List of definitions of terms and concepts related to geography
This glossary of geography terms is a list of definitions of terms and concepts used in
geography and related fields, including
Earth science,
oceanography,
cartography, and
human 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 one
chain (66
feet) by one
furlong (660 feet), equivalent to 43,560 square feet (0.001563 sq mi; 4,047 m2), or about 0.40
hectare.
A sub-discipline of geography which studies the spatial relationships between humans and
agriculture, as well as the cultural, political, and environmental processes that lead to parts of the Earth's surface being transformed into agricultural landscapes through
primary sector activities.
A distinctly triangular or fan-shaped deposit of sediment transported by water, often referred to as
alluvium. Alluvial fans usually form at the base of
mountains, 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 sloping
plain created by the long-term
deposition of
alluvium from one or more
rivers flowing from
highland regions, and typically characterized by various
fluvial landforms such as
braided streams,
terraces, and
meanders. Alluvial plains encompass the larger area over which a river's
floodplain has shifted through geological time.
Characteristic of or resembling the European
Alps, or any other high-elevation
mountain range or
mountainous environment (especially one deeply modified by
glacial erosion so as to contain characteristic
landforms such as
cirques,
horns, etc.), in
topography, climate, or ecological communities.[5]
A geographical location where there is little or no
tide, i.e. where the
tidal amplitude is zero or nearly zero because the height of
sea level does not differ significantly at
high tide and
low tide, and around which a tidal crest circulates once per tidal period (approximately every 12 hours). The 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 the
open ocean near the center of the basin, depend largely on the surrounding
topography and
bathymetry, 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]
anastomosing stream
Also anastomosed stream.
A
stream or
river composed of multiple, branching, interconnected, coexisting
channels that enclose floodbasins on
alluvial plains, usually formed when a slow-moving river encounters
avulsions that divert its flow, creating new channels on the floodplain.[8]
anecumene
Also anoecumene.
The part of the Earth's surface which is uninhabited and/or uninhabitable by human beings.[4] Contrast ecumene.
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 two
polar circles of
latitude, south of which the sun appears above the
horizon 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 the
Equator. Contrast Arctic Circle.
A
stream or other
watercourse 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 or
topography. For example, a landscape featuring a river with a dendritic drainage pattern may be altered by gradual, localized
tectonic uplift, but the river may be sufficiently powerful to erode through the new obstructions as rapidly as they are formed, carving a
gorge 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] Compare insequent stream.
1. Of or relating to
anthropogeny, 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 the
dip of the underlying surface rocks. It is frequently, though not necessarily, an
obsequent stream.[4]
A geological
upfold that has an arch-like
convex shape and its oldest
beds near its center, often visible at the Earth's surface in exposed
rock strata. Contrast syncline.
1. The
meridian of
longitude that is directly opposite or
antipodal 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 a
great circle that passes through the geographic poles.
2. The
180th meridian in particular, i.e. the meridian of longitude that is exactly 180 degrees both east and west of the
Prime Meridian, with which it forms a great circle dividing the Earth into the
Eastern and
Western Hemispheres. The 180th meridian is used as the approximate basis for the
International Date Line because it mostly passes through the open waters of the Pacific Ocean.
Any pair of points on the Earth's surface that are
diametrically 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 the
great-circle distance between them being approximately 20,000 kilometres (12,000 mi).
anywhere fix
A geographic position which a
GPS receiver is able to calculate without requiring information about its own location or the local time.[9]
apogean tide
The
tide when the Moon is at its furthest distance from Earth in its orbit (its
apogee), during which its gravitational pull is reduced, resulting in a smaller
tidal range than is usual, i.e. lower
high tides and higher
low tides.[4] Contrast perigean 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 from
local to
global, in disciplines such as civic planning,
land use and management, location policy, and population studies, among many others.[4]
apposed glacier
A
glacier resulting from the merging of two separate glaciers.[4]
A normally
permeable rock, underlying or overlying an
aquifer, which becomes impermeable because of the saturation of its pores by water, potentially creating a
confined aquifer.[4]
An underground layer of
water-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 a
spring, or may be extracted using man-made
wells. There are many different types of aquifer with various levels of
hydraulic conductivity.[4]
aquifuge
An
impermeable rock stratum which not only obstructs the passage of water but cannot absorb it, e.g. granite.[4]
A deep
gully cut by a stream that flows only part of the year; a dry
gulch. The term is used primarily in
desert areas in North America and South America.[2]
The northernmost of the Earth's two
polar circles of
latitude, north of which the sun appears above the
horizon 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 the
Equator. Contrast Antarctic Circle.
The direction toward which a
slope faces with respect to a
compass or to the Sun's position in the sky,[5] or the direction which a segment of
coastline faces as it meets the
sea.
The physiographic border between the
Piedmont and
Atlantic coastal plain regions of eastern North America. The name derives from the river rapids and
waterfalls that occur as the water flows from the hard rocks of the higher
piedmont onto the softer rocks of the
coastal plain.[2]
1. The sudden loss of land by the action of water.
2. The rapid abandonment by a
river or
stream of an existing
channel 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 includes
activity space, and it enlarges as new locations are discovered and new information is gathered.[4] See also search space and mental map.
axis
1. (
coordinate system) Any of the reference lines of a
Cartesian coordinate system, from which the signed distances to each coordinate are measured, e.g. the x-axis or the y-axis.
2. (of a
fold) The imaginary central line or plane dividing the limbs of the fold as symmetrically as possible; the crest from which
strata dip downward and away in an
anticline, or the lowest depth of the trough from which strata rise in opposite directions in a
syncline.[4]
3. (of the
Earth) The rotational axis of the Earth: the diameter between the
North Geographic Pole and the
South 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 the
Earth'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 (often
magnetic north) and a line from the observer to a point of interest projected perpendicularly to the
zenith on the same
plane as the reference vector. Azimuth is usually measured in
degrees and can be determined with a
compass.
azimuthal projection
A
map projection in which all
bearings 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 with
frontcountry; sparsely populated or uninhabited
wilderness. See also bush.
The part of the profile of a
hillslope that forms the steepest, typically linear portion of the slope, generally located in the middle and bounded by a convex
shoulder above and a concave
footslope below. The backslope may or may not include vertical or near-vertical
cliffs.[5]
1. A part of a
river in which there is little or no current, especially a side channel, a sluggish
meander, or a slowing and widening of the
main 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 larger
region or
state 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 the
bed of a river, stream, or shallow
sea, either fully or partially submerged, mid-channel or connected to the
shore, and usually made of sand, mud, gravel, or other loose sediment. See also bar and shoal.
The
stage during which the
channel of a river or stream is completely filled with water from
bank to bank, immediately preceding the
overbank stage, when the river overflows its banks and inundates the surrounding
floodplain.[4]
An elevated area of unconsolidated sediment such as sand or gravel which has been deposited by the flow of a
river or other moving body of water. See also shoal.
