Thisglossary of geography terms is a list of definitions of terms and concepts used ingeography and related fields, includingEarth science,oceanography,cartography, andhuman geography, as well as those describing spatial dimension, topographical features, natural resources, and the collection, analysis, and visualization of geographic data. It is split across two articles:
This page,Glossary of geography terms (A–M), lists terms beginning with the letters A through M.
A unit of area traditionally defined as the area of a plot of land onechain (66feet) by onefurlong (660 feet), equivalent to 43,560 square feet (0.001563 sq mi; 4,047 m2), or about 0.40hectare.
A sub-discipline of geography which studies the spatial relationships between humans andagriculture, as well as the cultural, political, and environmental processes that lead to parts of the Earth's surface being transformed into agricultural landscapes throughprimary sector activities.
A distinctly triangular or fan-shaped deposit of sediment transported by water, often referred to asalluvium. Alluvial fans usually form at the base ofmountains, where high-velocity rivers or streams meet a relatively flat area and lose the energy needed to carry large quantities of sediment, which ultimately spreads out in all available directions. They tend to be larger and more obvious in arid regions.
A wide, flat, gently slopingplain created by the long-termdeposition ofalluvium from one or morerivers flowing fromhighland regions, and typically characterized by variousfluvial landforms such asbraided streams,terraces, andmeanders. Alluvial plains encompass the larger area over which a river'sfloodplain has shifted through geological time.
Characteristic of or resembling the EuropeanAlps, or any other high-elevationmountain range ormountainous environment (especially one deeply modified byglacial erosion so as to contain characteristiclandforms such ascirques,horns, etc.), intopography, climate, or ecological communities.[5]
A geographical location where there is little or notide, i.e. where thetidal amplitude is zero or nearly zero because the height ofsea level does not change appreciably over time (meaning there is nohigh tide orlow tide), and around which a tidal crest circulates once per tidal period (approximately every 12 hours). Tidal amplitude increases, though not uniformly, with distance from these points. Amphidromic points are the consequence of resonance phenomena which occur when obstructing landmasses reflect tidal bulges back and forth across oceanic basins; their precise locations, usually in theopen ocean near the center of the basin, depend largely on the surroundingtopography andbathymetry, and also vary slightly with winds, currents, and the positions of the Sun and the Moon. There are at least a dozen well-defined amphidromic points across the Earth's oceans.[6][7]
The average difference in the height of sea level between high tide and low tide varies greatly across the Earth's oceans. At places known asamphidromic points (dark blue) – the central points around which tidal bulgescirculate twice daily – there is little or no change in sea level, and hence no high tides or low tides.
anastomosing stream
Alsoanastomosed stream.
Astream orriver composed of multiple, branching, interconnected, coexistingchannels that enclose floodbasins onalluvial plains, usually formed when a slow-moving river encountersavulsions that divert its flow, creating new channels on the floodplain.[8]
anecumene
Alsoanoecumene.
The part of the Earth's surface which is uninhabited and/or uninhabitable by human beings.[4] Contrastecumene.
The steepest angle of descent or dip, relative to the horizontal plane, at which a mass of loose, freely movable material such as sand or unconsolidated rock debris can remain stationary, i.e. without sliding downward, despite the pull of gravity.[4]
The southernmost of the Earth's twopolar circles oflatitude, south of which the sun appears above thehorizon for 24 continuous hours at least once per year (and is therefore visible at midnight) and also appears at least partially below the horizon for 24 continuous hours at least once per year (and is therefore not visible at noon). Its latitude is approximately 66°33′47.1″ south of theEquator. ContrastArctic Circle.
Astream or otherwatercourse that existed before the present form of the surrounding land surface was established and which maintains its original course and pattern despite changes in the local geology ortopography. For example, a landscape featuring a river with a dendritic drainage pattern may be altered by gradual, localizedtectonic uplift, but the river may be sufficiently powerful to erode through the new obstructions as rapidly as they are formed, carving agorge rather than being redirected, and thereby preserving its dendritic pattern even though it now flows over a landscape that typically produces very different drainage patterns.[4] Compareinsequent stream.
1. Of or relating toanthropogeny, the scientific study of the origins of human beings.
2. Having an origin in human activity; caused by or attributable to humans.[4]
anti-dip stream
A stream flowing in a direction approximately opposite to that of thedip of the underlying surface rocks. It is frequently, though not necessarily, anobsequent stream.[4]
A geologicalupfold that has an arch-likeconvex shape and its oldestbeds near its center, often visible at the Earth's surface in exposedrock strata. Contrastsyncline.
1. Themeridian oflongitude that is directly opposite orantipodal to a given meridian, i.e. the imaginary line that is exactly 180 degrees of longitude distant from the given meridian. Together, a meridian and its antimeridian form agreat circle that passes through the geographic poles.
2. The180th meridian in particular, i.e. the meridian of longitude that is exactly 180 degrees both east and west of thePrime Meridian, with which it forms a great circle dividing the Earth into theEastern andWestern Hemispheres. The 180th meridian is used as the approximate basis for theInternational Date Line because it mostly passes through the open waters of the Pacific Ocean.
Any pair of points on the Earth's surface that arediametrically opposite to each other, such that a straight line connecting them would pass through the Earth's center. Such points are as far away from each other as possible, with thegreat-circle distance between them being approximately 20,000 kilometres (12,000 mi).
anywhere fix
A geographic position which aGPS receiver is able to calculate without requiring information about its own location or the local time.[9]
apogean tide
Thetide when the Moon is at its furthest distance from Earth in its orbit (itsapogee), during which its gravitational pull is reduced, resulting in a smallertidal range than is usual, i.e. lowerhigh tides and higherlow tides.[4] Contrastperigean tide.
The apparent position of an object in space as seen by an observer, which, because of physical and geometric effects, may differ from the object's true position.
applied geography
The application of geographical knowledge and techniques to the solution of economic and social problems on any scale, ranging fromlocal toglobal, in disciplines such as civic planning,land use and management, location policy, and population studies, among many others.[4]
apposed glacier
Aglacier resulting from the merging of two separate glaciers.[4]
A normallypermeable rock, underlying or overlying anaquifer, which becomes impermeable because of the saturation of its pores by water, potentially creating aconfined aquifer.[4]
An underground layer ofwater-bearingpermeable rock, rock fractures, or unconsolidated materials such as gravel, sand, or silt, which is sufficiently porous to carry or conduct water yet also sufficiently coarse or non-absorptive to release the water and thereby permit its exposure to or access from the ground surface. Groundwater from aquifers may naturally emerge at the surface, e.g. at aspring, or may be extracted using man-madewells. There are many different types of aquifer with various levels ofhydraulic conductivity.[4]
A deepgully cut by a stream that flows only part of the year; a drygulch. The term is used primarily indesert areas in North America and South America.[2]
The northernmost of the Earth's twopolar circles oflatitude, north of which the sun appears above thehorizon for 24 continuous hours at least once per year (and is therefore visible at midnight) and also appears at least partially below the horizon for 24 continuous hours at least once per year (and is therefore not fully visible at noon). Its latitude is approximately 66°33′47.1″ north of theEquator. ContrastAntarctic Circle.
The direction toward which aslope faces with respect to acompass or to the Sun's position in the sky,[5] or the direction which a segment ofcoastline faces as it meets thesea.
assimilation
The process by which the rock forming the wall of a magma chamber in incorporated into the magma itself.
The physiographic border between thePiedmont andAtlantic coastal plain regions of eastern North America. The name derives from the river rapids andwaterfalls that occur as the water flows from the hard rocks of the higherpiedmont onto the softer rocks of thecoastal plain.[2]
1. The sudden loss of land by the action of water.
2. The rapid abandonment by ariver orstream of an existingchannel in favor of the formation of a new channel, typically because the new channel follows a steeper or less obstructed course.
awareness space
All of the locations of which an individual is "aware", i.e. about which they have knowledge above some minimum level, even those they may not have actually visited. Awareness space includesactivity space, and it enlarges as new locations are discovered and new information is gathered.[4] See alsosearch space andmental map.
axis
1. (coordinate system) Any of the reference lines of aCartesian coordinate system, from which the signed distances to each coordinate are measured, e.g. the x-axis or the y-axis.
2. (of afold) The imaginary central line or plane dividing the limbs of the fold as symmetrically as possible; the crest from whichstrata dip downward and away in ananticline, or the lowest depth of the trough from which strata rise in opposite directions in asyncline.[4]
3. (of theEarth) The rotational axis of the Earth: the diameter between theNorth Geographic Pole and theSouth Geographic Pole, passing through the planet's geometric center, around which the Earth rotates anti-clockwise (i.e. to the east) once every 23 hours and 56 minutes. This axis is constantly tilted at an angle of about 66°30' with respect to the plane of theEarth's orbit around the Sun, which is the primary cause of the seasonal weather cycles experienced at temperate and polar latitudes.
The angle formed between a reference vector (oftenmagnetic north) and a line from the observer to a point of interest projected perpendicularly to thezenith on the sameplane as the reference vector. Azimuth is usually measured indegrees and can be determined with acompass.
azimuthal projection
Amap projection in which allbearings are laid off correctly from the centerpoint of the map, so that all points on the map are true in distance and direction from the center.[4]
Any geographical area that is remote, isolated, undeveloped, or difficult to access, as contrasted withfrontcountry; sparsely populated or uninhabitedwilderness. See alsobush.
The part of the profile of ahillslope that forms the steepest, typically linear portion of the slope, generally located in the middle and bounded by a convexshoulder above and a concavefootslope below. The backslope may or may not include vertical or near-verticalcliffs.[5]
1. A part of ariver in which there is little or no current, especially a side channel, a sluggishmeander, or a slowing and widening of themain stem created by an obstruction to flow.
2. A place regarded as remote, underdeveloped, or culturally backward relative to other places; a place or state of stagnation, in which little or no economic, social, or intellectual progress occurs.
3. A secluded, peaceful place.
badia
In the Middle East, an arid area characterized by low or irregular precipitation and little or no vegetation.[4]
The political fragmentation of a largerregion orstate into multiple smaller regions or states, often implying mutual hostility or lack of cooperation between such units, as has occurred frequently in the Balkan Peninsula of southeastern Europe.
2. An elevation in thebed of a river, stream, or shallowsea, either fully or partially submerged, mid-channel or connected to theshore, and usually made of sand, mud, gravel, or other loose sediment. See alsobar andshoal.
Thestage during which thechannel of a river or stream is completely filled with water frombank to bank, immediately preceding theoverbank stage, when the river overflows its banks and inundates the surroundingfloodplain.[4]
An elevated area of unconsolidated sediment such as sand or gravel which has been deposited by the flow of ariver or other moving body of water. See alsoshoal.
Animpoundment built for seasonal floodwater storage and/or to create areservoir for irrigation, as opposed to adam, which instead serves the purpose of hydroelectric power generation, though the terms are sometimes used more or less interchangeably.
A long, narrowridge orshoal lying above thehighest high tide level (thereby creating anisland) and parallel to the mainlandcoast, from which it is separated by alagoon.[4] Barrier islands are analogous to very large sandbars deposited naturally by wave and tidal action, often in extensive chains along the coastline, but may also be created artificially bydredging. Though their size and shape change frequently, particularly during storms, they are important naturalbreakwaters which shelter areas of relatively calm waters wherewetlands and marine life flourish. See alsospit andtied island.
Diagram of various coastal landforms depicting abarrier island
In the Spanish-speaking world, aneighborhood or community within a larger urban area, generally with informal boundaries, though in some places the term may refer to a formalsubdivision of amunicipality.
Another name for adepression, particularly one that is approximately circular, level or nearly level at the bottom, and/or surrounded on all sides by land of uniform elevation.
1. The measurement of water depth, mainly ofseas andoceans but sometimes of deeplakes.
2. The study and depiction of the physical features orrelief of thefloor of a lake or ocean. In this sense bathymetry is considered the underwater equivalent ofhypsometry ortopography.
Acoastal body of water that is directly connected to but recessed from a larger body of water, such as anocean,sea,lake, or another bay. The land surrounding a bay usually shelters it from strong winds and waves, making bays ideal places forports andharbors.
The direction or position of an object, or the direction of an object's movement, relative to a fixed point. It is typically measured indegrees and can be determined with acompass. By convention,magnetic north is defined as having a bearing of zero degrees.
The solid rock in the Earth'scrust that underlies all soil and other loose material; the rock material that breaks down eventually to form soil.[2]
belt
Alsocorridor.
A largeregion ordistrict (often but not necessarily a broad, elongated area of vague or indeterminate boundaries) identified or associated with one or more particular, distinctive characteristics, e.g. of climate (banana belt), vegetation (Pine Belt), topography (Alpide belt), geology or mineral resources (Lead Belt), agriculture (Corn Belt), land use (green belt), language or ethnicity (Hindi Belt), or social/cultural demographics (Bible Belt).[4] See alsoregionalism.
bench
A narrow step, shelf, ledge, orterrace, typically backed by a steep slope, produced either naturally (e.g. by erosion, as with awave-cut bench) or artificially (e.g. by mining).[4]
Asurveying mark cut or embedded into a durable, fixed material, such as a rock or the wall of a building, for which the height above some designateddatum level has been accurately measured.
