the earlier traditions of men, and which separateswhat may be called the Palanthropic or Antediluvian age fromthe Neanthropic or Postdiluvian. Independently altogether ofhuman history, these are two geological ages distinguished bydifferent physical conditions and different species of animals;and the time has undoubtedly come when all the speculationsof archæologists respecting early man must be regulated bythese great geological facts, which are stamped upon those laterdeposits of the crust of the earth, which have been laid downsince man was its inhabitant. If they have only recently assumedtheir proper place in the geological chronology, this isdue to the great difficulty in the case of the more recentdeposits in establishing their actual succession and relations toeach other. These difficulties have, however, been overcome,and new facts are constantly being obtained to render our« 466 »knowledge more definite. Lest, however, the preceding sketchof the Palanthropic age—that in which gigantic men were contemporariesof a gigantic fauna now extinct—should be regardedas altogether fanciful, we may proceed to consider thegeological facts and classification as actually ascertained.

The Tertiary or Kainozoic period, the last of the four great"times" into which the earth's geological history is usuallydivided, and that to which man and the mammalia belong,was ingeniously subdivided by Lyell, on the ground of percentagesof marine shells and other invertebrates of the sea.According to this method, which with some modification indetails is still accepted, theEocene, or dawn of the recent,includes those formations in which the percentage of modernspecies of marine animals does not exceed 3-1/2, all the otherspecies found being extinct. TheMiocene (less recent) includesformations in which the percentage of living speciesdoes not exceed 35, and thePliocene (more recent) containsformations having more than 35 per cent, of recent species.To these three may be added thePleistocene, in which thegreat majority of the species are recent, and theModern orAnthropic, in which we are still living. Dawkins and Gaudrygive us a division substantially the same with Lyell's, exceptthat they prefer to take the evidence of the higher animalsinstead of the marine shells.. The Eocene thus includes thoseformations in which there are remains of mammals or ordinaryland quadrupeds, but none of these belong to recent speciesor genera, though they may be included in the same familiesand orders with the recent mammals. This is a most importantfact, as we shall see, and the only exception to it isthat Gaudry and others hold that a few living genera, as thoseof the dog, civet, and marten, are actually found in the laterEocene. The Miocene, on the same mammalian evidence,will include formations in which there are living genera ofmammals, but no species which survive to the present time.« 467 »The Pliocene and Pleistocene show living species, though inthe former these are very few and exceptional, while in thelatter they become the majority.

With regard to the geological antiquity of man, no geologistexpects to find any human remains in beds older than theTertiary, because in the older periods the conditions of theworld do not seem to have been suitable to man, and becausein these periods no animals nearly akin to man are known.On entering into the Eocene Tertiary we fail in like manner tofind any human remains; and we do not expect to find any,because no living species and scarcely any living genera ofmammals are known in the Eocene; nor do we find in itremains of any of the animals, as the anthropoid apes, for instance,most nearly allied to man. In the Miocene the case issomewhat different. Here we have living genera at least, andwe have large species of apes; but no remains of man havebeen discovered, if we except some splinters of flint found inbeds of this age at Thenay, in France, and some notchedbones. Supposing these objects to have been chipped ornotched by animals, which is by no means certain in the caseof the flints, the question remains, Was this done by man?Gaudry and Dawkins prefer to suppose that the artificer wasone of the anthropoid apes of the period. It is true that noapes are known to do such work now; but then other animals,as beavers and birds, are artificers, and some extinct animalswere of higher powers than their modern representatives. Butif there were Miocene apes which chipped flints and cut bones,this would, either on the hypothesis of evolution or that ofcreation by law, render the occurrence of man still less likelythan if there were no such apes. The scratched and notchedbones, on the other hand, indicate merely the gnawing of sharksor other carnivorous animals. For these reasons neither Dawkinsnor Gaudry, nor indeed any geologists of authority in theTertiary fauna, believe in Miocene man.

In the Pliocene, though the facies of the mammalian faunaof Europe becomes more modern, and a few modern speciesoccur, the climate becomes colder, and in consequence theapes disappear, so that the chances of finding fossil men arelessened rather than increased in so far as the temperateregions are concerned. In Italy, however, Capellini has describeda skull, an implement, and a notched bone supposedto have come from Pliocene beds. To this it may be objectedthat the skull—which I examined in 1883 in the museum atFlorence—and the implement are of recent type, and probablymixed with the Pliocene stuff by some slip of the ground. Asthe writer has elsewhere pointed out,[205] similar and apparentlyfatal objections apply to the skull and implements alleged tohave been found in Pliocene gravels in California. Dawkinsfurther informs us that in the Italian Pliocene beds supposedto hold remains of man, of twenty-one mammalia whose bonesoccur, all are extinct species, except possibly one, a hippopotamus.This, of course, renders very unlikely in a geologicalpoint of view the occurrence of human remains in these beds.

In the Pleistocene deposits of Europe—and this applies alsoto America—we for the first time find a predominance ofrecent species of land animals. Here, therefore, we may lookwith some hope for remains of man and his works, and here,in the later Pleistocene, or the early Modern, they are actuallyfound. When we speak, however, of Pleistocene man, therearise some questions as to the classification of the deposits,which it seems to the writer Dawkins and other British geologistshave not answered in accordance with geological facts,and a misunderstanding as to which may lead to serious error.They have extended the term Pleistocene over that Post-glacialperiod in which we find remains of man, and thus have splitthe "Anthropic" period into two; and they proceed to dividethe latter part of it into the Pre-historic and Historic periods,« 469 »whereas the name Pleistocene should not be extended to thePost-glacial age. The close of the Glacial period, introducinggreat physical and climatal changes, some new species ofmammalia and man himself, should be regarded as the end ofthe Pleistocene, and the introduction of what some Frenchgeologists have called theAnthropic period, which I have elsewheredivided into Palanthropic, corresponding to the so-calledPalæolithic age, and Neanthropic, corresponding to the laterstone and metal ages.[206] These may be termed respectively theearlier and later stages of the Modern period as distinguishedfrom the Pleistocene Tertiary.

In point of logical arrangement, and especially of geologicalclassification, the division into historic and pre-historic periodsis decidedly objectionable. Even in Europe the historic ageof the south is altogether a different thing from that of thenorth, and to speak of the pre-historic period in Greece and inBritain or Norway as indicating the same portion of time isaltogether illusory. Hence a large portion of the discussion ofthis subject has to be properly called "the overlap of history."Further, the mere accident of the presence or absence of historicaldocuments cannot constitute a geological period comparablewith such periods as the Pleistocene and Pliocene, andthe assumption of such a criterion of time merely confuses ourideas. On the one hand, while the whole Tertiary or Kainozoic,up to the present day, is one great geological period,characterized by a continuous though gradually changing faunaand series of physical conditions, and there is consequentlyno good basis for setting apart, as some geologists do, aQuaternary as distinct from the Tertiary period; on the otherhand, there is a distinct physical break between the Plioceneand the Modern in the great Glacial age. This, in its Arcticclimate and enormous submergence of the land, though itdid not exterminate the fauna of the northern hemisphere,« 470 »greatly reduced it, and at the close of this age some new formscame in. For this reason the division between the Pleistoceneand Anthropic ages should be made at the beginning of thePost-glacial age. The natural division would thus be:—

(a)Early Pleistocene, or first continental period. Landvery extensive, moderate climate. This passes into the precedingPliocene.

(b)Later Pleistocene, or glacial, including Dawkins' "MidPleistocene." In this there was a great prevalence of cold andglacial conditions, and a great submergence of the northernland.