An
impoundment built for seasonal floodwater storage and/or to create a
reservoir for irrigation, as opposed to a
dam, which instead serves the purpose of hydroelectric power generation, though the terms are sometimes used more or less interchangeably.
A long, narrow
ridge or
shoal lying above the
highest high tide level (thereby creating an
island) and parallel to the mainland
coast, from which it is separated by a
lagoon.[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 by
dredging. Though their size and shape change frequently, particularly during storms, they are important natural
breakwaters which shelter areas of relatively calm waters where
wetlands and marine life flourish. See also spit and tied island.
In the Spanish-speaking world, a
neighborhood or community within a larger urban area, generally with informal boundaries, though in some places the term may refer to a formal
subdivision of a
municipality.
An accurately measured line of known length on the Earth's surface, used as a base or reference line in
triangulation and other
surveying operations.[4]
Another name for a
depression, 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 of
seas and
oceans but sometimes of deep
lakes.
2. The study and depiction of the physical features or
relief of the
floor of a lake or ocean. In this sense bathymetry is considered the underwater equivalent of
hypsometry or
topography.
A
coastal body of water that is directly connected to but recessed from a larger body of water, such as an
ocean,
sea,
lake, or another bay. The land surrounding a bay usually shelters it from strong winds and waves, making bays ideal places for
ports and
harbors.
The direction or position of an object, or the direction of an object's movement, relative to a fixed point. It is typically measured in
degrees and can be determined with a
compass. By convention,
magnetic north is defined as having a bearing of zero degrees.
The solid rock in the Earth's
crust that underlies all soil and other loose material; the rock material that breaks down eventually to form soil.[2]
belt
Also corridor.
A large
region or
district (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 also regionalism.
bench
A narrow step, shelf, ledge, or
terrace, typically backed by a steep slope, produced either naturally (e.g. by erosion, as with a
wave-cut bench) or artificially (e.g. by mining).[4]
A
surveying 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 designated
datum level has been accurately measured.
A
crevasse or series of parallel crevasses that opens in a
glacier when a mass of moving ice detaches and pulls away from stagnant ice or
firn. Bergschrunds are common in mountainous areas, often forming seasonally near the back of a
cirque where the ice meets a steep or rocky
headwall. When the rift forms directly between ice and rock, the gap is called a
randkluft.[4]
1. A level space, shelf, or raised barrier separating two areas, often man-made and built of compacted earth. Berms often function as
impoundments,
fortification lines, or
border walls and other lines of demarcation.
2. A low, impermanent, nearly horizontal or landward-sloping shelf,
bench, or narrow
terrace on the
backshore of a
beach and parallel to the
shoreline, formed by waves which deposit material beyond the average
high water mark, e.g. during storms. Some beaches have no berms; others may have one or more.[5]
A bend or curve in a coastline, river, or other geographical feature typically indicating an especially large, open
bay that is shallower than a
sound.
In Australia, a branch of a river that is
cut off when the main stem changes course, leaving an elongated and often ephemeral
waterhole or
oxbow lake.[4]
The water of a slow-moving river
channel flowing through a forested
swamp or
wetland, characterized by high concentrations of
tannins leached from decaying vegetation, which gives it a darkly stained color and high acidity.
A hole or
fissure, especially a nearly vertical one, that is the landward opening of a
sea cave, frequently spouting or spraying air and
seawater as waves crash against the cave's other opening.[4]
A sandy
depression formed when
winderodes into patches of bare sand on otherwise vegetation-stabilized
sand dunes at the margins of coastal and arid ecosystems.
A steep slope or
cliff marking the outer margin of a
floodplain, especially one formed as the river erodes the concave bend of a
meander. See also cut bank.
A landscape of mixed woodland and
pasture, with fields and winding country lanes sunken between low, narrow ridges and banks surmounted by tall, thick
hedgerows, 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 with
lakes and
oceans, or they may collect and move water from one place to another, as with
rivers,
streams, and other
watercourses.
A type of
wetland which accumulates deposits of dead plant material, especially
mosses, known as
peat. 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 two
tidal bulges or by the constriction of an incoming tide as it travels up a
river,
firth, or narrow
bay, 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 a
well or tunnel.
A bald, steep-sided, dome-shaped hill, mountain, or rock
outcropping at least 30 metres (98 ft) in height and several hundred meters in width. Compare inselberg, tor, and nubbin.
A type of
administrative subdivision in certain English-speaking parts of the world. Though traditionally used to refer to a
fortress or a walled
town, modern usage of the term can variably refer to any town with its own local self-government, a formal or informal subdivision of a large
metropolis (as in
New York City and
London), or an entire administrative
region (as in the U.S. state of
Alaska).
The replacement of the narrow, congested, winding streets of an older town or neighborhood with wider, more modern streets or
boulevards, 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. a
border separating political or
administrative divisions, zones of occupation, natural areas, or private and public property.[4] See also frontier.
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 a
slope or hillside.
2. A heavily eroded area along a
river featuring steep
banks,
bluffs,
ravines, or
gorges. 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 an
ocean,
lake, or other
body 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 into
turbulence. Waves tend to break as they enter areas of shallow water, most reliably near
shorelines, where the decreasing depth of the sea floor beneath them
forces them to grow to a critical height at which point they overturn and the remaining forward energy is dissipated upon the
beach as
swash, though other forces may also cause breaking, including stormy weather and passing watercraft.
Any man-made structure built on the
coast of a body of water, typically the
sea, 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 from
coastal erosion and
longshore 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]
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 uninhabited
wilderness. See also backcountry, hinterland, outback, and bushveld.
In southern Africa, a tropical or subtropical woodland
ecoregion consisting largely of open
savanna with scattered trees; wild countryside as opposed to cultivated land.[4]
An isolated
hill or
mountain with steep or precipitous sides, usually having a smaller summit area than a
mesa.[2]
bypass
1. A
route 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 of
parcel-based land recording system containing a comprehensive record of interests in individual units of land within a
country or other polity, usually including a geometric description of each parcel's physical location, dimensions, and
boundaries that is linked to legal information detailing the nature of the interests (e.g. rights, restrictions, and responsibilities), the
ownership 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 or
mound of rocks, stones, or masonry, usually roughly conical or pyramidal in shape, constructed as a burial mound, to mark a
surveyed point, or as a
landmark or
waypoint to aid
routefinding on a
route that is otherwise unmarked and difficult to distinguish from the surrounding environment.[10]
A narrow, steep-sided
valley surrounding an
inlet formed in
karstic regions along the
Mediterranean coast, either by
fluvial erosion or the collapse of the roof of a
cave that has been subsequently partially submerged by a rise in
sea level.
A very large
cauldron-shaped
depression of volcanic origin which forms through the subsidence and collapse of the ground surface following the evacuation of an underlying
magma chamber. See also volcanic crater.
A deep cleft between
cliffs or
escarpments, or a rift between two mountain peaks, resulting from
weathering and the erosive activity of a
river over long periods of geologic time.