Acrevasse or series of parallel crevasses that opens in aglacier when a mass of moving ice detaches and pulls away from stagnant ice orfirn. Bergschrunds are common in mountainous areas, often forming seasonally near the back of acirque where the ice meets a steep or rockyheadwall. When the rift forms directly between ice and rock, the gap is called arandkluft.[4]
1. A level space, shelf, or raised barrier separating two areas, often man-made and built of compacted earth. Berms often function asimpoundments,fortification lines, orborder walls and other lines of demarcation.
2. A low, impermanent, nearly horizontal or landward-sloping shelf,bench, or narrowterrace on thebackshore of abeach and parallel to theshoreline, formed by waves which deposit material beyond the averagehigh water mark, e.g. during storms. Some beaches have no berms; others may have one or more.[5]
The study of the distribution ofbiologicalspecies andecosystems in geographic space and through geological time.
biogeosphere
The outer part of thelithosphere, specifically the part which is also part of thebiosphere, from the surface of the Earth to the greatest subterranean depths at which organic life can exist.[4]
The water of a slow-moving riverchannel flowing through a forestedswamp orwetland, characterized by high concentrations oftannins leached from decaying vegetation, which gives it a darkly stained color and high acidity.
A surface of broken, boulder-sized rock fragments found inperiglacial or volcanic environments,[10] createdin situ by processes other thanmass wasting, often byfrost weathering in the joints of larger rocks.[4]
A hole orfissure, especially a nearly vertical one, that is the landward opening of asea cave, frequently spouting or spraying air andseawater as waves crash against the cave's seaward opening.[4]
A sandydepression formed whenwinderodes into patches of bare sand on otherwise vegetation-stabilizedsand dunes at the margins of coastal and arid ecosystems.
A steep slope orcliff marking the outer margin of afloodplain, especially one formed as the river erodes the concave bend of ameander. See alsocut bank.
A landscape of mixed woodland andpasture, with fields and winding country lanes sunken between low, narrow ridges and banks surmounted by tall, thickhedgerows, especially as found in rural parts of western Europe.
Any significant accumulation of water, either natural or artificial, on the surface of the Earth. Bodies of water may hold or contain water, as withlakes andoceans, or they may collect and move water from one place to another, as withrivers,streams, and otherwatercourses.
A type ofwetland which accumulates deposits of dead plant material, especiallymosses, known aspeat. Bogs occur where the water at the ground surface is acidic and low in dissolved nutrients. They are one of four main types of wetland.
1. (tidal) A steep-fronted wave formed by the convergence of twotidal bulges or by the constriction of an incoming tide as it travels up ariver,firth, or narrowbay, temporarily reversing the direction of the current.[4]
2. (hole) A deep, man-made hole or shaft drilled into the ground, e.g. in mining, or for digging awell or tunnel.
A bald, steep-sided, dome-shaped hill, mountain, or rockoutcropping at least 30 metres (98 ft) in height and several hundred meters in width. Compareinselberg,tor, andnubbin.
A type ofadministrative subdivision in certain English-speaking parts of the world. Though traditionally used to refer to afortress or a walledtown, modern usage of the term can variably refer to any town with its own local self-government, a formal or informal subdivision of a largemetropolis (as inNew York City andLondon), or an entire administrativeregion (as in the U.S. state ofAlaska).
The replacement of the narrow, congested, winding streets of an older town or neighborhood with wider, more modern streets orboulevards, often according to a carefully plotted grid layout.[4]
Any line of demarcation, real or imaginary, visible or invisible, natural or artificial, with or without legal significance, which may be perceived from either or both sides of the line, indicating the place at which two or more geographical areas of distinct ownership, administration, legal jurisdiction, or any other quality meet; e.g. aborder separating political oradministrative divisions, zones of occupation, natural areas, or private and public property.[4] See alsofrontier.
A region of a country or other polity which supports a large proportion of the country's domestic food production (especially of wheat and other grains) due to its fertile soils, favorable climate, and/or relative accessibility to agricultural interests.
break
1. Any more or less abrupt change in the profile of aslope or hillside.
2. A heavily eroded area along ariver featuring steepbanks,bluffs,ravines, orgorges. The term is used chiefly in the plural (i.e.breaks) and primarily in the United States and Canada.
A transfer point on a transport route where the mode of transport or type of carrier changes and where large-volume shipments are reduced in size. For example, goods may be unloaded from a ship and transferred to trucks at an ocean port.[2]
A wave of water on the surface of anocean,lake, or otherbody of water with enough energy that, upon reaching a peak size or velocity, its crest "breaks" or overturns upon itself with a distinct forward curve, with the linear energy transforming intoturbulence. Waves tend to break as they enter areas of shallow water, most reliably nearshorelines, where the decreasing depth of the sea floor beneath themforces them to grow to a critical height at which point they overturn and the remaining forward energy is dissipated upon thebeach asswash, though other forces may also cause breaking, including stormy weather and passing watercraft.
Any man-made structure built on thecoast of a body of water, typically thesea, in order to reduce the intensity of wave action in an area adjacent to the shore, thereby providing safe harbourage for human activities in the inshore waters. Breakwaters may also be designed to protect the coastline fromcoastal erosion andlongshore drift.
Any previously developed area of land that is no longer in use, often with derelict buildings and infrastructure, in some contexts implying land that has been abandoned because of pollution or contamination.[4] Comparegreenfield.
Low-lying, woody, often dense vegetation or plant debris, e.g.scrub; a thicket of small trees and shrubs, or the plant community characterized by vegetation dominated by shrubs.
Wild, undeveloped, or uncultivated land, especially when covered by thick shrubs and vegetation; sparsely populated or uninhabitedwilderness. See alsobackcountry,hinterland,outback, andbushveld.
In southern Africa, a tropical or subtropical woodlandecoregion consisting largely of opensavanna with scattered trees; wild countryside as opposed to cultivated land.[4]
An isolatedhill ormountain with steep or precipitous sides, usually having a smaller summit area than amesa.[2]
bypass
1. Aroute which diverges around a place rather than traveling through it, especially a road or footpath built specifically for the purpose of diverting automobile or pedestrian traffic away from areas that are congested, blocked, under construction, or unsafe.[4]
A type ofparcel-based land recording system containing a comprehensive record of interests in individual units of land within acountry or other polity, usually including a geometric description of each parcel's physical location, dimensions, andboundaries that is linked to legal information detailing the nature of the interests (e.g. rights, restrictions, and responsibilities), theownership or control of those interests, and the economic value of the land and its improvements. The cadastre is a fundamental source of data used in resolving disputes between landowners.
A man-made stack ormound of rocks, stones, or masonry, usually roughly conical or pyramidal in shape, constructed as a burial mound, to mark asurveyed point, or as alandmark orwaypoint to aidroutefinding on aroute that is otherwise unmarked and difficult to distinguish from the surrounding environment.[11]
A narrow, steep-sidedvalley surrounding aninlet formed inkarstic regions along theMediterranean coast, either byfluvial erosion or the collapse of the roof of acave that has been subsequently partially submerged by a rise insea level.
A very largecauldron-shapeddepression of volcanic origin which forms through the subsidence and collapse of the ground surface following the evacuation of an underlyingmagma chamber. See alsovolcanic crater.
A topographic map ofNgorongoro Crater in northern Tanzania, the world's largest inactive, intact, and unfilled volcaniccaldera, which formed when an immense volcano erupted and collapsed on itself 2–3 million years ago. The floor of the caldera is 600 metres (2,000 ft) below its rim and covers more than 260 square kilometres (100 sq mi).
A deep cleft betweencliffs orescarpments, or a rift between two mountain peaks, resulting fromweathering and the erosive activity of ariver over long periods of geologic time.
1. A primarycity ortown of a country, state, province, or other subnational polity, especially one that is a seat of government for the entire polity, either by law or by virtue of being the physical location of the government's offices and meeting places, or both. A capital is often but not always the largest or most economically or historically important city of its constituent.[4] A polity may have one or more capitals, or none.
2. Any place considered to have informal primacy or importance with respect to some characteristic or association, e.g.Milan, Italy is sometimes unofficially called the "Fashion Capital of the World".
The total number of human beings that an area can support given the quality of the natural environment and the level of technology of the population.[2]
A map in which some thematic mapping variable, such as travel time, population, orgross national product, is substituted for traditional measures of land area or distance such that the geometry or space of the map is distorted in order to convey and emphasize the information of the alternate variable.
A track, road, or railway raised above a body of water or a low-lying place by virtue of being built upon a man-madeembankment, typically constructed of earth, masonry, wood, or concrete. Comparebridge.
Either of the two imaginary points in the sky at which an indefinitely extended projection of the Earth's axis of rotation intersects thecelestial sphere. As the Earth rotates upon its axis, the north and south celestial poles remain permanently fixed in the sky (directly overhead to observers at theNorth Pole andSouth Pole, respectively), and all other points appear to rotate around them.
The point in a geometric figure for which the coordinates are the average values of the coordinates of all other points in the figure, i.e. the arithmetic mean position of all points in the figure; or the point with the smallest possible average distance from all other points of the figure. In geography, thegeographical center of a region of the Earth's surface is the centroid of the two-dimensional shape of that region, as projected radially tosea level or onto ageoid.[11]
A unit of length equal to 66 feet (20.117 m), used especially in public landsurveys in the United States; 10 square chains is equal to 1 acre (0.40 hectares). Though the literal chains used to measure this distance have long been superseded, surveying tapes are often still called "chains", and measuring with a tape may be called "chaining".[12]
A class of terrestrial vegetation characterized by dense, impenetrable thickets of thorny shrubs or dwarf broadleaved trees, commonly found in northern Mexico and the southwestern United States.[2]
A steep-sidedcoastalgorge, typically of soft erodingcliffs of sandstone or clay, through which a river or stream flows to the sea. The term is used primarily in southern England.
A warm, dry wind experienced along the eastern side of theRocky Mountains in the United States and Canada. Most common in winter and spring, it can result in a rise in temperature of 20 °C (36 °F) in a quarter of an hour.[2]
Amap showing the distribution of a phenomenon by graded shading which indicates the density per unit area of that phenomenon; the darker the shading, the greater the density.[13]
An ephemeral, often highlysaline lake that forms seasonally with fluctuations in thewater table, usually in the winter, in thedesert basins of Northwest Africa.[14]
A steep-sidedvolcano formed by the explosive eruption of cinders that form around avent. Cinders arelava fragments about 1 centimetre (0.39 in) in diameter.[3]
The commercial, cultural, political, or historical focal point of acity orurban area, where a significant proportion of its population, workforce, business, traffic, administration, and/or other activity is concentrated, often though not necessarily located near its geographic center. The city center may include or overlap with acentral business district ordowntown area, and the terms are commonly used interchangeably.
A sovereignstate or small independentcountry that usually consists of a singlecity and its dependent territories.
clearing
1. The practice of permanently removing vegetation, especially trees and bushes, from aforest or woodland in order to use the space for another purpose, such as agriculture, civic development, or paths for roads, railways, or power lines.
Acoastline where the repeated action of ocean waves has formed steep and often precipitouscliffs, as opposed to a flat or gently slopingalluvial coast.
The vegetation that would exist in an area if growth had proceeded undisturbed for an extended period. This would be the "final" collection of plant types that presumably would remain forever, or until the stable conditions were somehow disturbed.[2]
Of, on, or pertaining to acoast or coastline, i.e. a boundary or transition betweenland andsea. Coastal areas are regions defined by interactions between terrestrial and marine processes.
A measure of the degree oflocalization or spatialconcentration of a given phenomenon, e.g. residential housing or industrial activity, within a particular space or spaces. Values for this variable, often mathematically symbolized asL, range from 0 (where the phenomenon is evenly distributed across all spaces) and 1 (where it is densely concentrated in one space and completely absent elsewhere).[10]
The complementary angle of a givenlatitude; i.e. the arithmetic difference between 90 degrees and the given latitude. For example, the colatitude of 36° 22′ 49″ is 53° 37′ 11″.[4]
Aterritory under the immediate complete political control of a sovereignmetropolitan state but otherwise distinct, often geographically, from the state's home territory. Colonies have no international representation independent of the metropolitan state and its ruling country controls its trade for its benefit. Comparesatellite state.
Loose, unconsolidated sediment that has been transported anddeposited at the base of ahillslope by any of various wash ormass movement processes, such assurface runoff,sheet erosion, orlandslides. Typically a heterogeneous mixture of rock types and sizes ranging from silt totalus boulders, colluvium is often derived fromeluvium, and differs fromalluvium, which is deposited primarily byfluvial activity.[14]
A steep, narrowvalley or a large hollow on the side of ahill orcoastline, especially one enclosed on all but one side. The term is used primarily in southern England, where it often implies a dryravine in a limestone or chalkescarpment. See alsocwm.