(a)Palanthropic,Post-glacial, or second continental period,in which the land was again very extensive, and Palæocosmicman was contemporary with some great mammals, as themammoth, now extinct, and the area of land in the northernhemisphere was greater than at present. This includes a latercold period, not equal in intensity to that of the Glacial periodproper, and was terminated by a great and very general subsidence,accompanied by the disappearance of Palæocosmic manand some large mammalia, and which may be identical withthe historical deluge.

(b)Neanthropic orRecent, when the continents attained theirpresent levels, existing races of men colonized Europe, andliving species of mammals. This includes both the Pre-historicand Historic periods.

On geological grounds the above should clearly be ourarrangement, though of course there need be no objection tosuch other subdivisions as historians and antiquarians may finddesirable for their purposes. On this classificationthe earliestcertain indications of the presence of man in Europe, Asia, orAmerica, so far as yet known, belong to the Modern or Anthropic« 471 »period alone. That man may have existed previously no oneneed deny, but no one can at present positively affirm on anyground of actual fact. It may be necessary here to explainthe contentions often made that in Britain and Western Europeman belongs to an interglacial period. When with Dr. JamesGeikie, the great Scottish glacialist, we hold that there wereseveral interglacial periods, the Glacial age may be extendedby including the warm period of the Palanthropic, and the coldat its termination, as one of the interglacial and Glacial periods.In this way, as a matter of classification, man appears in thelatest Interglacial periods. This, however, as above stated, Iregard as an error in arrangement; but it makes no practicaldifference as to the facts.

Inasmuch, however, as the human remains of the Post-glacialepoch are those of fully developed men of high type, it may besaid, and has often been said, that man in some lower stage ofdevelopmentmust have existed at a far earlier period. Thatis, he must, if certain theories as to his evolution from loweranimals are to be sustained. This, however, is not a mode ofreasoning in accordance with the methods of science. Whenfacts fail to sustain certain theories we are usually in the habitof saying "so much the worse for the theories," not "so muchthe worse for the facts," or at least we claim the right to holdour judgment in suspense till some confirmatory facts are forth-coming.

We have now to inquire as to the actual nature of the indicationsof man in Europe and Western Asia at the close of theGlacial or Pleistocene period. These are principally such ofhis tools or weapons as could escape decay when embedded inriver gravels, or in the earth and stalagmite of caverns or rockshelters, or buried with his bones in* caves of sepulture. Veryvaluable accessory fossils are the broken bones of the animalshe has used as food. Most valuable, and rarest of all, are well-preservedhuman skulls and skeletons. Some doubt may attach« 472 »to mere flint flakes, in the absence of other remains; but theother indications above referred to are indisputable, and whenproper precautions are taken to notice the succession of beds,and to eliminate the effects of any later disturbance of the deposits,human fossils become as instructive and indisputable asany others.

When the whole of the facts thus available are put together,we find that the earliest men of whom we have osseous remains,and who, undoubtedly, inhabited Europe and Western Asia inthe second continental period, before the establishment of thepresent geography, and before the disappearance of the mammothand its companions, were of two races or subraces, agreeingin certain respects, differing in others. Both have long ordolichocephalic heads, and seem to have been men of greatstrength and muscular energy, with somewhat coarse countenancesof Mongolian type, and they seem to have been ofroving habits, living as hunters and fishermen in a semi-barbarouscondition, but showing some artistic skill and taste in theircarvings on bone and other ornaments.

The earliest of the two races locally, though, on the whole,they were contemporaneous, is that known as the Cannstadt orNeanderthal people, who are characterized by a low forehead,with beetling brows, massive limb bones and moderate stature.So far as known they were the ruder and less artistic of the tworaces. The other, the Engis or Cromagnon race, was of highertype, with well-formed and capacious skull, and a countenancewhich, if somewhat broad, with high cheek bones, eyes lengthenedlaterally, and heavy lower jaw, must have been of somewhatgrand and impressive features. These men are of greatstature, some examples being seven feet in height, and withmassive bones, having strong muscular impressions. The Engisskull found in a cave in Belgium, with bones of the mammoth,the skeletons of the Cromagnon cave in the valley of the Vezere,in France, and those of the caves of Mentone, in Italy, represent« 473 »this race. Doubts, it is true, have been entertained as towhether the last-mentioned race is really palanthropic; but thelatest facts as to their mode of occurrence and associationsseem to render this certain. These men were certainly contemporaneouswith the mammoth, and they disappeared in thecataclysm which closed the earlier anthropic period. Attemptshave, however, been made to separate them into groups accordingto age, within this period;[207] and there can be no doubtthat both in France and England the lower and older strataof gravels and caves yield ruder and less perfect implementsthan the higher. Independently, however, of the fact that thevery earliest men may have been peaceful gatherers of fruit, andnot hunters or warriors, having need of lethal weapons, suchfacts may rather testify to local improvement in the conditionof certain tribes than to any change of race. Such local improvementwould be very likely to occur wherever a newlocality was taken possession of by a small and wanderingtribe, which, in process of time, might increase in numbersand in wealth, as well as in means of intercourse with othertribes. A similar succession would occur when caves, usedat first as temporary places of rendezvous by savage tribes,became afterwards places of residence, or were acquired byconquest on the part of tribes a little more advanced, in themanner in which such changes are constantly taking place inrude communities.

Yet on facts of this nature have been built extensive generalizationsas to a race of river-drift men, in a low and savage condition,replaced, after the lapse of ages, by a people somewhatmore advanced in the arts, and specially addicted to a cavernlife; and this conclusion is extended to Europe and Asia, sothat in every case where rude flint implements exist in rivergravels, evidence is supposed to be found of the earlier of theseraces. But no physical break separates the two periods; the« 474 »fauna remained the same; the skulls, so far as known, presentlittle difference; and even in works of art the distinction is invalidatedby grave exceptions, which are intensified by the fact,which the writer has elsewhere illustrated, that in the case ofthe same people their residences in caves, etc., and their placesof burial are likely to contain very different objects from thosewhich they leave in river gravels.

It is admitted that the whole of these Palæocosmic men areracially distinct from modern men, though most nearly alliedin physical characters to some of the Mongoloid races of thenorthern regions. Some of their characters also appear in thenative races of America, and occasional cases occur, when eventhe characters of the Cannstadt skull reappear in modern times.The skull of the great Scottish king Robert Bruce was of thistype; and his indomitable energy and governing power mayhave been connected with this fact. Attempts have even beenmade [208] to show an intimate connection between the cave menand the Esquimaux of Greenland and Arctic America, but, asWilson has well shown,[209] this is not borne out by their cranialcharacters, and the resemblances, such as they are, in arts andimplements, are common to the Esquimaux and many otherAmerican tribes. In many respects, however, the arts andmode of life, as well as some of the physical characters of thePalæocosmic men of Europe were near akin to those of theruder native races of America.

Perhaps one of the most curious examples of this is the caveat Sorde, in the western Pyrenees. On the floor of this cavelay a human skeleton, covered with fallen blocks of stone.With it were found forty canine teeth of the bear, and three ofthe lion, perforated for suspension, and several of these teethare skilfully engraved with figures of animals, one bearing theengraved figure of an embroidered glove. This necklace, no« 475 »doubt just such a trophy of the chase as would now be worn bya red Indian hunter, though more elaborate, must have belongedto the owner of the skull, who would appear to have perishedby a fall of rock, or to have had his body covered after deathwith stones. In the deposit near and under these remainswere flint flakes. Above the skull were several feet of refuse,stones, and bones of the horse, reindeer, etc., and "Palæolithic"flint implements, and above all were placed the remains ofthirty skulls and skeletons with beautifully chipped flint implements,some of them as fine as any of later age. After theburial of these the cave seems to have been finally closed withlarge stones. The French explorers of this cave refer the lowerand upper skulls to the same race, that of Cromagnon; butothers consider the upper remains as "Neolithic," though thereis no reason why a man who possessed a necklace of beautifullycarved teeth should not have belonged to a tribe which usedwell-made stone implements, or why the weapons buried withthe dead should have been no better than the chips and flakesleft by the same people in their rubbish heaps. In any casethe interment and this applies also to the Mentone cavesrecalls the habits of American aborigines. In some of thesecases we have even deposits of red oxide of iron, representingthe war paint of the ancient hunter.