1. A primary
city or
town 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, or
gross 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-made
embankment, typically constructed of earth, masonry, wood, or concrete. Compare bridge.
Either of the two imaginary points in the sky at which an indefinitely extended projection of the Earth's axis of rotation intersects the
celestial 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 the
North Pole and
South 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, the
geographical center of a region of the Earth's surface is the centroid of the two-dimensional shape of that region, as projected radially to
sea level or onto a
geoid.[10]
A unit of length equal to 66 feet (20.117 m), used especially in public land
surveys 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".[11]
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 special-purpose
map designed for
navigation, especially
nautical and
aeronautical navigation, or to present specific data or technical information.[11]
A steep-sided
coastalgorge, typically of soft eroding
cliffs 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 the
Rocky 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]
A
map 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.[12]
An ephemeral, often highly
saline lake that forms seasonally with fluctuations in the
water table, usually in the winter, in the
desert basins of Northwest Africa.[13]
A steep-sided
volcano formed by the explosive eruption of cinders that form around a
vent. Cinders are
lava fragments about 1 centimetre (0.39 in) in diameter.[3]
A sovereign
state or small independent
country that usually consists of a single
city and its dependent territories.
clearing
1. The practice of permanently removing vegetation, especially trees and bushes, from a
forest or woodland in order to use the space for another purpose, such as agriculture, civic development, or paths for roads, railways, or power lines.
A
coastline where the repeated action of ocean waves has formed steep and often precipitous
cliffs, as opposed to a flat or gently sloping
alluvial 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]
The complementary angle of a given
latitude; 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]
A
territory under the immediate complete political control of a sovereign
metropolitan state but otherwise distinct, often geographically, from the state's home territory. Colonies have no international representation independent of the metropolitan state. Compare satellite state.
Loose, unconsolidated sediment that has been transported and
deposited at the base of a
hillslope by any of various wash or
mass movement processes, such as
surface runoff,
sheet erosion, or
landslides. Typically a heterogeneous mixture of rock types and sizes ranging from silt to
talus boulders, colluvium is often derived from
eluvium, and differs from
alluvium, which is deposited primarily by
fluvial activity.[13]
A steep, narrow
valley or a large hollow on the side of a
hill or
coastline, especially one enclosed on all but one side. The term is used primarily in southern England, where it often implies a dry
ravine in a limestone or chalk
escarpment. See also cwm.
Also compass star, wind rose, or rose of the winds.
A figure on a
compass,
map, nautical chart, or monument used to display the orientation of the four
cardinal directions — North, East, South, and West — and their intermediate points.
compass survey
A
traverse which relies on the indications of a magnetic
compass for orienting the traverse as a whole or for determining the directions of individual lines.[10]
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 be contiguous.
One of several very large, contiguous
landmasses 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 of
continental crust on
continental plates.
The type of climate found in the interior of the major continents in the middle or
temperate 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 oceanic
drainage basins of a particular
continent. The river systems of a continent on opposite sides of a continental divide flow toward different oceans. See drainage divide.[2]
A portion of a
continent that is submerged beneath an area of relatively shallow water known as a shelf sea. Though continental shelves are usually treated as physiographic provinces of the
ocean, they are not part of the deep ocean basin proper but the flooded margins of the continent.
A line marked on a
topographic map which connects points of equal
elevation above or below a specified reference
datum. Multiple contour lines, each representing a different elevation, are depicted together to show the
shape of the
terrain within the map area.[3]
A long chain of
mountain ranges or
highlands, especially those formed by the same orogeny and spanning the length of a
continent along
tectonic boundaries. The term is used in particular to refer to the
American 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 also hearth.[2]
The process of mechanical
erosion 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.
A narrow
gully with a steep gradient in a mountainous terrain, often enclosed by sheer
cliffs and filled with snow or ice even during the summer months.
The
cardinal direction in which a vessel or aircraft is moving, or in which it is steered. This is not necessarily the same as the
heading, 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 as
skidding or
slipping. See also bearing.
1. A walled, rounded,
cirque-like opening at the head of a small
valley.
2. A small, narrow, sheltered
bay,
inlet,
tidal creek, or recess in an
estuary, often within a larger embayment.
3. A small, often approximately circular, wave-cut indentation or recess in a
cliff on a large body of water, especially one with a relatively narrow or secluded entrance.
4. A shallow tidal river, or the
backwater near the
mouth of a tidal river.
Any large, roughly circular
depression, pit, or hole in the Earth's surface. Craters are classified into different types based on their ultimate causes; see impact crater, volcanic crater, and pit crater.[3]
An old and stable region of
continentallithosphere, characterized by a thick
crust composed of ancient crystalline basement rock. Cratons are generally found in the interiors of
tectonic plates, having remained relatively unaffected by orogenic and tectonic activity for very long periods of time.[4]
A small, intermittent
stream that is larger than a
brook but smaller than a
river. 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 the
lithosphere. The Earth's crust is generally divided into two distinct types,
oceanic crust and
continental crust, both of which "float" on top of the
mantle.[3]
The totality of water in the solid phase on the Earth's surface, including
glaciers; sea, lake, and river
ice;
snow; and
permafrost. The cryosphere is sometimes considered a subset of the
hydrosphere.[3]
A branch of
human geography which studies the patterns and interactions of human
culture in relation to the natural environment and the human organization of space.
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 the
culture of a group diffused. See also hearth.[2]
A tunnel or conduit that channels water through or beneath an obstacle (e.g. through a man-made crossing of a
ravine that would otherwise block the natural flow of water), or any artificially buried
watercourse.
An arc-shaped,
dune-like mound of sediment on a
beach or
foreshore.[13] 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 continually
erodingbank along a meandering
river or
streamchannel, especially a bank that has been eroded into a nearly vertical
cliff. Cut banks generally form on the outside bend of a deep
meander, opposite the depositional
point bar that forms on the inside bend.
A term referring to the longitudinal profile of some
glaciatedvalleys which have been eroded into a series of consecutive
hanging 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 as
floodgates and
levees are more specifically designed to manage or prevent water flow into particular areas).
A type of thematic
map that uses areal symbols to visualize a
spatially dependent variable (e.g. population density) by refining a
choropleth 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 and
isarithmic 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 a
body 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]
deep
A trough-like
depression or trench in the
ocean floor, of limited extent but great depth, generally more than 5,500 metres (18,000 ft) below sea level.[4]
A unit of angular measure, represented by the º symbol. A circle is divided into 360 degrees; subdivisions of the degree include the
minute (1⁄60 of one degree) and the
second (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 reporting
latitudes and
longitudes.[1]
A landform at the
mouth of a
river where the
main stem splits up into several
distributaries. It is formed from the deposition of the sediment carried by the river as the flow leaves the mouth of the river. Compare estuary.[5]
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.