1. Traditionally, a political community founded for the benefit of all or most of the members of the community, i.e. for the public welfare or thecommon good; or astate or other polity in which the supreme power of government is vested in the people being governed; arepublic or ademocracy.[15]
2. A free association of otherwise individual, autonomous, self-governing territories organized as afederation orconfederation, with a jointly operated government being charged with responsibility for certain matters in the common interest, such as defense.[4]
A figure on acompass,map, nautical chart, or monument used to display the orientation of the fourcardinal directions — North, East, South, and West — and their intermediate points.
Atraverse which relies on the indications of a magneticcompass for orienting the traverse as a whole or for determining the directions of individual lines.[11]
The characteristic of a group of neighboring political or geographical divisions not being interrupted by politically unaffiliated land or water. Such divisions are said to becontiguous.
One of several very large, contiguouslandmasses into which the Earth's land area is divided, generally by geographical or political convention rather than any strict criteria.[1] Geologically, continents correspond largely to areas ofcontinental crust oncontinental plates.
The type of climate found in the interior of the major continents in the middle ortemperate latitudes. The climate is characterized by a great seasonal variation in temperatures, four distinct seasons, and a relatively small annual precipitation.[2]
The line of high ground that separates the different oceanicdrainage basins of a particularcontinent. The river systems of a continent on opposite sides of a continental divide flow toward different oceans. Seedrainage divide.[2]
A portion of acontinent that is submerged beneath an area of relatively shallow water known as ashelf sea. Though continental shelves are usually treated as physiographic provinces of theocean, they are not part of the deep ocean basin proper but the flooded margins of the continent.
A line marked on atopographic map which connects points of equalelevation above or below a specified referencedatum. Multiple contour lines, each representing a different elevation, are depicted together to show theshape of theterrain within the map area.[3]
A long chain ofmountain ranges orhighlands, especially those formed by the same orogeny and spanning the length of acontinent alongtectonic boundaries. The term is used in particular to refer to theAmerican Cordillera, an almost continuous system of parallel ranges lining the west coasts of North, Central, and South America.
core area
The portion of a country or territory that contains its economic, political, intellectual, and cultural focus. It is often the center of creativity and change. See alsohearth.[2]
The process of mechanicalerosion of the Earth's surface by the impact or grinding action of particles being transported across it, either by moving water, waves, glaciers, wind, or gravity.
Thecardinal direction in which a vessel or aircraft is moving, or in which it is steered. This is not necessarily the same as theheading, the direction in which the craft's bow or nose is pointed; any difference between heading and course is due to the motion of the air or water through which the vessel is moving, or other aerodynamic effects such asskidding orslipping. See alsobearing.
1. A walled, rounded,cirque-like opening at the head of a smallvalley.
2. A small, narrow, shelteredbay,inlet,tidal creek, or recess in anestuary, often within a larger embayment.
3. A small, often approximately circular, wave-cut indentation or recess in acliff on a large body of water, especially one with a relatively narrow or secluded entrance.
4. A shallow tidal river, or thebackwater near themouth of a tidal river.
An old and stable region ofcontinentallithosphere, characterized by a thickcrust composed of ancient crystalline basement rock. Cratons are generally found in the interiors oftectonic plates, having remained relatively unaffected by orogenic and tectonic activity for very long periods of time.[4]
A small, intermittentstream that is larger than abrook but smaller than ariver. The term is used primarily in the United States, Canada, and Australia.[5]
The thin shell of solid material that is the Earth's outermost layer and the outermost component of thelithosphere. The Earth's crust is generally divided into two distinct types,oceanic crust andcontinental crust, both of which "float" on top of themantle.[3]
The totality of water in the solid phase on the Earth's surface, includingglaciers; sea, lake, and riverice;snow; andpermafrost. The cryosphere is sometimes considered a subset of thehydrosphere.[3]
A branch ofhuman geography which studies the patterns and interactions of humanculture in relation to the natural environment and the human organization of space.
cultural landscape
The physical setting created by humans that reflects the identity and culture of the area.
The accumulated habits, attitudes, and beliefs of a group of people that define for them their general behavior and way of life; the total set of learned activities of a people.[2]
culture hearth
The area from which theculture of a particular group or population diffused. See alsohearth.[2]
A tunnel or conduit that channels water through or beneath an obstacle (e.g. through a man-made crossing of aravine that would otherwise block the natural flow of water), or any artificially buriedwatercourse.
An arc-shaped,dune-like mound of sediment on abeach orforeshore.[14] Cusps tend to be uniformly spaced in repeating patterns close to the shoreline, with the embayment of each arc made of fine-grained sand or gravel and the "horns" made of coarser sediment.
A continuallyerodingbank along a meanderingriver orstreamchannel, especially a bank that has been eroded into a nearly verticalcliff. Cut banks generally form on the outside bend of a deepmeander, opposite the depositionalpoint bar that forms on the inside bend.
A large air mass that rotates around a strong center of low atmospheric pressure. It can rotate clockwise or counter clockwise depending on which hemisphere it is in.
A term referring to the longitudinal profile of someglaciatedvalleys which have been eroded into a series of consecutivehanging valleys resembling stairs.
Any barrier, either natural or artificial, that stops or restricts the flow of water, either on the surface or underground. Man-made dams are most commonly built to impound rivers or streams, generally to retain water for purposes such as human consumption, irrigation, aquaculture, or power generation (whereas related structures such asfloodgates andlevees are more specifically designed to manage or prevent water flow into particular areas).
A type of thematicmap that uses areal symbols to visualize aspatially dependent variable (e.g. population density) by refining achoropleth map with ancillary information about the distribution of the variable. The dasymetric method attempts to improve the resolution of maps based on average or per-capita figures calculated for discrete administrative units, which tend to show sharp contrasts between adjacent areas, by supplementing these figures with additional geographic data that allow more precise categories to be constructed. Dasymetric maps are a hybrid of choropleth andisarithmic maps, combining their strengths and weaknesses in order to more accurately depict quantities that vary continuously across space.[4]
A place where water runoff from a relatively small, confined space emerges into a much larger, broader space, or where abody of water pours forth from a narrow opening, such as where a stream or river enters a lake or ocean.
A forest composed of trees which lose their leaves each year.[2]
decolonization
The process of ending the colonization of a region or a state.
deep
A trough-likedepression or trench in theocean floor, of limited extent but great depth, generally more than 5,500 metres (18,000 ft) below sea level.[4]
deferred junction
Aconfluence of twowatercourses in which atributary stream is prevented bylevees, natural or artificial, from immediately joining another stream or river and consequently is forced to flow parallel beside it, usually within a largefloodplain, for a considerable distance before the channels eventually merge, often at the convex bend of a largemeander.[4]
A unit of angular measure, represented by the º symbol. A circle is divided into 360 degrees; subdivisions of the degree include theminute (1⁄60 of one degree) and thesecond (1⁄3600 of one degree). Degrees are commonly used to divide the roughly spherical shape of the Earth for geographic and cartographic purposes, e.g. when reportinglatitudes andlongitudes.[1]
A landform at themouth of ariver where themain stem splits up into severaldistributaries. It is formed from the deposition of the sediment carried by the river as the flow leaves the mouth of the river. It is often affected by incoming tides. Compareestuary.[5]
A politically neutral area orbuffer zone in which treaties or agreements between polities or other competing factions forbid military installations, activities, or personnel. These zones are usually situated along an establishedboundary orfrontier separating territories controlled by adjacent military powers or alliances.
A word identifying a person or a group of people in relation to a particular place, usually derived from the name of the place (which may be any kind of place, formal or informal, of any size or scale, from a town or city to a region, province, country, or continent) and used to describe all residents or natives of that place, regardless of any ethnic, linguistic, religious, or cultural differences which may exist within the local population. Examples include "Vietnamese", describing a person from Vietnam; "Detroiter" for a person from the city of Detroit, Michigan; and "Macedonian" for a person from North Macedonia or the wider historical region of Macedonia.
Aterritory relying on or subject to the control of anothercountry, neither possessing full political independence nor forming an integral part of the controlling country's political or economic interests.
Any natural process by which material such as soil and rocks is added to alandform orlandmass, e.g. by the action of wind, water, ice, or gravity in transporting previouslyweathered surface material, which comes to rest when sufficient kinetic energy is lost and accumulates in layers of sediment. See alsosedimentation.
An area of land which has been damaged or devalued by some process, either natural or man-made (e.g. extractive industry), and/or simply neglected, causing it to be abandoned by human interests (and often other organisms) and leaving it incapable of being used productively in its present condition.[4] See alsobrownfield land.
An arid, barren area of land where littleprecipitation occurs and living conditions are consequently unfavorable for most plant and animal life. Deserts are characterized by exposure of the unprotected ground surface to processes ofdenudation as well as large variations in temperature between night and day. They are often classified by the amount of precipitation they receive, by their average temperature, by the causes of theirdesertification, or by their geographical location.
A ground surface, often found in arid environments, covered with interlocking rock fragments of pebble and cobble size, closely packed after the removal of finer rock material and smoothed or polished by blown sand so that eventually their upper surfaces are more or less uniformly flat.[4]
A conspicuous orange-yellow to black coating often present on exposed rock surfaces in arid environments, consisting of thin, hard, polished layers of metal oxides, especially iron and manganese, which form when minute quantities of matter migrate to the surface of the rock bycapillary action and are then precipitated by evaporation.[4]
The process by which a previously fertile area becomes increasingly arid, infertile, ordesert-like; a type of land degradation in which biological productivity is lost due either to natural or man-made processes, e.g.climate change oroverexploitation of soils for agriculture.
desire line
A straight line drawn on amap between the point of origin and the destination of a trip, i.e. the shortest distance between these two points, indicating the route a person would like or desire to follow if it were possible.[4]
Any path or trail, often a footpath, created as a consequence of erosion caused by repeated human or animal traffic, usually because it is the shortest or easiestroute to navigate between an origin and a destination. Desire paths often emerge as shortcuts where constructed paths or roads are circuitous, have gaps, or are non-existent.
A shallow artificialpond built to capture and hold rainwater or sea mist in order to provide water for livestock, made especially in areas where natural supplies of surface water are not readily available, such as on the chalk downlands of southern England.[4]
A type ofigneous intrusion in which a more mobile, ductile, or deformable rock or other material is forced to intrude into relatively brittle overlying rocks.
The scattered dispersion of a human population from its original homeland; or the members of a dispersed population, now residing in various locations to which they are not indigenous.
A three-dimensional computer graphics representation of a geographicterrain surface created fromelevation data. DEMs are the most common basis for digitally produced relief maps.
1. A ditch, wall, embankment, or ridge, natural or man-made, that is an obstacle to something else; another name for alevee.
2. Ingeology, anintrusion in which molten rock has ascended through an approximately verticalfissure and solidified into a wall of rock that is often harder or less permeable than the rocks of the surrounding strata.[4]
Theposition of one point relative to another without reference to the distance between them, usually expressed as the angular distance indegrees between a line connecting the two points and a reference direction. Incartography,navigation, andorienteering, direction is often considered only with respect to a two-dimensional plane (seecompass rose), but it is also commonly interpreted in three dimensions.[16]
Inhydrology, the volumetric flow rate of water through a particular cross-sectional area, i.e. the volume of water that passes a particular point along a waterway (e.g. a cross-section of astreamchannel) per unit time. The measure includes the volumes of any suspended solids, dissolved chemicals, or organic matter in addition to the water itself. Discharge is commonly measured for both natural and man-made hydrological systems, where it may be referred to by various names includingstreamflow andoutflow.
Acoastline which cuts transversely across the predominant orientation of the local geological strata, i.e. not parallel to them, as with aconcordant coastline.[4]
A landscape produced by significantstream erosion and incision of aplateau such that only a small part of the plateau surface is at or near the original elevation of the summit; much of the area instead occurs as erodedhills orbadlands.[5]
The decrease in cultural or spatial interactions between two places as the distance between them increases. This effect may be noticeable intowns andcities, where certain characteristics such as pedestrian traffic, building height, and land value tend to decline with greater distance from thecity center.
A type ofadministrative subdivision used by governments and institutions worldwide, typically at regional or local levels. Districts are commonly drawn to define the jurisdictions of special local government services, such as law enforcement and education, and often function more or less independently of themunicipal orcounty governments that designate them. The term can refer to a wide variety of official and colloquial subdivisions, includingelectoral districts,school districts, andshopping districts.
A shallow enclosedbasin or funnel-shapeddepression typical ofkarst landscapes, usually with a flat floor and linked to the underlying drainage system by a vertical shaft.[4] See alsosinkhole.
1. A steep-sidedmound that forms when very viscous lava is extruded from avolcanic vent.[3]
2. An uplifted area ofsedimentary rock with a downward dip in all directions, often caused by molten rock material pushing upward from below. The sediments have often eroded away, exposing the rocks that resulted when the molten material cooled.[2]
donga
In southern Africa, another name for agully orbadland carved by extreme erosion.[14]
An open, treeless expanse of gently undulating, elevatedgrassland, usually of chalk and supporting grazing for livestock. The term is used primarily in southern England, Australia, and New Zealand.[4]
In English-speaking North America, the commercial, cultural, and often historical and/or geographicalcenter of acity ortown, especially a large city within a majormetropolitan area, often synonymous with itscentral business district.