Widely different opinions have been held by archæologistsas to the connection of the Palanthropic and Neanthropic ages.It suits the present evolutionist and exaggerated uniformitarianismof our day to take for granted that the two are continuous,and pass into each other. But there are stubborn facts againstthis conclusion. Let us take, for example, the area representedby the British Islands and the neighbouring continent. In theearlier period Britain was a part of the mainland, and was occupiedby the mammoth, the woolly rhinoceros, and otheranimals, now locally or wholly extinct. The human inhabitantswere of a large-bodied and coarse race not now found« 476 »anywhere. In the later period all this is changed. Britainhas become an island. Its gigantic Post-glacial fauna has disappeared.Its human inhabitants are now small in stature anddelicate in feature, and represented to this day by parts of thepopulation of the south of Wales and Ireland. They buriedtheir dead in the peculiar cemeteries known as long barrows,and their implements and weapons are of a new type, previouslyunknown. All this shows a great interval of physical andorganic mutation. In connection with this we have the high-levelgravel and rubble, which Prestwich has shown to belongto this stage, and which proves a subsidence even greater thanthat to be inferred from the present diminution of the landarea. Knowing as we do that the close of the Glacial periodwas not more than 8,000 years ago, and deducting from thisthe probable duration of the Palanthropic age on the one hand,and that of modern history on the other, we must admit thatthe interval left for the great physical and faunal changes abovereferred to is too small to permit them to have occurred as theresult of slow and gradual operations. Considerations of thiskind have indeed some of the best authorities on the subject,as Cartailhac, Forel, and de Mortillet, to hold that there is"an immense space, a great gap, during which the fauna wasrenewed, and after which a new race of men suddenly made itsappearance, and polished stone instead of chipping it, and surroundedthemselves with domestic animals."[210] There is thus, inthe geological history of man an interval of physical and organicchange, corresponding to that traditional and historical delugewhich has left its memory with all the more ancient nations.Thus our men of the Palanthropic, Post-glacial or Mammothage are the same we have been accustomed to call Antediluvians,and their immediate successors are identical with the Basques« 477 »and ancient Iberians, a non-Aryan or Turanian people whoonce possessed nearly the whole of Europe, and included therude Ugrians and Laps of the north, the civilized Etruscans ofthe south, and the Iberians of the west, with allied tribes occupyingthe British Islands. This race, scattered and overthrownbefore the dawn of authentic history in Europe by the Celtsand other intrusive peoples, was unquestionably that whichsucceeded the now extinct Palæocosmic race, and constitutedthe men of the so-called "Neolithic period," which thus connectsitself with the modern history of Europe, from which itis not separated by any physical catastrophe like that whichdivides the older men of the mammoth age and the widelyspread continents of the Post-glacial period from our moderndays. This identification of the Neolithic men with theIberians, which the writer has also insisted on, Dawkins deservescredit for fully elucidating, and he might have carried itfarther, to the identification of these same Iberians with theBerbers, the Guanches of the Canary Islands, and the Caribbeanand other tribes of eastern and central America. On thesehitherto dark subjects light is now rapidly breaking, and wemay hope that much of the present obscurity will soon becleared away.

Supposing, then, that we may apply the term Anthropic tothat portion of the Kainozoic period which intervenes betweenthe close of the Glacial age and the present time, and that weadmit the division of this into two portions, the earlier, calledthe Palanthropic, and the later, which still continues, the Neanthropic,it will follow that one great physical and organic breakseparates the Palanthropic age from the preceding Glacial, anda second similar break separates the two divisions of the Anthropicfrom each other. This being settled, if we allow say2,500 years from the Glacial age for the first peopling of theworld and the Palanthropic age, and if we consider the modernhistory of the European region and the adjoining parts of Asia« 478 »and Africa to go back for 5,000 years, there will remain a spaceof from 500 to 1,000 years for the destruction of the Palæocosmicmen and the re-peopling of the old continent by suchsurvivors as founded the Neocosmic peoples. These laterpeoples, though distinct racially from their predecessors, mayrepresent a race contemporary with them in some regions inwhich it was possible to survive the great cataclysm, so that wedo not need to ask for time to develop such new race.[211]

We cannot but feel some regret that the grand old Palæocosmicrace was destined to be swept away by the flood, but itwas no doubt better for the world that it should be replaced bya more refined if feebler race. When we see how this has, insome of its forms, reverted to the old type, and emulated, if notsurpassed it in filling the earth with violence, we may, perhaps,congratulate ourselves on the extinction of the giant races of theolden time.

References:—"Fossil Men," London, 1880. The Antiquity of Man,Princeton Review. "Pre-historic Man in Egypt and the Lebanon,"Trans. Vict. Institute, 1884. Pre-historic Times in Egypt and Palestine,North American Review, June and July, 1892.

MAN IN NATURE.

DEDICATED TO THE MEMORY OF

MY DEAR FRIEND DR. P. P. CARPENTER,

at once an eminent Naturalist and

Educator—

equally a Lover of Nature,

of his Fellow Men and of God.

What is Nature—Man a Part of Nature—Distinctionbetween Man and other Animals—Man as anImitator of Nature—Man As at War With Nature—Manin Harmony With Nature

CHAPTER XVIII.

Few words are used among us more loosely than "nature."Sometimes it stands for the material universe as a whole.Sometimes it is personified as a sort of goddess, working herown sweet will with material things. Sometimes it expressesthe forces which act on matter, and again it stands for materialthings themselves. It is spoken of as subject to law, but justas often natural law is referred to in terms which imply thatnature itself is the lawgiver. It is supposed to be opposed tothe equally vague term "supernatural"; but this term is usednot merely to denote things above and beyond nature, if thereare such, but certain opinions held respecting natural things.On the other hand, the natural is contrasted with the artificial,though this is always the outcome of natural powers, and iscertainly not supernatural. Again, it is applied to the inherentproperties of beings for which we are unable to account, andwhich we are content to say constitute their nature. We cannotlook into the works of any of the more speculative writersof the day without meeting with all these uses of the word, andhave to be constantly on our guard lest by a change of itsmeaning we shall be led to assent to some proposition altogetherunfounded.

For illustrations of this convenient though dangerous ambiguity,I may turn at random to almost any page in Darwin'scelebrated work on the "Origin of Species." In the beginningofChapter III. he speaks of animals "in a state of nature"« 482 »that is, not in a domesticated or artificial condition, so that herenature is opposed to the devices of man. Then he speaks ofspecies as "arising in nature," that is, spontaneously producedin the midst of certain external conditions or environment outsideof the organic world. A little farther on he speaks of usefulvarieties as given to man by "the hand of Nature," whichhere becomes an imaginary person; and it is worthy of noticethat in this place the printer or proof-reader has given the wordan initial capital, as if a proper name. In the next section hespeaks of the "works of Nature" as superior to those of art.Here the word is not only opposed to the artificial, but seemsto imply some power above material things and comparablewith or excelling the contriving intelligence of man. I do notmean by these examples to imply that Darwin is in this respectmore inaccurate than other writers. On the contrary, he isgreatly surpassed by many of his contemporaries in the variedand fantastic uses of this versatile word. An illustration whichoccurs to me here, as at once amusing and instructive, is anexpression used by Romanes, one of the cleverest of the followersof the great evolutionist, and which appears to him togive a satisfactory explanation of the mystery of elevation innature. He says, "Nature selects the best individuals out ofeach generation to live." Here nature must be an intelligentagent, or the statement is simply nonsensical. The same alternativeapplies to much of the use of the favourite term "naturalselection." In short, those who use such modes of expressionwould be more consistent if they were at once to come back tothe definition of Seneca, that nature is "a certain divine purposemanifested in the world."