A
territory relying on or subject to the control of another
country, 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 a
landform or
landmass, e.g. by the action of wind, water, ice, or gravity in transporting previously
weathered surface material, which comes to rest when sufficient kinetic energy is lost and accumulates in layers of sediment. See also sedimentation.
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 also brownfield land.
An arid, barren area of land where little
precipitation 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 of
denudation 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 their
desertification, 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 by
capillary action and are then precipitated by evaporation.[4]
The process by which a previously fertile area becomes increasingly arid, infertile, or
desert-like; a type of land degradation in which biological productivity is lost due either to natural or man-made processes, e.g.
climate change or
overexploitation of soils for agriculture.
desire line
A straight line drawn on a
map 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 easiest
route 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 artificial
pond 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 of
igneous 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 geographic
terrain surface created from
elevation 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 a
levee.
2. In
geology, an
intrusion in which molten rock has ascended through an approximately vertical
fissure and solidified into a wall of rock that is often harder or less permeable than the rocks of the surrounding strata.[4]
The
position of one point relative to another without reference to the distance between them, usually expressed as the angular distance in
degrees between a line connecting the two points and a reference direction. In
cartography,
navigation, and
orienteering, direction is often considered only with respect to a two-dimensional plane (see
compass rose), but it is also commonly interpreted in three dimensions.[14]
In
hydrology, 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 a
streamchannel) 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 including streamflow and outflow.
A
coastline which cuts transversely across the predominant orientation of the local geological strata, i.e. not parallel to them, as with a
concordant coastline.[4]
A landscape produced by significant
stream erosion and incision of a
plateau 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 eroded
hills or
badlands.[5]
The decrease in cultural or spatial interactions between two places as the distance between them increases. This effect may be noticeable in
towns and
cities, where certain characteristics such as pedestrian traffic, building height, and land value tend to decline with greater distance from the
city center.
A type of
administrative 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 the
municipal or
county governments that designate them. The term can refer to a wide variety of official and colloquial subdivisions, including
electoral districts,
school districts, and
shopping districts.
A shallow enclosed
basin or funnel-shaped
depression typical of
karst landscapes, usually with a flat floor and linked to the underlying drainage system by a vertical shaft.[4] See also sinkhole.
1. A steep-sided
mound that forms when very viscous lava is extruded from a
volcanic vent.[3]
2. An uplifted area of
sedimentary 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 a
gully or
badland carved by extreme erosion.[13]
An open, treeless expanse of gently undulating, elevated
grassland, 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 geographical
center of a
city or
town, especially a large city within a major
metropolitan area, often synonymous with its
central business district.
The natural or artificial removal of surface and/or sub-surface water from an area with excess water, e.g. via
runoff facilitated by
channels such as
streams and
rivers, into which water collects and is transported to
sea level by gravity. The patterns, hierarchies, and evolution of drainage networks are widely studied in
physical geography disciplines.
Also catchment, drainage area, river basin, water basin, or watershed.
Any area of land where precipitation collects and drains into a common outlet, such as into a
river,
lake,
ocean, or any other
body of water. The drainage system includes all of the
surface water from precipitation
runoff and
snowmelt, as well as all of the
groundwater beneath the Earth's surface. Each drainage basin is separated topographically from adjacent basins by a
drainage divide.
Also ridgeline, watershed, water parting, water divide, or simply divide.
The topographical barrier that separates neighboring
drainage basins. Divides are often, though not always, located along conspicuous elevated
ridges or
mountain ranges.
1. A terrain feature formed by two parallel
ridges or
spurs with low ground in between them.
2. Another name for an
arroyo,
ravine, or
gulch, especially one with a broad floor and gently sloping sides.[5]
draw down
The maximum extent to which the
water table is reduced in
elevation as a result of pumping water from a
well that penetrates an
aquifer. The amount of draw down diminishes logarithmically with distance from the site of the well, a fact which determines the shape of the subsurface
cone of depression in the area surrounding the well.[13]
A type of
sea ice consisting of multiple
ice floes that are not attached to the
shoreline or any other fixed object such as a
shoal, and which are therefore free to "drift" under the influence of winds and
ocean currents. Contrast fast ice.
A
valley which was originally formed on land but later partially or entirely submerged beneath the sea due to a rise in sea level. See also fjord, calanque, and ria.
An elongated
hill in the shape of an inverted spoon or half-buried egg which is formed by
glacial ice acting on underlying unconsolidated
till or ground
moraine.
A type of farming practiced in semi-arid or dry grassland areas without irrigation, instead using such approaches as
fallowing, maintaining a finely broken surface, and growing drought-tolerant crops.[2]
An
ecoregion 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 tropical
savannas to hyper-arid extremes such as
deserts.
1. A collective term for the various fields of natural science related to the planet
Earth.
2. The branch of science that studies the physical constitution and characteristics of the Earth and its atmosphere, using methods and tools from
geography, 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 of
biogeographic province that is smaller than a
bioregion and which contains characteristic, ecologically and geographically distinct, and relatively uniform assemblages of biological
communities and species. Ecoregion boundaries often overlap within
ecotones and mosaic habitats, and most ecoregions contain habitats that differ from those described for their assigned
biome.
A transition area between two biological
communities, 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 traditional
downtown or
central business district in what was previously a
suburban residential or
rural area.
The transitional areas of "fringe" space at the boundaries of a
country,
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. Compare hinterland.
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 human
settlements of all types, incorporating concepts such as regional, metropolitan, and community
planning and dwelling design with the goal of achieving harmony between the inhabitants of a settlement and their physical, social, and cultural environments.
A branch of
human geography concerned with analysis of the organization, methods, results, and consequences of political
elections 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 to
sea level (or at least to a
referencegeoid used as an approximation of the Earth's mean sea level). Compare altitude, geopotential height, and depth.[1]
2. The vertical angle between the horizontal and a high point, e.g. between the
horizon and a star in the night sky, or between the base of a mountain and its
summit.[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]
Also endoreic basin, closed basin, or terminal basin.
A closed
drainage basin that allows little or no outflow to external bodies of water but converges instead into internal
lakes or
swamps which equilibrate through evaporation.
A place (e.g. a
port, 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 to
customs 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 to
duty-free ports with a high volume of re-export trade.
The point on the Earth's surface directly above the
focus of an
earthquake, 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 southern
hemispheres, defined by the intersection of the spheroid's surface and the plane perpendicular to its
axis of rotation, which results in a
great circle exactly midway between and hence equidistant from the planet's
geographic poles and is therefore defined as zero degrees
latitude.
2. The Earth's equator in particular (often capitalized as the Equator): 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 other
lines 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.
A boulder that has been carried from its source by a
glacier and deposited as the glacier melted. Such boulders are often conspicuous because they differ geologically from the surrounding rock.[2]
A
plain beneath which the
bedrock has been subjected to considerable subsurface
weathering, known as "etching". Erosion of the
regolith overlying an etchplain often exposes topographical irregularities such as
inselbergs.