The natural or artificial removal of surface and/or sub-surface water from an area with excess water, e.g. viarunoff facilitated bychannels such asstreams andrivers, into which water collects and is transported tosea level by gravity. The patterns, hierarchies, and evolution of drainage networks are widely studied inphysical geography disciplines.
Any area of land where precipitation collects and drains into a common outlet, such as into ariver,lake,ocean, or any otherbody of water. The drainage system includes all of thesurface water from precipitationrunoff andsnowmelt, as well as all of thegroundwater beneath the Earth's surface. Each drainage basin is separated topographically from adjacent basins by adrainage divide.
Alsoridgeline,watershed,water parting,water divide, or simplydivide.
The topographical barrier that separates neighboringdrainage basins. Divides are often, though not always, located along conspicuous elevatedridges ormountain ranges.
1. A terrain feature formed by two parallelridges orspurs with low ground in between them.
2. Another name for anarroyo,ravine, orgulch, especially one with a broad floor and gently sloping sides.[5]
draw down
The maximum extent to which thewater table is reduced inelevation as a result of pumping water from awell that penetrates anaquifer. The amount of draw down diminishes logarithmically with distance from the site of the well, a fact which determines the shape of the subsurfacecone of depression in the area surrounding the well.[14]
A type ofsea ice consisting of multipleice floes that are not attached to theshoreline or any other fixed object such as ashoal, and which are therefore free to "drift" under the influence of winds andocean currents. Contrastfast ice.
Avalley which was originally formed on land but later partially or entirely submerged beneath the sea due to a rise in sea level. See alsofjord,calanque, andria.
An elongatedhill in the shape of an inverted spoon or half-buried egg which is formed byglacial ice acting on underlying unconsolidatedtill or groundmoraine.
A type of farming practiced in semi-arid or dry grassland areas without irrigation, instead using such approaches asfallowing, maintaining a finely broken surface, and growing drought-tolerant crops.[2]
Anecoregion or more generally any land area defined by a relative scarcity of water, where precipitation is evenly balanced or exceeded by evaporation from surfaces and evapotranspiration by plants. Drylands encompass all sub-humid and arid environments, from tropicalsavannas to hyper-arid extremes such asdeserts.
1. A collective term for the various fields of natural science related to the planetEarth.
2. The branch of science that studies the physical constitution and characteristics of the Earth and its atmosphere, using methods and tools fromgeography, geology, physics, chemistry, biology, and mathematics to build a quantitative understanding of how the Earth works and changes over time.
The economic advantages that accrue to an activity by locating close to other activities; benefits that follow from complementarity or shared public services.[2]
A type ofbiogeographic province that is smaller than abioregion and which contains characteristic, ecologically and geographically distinct, and relatively uniform assemblages of biologicalcommunities and species. Ecoregion boundaries often overlap withinecotones and mosaic habitats, and most ecoregions contain habitats that differ from those described for their assignedbiome.
A transition area between two biologicalcommunities, where different communities meet and integrate. It may manifest as a gradual blending of the communities across a broad area, or as an abrupt boundary line.
1. The habitable world according to the ancient Greeks; the part of the Earth's surface that is suitable for permanent human settlement, e.g. because it is climatically tolerable and physically occupiable.[4]
2. All of human civilization considered collectively.
A concentration of businesses, commercial buildings, or retail and entertainment venues situated outside of a traditionaldowntown orcentral business district in what was previously asuburban residential orrural area.
The transitional areas of "fringe" space at the boundaries of acountry,city, or other artificial geographical entity, often distinguished by a partly man-made, partly natural landscape that is in the earliest stages of human management and organization. Comparehinterland.
effective accessibility
The extent to which a place or service is actually accessible, governed not only by the distance to be traveled but also by whether or not the means of transport, the time available, and social circumstances make access possible.[4]
The scientific study of humansettlements of all types, incorporating concepts such as regional, metropolitan, and communityplanning and dwelling design with the goal of achieving harmony between the inhabitants of a settlement and their physical, social, and cultural environments.
A branch ofhuman geography concerned with analysis of the organization, methods, results, and consequences of politicalelections in the context of geographic space and using geographical techniques.
1. The height of a geographic location above or below a fixed reference point; in particular, the height of a point on the Earth's surface with respect tosea level (or at least to areferencegeoid used as an approximation of the Earth's mean sea level). Comparealtitude,geopotential height, anddepth.[1]
2. The vertical angle between the horizontal and a high point, e.g. between thehorizon and a star in the night sky, or between the base of a mountain and itssummit.[4]
3. In architecture, a view of one of the sides of a building, or a drawing of this view.[4]
A tract or territory completely surrounded by and enclosed within the territory of exactly one other state, country, or other political entity. Unlike enclaves,exclaves can be surrounded by more than one other state.[2]
The independent country ofLesotho is completelyenclaved by the country ofSouth Africa. The country ofEswatini, to the east, is not an enclave because it borders two countries: South Africa andMozambique.
A closeddrainage basin that allows little or no outflow to external bodies of water but converges instead into internallakes orswamps which equilibrate through evaporation.
A place (e.g. aport, city, or trading post) to which physical goods or merchandise are brought to be stored temporarily while awaiting export to another country, and where they are not liable tocustoms duties.[4] Though the term once described important commercial centers situated along long-distance trade routes, modern customs areas have largely made such entrepôts obsolete, and the term is now more commonly used to refer toduty-free ports with a high volume of re-export trade.
Everything on and around the Earth's surface and atmosphere; the complex of physical, chemical, and biological elements which comprise the natural world, especially as contrasted withman-made objects or spaces.
The point on the Earth's surface directly above thefocus of anearthquake, near which the seismic waves produced by the earthquake are usually most noticeable.
1. An imaginary line dividing a spheroid such as a planet into northern and southernhemispheres, defined by the intersection of the spheroid's surface and the plane perpendicular to itsaxis of rotation, which results in agreat circle exactly midway between and hence equidistant from the planet'sgeographic poles and is therefore defined as zero degreeslatitude.
2. The Earth's equator in particular (often capitalized as theEquator): the imaginary circle of latitude halfway between the geographic poles which is assigned a latitude of zero degrees (0°) and therefore used as a reference point from which all otherlines of latitude are measured. At 40,074 kilometres (24,901 mi) in circumference, is the largest great circle of the Earth.[1] Places located on or near the Equator experience approximately the same amount of daylight year-round, which causes local daytime temperatures and climate patterns to be relatively stable throughout the year.
Equally distant from a point, object, or location; e.g. a given locationA is said to be equidistant from two other locationsB andC ifB andC each have the same distance fromA.
A boulder that has been carried from its source by aglacier and deposited as the glacier melted. Such boulders are often conspicuous because they differ geologically from the surrounding rock.[2]
Aplain beneath which thebedrock has been subjected to considerable subsurfaceweathering, known as "etching". Erosion of theregolith overlying an etchplain often exposes topographical irregularities such asinselbergs.
ethnic group
A group of people in a country who share a unique culture and identity.
A portion of a state or territory that is geographically separated from the main part by surrounding foreign territory of one or more other states or political entities. Many exclaves are alsoenclaves.
exotic stream
Astream found in an area that is too dry to have spawned such a flow. The flow originates in some moister section.[2]
Agricultural land that is plowed or tilled but left unseeded during agrowing season. Fallowing is usually done to conserve moisture and soil nutrients.[2]
A selected point in aprojected coordinate system from which the position of any place can be expressed in terms of its coordinates with respect to the selected point. The false origin differs from thetrue origin in order to exclude negative values.[4]
Sea ice that is more or less securely "fastened" to acoastline,to the sea floor, or to groundedicebergs, and which therefore does not move with currents and winds (unlikedrift ice). The formation of fast ice is usually seasonal and its properties vary with water depth,topography of the sea floor,tides, and pressure from adjacent drift ice.
An area of numerousfractures in the Earth's crust along which movement has occurred. The movement may be in any direction and involve material on either or both sides of the fractures.[2]
A form of government in which powers and functions are divided between a central government and a number of political subdivisions that have a significant degree of political autonomy.[2]
A wild, barren, high-altitudemoor orupland, or a treelessalpinetundra, often studded with boulders or rockoutcrops; or a broad, isolated mountainsummit. The term is used primarily in northern England, Scotland, and Fennoscandia.[4]
An area of spongy, waterlogged ground containing decaying vegetation that accumulates over time intopeat, and which is supplied with an input of mineral-richsurface orgroundwater and thereby directly connected to a larger hydrological system. This external input typically results in higher mineral concentrations and a more alkalinepH than other peat-forming ecosystems such asbogs. Fens are one of four main types ofwetland, along with bogs,marshes, andswamps.
field
1. Any large, open, outdoor space, natural or man-made, especially one with a natural surface covering such as grass or soil and having few trees and structures, permitting longsightlines.
2. (variable) A property, quantity, or observation (e.g. temperature, soil moisture, population density, etc.) that can be theoretically assigned to any point of space and which varies across space. Both scalar and vector fields are found inGIS applications, although the former is more common. Alsospatially dependent variable.
The size and shape of the Earth as studied ingeodesy. Applications requiring varying levels of precision have led to the development of many different models of the Earth, ranging from simple spheres to much more accurate approximations such asgeoids.
A type of ice that is at an intermediate stage betweensnow andglacial ice. More specifically, firn is partially compactednévé left over from past seasons which has subsequently recrystallized into a form that is harder and denser than névé.
first bottom
A colloquial term loosely applied to the topographically lowest step of afloodplain that experiences regular flooding (though the frequency considered "regular" is inconsistently specified), i.e. the first part to be inundated when a flood occurs. The term is used primarily in the Midwestern United States.
Another name for a coastalinlet,strait, orbay associated with themouth of a largeriver, where thetidal effects ofseawater passing upriver have widened the riverbed into anestuary. The term is used primarily in Scotland.
A series of shallow steps down which water is allowed to flow, designed to permitsalmon or other anadromous fish to circumvent artificial barriers such asdams as they swim upstream to spawn.[2]
Ahollow ordepression within abog, often water-filled and usually occurring as part of a repeated series of such depressions which are elongated and parallel to each other and separated by intervening ridges known asstrings.
A primarily vertical artificial barrier designed to temporarily contain the waters of ariver or otherwaterway which may rise to high levels during flooding events. Flood walls are narrower and typically easier to build thandikes orlevees, so they are mainly used in locations where space is limited or where building more traditional flood-control structures would interfere with other interests.
2. A large-capacitychannel orculvert designed to capture and divert floodwaters or excess streamflow from populous or flood-prone areas and eventually drain it into a river or other body of water, e.g. an artificial drainage canal bounded bylevees. They often run below street level in larger cities.
3. A road crossing of a flood-prone channel, built at or close to the natural ground level. It is similar to acauseway but crosses a shallow and often drydepression that is subject to flooding, rather than a continuously flooded waterway.
4. A part of afloodplain kept clear of encumbrances and reserved for emergency diversion of floodwaters.
Aglacial landform created by the movement of a glacier around a boulder, consisting of a lineation or streamlined furrow orridge parallel to the direction of ice movement. They generally form in newly depositedtill or olderdrift and can reach heights of 25 metres (82 ft) and lengths of 20 kilometres (12 mi).
The characteristic of a place that follows from its interconnections with more than one other place. When interaction within a region comes together at a single place (i.e. when the movement focuses on that location), the place is said to possess focality.
A geographic transition zone defined by gradual increases in elevation betweenplains or low-reliefhills and adjacent topographically higher hills,mountains, oruplands.
footslope
The part of the profile of ahillslope that forms the concave surface at the base of the slope. It is a transition area between sites of erosion and transport higher up the slope (e.g. theshoulder andbackslope) and sites of deposition further down the slope (thetoeslope).[5]
A place, natural or man-made, where a river or stream is shallow enough to be crossed by wading, or by getting a vehicle's wheels wet (as opposed to crossing a permanently drybridge). Fords may be seasonal or temporary, becoming impassable during high water.
foredeep
A relatively narrow, deep, elongated, and steep-sided trough in theocean floor, usually near or parallel to a mountainous land area or associated with anarchipelago, or such a trough when infilled with sediment.[4] See alsoforeland basin.
foreland
1. Any land area or territory located in front of something else.
2. A landform projecting into the sea, e.g. acape orheadland.
3. The seaward trading area associated with a particularport orharbor.[4]
4. (glaciology) The area between the current leading edge of aglacier and themoraines of the most recent maximum.
A type of structuralendmember basin that develops adjacent and parallel to amountain range as a result oflithospheric flexure during its orogeny. Topographic loading and downflexure creates space in the basin that is filled by sediment eroded from the range. Comparerift basin.
The influence and restraining effect of distance on all forms of movement, based on the fundamental geographical principle that movement necessarily incurs one or more costs, in the form of physical effort, energy, time, and/or other resources, and that these costs are directly proportional to the distance traveled. Such costs effectively resist the propensity for movement, akin to the friction of classical mechanics, and hence the concept of physical distance is a critical factor in determining whether or not a given movement, event, or process occurs.
Someone who lives in one country and works in a neighboring country, commuting across the internationalborder each workday and returning to their country of residence on a nightly or weekly basis;[17] someone who lives and works across political or geographicalfrontiers.