The derivation of the word gives us the idea of somethingproduced or becoming, and it is curious that the Greekphysis,though etymologically distinct, conveys the same meaning—acoincidence which may perhaps lead us to a safe and serviceabledefinition. Nature, rightly understood, is, in short, an« 483 »orderly system of things in time and space, and this not invariable,but in a state of constant movement and progress, wherebyit is always becoming something different from what it was.Now man is placed in the midst of this orderly, law-regulatedyet ever progressive system, and is himself a part of it; and ifwe can understand his real relations to its other parts, we shallhave made some approximation to a true philosophy. Thesubject has been often discussed, but is perhaps not yet quiteexhausted.[212]

Regarding man as a part of nature, we must hold to hisentering into the grand unity of the natural system, and mustnot set up imaginary antagonisms between man and nature asif he were outside of it. An instance of this appears in Tyndall'scelebrated Belfast address, where he says, in explanationof the errors of certain of the older philosophers, that "the experienceswhich formed the weft and woof of their theories werechosen not from the study of nature, but from that which laymuch nearer to them—the observation of Man": a statementthis which would make man a supernatural, or at least a preternaturalbeing. Again, it does not follow, because man is a partof nature, that he must be precisely on a level with its otherparts. There are in nature many planes of existence, and manis no doubt on one of its higher planes, and possesses distinguishingpowers and properties of his own. Nature, like a perfectorganism, is not all eye or all hand, but includes variousorgans, and so far as we see it in our planet, man is its head,though we can easily conceive that there may be higher beingsin other parts of the universe beyond our ken.

The view which we may take of man's position relatively tothe beings which are nearest to him, namely, the lower animals,will depend on our point of sight—whether that of mere anatomy« 484 »and physiology, or that of psychology and pneumatology aswell. This distinction is the more important, since, under thesomewhat delusive term "biology," it has been customary tomix up all these considerations, while, on the other hand, thoseanatomists who regard all the functions of organic beings asmerely mechanical and physical, do not scruple to employ thisterm biology for their science, though on their hypothesis therecan be no such thing as life, and consequently the use of theword by them must be either superstitious or hypocritical.

Anatomically considered, man is an animal of the classMammalia. In that class, notwithstanding the heroic efforts ofsome modern detractors from his dignity to place him with themonkeys in the orderPrimates, he undoubtedly belongs to adistinct order. I have elsewhere argued that, if he were an extinctanimal, the study of the bones of his hand, or of his head,would suffice to convince any competent palæontologist that herepresents a distinct order, as far apart from the highest apes asthey are from the carnivora. That he belongs to a distinctfamily no anatomist denies, and the same unanimity of courseobtains as to his generic and specific distinctness. On the otherhand, no zoological systematist now doubts that all the races ofmen are specifically identical. Thus we have the anatomicalposition of man firmly fixed in the system of nature, and hemust be content to acknowledge his kinship not only with thehigher animals nearest to him, but with the humblest animalcule.With all he shares a common material and many common featuresof structure.

When we ascend to the somewhat higher plane of physiologywe find in a general way the same relationship to animals. Ofthe four grand leading functions of the animal, nutrition, reproduction,voluntary motion, and sensation, all are performed byman as by other animals. Here, however, there are somemarked divergences connected with special anatomical structures,on the one hand, and with his higher endowments on the« 485 »other. With regard to food, for example, man might be supposedto be limited by his masticatory and digestive apparatusto succulent vegetable substances. But by virtue of his inventivefaculties he is practically unlimited, being able by artificialprocesses to adapt the whole range of vegetable and animalfood substances to his use. He is very poorly furnished withnatural tools to aid in procuring food, as claws, tusks, etc.,but by invented implements he can practically surpass all othercreatures. The long time of helplessness in infancy, whileit is necessary for the development of his powers, is a practicaldisadvantage which leads to many social arrangements andcontrivances specially characteristic of man. Man's sensorypowers, while inferior in range to those of many other animals,are remarkable for balance and completeness, leading to perceptionsof differences in colours, sounds, etc., which lie at thefoundation of art. The specialization of the hand again connectsitself with contrivances which render an animal naturally defencelessthe most formidable of all, and an animal naturallygifted with indifferent locomotive powers able to outstrip allothers in speed and range of locomotion. Thus the physiologicalendowments of man, while common to him with otheranimals, and in some respects inferior to theirs, present in combinationwith his higher powers points of difference which leadto the most special and unexpected results.

In his psychical relations, using this term in its narrowersense, we may see still greater divergencies from the line ofthe lower animals. These may no doubt be connected withhis greater volume of brain; but recent researches seem toshow that brain has more to do with motory and sensorypowers than with those that are intellectual, and thus, that alarger brain is only indirectly connected with higher mentalmanifestations. Even in the lower animals it is clear that theferocity of the tiger, the constructive instinct of the beaver, andthe sagacity of the elephant depend on psychical powers which« 486 »are beyond the reach of the anatomist's knife, and this is stillmore markedly the case in man. Following in part the ingeniousanalysis of Mivart, we may regard the psychical powersof man as reflex, instinctive, emotional, and intellectual; andin each of these aspects we shall find points of resemblance toother animals, and of divergence from them. In regard to reflexactions, or those which are merely automatic, inasmuch asthey are intended to provide for certain important functionswithout thought or volition, their development is naturally inthe inverse ratio of psychical elevation, and man is consequently,in this respect, in no way superior to lower animals.The same may be said with reference to instinctive powers,which provide often for complex actions in a spontaneous andunreasoning manner. In these also man is rather deficientthan otherwise; and since, from their nature, they limit theirpossessors to narrow ranges of activity, and fix them withina definite scope of experience and efficiency, they would beincompatible with those higher and more versatile inventivepowers which man possesses. The comb-building instinct ofthe bee, the nest-weaving instinct of the bird, are fixed andinvariable things, obviously incompatible with the varied contrivanceof man; and while instinct is perfect within its narrowrange, it cannot rise beyond this into the sphere of unlimitedthought and contrivance. Higher than mere instinct are thepowers of imagination, memory, and association, and here manat once steps beyond his animal associates, and develops thesein such a variety of ways, that even the rudest tribes of men,who often appear to trust more to these endowments than tohigher powers, rise into a plane immeasurably above that ofthe highest and most intelligent brutes, and toward which theyare unable, except to a very limited degree, to raise those ofthe more domesticable animals which they endeavour to traininto companionship with themselves. It is, however, in thesedomesticated animals that we find the highest degree of approximation« 487 »to ourselves in emotional development, and this isperhaps one of the points that fits them for such human association.In approaching the higher psychical endowments, theaffinity of man and the brute appears to diminish and at lengthto cease, and it is left to him alone to rise into the domain ofthe rational and ethical.

Those supreme endowments of man we may, following thenomenclature of ancient philosophy and of our Sacred Scriptures,call "pneumatical" or spiritual. They consist of consciousness,reason, and moral volition. That man possessesthese powers every one knows; that they exist or can be developedin lower animals no one has succeeded in proving.Here, at length, we have a severance between man and materialnature. Yet it does not divorce him from the unity of nature,except on the principles of atheism. For if it separates himfrom animals, it allies him with the Power who made andplanned the animals. To the naturalist the fact that suchcapacities exist in a being who in his anatomical structure soclosely resembles the lower animals, constitutes an evidence ofthe independent existence of those powers and of their spiritualcharacter and relation to a higher power which, I think, nometaphysical reasoning or materialistic scepticism will sufficeto invalidate. It would be presumption, however, from thestandpoint of the naturalist to discuss at length the powers ofman's spiritual being. I may refer merely to a few pointswhich illustrate at once his connection with other creatures,and his superiority to them as a higher member of nature.