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 also
enclaves.
exotic stream
A
stream found in an area that is too dry to have spawned such a flow. The flow originates in some moister section.[2]
An adjective describing a region or district that lies outside a
city and usually beyond its
suburbs; a place of this type is called an exurb. Compare rural.[2]
Agricultural land that is plowed or tilled but left unseeded during a
growing season. Fallowing is usually done to conserve moisture and soil nutrients.[2]
A selected point in a
projected 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 the
true origin in order to exclude negative values.[4]
Sea ice that is more or less securely "fastened" to a
coastline,
to the sea floor, or to grounded
icebergs, and which therefore does not move with currents and winds (unlike
drift 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 numerous
fractures 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-altitude
moor or
upland, or a treeless
alpinetundra, often studded with boulders or rock outcrops; or a broad, isolated mountain
summit. 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 into
peat, and which is supplied with an input of mineral-rich
surface or
groundwater and thereby directly connected to a larger hydrological system. This external input typically results in higher mineral concentrations and a more alkaline
pH than other peat-forming ecosystems such as
bogs. Fens are one of four main types of
wetland, along with bogs,
marshes, and
swamps.
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 long
sightlines.
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 in
GIS applications, although the former is more common. Also spatially dependent variable.
The size and shape of the Earth as studied in
geodesy. 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 as
geoids.
A type of ice that is at an intermediate stage between
snow and
glacial ice. More specifically, firn is partially compacted
névé 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 a
floodplain 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 coastal
inlet,
strait, or
bay associated with the
mouth of a large
river, where the
tidal effects of
seawater passing upriver have widened the riverbed into an
estuary. The term is used primarily in Scotland.
A series of shallow steps down which water is allowed to flow, designed to permit
salmon or other anadromous fish to circumvent artificial barriers such as
dams as they swim upstream to spawn.[2]
A
hollow or
depression within a
bog, 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 as strings.
A primarily vertical artificial barrier designed to temporarily contain the waters of a
river or other
waterway which may rise to high levels during flooding events. Flood walls are narrower and typically easier to build than
dikes or
levees, 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-capacity
channel or
culvert 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 by
levees. 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 a
causeway but crosses a shallow and often dry
depression that is subject to flooding, rather than a continuously flooded waterway.
4. A part of a
floodplain kept clear of encumbrances and reserved for emergency diversion of floodwaters.
A
glacial landform created by the movement of a glacier around a boulder, consisting of a lineation or streamlined furrow or
ridge parallel to the direction of ice movement. They generally form in newly deposited
till or older
drift 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 between
plains or low-relief
hills and adjacent topographically higher hills,
mountains, or
uplands.
footslope
The part of the profile of a
hillslope 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. the
shoulder and
backslope) and sites of deposition further down the slope (the
toeslope).[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 dry
bridge). Fords may be seasonal or temporary, becoming impassable during high water.
foredeep
A relatively narrow, deep, elongated, and steep-sided trough in the
ocean floor, usually near or parallel to a mountainous land area or associated with an
archipelago, or such a trough when infilled with sediment.[4] See also foreland basin.
foreland
1. Any land area or territory located in front of something else.
2. A landform projecting into the sea, e.g. a
cape or
headland.
3. The seaward trading area associated with a particular
port or
harbor.[4]
4. (
glaciology) The area between the current leading edge of a
glacier and the
moraines of the most recent maximum.
A type of structural
endmember basin that develops adjacent and parallel to a
mountain range as a result of
lithospheric flexure during its orogeny. Topographic loading and downflexure creates space in the basin that is filled by sediment eroded from the range. Compare rift 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 international
border each workday and returning to their country of residence on a nightly or weekly basis;[15] someone who lives and works across political or geographical
frontiers.
1. The area near or beyond a political or geographical
boundary; a
march or borderland.
2. The area near or beyond the edge of a settled or civilized area, consisting of sparsely populated or uninhabited wilderness. See also hinterland and edgeland.
functional diversity
The characteristic of a place where a variety of different activities (economic, political, or social) occur, most often associated with
urban places.[2]
A narrow strip of trees or shrubs lining both
banks 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 a
map or
atlas and containing information concerning the geographical make-up, social statistics, and physical features of a
country,
region, or
continent.
A concise, human-readable series of letters, numbers, and/or other symbols used to represent and uniquely identify a particular geographic entity so as to distinguish it from other geographic entities in a finite set or database.
In many
geographic information systems, an imaginary polygon on the surface of the Earth with dimensions 1
degree of
latitude by 1 degree of
longitude, or approximately 111 by 111 kilometres (69 by 69 miles) at the
Equator, 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, however, such that the shape of a geocell becomes increasingly trapezoidal at higher latitudes.
Also geospatial data, georeferenced information, and geoinformation.
Any data or information having an implicit or explicit association with one or more locations on the Earth, especially that used for
georeferencing in
GIS databases.
The science of accurately measuring and understanding the Earth's
geometric shape, orientation in space, and
gravitational field and how these properties change over time.
Also geodetic system, geodetic reference datum, or geodetic reference system.
A
coordinate system and set of reference points used for locating places on the Earth, which defines
horizontal and
vertical coordinates upon a particular
reference ellipsoid that approximates the
figure of the Earth. Geodetic datums are used in
geodesy,
navigation, and
surveying applications to translate positions indicated on paper or digital
maps to their actual positions on the Earth; because the Earth is an imperfect ellipsoid, localized datums such as the
ED50 covering only specific countries or regions are often more accurate representations of their area of coverage than global standards such as the
WGS 84 of the
World 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.
A
coordinate 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 as
elevation and two or three other numbers represent a horizontal position such as
latitude and
longitude.
Any system of computer software tools designed to allow users to record, store, manipulate, analyze, manage, and present large sets of spatial or
geographic data.
A digital public-domain database developed by the
U.S. Geological Survey and the
U.S. Board on Geographic Names which contains name and locative information about more than two million physical and cultural features located throughout the
United States and its territories. Each feature recorded in the database receives a unique feature
record identifier called a GNIS identifier.
geographical inertia
Also geographical 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 one
minute of arc along the Earth's
Equator: approximately 1,855.3 metres (1.1528 mi; 1.8553 km). The precise length varies with the
reference ellipsoid used to approximate the
shape of the Earth. Regardless of the particular ellipsoid, the length of one
degree of
longitude at the Equator is equal to exactly 60 geographical miles.
The shape that the surface of the Earth's
oceans would take under the influence of
Earth's gravity and
rotational acceleration alone, in the absence of other influences such as winds and
tides. It is often characterized as the precise mathematical
figure of the Earth: a smooth but irregular gravitational
equipotential surface at every point of which, by definition, the direction of the force of gravity is always perpendicular and
spirit 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. A
reference ellipsoid is an idealized approximation of the more complex and accurate geoid.
The science and technology which develops and uses
information science infrastructures to address problems and analyze data within
geography,
cartography,
geoscience, and related branches of science and engineering.