1. The area near or beyond a political or geographicalboundary; amarch or borderland.
2. The area near or beyond the edge of a settled or civilized area, consisting of sparsely populated or uninhabited wilderness. See alsohinterland andedgeland.
functional diversity
The characteristic of a place where a variety of different activities (economic, political, or social) occur, most often associated withurban places.[2]
functional region
An area of the Earth's surface that is defined by its interaction with or connectivity to other regions.
A narrow strip of trees or shrubs lining bothbanks of a river or stream in otherwise treeless, open country. Above very narrow streams, the foliage on each side may meet in the canopy.[4]
A geographical dictionary or directory used in conjunction with amap oratlas and containing information concerning the geographical make-up, social statistics, and physical features of acountry,region, orcontinent.
A narrowinlet within a deep cleft in a rockycoastline, sheltered by tall, near-vertical cliffs created by wave-driven erosion along faults and bedding planes in the rock. The term is primarily used in the islands of northern Scotland.
A technology that restricts access to online content according to an Internet user's geographical location, which may be determined by any of various geolocation techniques, including checking the user'sIP address against a blacklist, triangulatingGPS queries, and measuring thelatency of a signal traveling between the user's computer and another endpoint in the network.
A concise, human-readable series of letters, numbers, and/or other symbols which represents and uniquely identifies a particular geographic entity so as to distinguish it from other geographic entities in a finite set or database.
The conversion of a text-based description of a physical location, such as the name of a place or a street address, intogeographic coordinates, e.g.latitude andlongitude, which can then be plotted in a spatialcoordinate system and represented on amap to locate and uniquely identify its position on the Earth's surface. The reverse process, where geographic coordinates are converted into a text-based description, is known asreverse geocoding.
In manygeographic information systems, an imaginary polygon on the surface of the Earth with dimensions 1degree oflatitude by 1 degree oflongitude, or approximately 111 by 111 kilometres (69 by 69 miles) at theEquator, representing an area equal to about 12,321 square kilometres (4,757 square miles). The east-west distance equal to 1 degree of longitude gradually decreases as one approaches the poles, such that the shape of a geocell becomes increasingly trapezoidal at higher latitudes.
Any data or information having an implicit or explicit association with one or more locations on the Earth, especially that used forgeoreferencing inGIS databases.
Ingeodesy, the shortest line on a specific surface between two particular points on that surface. The geodesic between a given two points on a flat plane is a segment of a straight line drawn between those points; the geodesic between two points on a sphere is a shorterarc of thegreat circle which connects both points. Geodesics may also be plotted on the surface of an ellipsoid, such as an idealizedreference ellipsoid used to model theshape of the Earth.[11]
The science of accurately measuring and understanding the Earth'sgeometric shape, orientation in space, andgravitational field and how these properties change over time.
Acoordinate system and set of reference points used for locating places on the Earth, which defineshorizontal andvertical coordinates upon a particularreference ellipsoid that approximates thefigure of the Earth. Geodetic datums are used ingeodesy,navigation, andsurveying applications to translate positions indicated on paper or digitalmaps to their actual positions on the Earth; because the Earth is an imperfect ellipsoid, localized datums such as theED50 covering only specific countries or regions are often more accurate representations of their area of coverage than global standards such as theWGS 84 of theWorld Geodetic System.
A virtual boundary or perimeter drawn around a real-world geographic area in a GIS software application, allowing distinctions between the properties of adjacent places which cannot be physically made on the ground to be made and stored digitally in an electronic database.
Acoordinate system used in geography that enables every location on Earth to be specified by a set of numbers, letters, or symbols. Geographic coordinates are often chosen such that one of the numbers represents a vertical position such aselevation and two or three other numbers represent a horizontal position such aslatitude andlongitude.
Any system of computer software tools designed to allow users to record, store, manipulate, analyze, manage, and present large sets of spatial orgeographic data.
A digital public-domain database developed by theU.S. Geological Survey and theU.S. Board on Geographic Names which contains name and locative information about more than two million physical and cultural features located throughout theUnited States and its territories. Each feature recorded in the database receives a unique featurerecord identifier called aGNIS identifier.
geographic pattern
Any observable model, style, or trend in some element ofgeography, generally observed onmaps.
A particular method that brings changes to the physical or human geography.
geographical inertia
Alsogeographical momentum.
The tendency of a place with established installations and services to maintain its size and its importance as a focus of economic or industrial activity after the conditions originally influencing its development have appreciably altered, ceased to be relevant, or disappeared.[4]
A unit of length defined as the distance equal to oneminute of arc along the Earth'sEquator: approximately 1,855.3 metres (1.1528 mi; 1.8553 km). The precise length varies with thereference ellipsoid used to approximate theshape of the Earth. Regardless of the particular ellipsoid, the length of onedegree oflongitude at the Equator is equal to exactly 60 geographical miles.
The shape that the surface of the Earth'soceans would take under the influence ofEarth's gravity androtational acceleration alone, in the absence of other influences such as winds andtides. It is often characterized as the precise mathematicalfigure of the Earth: a smooth but irregular gravitationalequipotential surface at every point of which, by definition, the direction of the force of gravity is always perpendicular andspirit levels are always parallel. Its shape results from anomalies in the Earth's gravitational field caused by the uneven distribution of mass within and on the Earth's surface. Areference ellipsoid is an idealized approximation of the more complex and accurate geoid.
The science and technology which develops and usesinformation science infrastructures to address problems and analyze data withingeography,cartography,geoscience, and related branches of science and engineering.
The identification or estimation of the real-world geographiclocation of an object, involving the generation of a set ofgeographic coordinates in order to determine a more meaningful description of location, such as a street address.
The study of the arrangement and form of the Earth'scrust and of the relationship between these physical features and the geologic structures beneath.[2]
1. The potential of the Earth'sgravitational field, expressed as the sum,U, of thegravitational potentialVg of the Earth at pointP and the rotational potentialVc at the same point, i.e.U = Vg + Vc.[11]
2. The negative of the sum of the gravitational potentialVg and the rotational potentialVc, i.e.U = −(Vg + Vc). This alternative definition is often used by physicists.[11]
3. Thepotential energy of a unit mass relative to thegeoid, numerically equivalent to thework which would be done in lifting the mass from the geoid against the force of gravity to the elevation at which the mass is actually located.[11]
The study of geographical knowledge from any and all points of view, past or present, true or false;[18] the study of the nature and expression of geographical ideas.[4]
A branch ofstatistics which involves the organization, management, and analysis of spatial and spatiotemporal datasets. Geostatistical algorithms are often incorporated inGIS software applications.
A section of a city occupied by members of a minority group who live there because of social restrictions on their residential choices. Originally, the term referred specifically to a section of a European city to whichJews were confined.[2]
A deserted or abandoned village, town, or city, especially one in which remaining buildings and infrastructure such as roads are still visible. The term is also sometimes used to refer to settlements that are still populated, but significantly less so than in previous years.
The mass of rocks and finely ground material carried by aglacier and deposited when the ice melts. This creates an unstratified material of varying composition.[2]
A persistent mass of denseice that moves slowly but constantly under its own weight, and which is composed largely of compactedsnow that forms over very long periods of time wherever the annual accumulation of snow exceeds its rate of melting and sublimation. Glaciers slowly deform and abrade the land beneath them, causing many unique geomorphological processes and creating a huge variety of landforms includingcirques,moraines, andfjords. They form exclusively on land and are distinct from the much thinner ice that forms on bodies of water.[3]
The scientific study ofglaciers, including their formation, composition, behavior, causes, effects, and distribution;[19] or more generally of ice or any natural phenomena involving ice.
A smooth, gently sloping surface at the foot of ahill,mountain, or any other highpromontory, whether natural or artificial. In the latter case, the term is used in particular to describe a stone or earthenslope constructed at the base of some historical military fortifications.[19]
Acity which functions as an important or primary node in theglobal economy. Though criteria are not strictly defined, a global city typically is very large; dominates trade and economic interactions within a large surrounding area; supports a large and demographically diverse population; serves as a center of ideas and innovation in business, science, culture, and politics; and/or is a headquarters for major financial institutions, multinational corporations, or worldwide media and communications networks.
Asatellite-basedradionavigationpositioning system owned and operated by theUnited States Department of Defense and made available for use by both the military and the general public. It is one of severalGNSS standards that providesgeolocation and time information, transmitted viamicrowave signals, to enabledsatellite navigation devices, known asGPS receivers, anywhere on or near the Earth where there is an unobstructed line of sight to at least four GPS satellites. Modern state-of-the-art GPS receivers can accurately pinpoint locations to within 30 centimetres (0.98 ft).
The process of interaction and integration among people, companies, governments, and cultures across the world. A complex and multifaceted phenomenon, globalization is considered largely the result of economically motivated advances in transportation and communication technologies in the past several centuries which have dramatically increased interactions between otherwise isolated groups of people.
A true-to-scalemap of the Earth that duplicates its round shape and correctly represents relative areas, sizes, and shapes of physical features, distances, and directions.[1]
1. An irregularly shapedparcel of land of any size, often approximately triangular, that is left between two adjoiningsurveyed parcels as the result of incomplete or inaccurateboundary surveys.[16]
2. A lune-shapedmap which may be fitted to the surface of aglobe with a negligible amount of distortion.[16]
Adepression orvalley bounded on either side by distinct, parallelescarpments orfaults and formed by the downward displacement of a block of the Earth'scrust. Grabens often occur side-by-side withhorsts, their uplifted or non-displaced counterparts, in a repeated series of vertical displacements.
A physical surface that is inclined with respect to the horizontal, or the angle between that surface and the horizontal, typically expressed in degrees, or calculated as a ratio of "rise" (vertical distance) to "run" (horizontal distance) and expressed as a fraction or percentage; a larger number indicates a steeper incline. The term "grade" is often used to describe the incline of man-made surfaces such as roads and the roofs of buildings, whereas the term "slope" is more commonly used to describe natural surfaces such as the sides ofhills ormountains or thebeds andbanks ofwatercourses.
Any land area where the vegetation is dominated by grasses (i.e. plants of the botanical familyPoaceae), sometimes also inclusive ofgrass-like plants of other families. A large and importantbiome occurring worldwide, grasslands may be natural or created for agricultural purposes.
The measurement of the strength of agravitational field, especially the Earth's gravitational field, typically by calculating the acceleration due to gravity at a particular point on the Earth's surface. Because it can vary widely across the surface, knowing the local magnitude of the gravitational force is often necessary in order to produce accurate geographical data.
Any circle on the surface of a sphere created by the intersection of the sphere and aplane that passes through its center. A great circle divides the sphere into two equal hemispheres, and all of a sphere's great circles have the same center and circumference, which by definition is the largest possible circumference of the sphere. The mathematical properties of great circles make them useful ingeodesy, where they are often visualized upon the surface of the Earth (despite the fact that the Earth isnot a perfect sphere): for example, theEquator of the idealized Earth is a great circle, and anymeridian with itsantimeridian forms a great circle. Because the shortest path between any two points on the surface of a sphere follows the arc of a great circle,great-circle distances are often used as approximations ofgeodesics for the purposes of air and sea navigation. See alsosmall circle.
The horizontal direction orbearing followed by the arc of agreat circle through a given pair of terrestrial points, expressed as the angular distance from a reference direction.[16]
The length of a line between two points which follows the arc of agreat circle as defined by the intersection of the Earth's surface with an imaginary plane passing through the Earth's center. It is the shortest route between those two points on the Earth's surface.[2]
A special land-usezone designated in some cities to prevent development of wild, undeveloped, or agricultural land surrounding or adjacent tourban areas, in order to conserve natural ecosystems, to allow the return and establishment of wildlife, and/or to createurban green space for aesthetic or recreational purposes. The term may also refer more specifically to the boundary between developed and undeveloped areas rather than to the undeveloped area itself.
A previously undeveloped plot of land for which development is proposed or on which it is in progress,[4] or which is intentionally not being developed so as to permit it to evolve naturally. Comparebrownfield.
The part of the year during which local weather conditions (i.e. temperature and precipitation) permit the normal growth ofplants in a given location. What defines a "growing season" is often informal and colloquial, and may vary widely by location and from year to year; in many places, the local growing season is defined as the period of time between the average date of the lastfrost (in temperate parts of theNorthern Hemisphere, this typically occurs in the spring) to the average date of the first frost (in the autumn).[2]
A rigid, man-made hydraulic structure extending from an oceanshore or riverbank, constructed to interrupt water flow and limit the movement of sediment bylongshore drift.
A landform resembling a large ditch or a smallravine created by the action of swift running water eroding deeply and sharply into soil, typically on a hillside.