And, first, we may notice those axiomatic beliefs which lie atthe foundation of human reasoning, and which, while apparentlyin harmony with nature, do not admit of verificationexcept by an experience impossible to finite beings. Whetherthese are ultimate truths, or merely results of the constitutionbestowed on us, or effects of the direct action of the creativemind on ours, they are to us like the instincts of animals infallible« 488 »and unchanging. Yet, just as the instincts of animalsunfailingly connect them with their surroundings, our intuitivebeliefs fit us for understanding nature and for existing in itas our environment. These beliefs also serve to connect manwith his fellow man, and in this aspect we may associate withthem those universal ideas of right and wrong, of immortality,and of powers above ourselves, which pervade humanity.

Another phase of this spiritual constitution is illustrated bythe ways in which man, starting from powers and contrivancescommon to him and animals, develops them into new andhigher uses and results. This is markedly seen in the gift ofspeech. Man, like other animals, has certain natural utterancesexpressive of emotions or feelings. He can also, like some ofthem, imitate the sounds produced by animate or inanimateobjects; while the constitution of his brain and vocal organsgives him special advantages for articulate utterance. Butwhen he develops these gifts into a system of speech expressingnot mere sounds occurring in nature, but by associationand analogy with these, properties and relations of objects andgeneral and abstract ideas, he rises into the higher sphere ofthe spiritual. He thus elevates a power of utterance commonto him with animals to a higher plane, and connecting it withhis capacity for understanding nature and arriving at generaltruths, asserts his kinship to the great creative mind, and furnishesa link of connection between the material universe andthe spiritual Creator.

The manner of existence of man in nature is as well illustratedby his arts and inventions as by anything else; andthese serve also to enlighten us as to the distinction betweenthe natural and the artificial. Naturalists often represent manas dependent on nature for the first hints of his useful arts.There are in animal nature tailors, weavers, masons, potters,carpenters, miners, and sailors, independently of man, andmany of the tools, implements, and machines which he is said« 489 »to have invented were perfected in the structures of lower animalslong before he came into existence. In all these thingsman has been an assiduous learner from nature, though insome of them, as for example in the art of aërial navigation,he has striven in vain to imitate the powers possessed by otheranimals. But it may well be doubted whether man is in thisrespect so much an imitator as has been supposed, and whetherthe resemblance of his plans to those previously realized innature does not depend on that general fitness of things whichsuggests to rational minds similar means to secure similarends. But in saying this we in effect say that man is not onlya part of nature, but that his mind is in harmony with theplans of nature, or, in other words, with the methods of thecreative mind. Man is also curiously in harmony with externalnature in the combination in his works of the ideas ofplan and adaptation, of ornament and use. In architecture,for example, devising certain styles or orders, and these forthe most part based on imitations of natural things; he adaptsthese to his ends, just as in nature types of structure are adaptedto a great variety of uses, and he strives to combine, as innature, perfect adaptation to use with conformity to type orstyle. So, in his attempts at ornament he copies natural forms,and uses these forms to decorate or conceal parts intended toserve essential purposes in the structure. This is at least thecase in the purer styles of construction. It is in the more debasedstyles that arches, columns, triglyphs, or buttresses areplaced where they can serve no useful purpose, and becomemere excrescences. But in this case the abnormality resultingbreeds in the beholder an unpleasing mental confusion, andcauses him, even when he is unable to trace his feelings totheir source, to be dissatisfied with the result. Thus man isin harmony with that arrangement of nature which causesevery ornamental part to serve some use, and which unitesadaptation with plan.

The following of nature must also form the basis of thosefine arts which are not necessarily connected with any utility,and in man's pursuit of art of this kind we see one of the mostrecondite and at first sight inexplicable of his correspondenceswith the other parts of nature; for there is no other creaturethat pursues art for its own sake. Modern archæological discoveryhas shown that the art of sculpture began with theoldest known races of man, and that they succeeded in producingvery accurate imitations of natural objects. But from thisprimitive starting-point two ways diverge. One leads to theconventional and the grotesque, and this course has beenfollowed by many semi-civilized nations. Another leads toaccurate imitation of nature, along with new combinationsarising from the play of intellect and imagination. Let us lookfor a moment at the actual result of the development of thesediverse styles of art, and at their effect on the culture of humanityas existing in nature. We may imagine a people whohave wholly discarded nature in their art, and have devotedthemselves to the monstrous and the grotesque. Such apeople, so far as art is concerned, separates itself widely fromnature and from the mind of the Creator, and its taste andpossibly its morals sink to the level of the monsters it produces.Again, we may imagine a people in all respectsfollowing nature in a literal and servile manner. Such a peoplewould probably attain to but a very moderate amount of culture,but having a good foundation, it might ultimately buildup higher things. Lastly, we may fancy a people who, likethe old Greeks, strove to add to the copying of nature a higherand ideal beauty by combining in one the best features ofmany natural objects, or devising new combinations not foundin nature itself. In the first of these conditions of art we havea falling away from or caricaturing of the beauty of nature. Inthe second we have merely a pupilage to nature. In the thirdwe find man aiming to be himself a creator, but basing his« 491 »creations on what nature has given him. Thus all art worthyof the name is really a development of nature. It is true theeccentricities of art and fashion are so erratic that they mayoften seem to have no law. Yet they are all under the ruleof nature; and hence even uninstructed common sense, unlessdulled by long familiarity, detects in some degree their incongruity,and though it may be amused for a time, at lengthbecomes wearied with the mental irritation and nervous disquietwhich they produce.

I may be permitted to add that all this applies with stillgreater force to systems of science and philosophy. Ultimatelythese must be all tested by the verities of nature to which mannecessarily submits his intellect, and he who builds for aye mustbuild on the solid ground of nature. The natural environmentpresents itself in this connection as an educator of man.From the moment when infancy begins to exercise its senseson the objects around, this education begins training thepowers of observation and comparison, cultivating the conceptionof the grand and beautiful, leading to analysis and abstractand general ideas. Left to itself, it is true this natural educationextends but a little way, and ordinarily it becomes obscuredor crushed by the demands of a hard utility, or by anartificial literary culture, or by the habitude of monstrosity andunfitness in art. Yet, when rightly directed, it is capable ofbecoming an instrument of the highest culture, intellectual,æsthetic, and even moral. A rational system of educationwould follow nature in the education of the young, and dropmuch that is arbitrary and artificial. Here I would merelyremark, that when we find that the accurate and systematicstudy of nature trains most effectually some of the more practicalpowers of mind, and leads to the highest development oftaste for beauty in art, we see in this relation the unity of manand nature, and the unity of both with something higher thaneither.

It may, however, occur to us here, that when we considerman as an improver and innovator in the world, there is muchthat suggests a contrariety between him and nature, and that,instead of being the pupil of his environment, he becomes itstyrant. In this aspect man, and especially civilized man, appearsas the enemy of wild nature, so that in those districts whichhe has most fully subdued, many animals and plants have beenexterminated, and nearly the whole surface has come under hisprocesses of culture, and has lost the characteristics whichbelonged to it in its primitive state. Nay more, we find thatby certain kinds of so called culture man tends to exhaust andimpoverish the soil, so that it ceases to minister to his comfortablesupport, and becomes a desert. Vast regions of theearth are in this impoverished condition, and the westwardmarch of exhaustion warns us that the time may come wheneven in comparatively new countries, like America, the land willcease to be able to sustain its inhabitants. Behind this standsa still farther and portentous possibility. The resources ofchemistry are now being taxed to the utmost to discovermethods by which the materials of human food may be producedsynthetically, and we may possibly, at some future time,find that albumen and starch may be manufactured cheaplyfrom their elements by artificial processes. Such a discoverymight render man independent of the animal and vegetablekingdoms. Agriculture might become an unnecessary and unprofitableart. A time might come when it would no longerbe possible to find on earth a green field, or a wild animal;and when the whole earth would be one great factory, in whichtoiling millions were producing all the materials of food, clothing,and shelter. Such a world may never exist, but its possibleexistence may be imagined, and its contemplation bringsvividly before us the vast powers inherent in man as a subverterof the ordinary course of nature. Yet even this ultimateannulling of wild nature would be brought about not by anything« 493 »preternatural in man, but simply by his placing himselfin alliance with certain natural powers and agencies, and bytheir means attaining dominion over the rest.