The identification or estimation of the real-world geographic
location of an object, involving the generation of a set of
geographic 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's
crust and of the relationship between these physical features and the geologic structures beneath.[2]
The study of geographical knowledge from any and all points of view, past or present, true or false;[16] the study of the nature and expression of geographical ideas.[4]
A branch of
statistics which involves the organization, management, and analysis of spatial and spatiotemporal datasets. Geostatistical algorithms are often incorporated in
GIS 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 which
Jews 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 a
glacier and deposited when the ice melts. This creates an unstratified material of varying composition.[2]
A persistent mass of dense
ice that is constantly moving under its own weight, and which is composed largely of compacted
snow that forms where the annual accumulation of snow exceeds its melting and sublimation over very long periods of time. Glaciers slowly deform and abrade the land beneath them, creating a huge variety of landforms including
cirques,
moraines, and
fjords. They form exclusively on land and are distinct from the much thinner ice that forms on bodies of water.[3]
The scientific study of
glaciers, including their formation, composition, behavior, causes, effects, and distribution;[17] or more generally of ice or any natural phenomena involving ice.
A smooth, gently sloping surface at the foot of a
hill,
mountain, or any other high
promontory, whether natural or artificial. In the latter case, the term is used in particular to describe a stone or earthen
slope constructed at the base of some historical military fortifications.[17]
A
city which functions as an important or primary node in the
global 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.
A
satellite-based
radionavigationpositioning system owned and operated by the
United States Department of Defense and made available for use by both the military and the general public. It is one of several
GNSS standards that provides
geolocation and time information, transmitted via
microwave signals, to enabled
satellite navigation devices, known as GPS 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-scale
map 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 shaped
parcel of land of any size, often approximately triangular, that is left between two adjoining
surveyed parcels as the result of incomplete or inaccurate
boundary surveys.[14]
2. A lune-shaped
map which may be fitted to the surface of a
globe with a negligible amount of distortion.[14]
A
depression or
valley bounded on either side by distinct, parallel
escarpments or
faults and formed by the downward displacement of a block of the Earth's
crust. Grabens often occur side-by-side with
horsts, their uplifted or non-displaced counterparts, in a repeated series of vertical displacements.
Also slope, incline, gradient, pitch, rise, or mainfall.
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 of
hills or
mountains or the
beds and
banks of
watercourses.
Any land area where the vegetation is dominated by grasses (i.e. plants of the botanical family
Poaceae), sometimes also inclusive of
grass-like plants of other families. A large and important
biome occurring worldwide, grasslands may be natural or created for agricultural purposes.
The measurement of the strength of a
gravitational 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 a
plane 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 in
geodesy, where they are often visualized upon the surface of the Earth (despite the fact that the Earth is
not a perfect sphere): for example, the
Equator of the idealized Earth is a great circle, and any
meridian with its
antimeridian 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 of
geodesics for the purposes of air and sea navigation. See also small circle.
great-circle bearing
The horizontal direction or
bearing followed by the arc of a
great circle through a given pair of terrestrial points, expressed as the angular distance from a reference direction.[14]
The length of a line between two points which follows the arc of a
great 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-use
zone designated in some cities to prevent development of wild, largely undeveloped, or agricultural land surrounding or adjacent to
urban areas, in order to conserve natural ecosystems, to allow the return and establishment of wildlife, and/or to create
urban 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.
The part of the year during which local weather conditions (i.e. temperature and precipitation) permit the normal growth of
plants 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 last
frost (in temperate parts of the
Northern 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 ocean
shore or river
bank, constructed to interrupt water flow and limit the movement of sediment by
longshore drift.
A landform resembling a large ditch or a small
ravine created by the action of swift running water eroding deeply and sharply into soil, typically on a hillside.
Any large system of circulating
ocean currents, particularly those related to large-scale wind movements. Gyres are caused by the
Coriolis effect and play a fundamental role in the global
thermohaline circulation.
A device consisting of a spinning disc or rotor mounted in such a way as to preserve the orientation and
angular 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 the
attitude and/or
course of a moving object such as an airborne or waterborne vehicle or camera. Modern digital gyroscopes and their associated readouts are widely used in
navigation and
geodesy as the basic sensor in
direction-seeking, direction-keeping, and attitude stabilization systems.[14]
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 a
map to indicate the general orientation and steepness of
topographicalterrain. Such lines vary in length, thickness, and spacing, with steeper slopes indicated by shorter, heavier, and more closely spaced lines.[11]
haff
A coastal
lagoon of
fresh or
brackish water on the south coast of the Baltic Sea, fed by a stream which is blocked by a
nehrung, through which it is linked to the sea by a
channel.[4]
halo effect
In the context of geography, the detrimental effect of a
border 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 single
homestead to a
town.[4]
A
desert landscape consisting of high, largely barren, rocky
plateaus where most of the sand has been removed by
deflation, and thus lacking most surficial materials other than boulders and exposed
bedrock.[13]
A small human settlement, variably defined as one the size of a
town,
village, or
parish or as a smaller subdivision of or satellite entity to a larger settlement.
A
tributaryvalley 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 differential
glacial erosion, when adjacent areas beneath a glacier are subjected to different rates of erosion.
The
compassdirection 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 its
course; 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 as
skidding or
slipping. See also bearing.
1. Another name for the
source of a
river,
stream, or other
watercourse, i.e. the point or points furthest from the
mouth of a particular stream, at which precipitation,
meltwater, or
groundwater first accumulates into a persistent, identifiable, and/or named
body of water whose contents ultimately empty into the particular stream; or all of the uppermost streams of a
watershed considered collectively (of which there may be thousands), typically including all streams identified as first-order through third-order in conventional
stream order systems.
2. The entire
region, inclusive of land, surrounding these sources, often abutting the boundary of a
drainage divide that separates different watersheds.
A metric unit of area defined by a square with sides of 100 metres, equal to 10,000 m2 or 2.471
acres. 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 a
windbreak for crops in adjacent fields.
One half of the Earth, usually conceived as resulting from the division of the globe into two equal parts of either
north and
south or
east and
west.[1]
heteroclinal fold
A geological
fold of which one side is sloped at an angle steeper than that of the other side.[4]
high plain
A
plain lying at a high
elevation, generally above 600 metres (2,000 ft).[4]
A natural or man-made demarcation that indicates the maximum rise of a
body 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 a
flood or
storm 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. a
tidal cycle). A natural delineation created by debris deposited by a high tide is called a
strandline. See also wash margin and mean high water.
1. Any elevated region of land, often one that is
mountainous or situated atop a
plateau. The term is sometimes reserved for relatively low-elevation
mountain ranges or
foothills.
2. Any area of land (mountainous or otherwise) that is higher in
elevation relative to another area. In this sense, the term is often used as a conditional descriptor to distinguish related
habitats or
ecosystems, especially freshwater
riparian 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 between
populated 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 particular
settlement or establishment, i.e. its
sphere of influence.[4]
A branch of
human 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 projecting
ridge or
outcropping of land, its height ending abruptly or steeply. The term is used primarily in
placenames in Great Britain.