A device consisting of a spinning disc or rotor mounted in such a way as to preserve the orientation andangular velocity of its axis of rotation with respect to an inertial reference frame, irrespective of perturbations to the mounting itself, which makes it possible to measure and maintain an unbiased equilibrium in theattitude and/orcourse of a moving object such as an airborne or waterborne vehicle or camera. Modern digital gyroscopes and their associated readouts are widely used innavigation andgeodesy as the basic sensor indirection-seeking, direction-keeping, and attitude stabilization systems.[16]
An individual's sense of "home", or of their place in the world, comprising socially ingrained habits, beliefs, skills, and dispositions based on their geographical environment, cultural origin, inheritance, experiences, and the social networks they develop throughout their life, all of which may be subject to refashioning with passing time or increasing distance.[4]
Any of a series of non-numerical lines used on amap to indicate the general orientation and steepness oftopographicalterrain. Such lines vary in length, thickness, and spacing, with steeper slopes indicated by shorter, heavier, and more closely spaced lines.[12]
haff
A coastallagoon offresh orbrackish water on the south coast of the Baltic Sea, fed by a stream which is blocked by anehrung, through which it is linked to the sea by achannel.[4]
halo effect
In the context of geography, the detrimental effect of aborder or other boundary on locations close to it, making those locations unattractive to people intending to visit or settle there; e.g. a political boundary in disputed territory, where immigration across the boundary occurs frequently. There may also be beneficial effects on such locations.[4]
ham
In southern England, a plot of meadow land, especially a tract of rich pasture near a river; or a small settlement, ranging in size from a singlehomestead to atown.[4]
Adesert landscape consisting of high, largely barren, rockyplateaus where most of the sand has been removed bydeflation, and thus lacking most surficial materials other than boulders and exposedbedrock.[14]
A small human settlement, variably defined as one the size of atown,village, orparish or as a smaller subdivision of or satellite entity to a larger settlement.
Atributaryvalley that is higher in elevation than the main valley into which it drains, such that it appears to be "hanging" above the lower valley. Hanging valleys are commonly the result of differentialglacial erosion, when adjacent areas beneath a glacier are subjected to different rates of erosion.
Thecompassdirection in which the bow or nose of a moving vessel or aircraft is pointed. This is not necessarily the same direction in which the vessel is actually traveling, known as itscourse; any difference between heading and course is due to the motion of the air or water through which the vessel is moving, or other aerodynamic effects such asskidding orslipping. See alsobearing.
1. Another name for thesource of ariver,stream, or otherwatercourse, i.e. the point or points furthest from themouth of a particularchannel at which precipitation,meltwater, orgroundwater first accumulates into a persistent, identifiable, and/or namedbody of water whose contents ultimately empty into that particular channel; or all of the uppermosttributaries of awatershed considered collectively (of which there may be thousands), typically including all streams identified as first-order through third-order in conventionalstream order systems.
2. The entireregion, inclusive of land, surrounding these sources, often abutting the boundary of adrainage divide that separates distinct watersheds.
A metric unit of area defined by a square with sides of 100 metres, equal to 10,000 m2 or 2.471acres. There are 100 hectares in 1 square kilometre (km2).[4]
A line of closely spaced shrubs or trees, planted and trained so as to form a barrier, to mark the boundary between two neighboring areas, or to serve as awindbreak for crops in adjacent fields.
A natural or man-made demarcation that indicates the maximum rise of abody of water over land. Though not necessarily an actual physical mark, river or sea waters rising to a high point often leave a lasting physical impression such as a noticeable discoloration or deposition of debris; such a mark is often the result of aflood orstorm surge. High water marks may reflect an all-time high, an annual high, or the high point for some other division of time (e.g. atidal cycle). A natural delineation created by debris deposited by a high tide is called astrandline. See alsowash margin andmean high water.
1. Any elevated region of land, often one that ismountainous or situated atop aplateau. The term is sometimes reserved for relatively low-elevationmountain ranges orfoothills.
2. Any area of land (mountainous or otherwise) that is higher inelevation relative to another area. In this sense, the term is often used as a conditional descriptor to distinguish relatedhabitats orecosystems, especially freshwaterriparian areas, on the basis of elevation above sea level.
Any major public or private road or other thoroughfare on land, especially one that is paved and capable of supporting high-capacity, rapid transit betweenpopulated places.
1. An area that is tributary to a place and linked to that place through lines of exchange or interaction.[2]
2. The area, not necessarily settled itself, that is nonetheless influenced by a particularsettlement or establishment, i.e. itssphere of influence.[4]
A branch ofhuman geography that studies the ways in which geographic phenomena have changed over time, especially (though not necessarily limited to) geographic change as it relates to human activity; the geography of the past, whether real, perceived, or theoretical.[4]
hoe
A projectingridge oroutcropping of land, its height ending abruptly or steeply. The term is used primarily inplacenames in Great Britain.
A long, narrowridge or series ofhills with a narrow crest and steep, symmetrical slopes of nearly equal inclination on both flanks, especially one created by the differential erosion of anoutcropping which exposeshomoclinal sedimentary rock strata. Compareesker,drumlin, andcuesta.
Aerial view of ahogback in the southwestern United States
holding
Land owned or occupied by legal right for the purpose of agriculture.[4]
homestead
1. (dwelling) A house or home, especially an isolated farmhouse with its associated outbuildings on a large agricultural holding such as aranch; or a smallrural settlement of dispersed farms.[4]
2. (legal concept) In the United States, a plot of land given legal meaning by a series of federal laws granting applicants ownership of land in the public domain upon the condition that they live on it andimprove it. Homesteaders were initially granted plots of 160 acres (0.65 km2), which was considered adequate to support a single family, but later as much as 640 acres (2.6 km2).
The apparent line that separates the ground from the sky, dividing all visible directions into two categories: those that intersect the Earth's surface and those that do not. When not obscured by buildings, trees, or mountains, the true horizon can be useful in navigation and determining positional orientation. In perfect visibility, to an observer on Earth standing at an elevation of 3 metres (10 ft) from the horizontal, the horizon in any direction is approximately 6.5 kilometres (4 mi) distant; at 30 metres (100 ft), it is 21 kilometres (13 mi) away.[4]
horizontal equivalent
The distance between two points on a land surface when projected on to a perfectly horizontal (i.e. flat) plane, e.g. on amap, as opposed to measuring the actual physical length along the real-world surface, which can be greatly increased byslopes and other topographic variations. The distance between the start and end points of any route, even if at the same elevation, will often appear to be much shorter on a map than the shortest route that could actually be walked between them, because of the influence of real-world changes in vertical displacement along the path followed by the route.[4]
horn
Amountain formed by the back-to-back abutment of three or four adjacentcirques, leaving a distinctly pyramidal peak.[13]
A raised block of the Earth'scrust, bounded by parallelescarpments orfaults, that has been displaced upward or has remained stationary while adjacent blocks on either side, known asgrabens, have been displaced downward. Horsts and grabens often occur side-by-side in a repeated series of vertical displacements.
An area in the middle of alithospheric plate wheremagma rises from themantle and erupts at the Earth's surface, despite being far from the plate'stectonic boundaries.Volcanoes often occur above a hotspot.[3]
hum
A residual hill in limestone country, resembling a haystack, left standing when the surrounding land surface is eroded.[4]
The branch of geography that studies humans and their communities, cultures, economies, and interactions with the environment by examining their relations with and across space and place. Along withphysical geography, it is one of the two major sub-fields of geography.
human–environment interaction
The interdependent relationship between humans and the environment.
humanistic geography
Alsohumanist geography.
An approach inhuman geography which emphasizes the subjective as distinct from the objective in that it stresses the importance of perception, creativity, thinking, and beliefs as well as human experience and values in the formation of the attitudes of people toward their environment and in affecting their relationships with it.[4]
In England, Scandinavia, and many other parts of the world, an administrative subdivision of a larger region, often acounty orshire, with its own judicial authority.[4]
A graph showing the rate of flow (i.e. thedischarge) of water past a specific point of measurement in a river or other channel over time, typically expressed in cubic metres or cubic feet per second (m3 or ft3/s).
The totality of the water found on, under, and above the Earth's surface in liquid, solid, and gaseous forms, including alloceans,lakes,rivers, andstreams, as well as all ice andglaciers and subsurfacegroundwater. Some definitions restrict the hydrosphere to liquid water only, instead placing solid forms in thecryosphere and gaseous forms in theatmosphere.[3]
The geographic representation on amap of features related toelevation,altitude, and other measures ofheight above a reference surface (and sometimes inclusive of depths below the reference surface as well).
Any instrument used to measure the height orelevation of an object above a reference surface, either by trigonometry or by measuring changes in atmospheric pressure or boiling point. Trigonometric principles are applied when viewing the measured object from a distance, e.g. when determining the heights of trees or buildings, or whensurveying the elevations of distant landforms; whereas the principle that atmospheric pressure decreases predictably with elevation abovesea level is applied in instruments that measure their own height (i.e. the elevation of the instrument's location).[19]
The study or measurement of theelevation or depth of features of the Earth's surface relative to meansea level. In a narrower sense, hypsometry may refer to land elevations only, and therefore is sometimes viewed as the terrestrial equivalent ofbathymetry.
Any very long period of Earth's history during which surface and atmospheric temperatures are greatly reduced, resulting in the development or expansion of continental andpolar ice sheets and widespreadglaciation. The most recent such period was thePleistocene Epoch, which ended approximately 12,000 years ago.[2]
A flattened, often dome-shaped mass of ice that covers less than 50,000 square kilometres (19,000 sq mi) of land area and is not constrained by topographical features such as mountains; larger masses of ice are termedice sheets. Contrastpolar ice cap.
A mass ofglacial ice that covers more than 50,000 square kilometres (19,000 sq mi) of land area; smaller masses of ice may be termedice caps orice shelves. The twopolar ice sheets are the only ice sheets that currently exist on Earth.
A large floating platform of ice formed when aglacier orice sheet in acoastal area flows onto theocean surface. By contrast,sea ice is formed directly over the water and is typically much thinner.
A region of relatively fast-moving ice within anice sheet that flows like a stream under its own weight (making it essentially equivalent to aglacier) and empties into the ocean. Ice streams are responsible for the majority of the mass lost from both the Antarctic and Greenland ice sheets.
A portion of aglacier where a steepening or narrowing of the underlying bed causes the ice to move more rapidly than elsewhere, resulting in a chaotic, highly fractured surface characterized by numerouscrevasses andseracs.
A type ofcrater formed by the hypervelocity collision of a solid astronomical body, such as ameteor, with the Earth's surface. Unlikevolcanic craters, impact craters typically have raised rims higher in elevation and depressed floors lower in elevation than the surrounding terrain.
Any land area which has been intentionally altered from its natural condition by human activity, such as ploughing, clearing, cultivation, or some other form of management, and thereby made more valuable or productive for human purposes (not necessarily to the benefit of any other organism or the environment in general). Legal definitions vary with location, but in most countries the term refers primarily to certain types of agricultural land or to property which has been developed for residential or commercial use.[4]
An instrument used to measure angles ofslope,elevation, ordepression with respect to the direction of the gravitational force, i.e. in the vertical plane, including both inclines and declines. The measure may be expressed in degrees, percentage points, or topos.[14]
index contour
Acontour line drawn with a heavier line weight to distinguish it from intermediate contours. Depending on thecontour interval, index contours are usually indicated every fourth or fifth contour, along with their assigned numerical values, in order to facilitate ease of interpretation.[16]
The broad set of facilities and interrelated systems that serve acity,country, or any other inhabited area, encompassing the structures and services necessary for its industries, economies, and residential spaces to function, i.e. for the human population occupying these spaces to get what they want or need when they want or need it. Infrastructure may include public and private physical structures such as roads, railways, bridges, tunnels,water reservoirs,canals, sewers, and electrical and telecommunications networks, among other things. A well-developed infrastructure is essential to enable, sustain, and improve living and working conditions in any society or organization.
A generally flatcoastline whose shape has been largely defined by the penetration of the sea into relatively low-lying areas of the land surface, often as a result ofcrustal movements or a rise insea level, such that the boundary between land and water closely matches the topographic contours of the land prior to its being covered by seawater.
A very large, isolated expanse of open water in the interior of alandmass, either completely surrounded by dry land or connected to theocean by a river,strait, or other narrowwaterway.
An isolated rockyhill, knob,ridge, or smallmountain that rises abruptly from a virtually level surroundingplain. Comparemogote.
inset
A subsection of amap that is reserved for depicting another map of the same place at a differentscale, often a smaller scale to show relativelocation within a larger geographic area (e.g. a country's location on theglobe) or a larger scale to show increased detail (e.g. of public transit routes in adowntown area), or with different features or overlays in order to provide additional information that would be difficult to interpret if presented in the main map area. Insets are usually outlined with an obvious boundary to prevent confusion, and may include their own set of cartographic elements such as a scale,graticule, andlegend.[20]
(relative to a position on a body of water) Near to or moving towards theshore; shorewards of a position as opposed to seawards of it. See alsoonshore andoffshore.
Of or relating to anisland, or suggestive of the isolated condition of an island.[2]
integrated drainage
A drainage pattern in whichstream systems have developed to the point that all parts of the landscape drain into some part of a stream and to a common base level, the initial or original surfaces having essentially eroded away entirely, such that few or nocloseddrainage systems are present.[5]
The branch of geography that describes and explains the spatial aspects of interactions between human individuals or societies and their natural environment.
intercardinal directions
Alsointermediate directions orordinal directions.