Here there rises before us a spectre which science andphilosophy appear afraid to face, and which asks the dreadquestion,—What is the cause of the apparent abnormality inthe relations of man and nature? In attempting to solvethis question, we must admit that the position of man, evenhere, is not without natural analogies. The stronger preysupon the weaker, the lower form gives place to the higher,and in the progress of geological time old species have diedout in favour of newer, and old forms of life have beenexterminated by later successors. Man, as the newest andhighest of all, has thus the natural right to subdue and rulethe world. Yet there can be little doubt that he uses thisright unwisely and cruelly, and these terms themselves explainwhy he does so, because they imply freedom of will. Givena system of nature destitute of any being higher than theinstinctive animal, and introduce into it a free rational agent,and you have at once an element of instability. So long ashis free thought and purpose continue in harmony with thearrangements of his environment, so long all will be harmonious;but the very hypothesis of freedom implies that hecan act otherwise, and so perfect is the equilibrium of existingthings, that one wrong or unwise action may unsettle the nicebalance, and set in operation trains of causes and effectsproducing continued and ever-increasing disturbance. Thusthe most primitive state of man, though destitute of all mechanicalinventions, may have been better in relation to theother parts of nature than any that he has subsequentlyattained to. His "many inventions" have injured him inhis natural relations. This "fall of man" we know as amatter of observation and experience has actually occurred,and it can be retrieved only by casting man back again into« 494 »the circle of merely instinctive action, or by carrying himforward until, by growth in wisdom and knowledge, he becomesfitted to be the lord of creation. The first method has beenproved unsuccessful by the rebound of humanity against allthe attempts to curb and suppress its liberty. The secondhas been the effort of all reformers and philanthropists sincethe world began, and its imperfect success affords a strongground for clinging to the theistic view of nature, for solicitingthe intervention of a Power higher than man, and for hopingfor a final restitution of all things through the intervention ofthat Power. Mere materialistic evolution must ever andnecessarily fail to account for the higher nature of man, andalso for his moral aberrations. These only come rationallyinto the system of nature under the supposition of a HigherIntelligence, from whom man emanates, and whose nature heshares.

But on this theistic view we are introduced to a kind ofunity and of evolution for a future age, which is the greattopic of revelation, and is not unknown to science and philosophy,in connection with the law of progress and developmentdeducible from the geological history, in which anascending series of lower animals culminates in man himself.Why should there not be a new and higher plane of existenceto be attained to by humanity—a new geological period, soto speak, in which present anomalies shall be corrected, andthe grand unity of the universe and its harmony with itsMaker fully restored. This is what Paul anticipates when hetells us of a "pneumatical" or spiritual body, to succeed tothe present natural or "psychical" one, or what Jesus Himselftells us when He says that in the future state we shall be liketo the angels. Angels are not known to us as objects ofscientific observation, but such an order of beings is quiteconceivable, and this not as supernatural, but as part of theorder of nature. They are created beings like ourselves,« 495 »subject to the laws of the universe, yet free and intelligentand liable to error, in bodily constitution freed from many ofthe limitations imposed on us, mentally having higher rangeand grasp, and consequently masters of natural powers notunder our control. In short, we have here pictured to usan order of beings forming a part of nature, yet in theirpowers as miraculous to us as we might be supposed to beto lower animals, could they think of such things. This ideaof angels bridges over the great natural gulf between humanityand deity, and illustrates a higher plane than that of manin his present state, but attainable in the future. Dim perceptionsof this would seem to constitute the substratum ofthe ideas of the so-called polytheistic religions. Christianityitself is in this aspect not so much a revelation of the supernaturalas the highest bond of the great unity of nature. Itreveals to us the perfect Man, who is also one with God, andthe mission of this Divine Man to restore the harmonies ofGod and humanity, and consequently also of man with hisnatural environment in this world, and with his spiritual environmentin the higher world of the future. If it is truethat nature now groans because of man's depravity, and thatman himself shares in the evils of this disharmony with naturearound him, it is clear that if man could be restored to histrue place in nature he would be restored to happiness andto harmony with God, and if, on the other hand, he can berestored to harmony with God, he will then be restored alsoto harmony with his natural environment, and so to life andhappiness and immortality. It is here that the old story ofEden, and the teaching of Christ, and the prophecy of theNew Jerusalem strike the same note which all material naturegives forth when we interrogate it respecting its relations toman. The profound manner in which these truths appear inthe teaching of Christ has perhaps not been appreciated as itshould, because we have not sought in that teaching the« 496 »philosophy of nature which it contains. When He points tothe common weeds of the fields, and asks us to consider thegarments more gorgeous than those of kings in which Godhas clothed them, and when He says of these same wildflowers, so daintily made by the Supreme Artificer, that to-daythey are, and to-morrow are cast into the oven, He gives usnot merely a lesson of faith, but a deep insight into that wantof unison which, centring in humanity, reaches all the wayfrom the wild flower to the God who made it, and requiresfor its rectification nothing less than the breathing of thatDivine Spirit which first evoked order and life out of primevalchaos.

References:—Articles inPrinceton Review on Man in Nature and onEvolution. "The Story of the Earth and Man." London,1890. "Modern Ideas of Evolution." London, 1891. Nature as anEducator.Canadian Record of Science, 1890.

INDEX OF PRINCIPAL TOPICS.

Air-breathers, their Origin and History,257,303.

Alpine and Arctic Plants, their Geological History,425.

American Stone Age,464.

Animals, their Apparition and Succession,169.

---- their Geological History,176,187,194.

---- Permanent Forms of,87,180.

Anthropic Age,461.

Antiquity of Man,469.

Arctic Climates in the Past,213.

Atlantic, its Origin and History,57.

---- Cosmical Functions of,72.

---- its Influence on Climate,81.

---- Deposits in,83.

---- Migrations across,84.

---- Future of,90.

Azores, their Animals,408.

Baphetes planiceps,263.

Bay of Fundy, its Deposits,312.

---- Footprints on Shores of,311.

Bermudas, their Flora, etc.,85.

Boulders, Belts of, on Lower St. Lawrence,345.

Boulder-Clay, Nature, etc., of,360.

Cave Men,476.

Cannstadt Race,474

Chaos, Vision of,90.

Chronology of Pleistocene,470.

Climate, its Causes,81.

---- as related to Plants,215.

Climatal Changes,382.

Coal, its Nature and Structure,235.

---- its Origin and Growth,233.

---- Summary of Facts relating to,241.

---- of Mesozoic and Tertiary,249.

---- its Connection with Erect Forests,296.

Continents and Islands,402.

---- Permanence of,31,403.

Contrast of land and sea-borne Ice,360.

Cordilleran Glaciers,369.

Cromagnon Race,474.

Crust and Sub-crust,62.

Dawn of Life,95.

Deluge, The,467.

Dendrerpeton Acadianum,270.

Determination in Nature,329.

Development of Life,23.

---- Laws of,194.

