Ingeology,catastrophism is the theory that theEarth has largely been shaped by sudden, short-lived, violent events, possibly worldwide in scope.[1]This contrasts withuniformitarianism (sometimes calledgradualism), according to which slow incremental changes, such aserosion, brought about all the Earth's geological features. The proponents of uniformitarianism held that the present was "the key to the past", and that all geological processes (such aserosion) throughout the past resembled those that can be observed today. Since the 19th-century disputes between catastrophists and uniformitarians, a more inclusive and integrated view of geologic events has developed, in which thescientific consensus accepts that some catastrophic events occurred in the geologic past, but regards these as extreme examples of explicable natural processes.
Proponents of catastrophism proposed that eachgeological epoch ended with violent and sudden natural catastrophes such as majorfloods and the rapid formation of major mountain chains. Plants and animals living in the parts of the world where such events occurred became extinct, to be replaced abruptly by the new forms whose fossils defined the geological strata. Some catastrophists attempted to relate at least one such change to theBiblical account ofNoah's flood.
The French scientistGeorges Cuvier (1769–1832) popularised the concept of catastrophism in the early 19th century; he proposed that new life-forms had moved in from other areas after local floods, and avoided religious or metaphysical speculation in his scientific writings.[2][3]
In the early development ofgeology, efforts were made in a predominantlyChristian western society to reconcile biblical narratives ofCreation and theuniversal flood with new concepts about the processes which had formed the Earth. The discovery of other ancient flood myths was taken as explaining why the flood story was "stated in scientific methods with surprising frequency among theGreeks", an example beingPlutarch's account of theOgygian flood.[4]
The leading scientific proponent of catastrophism in the early nineteenth century was the Frenchanatomist andpaleontologistGeorges Cuvier. His motivation was to explain the patterns ofextinction andfaunal succession that he and others were observing in thefossil record. While he did speculate that the catastrophe responsible for the most recent extinctions in Eurasia might have been the result of the inundation of low-lying areas by the sea, he did not make any reference toNoah's flood.[2] Nor did he ever make any reference to divine creation as the mechanism by which repopulation occurred following the extinction event. In fact Cuvier, influenced by the ideas of theEnlightenment and the intellectual climate of theFrench Revolution, avoided religious or metaphysical speculation in his scientific writings.[3] Cuvier also believed that thestratigraphic record indicated that there had been several of these revolutions, which he viewed as recurring natural events, amid long intervals of stability during the history of life on Earth. This led him to believe the Earth was several million years old.[5]
By contrast in Britain, wherenatural theology was influential during the early nineteenth century, a group of geologists includingWilliam Buckland andRobert Jameson interpreted Cuvier's work differently. Cuvier had written an introduction to a collection of his papers on fossil quadrupeds, discussing his ideas on catastrophic extinction. Jameson translated Cuvier's introduction into English, publishing it under the titleTheory of the Earth. He added extensive editorial notes to the translation, explicitly linking the latest of Cuvier's revolutions with the biblical flood. The resulting essay was extremely influential in the English-speaking world.[6] Buckland spent much of his early career trying to demonstrate the reality of the biblical flood using geological evidence. He frequently cited Cuvier's work, even though Cuvier had proposed an inundation of limited geographic extent and extended duration, whereas Buckland, to be consistent with the biblical account, was advocating a universal flood of short duration.[7] Eventually, Buckland abandonedflood geology in favor of theglaciation theory advocated byLouis Agassiz, following a visit to the Alps where Agassiz demonstrated the effects of glaciation at first hand. As a result of the influence of Jameson, Buckland, and other advocates of natural theology, the nineteenth century debate over catastrophism took on much stronger religious overtones in Britain than elsewhere in Europe.[8]