The set of four intermediate directions used incartography andnavigation, each of which is located halfway between a pair ofcardinal directions: northeast (NE), southeast (SE), southwest (SW), and northwest (NW). They are often included in thecompass rose and are used to define further subdivisions such as thesecondary-intercardinal directions.
A narrow, elongated, andplateau-like orridge-like landform between twovalleys, or an area of higher ground between two rivers in the samedrainage basin.
Astream or otherwatercourse in which water does not flow continuously but dries up occasionally, often predictably with the seasons, as opposed to aperennial stream which flows year-round. See alsobourne.[4]
Ingeographic information science, the estimation of the values ofspatially dependent variables at unsampled points based on known values of surrounding points, under the assumption that any unknown quantity can be calculated based on its distance to each surrounding quantity. Interpolation techniques such as spline andkriging are commonlyraster operations, but can also be applied invector environments using atriangulated irregular network to model a surface.[9]
Any place where the contiguous geographic area represented in amap projection has been split, separating to distant parts of the projection certain features and locations which are in reality much closer to each other, in order to permit the representation of a three-dimensional space on a two-dimensional map. Allworld maps, for example, have at least one interruption, conventionally along the length of a singlemeridian, thus forming an east–west boundary despite that the approximately sphericalshape of the Earth is continuous, with no such boundaries; features on either side of the interruption, though very close to each other on the actual Earth, are depicted on opposite edges of the map, appearing to be separated by thousands of miles. Some world map projections attempt to reduce distortion of scale by having more than one interruption, which divide the projected area into multiplegores, each with its own central meridian.[9]
intervening opportunity
The existence of a closer, less expensive opportunity for obtaining a good or service, or for a migration destination. Such opportunities lessen the attractiveness of more distant places.[2]
A system of navigable inlandwaterway channels, maintained throughdredging and sheltered for the most part by a series of linear offshore islands, that follows the Atlantic and Gulf Coasts of the United States more than 4,800 kilometres (3,000 mi) fromBoston, Massachusetts, around the southern tip ofFlorida, toBrownsville, Texas.[2]
Any piece of sub-continental land that is entirely surrounded by water; or more generally, any isolated habitat that is surrounded by a different habitat, including different types of land.
Any line on amap connecting places of equal value of some specified variable. The variable may be a physical or natural quantity, such as elevation above sea level (as withcontour lines) or temperature (as withisotherms), or a quantity related to social or economic statistics, such as population, wealth, or transport costs.
The state of gravitational equilibrium between the Earth'scrust and itsmantle, such that the crust "floats" at anelevation that depends on its thickness and density. This concept is invoked to explain how differenttopographic heights can exist at Earth's surface. Isostatic theory maintains that where equilibrium exists at the surface, equal mass must underlie equal surface area, and that the thickness of crustal features and the depth of the world'soceans tend to change over time in order to compensate for the uneven distribution of mass in thelithosphere. For example, the instability ofcontinental margins where high mountains are found adjacent to deep oceanic trenches is explained by the subterranean movement of magma to effect a return to regional equilibrium, a process known as isostatic adjustment.[4]
The theory ofisostasy explains the phenomena ofplate tectonics in terms of the tendency of Earth'scrust andmantle to gravitationally balance each other, such that e.g. a change in the mass of the crust results in local displacement of the mantle underlying it.
Any man-made structure that projects from land out into a body of water, serving as abreakwater, a walkway, or a landing stage for watercraft, or, in pairs, as a means of constricting achannel.
A meeting or intersection of two or moreroutes of travel, as of roads, rivers, or lines on a map, or a place at which a single route diverges into two or more different routes.
Water present within or derived from themagma of the Earth'smantle and which when brought to the surface byvolcanic eruptions is entering thewater cycle for the first time (or at least for the first time in millions of years, having previously circulated in the oceans or the atmosphere but becomingsubducted beneath the surface and returned to the mantle).[21]
An irregularly shapedhill ormound composed of sand, gravel, andglacial till which accumulates in a depression on a retreatingglacier and is subsequently deposited on the land surface with further melting of the glacier. Kames are often associated withkettles.
Kames andkettles are just two of the many characteristic landforms created in the wake of a meltingglacier.
A furrow orchannel varying in depth from a few millimetres to more than a metre, and separated from others byridges, caused by solution on limestone surfaces.[4]
1. A point of abrupt inflection in the longitudinal profile of ariver or itschannel orvalley, such as occurs at awaterfall.
2. Any interruption or break in the character of aslope.[5]
knob
A peak or projection from the top of ahill ormountain, or any rounded protrusion of land, especially a small butprominent orisolated hill with steep sides; a boulder or an area ofresistant rock protruding from the side of a hill or mountain. The term is used primarily in the southern United States.[5]
In Russia and other Slavic countries, a generic term for aregion, historically and politically reserved forborder regions in particular, and variously translated asmarch,frontier, orterritory. The term is cognate with thename of Ukraine.
AlsoGaussian process regression andWiener–Kolmogorov prediction.
Ingeostatistics, aninterpolation technique in which, for a givenspatially dependent variable, a predicted value for an unmeasured location is derived by weighting the surrounding measured values based on the distance between them and to the unmeasured location, as well as the overall spatial arrangement of the measured points. Widely used inGIS applications, kriging is based onregionalized variable theory, which assumes that the spatial variation in the data being modeled is homogeneous across the surface.[9]
A nearly level land area formed by the infilling of alake with sediment and the complete drainage or evaporation of water from the lake, leaving the deposited sediments behind.[2]
Abody of water localized in abasin and surrounded entirely by land. Lakes are often defined as separate from anyriver or stream that serves to feed or drain them.
Any piece of land connecting larger land areas that are otherwise separated by water, especially one over which living organisms, such as terrestrial animals and plants, are able to cross and thereby colonize previously inaccessible lands. Land bridges may be created byfalling sea levels,tectonic activity, orpost-glacial rebound. Compareisthmus.
The physical material present on the surface of the Earth, including categories such as vegetation (grasslands, shrubs, forests, etc.), bare ground, water, asphalt and artificial surfaces, and many others.
A natural feature of the solid surface of the Earth. A combined set of landforms makes up theterrain of a given area, and their arrangement in a landscape is known astopography.
1. (of a country or other polity, or a geographical region) Completely surrounded by land and thus lacking a marinecoastline; having no territory directly connected to or bordering theocean.
2. (of a property or parcel of land) Completely surrounded by privately owned property and having no access to a public road.
Any natural or artificial feature that is recognizable enough to be used fornavigation; a feature that stands out enough from its environment to be visible across long distances.
1. A broad or distinct area of land consisting of a collection oflandforms which define a generalgeomorphologic form or setting, e.g. amountain range,valley,plain,coast, etc. Landforms within a landscape are spatially associated but may vary in formation processes and age.[5]
2. The visible features of an area of land, its landforms, and how they integrate with natural or man-made features. In the broadest sense, landscapes may include geophysical landforms such as hills and mountains;bodies of water such as rivers, lakes, and the sea; living elements ofland cover such as vegetation; human elements such as buildings, structures, and various forms ofland use; and transitory elements such as lighting and weather conditions. They reflect both physical origins and thecultural overlay of human presence in a living synthesis of people and place.
landscape studies
A branch of geography which examines the structure and organization oflandscapes, focusing on landscapes as the settings for cultural and ecological patterns, processes, and histories, as well as on the social and cultural evolution of landscapes, including the ways in which they shape and are shaped by human societies and the interrelationships betweenplace-making and personal and social memory.[10]
A suddenmass movement of earth from a hill, mountain, or cliff, in which displaced material slides, flows, falls, or collapses under the force of gravity yet often retains form as it moves; or the visible evidence of this movement after the displaced material has come to rest. Landslides may have many causes, though they are commonly associated with heavy precipitation, undergroundaquifers, wave action, and earthquakes.[10]
A measure of distance north or south of theEquator. One degree of latitude equals approximately 111 kilometers (69 mi).[2] Lines of latitude, also calledcircles of latitude orparallels, are the imaginary lines that cross the surface of the Earth in an east-west direction (parallel to the Equator) and measure how far north or south of the Equator a place is located.[1]
The term used formagma once it has erupted onto the Earth's surface.[3]
layer of no motion
Inoceanography, a hypothetical layer at some depth in the ocean within which the water is assumed to be at rest, implying that the isobaric surfaces within that layer are level and hence that such surfaces can be used as points of reference when calculating absolute-gradientcurrents.[11]
The side orslope of a physical feature (such as ahill ormountain) which faces downwind, i.e. away from the direction in which the wind is blowing, or which faces away from an advancingglacier orice sheet. The lee side is often sheltered by the topography from exposure to the wind and any moisture it brings.[5]
An elongated naturally occurringridge or an artificially constructed wall or barrier which regulates water levels in areas prone to flooding. It is usually earthen and often parallel to the course of ariver or acoastline.
The Earth's hard, outermost shell. It comprises the crust and the upper part of the mantle. It is divided into a mosaic of 16 major slabs or plates, which are known aslithospheric plates ortectonic plates.[3]
A type of easily worked, highly fertilesoil composed of clay, silt, and sand in an approximate ratio of 20:40:40. Loams generally heat rapidly, are well-aerated, and drain neither too quickly nor too slowly.[13]
A movement or philosophy that prioritizes local or small-scale politics, issues, and values overregional or broader concerns, rejecting things likecentralized government and economicoutsourcing in favor of local production and consumption of goods, local control of government, and the promotion of local history, local culture, and local identity.[10]
localization
The set of processes by which social, cultural, economic, or other activities become embedded in specific places orlocations, rather than in alternative places or across many places, either in contrast to or as a related aspect ofglobalization. In the former sense localization may be deliberately practiced as a form of resistance to globalization through the promotion of increased local control, self-government, and economic self-sufficiency.[22] See alsodeglobalization.
A measure of distance east or west of thePrime Meridian, a line drawn between theNorth andSouth Poles and passing through theRoyal Observatory atGreenwich, England.[2] Lines of longitude, also calledmeridians, are the imaginary lines that cross the surface of the Earth in a north-south direction (parallel to the Prime Meridian) and measure how far east or west of the Prime Meridian a place is located.[1]
A geological process by which sediment is transported along acoast parallel to theshoreline due to incoming wind-driven waves meeting the shore at an oblique angle; this generates a water current which moves unidirectionally along the shore within thesurf zone. A well-known example occurs on sandybeaches whenbreaking waves send swash up the beach at an angle but gravity drains thebackwash straight downslope, perpendicular to the shoreline, causing the same sand particles to gradually move down the beach over multiple cycles. The same process occurs at many different scales and affects all sediment sizes, and can vary with the wind direction even at the same location.
Any area of land that is lower inelevation relative to another area. The term is often used as a conditional descriptor to distinguish relatedhabitats orecosystems, especially freshwaterriparian areas, on the basis of elevation above sea level. Lowland areas are usually relatively flat and characterized by slow-flowing waterways andalluvial plains. Contrasthighland andupland.
A broad, shallow, flat-bottomedvolcanic crater created by an eruption involvinggroundwater coming into contact withmagma. Maars commonly have low rims and subtlerelief and characteristically fill with water to formcrater lakes.
Molten rock containing liquids, crystals, and dissolved gases that forms within the upper part of the Earth'smantle andcrust. When erupted onto the Earth's surface, it is calledlava.[3]
A local deviation from the predicted value of theEarth's magnetic field, due either to the presence of rocks formed in past geological eras which have preserved internal magnetizations that differ from modern magnetic alignments, or to local abundances or deficiencies of ferromagnetic minerals.[4]
The angle on the horizontal plane betweenmagnetic north andtrue north. Becausecompass needles always point to magnetic north, and because theMagnetic North Pole and theGeographic North Pole are not in precisely the same location, the north direction indicated by a compass may be slightly different from the direction of geographic north, depending on the user's location on the Earth. The user can compensate for this discrepancy by adding the known declination angle for their location to the magneticbearing reported by their compass, yielding the true bearing with respect to true north.
The angle made with the horizontal by theEarth's magnetic field lines. Locations in theNorthern Hemisphere usually have positive values of inclination, indicating that the magnetic field is angled downward, into the Earth; the angle increases as one approaches theNorth Magnetic Pole, where the field lines point vertically downward, perpendicular to the horizontal. Locations in theSouthern Hemisphere usually have negative inclination, indicating that the field lines are angled upward, away from the Earth, with the maximum angle located at theSouth Magnetic Pole. Dip angle is in principle the angle made by the needle of a vertically heldcompass, though in practice ordinary compass needles may be deliberately weighted against dip, or may be unable to move freely in the correct plane. Magnetic dip can be measured more reliably with adip circle.
The primary downstreamchannel of ariver, as contrasted with itstributaries. Virtually all of the water in a river'sdrainage basin eventually flows through the main stem.
A term used to denote acontiguouslandmass or political territory relative to its politically associated but geographically remoteoutlying territories. It is variously used to refer to thecontinental (i.e. non-insular) part of a polity relative to itsexclaves or oceanic islands; or to the largest or most politically, economically, and/or demographically significant island within anisland nation. For example, continental Europe is often considered "the mainland" relative to the British Isles, while the island of Great Britain is considered "the mainland" relative to Northern Ireland and the many smaller islands that constitute the United Kingdom.