Distribution of Animals and Plants,401.

Drift of Western Canada,369

Early Man,459.

Engis Race,472.

Eozoon, Discovery of,111.

---- Nature of,112.

---- Contemporaries of,129.

---- Teachings of,135.

Eozoon, Preservation of and Structure,143.

Eyes, earliest Types of,331.

Evolution, its partial Character,188.

Flora of White Mountains,421.

Floras originate in the Arctic,297.

Floating Ice,360.

Footprints of Reptiles,260.

---- of Limulus,319.

Fossils, Preservation of,136.

Fucoids,311.

Galapagos, how Peopled,412.

Geographical Changes and Climate,390.

Geological Record, Imperfection of,40.

Glaciers, Work of,353.

Glacial Period, Conditions of,375.

Gulf Stream,388.

Hydrous Silicates,144.

Huronian as a Geological System,104.

Hylonomus Lyelli,279.

Icebergs, their Nature and Work,348.

Ice Age, the,343.

Imperfection of the Geological Record,40.

Land and Water,58.

Land Snails, Earliest,247.

Labyrinthodonts, their Origin and History,265.

Laurentian System,97.

---- Life in the,107.

Laurentide Glaciers,364,368.

Leda Clay of Lower St. Lawrence,365.

Life, First Appearance of,19,96,157.

Limbs, the Earliest,337.

Limulus, Footprints of,319.

Magmas under Crust of the Earth,63.

Mammoth Age,466.

Man in Nature,484.

---- Early,461.

---- an Imitator of Natural Objects,490.

---- at War with other Natural Agencies,495.

---- in harmony with Nature,496.

Markings, Footprints, etc.,301.

---- Rill and Rain, etc.,317.

Microsauria,279.

Migrations of Plants,434.

Millipedes of Carboniferous Age,295.

Mineral Charcoal,237.

Missouri Coteau,271.

Mountains, Origin of,33.

---- Classes of,66.

Mount Washington,426.

Nature, Various Senses of the Term,483.

Neanthropic Age,472.

Ocean, the Atlantic,58,67.

Oceanic Islands,407.

Palanthropic Age,462.

Permanence of Continents,31,403.

---- of Animal Forms,87,180.

Plants, Geological History of,202.

---- as Indicators of Time and Climate,229.

---- of the Erian, Carboniferous, etc.,202.

---- of the Pleistocene,439.

Pleistocene, Tabular View of,472.

Polygenesis of Species,418.

Pre-determination in Nature,329.

Primitive Rocks,16.

Protozoa, their Place in Nature,152.

Pseudo-Fucoids,318.

Pupa vetusta,288.

Races of Early Men,474.

Rill Marks,317.

Scorpions, Carboniferous,295.

Sigillariæ, Erect,276.

Sorde, Cave of,476.

Species, Permanence of,87,180.

---- Origin of,418.

Sponges in Cambro-Silurian,46.

Spore-cases in Coal,234.

Stigmaria,246.

Stone Age in America,464.

Terraces of Lower St Lawrence,346.

Tides of the Bay of Fundy,312.

Time, Geological,416.

Tracks of Animals,51.

Trees, Erect, with Animal Remains,276.

Tuckerman's Ravine,427.

Underclays, their Origin and Nature,236.

Vegetable Life, the Earliest,338.

Vegetable Kingdom, its History,202.

Vertebrates, History of,183.

Vision of Creation,90.

Worlds, the Making of,9,14.

Worm Tracks,318.

White Mountains,426.

Zoological Regions,405.

Modern Science in Bible Lands. By SirJ. W. Dawson,C.M.G., LL.D., F.R.S. With Maps and Illustrations.12mo, Cloth, $2 00.

The special object of the work, the author tells us, is "to notice thelight which the scientific explorations of the countries of the Biblemay throw on the character and statements of the book." It containsmuch interesting and valuable matter, and Sir J. W. Dawson's opinionsand explanations will doubtless meet with the respect and attentionwhich they merit.—Academy, London.

Will add to Professor Dawson's deservedly high reputation as a scientist,and will be found to possess the same fascination for the readerthat has characterized his previous works.... The work is not onlya most interesting and valuable one from a scientific point of view, butwill prove a notable addition to Biblical literature.—Boston Traveller.

One of the most valuable of recent books for Bible students....This volume is a treatment at once scientific, and in the best sense popular,of such phases of Bible lands as most impressed themselves on theprofessor's mind when journeying in the East.—Boston Advertiser.

The author writes delightfully, even in his technical passages. Hisbook gives freshness to antiquity, and his personal adventures andexperiences, though told modestly, show him to be heroic as a student ofscience and religion—Philadelphia Bulletin.

A very interesting and instructive work.... Not its least charm is theagreeable style in which it is written, and which makes portions of itread like pages from a romance—New York Sun.

A valuable book with a valuable aim.... The whole book is vigorous,clear, strong, and adds another word of deep and honest thoughtto correct errors, dissipate doubts, and stimulate faith.—Zion's Herald,Boston.

A work of great scientific and Biblical value.—Lutheran Observer,Philadelphia.

The book is plain, straightforward, and interesting, and its scientificfacts and deductions are of value.—Western Christian Advocate, Cincinnati.

Professor Dawson in this volume adds to his well-earned fame, and wepredict for it an extensive sale.—Evangelist, New York.

Of priceless value for those who would read with understanding theonly real history the world has ever had, or will have, of the first threethousand years of man's life in the world.—Standard, Chicago.

The above work in for sale by all booksellers, or will be sent by the publishers,postage prepaid, to any part of the United States, Canada, or Mexico, on receiptof price.

The Story of the Earth and Man. ByJ. W. Dawson,LL.D., F.R.S., F.G.S., Principal and Vice-Chancellorof McGill University, Montreal. New Edition withCorrections and Additions. With a Colored Diagramand Illustrations. 12mo, Cloth, $1 50.

This little book is, on the whole, the best popular geology that hasever come from the press. The subject is one that possesses the strongestpossible interest for the writer and awakens his greatest enthusiasm.One of the strongest and most interesting chapters in the volume is thefirst of the two on primitive man. The whole book is remarkable for itssimplicity, clearness, interest, and vitality.—Mail and Express, N. Y.

The book is a recognized authority on the subject of which it treats,and worthy of a place in the library.—S. S. Journal, N. Y.

We advise any of our readers who have been carried away with theevolution craze as something that indicates advanced thinking to readthis most valuable work.—Christian Standard, Cincinnati, O.

The author is an able opponent of the theories of the evolutionists,and his discussion of the theme is interesting. His account of the lowestand earliest form of animal life as exemplified in what he calls the"dawn animal," found by him in fossil state in Canada, is of special interest.—BrooklynEagle.

The last two chapters of the work on "Primitive Man" contain anunanswerable argument against the Darwinian theory of evolution, andwill be found invaluable by all who are called to face that phase ofmodern infidelity. We most earnestly commend the volume.—ChicagoInterior.

This work has stood the test of criticism, and has won its way to theposition of a standard text-book. The learned author does not accepttheories for scientific facts, nor permit himself to be led away by mereclamor. He goes to the bottom of things, and gets at the truth if possible.He does not presume to build a scientific system upon finely wroughtsuppositions. What is known of the history of the earth and man thestudent will find in this book. It comes up to date with its facts. Wedo not know its equal as a text-book on this subject. It is sufficientlyillustrated, and beautifully printed, and has a copious index.—San FranciscoChristian Advocate.

We cannot but give the greatest respect to the writer of this book,who presents so vividly the history of the world's progress, and we cannotbut express admiration for that clear and precise style he possesses.—N. Y. Times.

The Origin of the World, according to Revelation andScience. ByJ. W. Dawson, LL.D., F.R.S., F.G.S.12mo, Cloth, $2 00.