A long, narrow
ridge or series of
hills with a narrow crest and steep, symmetrical slopes of nearly equal inclination on both flanks, especially one created by the differential erosion of an
outcropping which exposes
homoclinal sedimentary rock strata. Compare esker, drumlin, and cuesta.
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 a
ranch; or a small
rural 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 and
improve 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 a
map, as opposed to measuring the actual physical length along the real-world surface, which can be greatly increased by
slopes 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
A
mountain formed by the back-to-back abutment of three or four adjacent
cirques, leaving a distinctly pyramidal peak.[12]
A raised block of the Earth's
crust, bounded by parallel
escarpments or
faults, that has been displaced upward or has remained stationary while adjacent blocks on either side, known as
grabens, 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 a
lithospheric plate where
magma rises from the
mantle and erupts at the Earth's surface, despite being far from the plate's
tectonic 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 with
physical geography, it is one of the two major sub-fields of geography.
humanistic geography
Also humanist geography.
An approach in
human 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 a
county or
shire, with its own judicial authority.[4]
A graph showing the rate of flow (i.e. the
discharge) 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 all
oceans,
lakes,
rivers, and
streams, as well as all ice and
glaciers and subsurface
groundwater. Some definitions restrict the hydrosphere to liquid water only, instead placing solid forms in the
cryosphere and gaseous forms in the
atmosphere.[3]
The geographic representation on a
map of features related to
elevation,
altitude, and other measures of
height above a reference surface (and sometimes inclusive of depths below the reference surface as well).
Any instrument used to measure the height or
elevation 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 when
surveying the elevations of distant landforms; whereas the principle that atmospheric pressure decreases predictably with elevation above
sea level is applied in instruments that measure their own height (i.e. the elevation of the instrument's location).[17]
The study or measurement of the
elevation or depth of features of the Earth's surface relative to mean
sea level. In a narrower sense, hypsometry may refer to land elevations only, and therefore is sometimes viewed as the terrestrial equivalent of
bathymetry.
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 and
polar ice sheets and widespread
glaciation. The most recent such period was the
Pleistocene 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 termed
ice sheets. Contrast polar ice cap.
A mass of
glacial ice that covers more than 50,000 square kilometres (19,000 sq mi) of land area; smaller masses of ice may be termed
ice caps or
ice shelves. The two
polar ice sheets are the only ice sheets that currently exist on Earth.
A large floating platform of ice formed when a
glacier or
ice sheet in a
coastal area flows onto the
ocean surface. By contrast,
sea ice is formed directly over the water and is typically much thinner.
A region of relatively fast-moving ice within an
ice sheet that flows like a stream under its own weight (making it essentially equivalent to a
glacier) 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 large chunk of
fresh water ice which has broken away from a larger body of ice (such as a
glacier or
ice shelf) and is floating freely in open water.
A portion of a
glacier 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 numerous
crevasses and
seracs.
A type of
crater formed by the hypervelocity collision of a solid astronomical body, such as a
meteor, with the Earth's surface. Unlike
volcanic 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]
Also clinometer, declinometer, tilt meter, gradient meter, slope gauge, and level gauge.
An instrument used to measure angles of
slope,
elevation, or
depression 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.[13]
index contour
A
contour line drawn with a heavier line weight to distinguish it from intermediate contours. Depending on the
contour interval, index contours are usually indicated every fourth or fifth contour, along with their assigned numerical values, in order to facilitate ease of interpretation.[14]
The broad set of facilities and interrelated systems that serve a
city,
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 flat
coastline 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 of
crustal movements or a rise in
sea 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 a
landmass, either completely surrounded by dry land or connected to the
ocean by a river,
strait, or other narrow
waterway.
An isolated rocky
hill, knob,
ridge, or small
mountain that rises abruptly from a virtually level surrounding
plain. Compare mogote.
inset
A subsection of a
map that is reserved for depicting another map of the same place at a different
scale, often a smaller scale to show relative
location within a larger geographic area (e.g. a country's location on the
globe) or a larger scale to show increased detail (e.g. of public transit routes in a
downtown 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, and
legend.[18]
(relative to a position on a body of water) Near to or moving towards the
shore; shorewards of a position as opposed to seawards of it. See also onshore and offshore.
Of or relating to an
island, or suggestive of the isolated condition of an island.[2]
integrated drainage
A drainage pattern in which
stream 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 no
closeddrainage systems are present.[5]
Also integrative geography, environmental geography, or human–environment geography.
The branch of geography that describes and explains the spatial aspects of interactions between human individuals or societies and their natural environment.
intercardinal directions
Also intermediate directions or ordinal directions.
The set of four intermediate directions used in
cartography and
navigation, each of which is located halfway between a pair of
cardinal directions: northeast (NE), southeast (SE), southwest (SW), and northwest (NW). They are often included in the
compass rose and are used to define further subdivisions such as the
secondary-intercardinal directions.
A narrow, elongated, and
plateau-like or
ridge-like landform between two
valleys, or an area of higher ground between two rivers in the same
drainage basin.
In
geographic information science, the estimation of the values of
spatially 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 and
kriging are commonly
raster operations, but can also be applied in
vector environments using a
triangulated irregular network to model a surface.[9]
Any place where the contiguous geographic area represented in a
map 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. All
world maps, for example, have at least one interruption, conventionally along the length of a single
meridian, thus forming an east–west boundary despite that the approximately spherical
shape 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 multiple
gores, 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 inland
waterway channels, maintained through
dredging 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) from
Boston, Massachusetts, around the southern tip of
Florida, to
Brownsville, 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 a
map 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 with
contour lines) or temperature (as with
isotherms), or a quantity related to social or economic statistics, such as population, wealth, or transport costs.
The state of gravitational equilibrium between the Earth's
crust and its
mantle, such that the crust "floats" at an
elevation that depends on its thickness and density. This concept is invoked to explain how different
topographic 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's
oceans tend to change over time in order to compensate for the uneven distribution of mass in the
lithosphere. For example, the instability of
continental 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]
Any man-made structure that projects from land out into a body of water, serving as a
breakwater, a walkway, or a landing stage for watercraft, or, in pairs, as a means of constricting a
channel.
A meeting or intersection of two or more routes 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.
An irregularly shaped
hill or
mound composed of sand, gravel, and
glacial till which accumulates in a depression on a retreating
glacier and is subsequently deposited on the land surface with further melting of the glacier. Kames are often associated with
kettles.
A furrow or
channel varying in depth from a few millimetres to more than a metre, and separated from others by
ridges, caused by solution on limestone surfaces.[4]
1. A point of abrupt inflection in the longitudinal profile of a
river or its
channel or
valley, such as occurs at a
waterfall.