Uniformitarian explanations for the formation ofsedimentary rock and an understanding of the immense stretch ofgeological time, or as the concept came to be knowndeep time, were found in the writing ofJames Hutton, sometimes known as the father of geology, in the late 18th century. The geologistCharles Lyell built upon Hutton's ideas during the first half of 19th century and amassed observations in support of the uniformitarian idea that the Earth's features had been shaped by same geological processes that could be observed in the present acting gradually over an immense period of time. Lyell presented his ideas in the influential three volume work,Principles of Geology, published in the 1830s, which challenged theories about geological cataclysms proposed by proponents of catastrophism like Cuvier and Buckland.[9] One of the key differences between catastrophism and uniformitarianism is that uniformitarianism requires vast timelines for continued processes, whereas catastrophism accepts that there appeared to have been abrupt changes. Today most geologists combine catastrophist and uniformitarianist standpoints, taking the view thatEarth's history is a slow, gradual story punctuated by occasional natural catastrophic events that have affected Earth and its inhabitants.[10]
From around 1850 to 1980, most geologists endorseduniformitarianism ("The present is the key to the past") andgradualism (geologic change occurs slowly over long periods of time) and rejected the idea that cataclysmic events such asearthquakes,volcanic eruptions, or floods of vastly greater power than those observed at the present time, played any significant role in the formation of the Earth's surface. Instead they believed that the earth had been shaped by the long term action of forces such as volcanism, earthquakes, erosion, and sedimentation, that could still be observed in action today. In part, the geologists' rejection was fostered by their impression that the catastrophists of the early nineteenth century believed that God was directly involved in determining the history of Earth. Some of the theories about Catastrophism in the nineteenth and early twentieth centuries were connected withreligion and catastrophic origins were sometimes consideredmiraculous rather than natural events.[11]
The rise in uniformitarianism made the introduction of a new catastrophe theory very difficult. In 1923J Harlen Bretz published a paper on thechanneled scablands formed by glacialLake Missoula in Washington State, USA. Bretz encountered resistance to his theories from the geology establishment of the day, kicking off an acrimonious 40 year debate. Finally in 1979 Bretz received thePenrose Medal; theGeological Society of America's highest award.[12]
In the 1950s,Immanuel Velikovsky propounded catastrophism in several popular books. He speculated that the planetVenus is a former "comet" which was ejected fromJupiter and subsequently 3,500 years ago made two catastrophic close passes by Earth, 52 years apart, and later interacted with Mars, which then had a series of near collisions with Earth which ended in 687 BCE, before settling into its currentorbit. Velikovsky used this to explain the biblicalplagues ofEgypt, the biblical reference to the "Sun standing still" for a day (Joshua 10:12 & 13, explained by changes in Earth's rotation), and the sinking ofAtlantis. Scientists vigorously rejected Velikovsky's conjectures.[13]
Neocatastrophism is the explanation of sudden extinctions in the palaeontological record by high magnitude, low frequency events (such as asteroid impacts, super-volcanic eruptions, supernova gamma ray bursts, etc.), as opposed to the more prevalentgeomorphological thought which emphasises low magnitude, high frequency events.[14]
In 1980,Walter andLuis Alvarez published a paper suggesting that a 10 kilometres (6.2 mi)asteroidstruck Earth 66 million years ago at the end of theCretaceous period. The impact wiped out about 70% of all species, including the non-aviandinosaurs, leaving behind theCretaceous–Paleogene boundary (K–T boundary). In 1990, a 180 kilometres (110 mi) candidate crater marking the impact was identified atChicxulub in theYucatán Peninsula ofMexico. These events sparked a wide acceptance of a scientifically based catastrophism with regard to certain events in the distant past.
Since then, the debate about theextinction of the dinosaurs and othermass extinction events has centered on whether the extinction mechanism was the asteroid impact, widespread volcanism (which occurred about the same time), or some other mechanism or combination. Most of the mechanisms suggested are catastrophic in nature.
The observation of theShoemaker-Levy 9 cometary collision with Jupiter illustrated that catastrophic events occur as natural events.
Modern theories also suggest that Earth's anomalously largemoon was formed catastrophically. In a paper published inIcarus in 1975,William K. Hartmann andDonald R. Davis proposed that a catastrophic near-miss by a largeplanetesimal early in Earth's formation approximately 4.5 billion years ago blew out rocky debris, remelted Earth and formed theMoon, thus explaining the Moon's lesser density andlack of an iron core.[15] The impact theory does have some faults; some computer simulations show the formation of a ring or multiple moons post impact, and elements are not quite the same between the Earth and Moon.[16][17][18]