The revised work is a cyclopædia that will be welcome to all who desirea reconciliation of science and religion, in which the Scriptures retaintheir authority. The appendices contain valuable scientific criticism,and the treatise meets the controversy as it is to-day.—NorthAmerican, Philadelphia, Pa.

To all reverent students of the Bible this work will prove a valuableboon in enabling them to determine the precise import of Biblical referencesto creation, and how these may be harmonized with modern discovery....In an appendix the volume furnishes several short essays onspecial points collateral to the general subject, and important to the solutionof some of its phases.—N. Y. Evangelist.

Briefly described, the book is a singularly suggestive study of the firstchapter of Genesis considered as an inspired revelation in the light ofmodern science.—Evening Post, N. Y.

The book will commend itself to both scholars and the common people;for, while the latter can understand, the former can enjoy it.—TheChurchman, N. Y.

Although most scientists and many theologians will doubtless differwith the author's conclusions, yet he has shown so much ingenuity andcare in sustaining them, and is so evidently inspired by a regard for whathe desires to be the truth, that his book will command the attention ofcandid inquirers of whatever shade of belief.—Boston Globe.

Mr. Dawson has devoted much study to the treatment of the subjectdiscussed in this volume. He has sought to get at the truth alone....The writer's style is clear and vigorous, and he has patiently wroughtout his theories from a wide and comprehensive range of observation.—Union-Argus,Brooklyn, N. Y.

The work treats of the mystery of "origins," the beginning of creation,the "desolate void," the various created objects light, land, plants,animals, and finally man, whose unity of origin and antiquity are madethe subject of two chapters. An appendix, containing short essays onspecial points, is a valuable feature of the book.—Observer, N. Y.

Whether the reader accepts Dr. Dawson's conclusions or not, he willfind the work a wonderfully suggestive study, and singularly fair in its treatmentof the opinions and theories it antagonizes.—Free Press, Detroit, Mich.

As a summary of creation, the book is lively and fresh. It will befound interesting and profitable to all students of this alluring theme.—ChristianAdvocate, N. Y.

At least no student of theology can afford not to possess this most excellentwork.—Pittsburg Dispatch.

The Geographical Distribution of Animals. With aStudy of the Relations of Living and Extinct Faunas, aselucidating the Past Changes of the Earth's Surface. ByAlfred Russel Wallace. With Colored Maps andnumerous Illustrations. 2 vols., Cloth, $10 00.

The Earth. ByÉlisée Reclus. With 234 Maps and Illustrations,and 23 Page Maps printed in Colors. 8vo,Cloth, $5 00; Half Calf, $7 25.

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Cosmos: a Sketch of a Physical Description of the Universe.ByAlexander Von Humboldt. Translated fromthe German byE. C. Otté. 2 vols., 12mo, Cloth, $3 00.

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A Naturalist's Wanderings in the Eastern Archipelago.A Narrative of Travel and Exploration from1878 to 1883. ByHenry O. Forbes, F.R.G.S., etc.Many Illustrations and Colored Maps. 8vo, Cloth, $5 00.

The Voyage of the "Challenger." The Atlantic: APreliminary Account of the General Results of the ExploringVoyage of H.M.S. "Challenger" during the Year1873 and the Early Part of the Year 1876. By Sir C.Wyville Thomson, Knt., LL.D., F.R.S.,etc. With manyColored Maps, Charts, and Illustrations. 2 vols., 8vo,Cloth, $12 00.

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		PAGE
Cape Trinity on the Saguenay	Frontispiece
Folding of the Earth's Crust	To face	9
Cambro-Silurian Sponges	"	39
Map of the North Atlantic	"	57
Nature-print of Eozoon	"	95
Laurentian Hills, Lower St. Lawrence		100
Section from Petite Nation Seigniory to St. Jerome		101
The Laurentian Nucleus of the American Continent		103
Attitude of Limestone at St. Pierre		109
Weathered Eozoon and Canals	To face	112
" " "		113
Group of Canals in Eozoon		115
Amœba and Actinophrys		119
Minute Foraminiferal Forms		123
Section of a Nummulite		127
Portion of Shell of Calcarina		128
Weathered Eozoon with Oscular tubes	To face	135
Diagram showing different States of Fossilization of a Cell of a Tabulate Coral		139
Slice of Crystalline Lower Silurian Limestone		141
Walls of Eozoon penetrated with Canals		141
Joint of a Crinoid		145
Shell from a Silurian Limestone, Wales		146
Casts of Canals of Eozoon in Serpentine		147
Canals of Eozoon		147
Primordial Trilobites	To face	169
Primitive Fishes	"	184
Devonian Forest	"	201
Coal Section in Nova Scotia		233
Skeleton ofHylonomus Lyelli« x »	To face	257
Footprints ofHylopus Logani	"	260
Humerus and Jaws ofDendrerpeton	"	272
Reptiliferous Tree	"	276
Microsaurian, restored	"	278
Dolichosoma longissimum, restored	"	286
Pupa andConulus	"	288
Millipedes and Insect	"	296
Footprints ofLimulus	"	311
Rusichnites Grenvillensis	"	322
Restoration ofProtospongia tetranenia	"	329
Giant Net-sponge	"	336
Boulder Beach, Little Metis	"	345
Palæogeography of North America	"	383
Distribution of Animals in Time	"	401
Tuckerman's Ravine and Mount Washington	"	425
Pre-historic Skulls	"	459
Primitive Sculpture	"	481

CHAPTER I. Page
The Starting-point	3
CHAPTER II.
World-making	9
CHAPTER III.
The Imperfection of the Geological Record	39
CHAPTER IV.
The History of the North Atlantic	57
CHAPTER V.
The Dawn of Life	95
CHAPTER VI.
What May Be Learned from Eozoon	135
CHAPTER VII.
The Apparition and Succession of Animal Forms	169
CHAPTER VIII.
The Genesis and Migrations of Plants	201
CHAPTER IX.
The Growth of Coal	233
CHAPTER X.« viii »
The Oldest Air-breathers	257
CHAPTER XI.
Markings, Footprints, and Fucoids	311
CHAPTER XII.
Pre-determination in Nature	329
CHAPTER XIII.
The Great Ice Age	345
CHAPTER XIV.
Causes of Climatal Change	363
CHAPTER XV.
The Distribution of Animals and Plants As Related to Geographical and Geological Changes	401
CHAPTER XVI.
Alpine and Arctic Plants in Connection With Geological History	425
CHAPTER XVII.
Early Man	459
CHAPTER XVIII.
Man in Nature	481

GREATER PERIODS.	SYSTEMS OF FORMATIONS.	CHARACTERISTIC FOSSILS.
Archæan or Eozoic	Pre-Laurentian Laurentian		Protozoa	Protophyta
Palæozoic	Huronian		Crustaceans	Algæ
	Cambrian		Molluscs	Cryptogamous
	Cambro-Silurian [A]		Worms	and
	Silurian [B]		Corals, etc,	Gymnospermous
	Devonian		Fishes	Plants.
	Carboniferous		Amphibians
	Permian
Mesozoic	Triassic		Reptiles	Pines and
	Jurassic		Birds	Cycads
	Cretaceous		Earliest Mammals.	Trees of modern types.
Kainozoic or Tertiary	Eocene		Higher Mammals
	Miocene		of extinct forms
	Pliocene		Recent Mammals	Modern Plants,
	Pleistocene		and
	Modern		Man.


North America in Periods of Warm and Cold Submergence.(A) Early Cretaceous. (B) Glacial or Pleistocene. Shaded portion land. Unshaded portion.—Snow-clad mountains.—Crosses.—Ice-laden sea. These maps illustrate the probable geographical conditions of warm and cold periods. (p. 388.)

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SOME
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