A deep, closedvalley (usually drained by a singlewadi) surrounded by steep walls of resistant rock and superficially resembling acrater. The term is used primarily in the deserts of Israel and Egypt.
mammilated
Smooth and rounded in appearance, used of various landforms of different sizes from individual rocks to entire landscapes.[13]
The layer of the Earth's interior between thecrust and thecore, consisting of ultrabasic rock which is predominantly solid under the immense pressure of overlying rock but behaves as a viscous fluid over geological time scales or if this pressure is relieved (as withmagma penetrating the crust). The mantle is about 2,900 kilometers (1,800 mi) thick, making up 84% of the Earth's volume and 67% of its mass. The uppermost sub-layer is known as theasthenosphere; thelithosphere is composed of the topmost 65–70 kilometres (40–43 mi) of the mantle and the crust.[3][4]
A picture of aplace drawn at an establishedscale on a two-dimensionalplane surface, often depicting natural and manmade features on or under the surface of the Earth or other planetary body, typically with the features positioned as accurately as possible relative to acoordinate reference system.[1][16] More generally, a map is any graphical representation of locative information about the relativepositions of particular features within a space or place.
A graphical key identifying the relationships between the individualmaps of amap series, their coverage areas, and/or their production status or availability. Index maps enable users to find a map or set of maps covering a particular region of interest by overlaying a grid or a set of rectangles on a map of a larger geographical area. Each grid unit or rectangle is labeled with a name or number corresponding to a specificmap sheet which depicts the indicated area in greater detail.[16]
A systematic transformation of thelatitudes andlongitudes of locations from the surface of a three-dimensional shape, such as asphere or anellipsoid, into locations on a two-dimensionalplane.Maps of locations on the Earth require map projections to represent features in a convenient format that is easy to view and interpret, though all map projections necessarily distort the true properties of the Earth's surface to some degree.
A group of topographic or thematicmap sheets usually having the samescale andcartographic specifications and collectively identified by the publisher or producing agency as belonging to the same group.[16]
An individualmap orchart printed on a single page or sheet of paper, either complete in itself or part of amap series.[16]
mapping
The process of designing, drawing, or creating amap. The term is used in particular to refer to the application ofcartographic techniques in order to makeplanimetric ortopographic maps, but may also be used for any map, and in the broadest sense may refer to the gathering of geographical data of any kind.[11]
Aboundary,frontier, orborderland, as opposed to an interiorheartland. In medieval Europe, a march was the land surrounding a border between realms, or a neutralbuffer zone under the joint control of two or more realms with conflicting laws or territorial claims.[4]
1. The line or edge along which the surface of a body of water meets the land.[11]
2. In property law, theboundary of a piece of land which is bounded by astream orwatercourse, often with the center of the stream or thethalweg defining the legal boundary.[11]
3. The mostly blank, unused space lying beyond theneatline of a map and completely surrounding the map area.[11] See alsosurround.
Land that is of low agricultural value because any crops produced from it would be worth the same or less than the costs paid to produce them, either because the rights orimprovements required to cultivate it are very expensive, or the market prices for the crops are very low, or for any other reason. A change in economic conditions may allow formerly marginal lands to become profitable again.
marginal sea
1. Asea or other large area of theocean that is partially enclosed by land and/orsubmarine ridges yet still adjacent to, widely open to, and connected to the larger ocean at the surface; e.g. theYellow Sea andHudson Bay.[11]
Those waters along anation'scoast within which the nation has exclusive jurisdiction except for the right of innocent passage of foreign vessels.[11] See alsoterritorial waters.
marine
1. Of, relating to, found in, or produced by thesea orocean.
2. Of or relating to shipping ornavigation, particularly by watercraft.[4]
A climate strongly influenced by anoceanic environment, typically found onislands and thewindward shores ofcontinents. It is characterized by small daily and yearly temperature variation and high relative humidity.[2]
market orientation
The tendency of a firm or industry to be located close to wherever demand for the commodities it produces is strongest.[4]
A type ofwetland dominated by herbaceous rather than woody plant species and often found at the edges of lakes and streams, where it forms a transition between aquatic and terrestrial ecosystems.
1. Any section of the Earth'scrust which is demarcated byfaults orflexures and tends to retain its internal structure while being displaced as a whole.
2. A single largemountain mass or compact group of connected mountains forming an independent portion of amountain range.
mayen
In Switzerland and the Central Alps, a large shelf or ledge, intermediate between high alpine meadows and valley floors, where cattle are allowed to rest briefly during their annual movements between summer and winter pasture.[4]
The averagesea level of one or more of the Earth's coastal bodies of water, such asoceans andseas, or at a particular location, from which heights such aselevation andaltitude are measured.
One of a series of regularsinuous curves, bends, loops, turns, or windings in themain channel of ariver,stream, or otherwatercourse. Meanders are produced by the repetitive upstream erosion and downstream deposition of sediments along the banks of a watercourse as the water flows back and forth across the axis of avalley orfloodplain.
The process by which thestrip of land separating the two closest parts of ameandering river or streamchannel is breached by the river's flow, forming a new, shorter channel that effectively "shortcuts" the loop of the meander and causes it to be gradually abandoned until it is completely isolated from the main flow. The river's course suddenly becomes much straighter, and the abandoned meander often forms aslackwater or anoxbow lake, or becomes loaded with sediment and dries up entirely, leavingvisible traces of the former channel.
Ameander cutoff occurs when a river erodes through the neck of a pronounced meander, creating a "shortcut" that isolates the meander loop from the river's main channel.
meander neck
The narrow strip of land separating the river on each side of a well-developedmeander.[4] If this strip is completely eroded away, acutoff occurs. See alsoneck.
A branch ofhuman geography that studies the geographical aspects of health and the provision of healthcare, examining the spatial distribution of human diseases, mortality, morbidity, and the environmental factors conducive to human health and illness.[4]
A very largecity, typically with a population of at least 10 million people. Precise definitions vary, but criteria are usually based on total population and/or population density.
An exceptionally largealluvial fan, variously defined as being more than 100 kilometres (62 mi) long from apex to toe or having a surface area of more than 10,000 square kilometres (3,900 sq mi).
The conception of an actual geographic space as it exists within a person's mind; an imagined "map" of the spatial relationships and orientations of physical objects and locations within the real-world environment, reflecting the knowledge and prejudices of the individual and characteristic of the way the individual acquires, classifies, stores, retrieves, and interprets geographic information.[10]
Aconformalcylindricalmap projection in which theequator is represented by a straight line true to scale andmeridians are represented by parallel straight lines perpendicular to the equator and uniformly spaced according to the distances between them at the equator.Lines of latitude are also represented by a system of straight lines which are perpendicular to all of the meridians and therefore parallel to the equator, though their spacing is not uniform but rather increases with increasing distance from the equator in order to conform with the expanding scale resulting from the parallel representations of the meridians.[16] The standard Mercator projection has long been popular innavigation because it represents north as up and south as down everywhere in the world while preserving local directions and shapes, though it also greatly inflates the size of objects near the geographic poles.
A shallowpond,lake, orwetland. The term is used primarily in Great Britain and other parts of Western Europe.
mereing
A type ofsurveying in which boundaries are established with respect to ground features present at the time of the survey, which may include natural features and may or may not remain unchanged over time, e.g. ametes and bounds survey.[9]
A line oflongitude, i.e. any imaginary line connecting points of equal longitude and running perpendicular to alllines of latitude, intersecting them at right angles. Unlike lines of latitude, meridians are all the same length, but are not parallel to each other, instead converging at thegeographic poles. Each meridian is half of agreat circle drawn on the Earth's surface; the other half, connecting all of the meridian'santipodes, is termed anantimeridian. Meridians are numbered according to their longitudinal measure in angulardegrees (further subdivided intominutes andseconds) up to 180 degrees east or west of an arbitrarily designated zero orprime meridian, by convention theInternational Reference Meridian.
Of, relating to, or characteristic of the south, especially of the inhabitants of a southern region or territory, in particular southern Europe.[4] Contrastseptentrional.
A system ofland survey that defines parcels of land according to visible natural landscape features and distance. The resultant field pattern is usually very irregular in shape.[2]
A largecity orconurbation which is considered a significant economic, political, or cultural center for acountry or geographic region and/or an important hub for regional or international connections and communications.
A region consisting of one or more densely populatedurban cores (often ametropolis) and its less populous surrounding territories, including satellitecities,towns, and interveningrural areas, all of which are socioeconomically tied to the core as typically measured bycommuting patterns. A metropolitan area usually comprises multipleneighborhoods,jurisdictions, andmunicipalities, with its inhabitants sharing industry, housing, and many other forms of infrastructure.
An isolated, rounded, steep-sidedhill composed of either limestone, marble, or dolomite and surrounded by nearly flatalluvial plains, especially as found intropical regions.
AlsoMoho discontinuity,Moho boundary, or simplyMoho.
The boundary between the Earth'scrust and themantle, as defined by the abrupt change in velocity of seismicP waves traveling across this boundary, which occurs as the waves pass through different densities of rock.[11]
A long, massive, man-made stone or earthen structure used as apier orbreakwater, or as acauseway between places separated by water, but designed to prevent the free movement of water underneath it (unlike a true pier).
Of or pertaining to amountain or mountains; mountainous; occurring at highelevation. The term is used in particular to describebiomes or ecological communities occupying cool, humid zones at or neartimberline.[19] See alsoalpine.
monticule
A secondarycone on the side of a largervolcano, or any small mountain or large hill.[19]
An upland habitat andecoregion characterized by low-growing vegetation on acidic soils and generally referring to uncultivatedhills but also including low-lyingwetlands.
The rocks and soil carried and deposited by aglacier. Aterminal moraine, either a ridge or low hill running perpendicular to the direction of ice movement, is often visible near the end of a retreating glacier, indicating the glacier's maximum advance.[2]
A vertical, cylindrical shaft, up to 25–30 metres (82–98 ft) deep, by which surfacemeltwater flows into aglacier, usually formed at lines of structural weakness in the ice.[14]
Any heaped pile of earth, gravel, sand, rocks, or debris, typically with a rounded top and of topographically higherelevation than its immediate surroundings.
A largelandform that rises prominently above the surrounding land in a limited area, usually in the form of a rocky peak with great verticalrelief; a mountain is generally considered steeper than ahill. Mountains are formed byvolcanic ortectonic forces and erode slowly through the actions of rivers, glaciers, andweathering. Most exist within extensivemountain ranges.
A series of neighboringmountains orhills, often closely arranged in a line and connected by high ground. Individual mountains within the same mountain range are usually the result of the sameorogeny, and often (though not always) share a common form, alignment, and geology.
1. The place where ariver orstream flows into another body of water, such as alake or another river but especially asea orocean.Deltas andestuaries occur near the mouths of rivers.
2. The lower or downstream end or the most accessible entrance of avalley,canyon,ravine, orcave.
A type of coastalwetland consisting of exposed layers ofbay mud formed by the deposition of silts, clays, and marine animaldetritus bytides orrivers. Mudflats usually form within theintertidal zone of relatively sheltered areas such asbays andlagoons.
The ability to use more than one language when speaking or writing. This term often refers to the presence of more than two populations of significant size within a single political unit, each group speaking a different language as their primary language.[2]
A type of general-purposeurbanadministrative subdivision havingcorporate status and powers of self-government orjurisdiction as granted by national and/or state laws to which it is subordinate. Municipalities are often included within but usually distinguished from larger administrative divisions such ascounties, though the nature of their territorial boundaries and political jurisdictions can vary considerably in different parts of the world.
^Dennis Bryant (2014-11-25)."Amphidromic point".Maritime Logistics Professional. New Wave Media.
^Bart Makaske,"Anastomosing rivers: a review of their classification, origin and sedimentary products",Earth-Science Reviews, 53: 3–4, 2001, pp. 149–196, ISSN 0012-8252,https://doi.org/10.1016/S0012-8252(00)00038-6.
^abcdefWade, Tasha; Sommer, Shelly, eds. (2006).A to Z GIS: An Illustrated Dictionary of Geographic Information Systems (2nd ed.). Redlands, California: ESRI Press.ISBN978-1-58948-140-4.
^abcdefgMayhew, Susan (2023).A Dictionary of Geography (6th ed.). Oxford: Oxford University Press.ISBN9780192896391.
^John K. Wright (1947). "Terrae Incognitae: The Place of the Imagination in Geography", Annals of the Association of American Geographers, 37:1, 1–15, doi:10.1080/00045604709351940
^17USC105, U.S. Copyright Office (December 15, 2009),"§ 105. Subject matter of copyright",U.S. Copyright Office - Copyright Law: Chapter 1, Title 17 of the United States Code, Circular 92, Washington, DC: U.S. Copyright Office, retrievedOctober 2, 2010,United States Government works: Copyright protection under this title is not available for any work of the United States Government, but the United States Government is not precluded from receiving and holding copyrights transferred to it by assignment, bequest, or otherwise.{{citation}}: CS1 maint: numeric names: authors list (link)