2. Any interruption or break in the character of a
slope.[5]
knob
A peak or projection from the top of a
hill or
mountain, or any rounded protrusion of land, especially a small but
prominent or
isolated hill with steep sides; a boulder or an area of
resistant 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 a
region, historically and politically reserved for
border regions in particular, and variously translated as
march,
frontier, or
territory. The term is cognate with the
name of Ukraine.
Also Gaussian process regression and Wiener–Kolmogorov prediction.
In
geostatistics, an
interpolation technique in which, for a given
spatially 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 in
GIS applications, kriging is based on
regionalized 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 a
lake with sediment and the complete drainage or evaporation of water from the lake, leaving the deposited sediments behind.[2]
A
body of water localized in a
basin and surrounded entirely by land. Lakes are often defined as separate from any
river 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 by
falling sea levels,
tectonic activity, or
post-glacial rebound. Compare isthmus.
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 the
terrain of a given area, and their arrangement in a landscape is known as
topography.
1. (of a country or other polity, or a geographical region) Completely surrounded by land and thus lacking a marine
coastline; having no territory directly connected to or bordering the
ocean.
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 for
navigation; 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 of
landforms which define a general
geomorphologic form or setting, e.g. a
mountain 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 of
land cover such as vegetation; human elements such as buildings, structures, and various forms of
land use; and transitory elements such as lighting and weather conditions. They reflect both physical origins and the cultural overlay of human presence in a living synthesis of people and place.
A measure of distance north or south of the
Equator. One degree of latitude equals approximately 110 kilometers (68 mi).[2] Lines of latitude, also called
circles of latitude or parallels, 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 for
magma once it has erupted onto the Earth's surface.[3]
layer of no motion
In
oceanography, 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-gradient
currents.[10]
The side or
slope of a physical feature (such as a
hill or
mountain) which faces downwind, i.e. away from the direction in which the wind is blowing, or which faces away from an advancing
glacier or
ice sheet. The lee side is often sheltered by the topography from exposure to the wind and any moisture it brings.[5]
An elongated naturally occurring
ridge 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 a
river or a
coastline.
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 as
lithospheric plates or
tectonic plates.[3]
A series of rigid slabs (16 major ones at present) that make up the Earth's outer shell. These plates float on top of a softer, more plastic layer in the Earth's
mantle.[3]
A type of easily worked, highly fertile
soil 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.[12]
A measure of distance east or west of the
Prime Meridian, a line drawn between the
North and
South Poles and passing through the
Royal Observatory at
Greenwich, England.[2] Lines of longitude, also called
meridians, 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 a
coast parallel to the
shoreline 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 the
surf zone. A well-known example occurs on sandy
beaches when
breaking waves send swash up the beach at an angle but gravity drains the
backwash 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 in
elevation relative to another area. The term is often used as a conditional descriptor to distinguish related
habitats or
ecosystems, especially freshwater
riparian areas, on the basis of elevation above sea level. Lowland areas are usually relatively flat and characterized by slow-flowing waterways and
alluvial plains. Contrast highland and upland.
A broad, shallow, flat-bottomed
volcanic crater created by an eruption involving
groundwater coming into contact with
magma. Maars commonly have low rims and subtle
relief and characteristically fill with water to form
crater lakes.
Molten rock containing liquids, crystals, and dissolved gases that forms within the upper part of the Earth's
mantle and
crust. When erupted onto the Earth's surface, it is called
lava.[3]
A local deviation from the predicted value of the
Earth'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 between
magnetic north and
true north. Because
compass needles always point to magnetic north, and because the
Magnetic North Pole and the
Geographic 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 magnetic
bearing reported by their compass, yielding the true bearing with respect to true north.
The angle made with the horizontal by the
Earth's magnetic field lines. Locations in the
Northern Hemisphere usually have positive values of inclination, indicating that the magnetic field is angled downward, into the Earth; the angle increases as one approaches the
North Magnetic Pole, where the field lines point vertically downward, perpendicular to the horizontal. Locations in the
Southern Hemisphere usually have negative inclination, indicating that the field lines are angled upward, away from the Earth, with the maximum angle located at the
South Magnetic Pole. Dip angle is in principle the angle made by the needle of a vertically held
compass, 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 a
dip circle.
The primary downstream
channel of a
river, as contrasted with its
tributaries. Virtually all of the water in a river's
drainage basin eventually flows through the main stem.
A term used to denote a
contiguouslandmass or political territory relative to its politically associated but geographically remote
outlying territories. It is variously used to refer to the
continental (i.e. non-
insular) part of a polity relative to its
exclaves or oceanic islands; or to the largest or most politically, economically, and/or demographically significant island within an
island 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, closed
valley (usually drained by a single
wadi) surrounded by steep walls of resistant rock and superficially resembling a
crater. 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.[12]
The layer of the Earth's interior between the
crust and the
core, 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 with
magma 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 the
asthenosphere; the
lithosphere is composed of the topmost 65–70 kilometres (40–43 mi) of the mantle and the crust.[3][4]
A picture of a
place drawn at an established
scale on a two-dimensional
plane 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 a
coordinate reference system;[1][14] more generally, any graphical representation of locative information about the relative
positions of particular features within a space or place.
A graphical key identifying the relationships between the individual
maps of a
map 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 specific
map sheet which depicts the indicated area in greater detail.[14]
A systematic transformation of the
latitudes and
longitudes of locations from the surface of a three-dimensional shape, such as a
sphere or an
ellipsoid, into locations on a two-dimensional
plane.
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 thematic
map sheets usually having the same
scale and
cartographic specifications and collectively identified by the publisher or producing agency as belonging to the same group.[14]
An individual
map or
chart printed on a single page or sheet of paper, either complete in itself or part of a
map series.[14]
mapping
The process of designing, drawing, or creating a
map. The term is used in particular to refer to the application of
cartographic techniques in order to make
planimetric or
topographic 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.[10]
A
boundary,
frontier, or
borderland, as opposed to an interior
heartland. In medieval Europe, a march was the land surrounding a border between realms, or a neutral
buffer 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.[10]
2. In property law, the
boundary of a piece of land which is bounded by a
stream or
watercourse, often with the center of the stream or the
thalweg defining the legal boundary.[10]
3. The mostly blank, unused space lying beyond the
neatline of a map and completely surrounding the map area.[10] See also surround.
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 or
improvements 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. A
sea or other large area of the
ocean that is partially enclosed by land and/or
submarine ridges yet still adjacent to, widely open to, and connected to the larger ocean at the surface; e.g. the
Yellow Sea and
Hudson Bay.[10]
2.
Also territorial sea, marine belt, and maritime belt.
Those waters along a
nation's
coast within which the nation has exclusive jurisdiction except for the right of innocent passage of foreign vessels.[10] See also territorial waters.
marine
1. Of, relating to, found in, or produced by the
sea or
ocean.
2. Of or relating to shipping or navigation, particularly by watercraft.[4]
A climate strongly influenced by an
oceanic environment, typically found on
islands and the
windward shores of
continents. 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 of
wetland 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's
crust which is demarcated by
faults or
flexures and tends to retain its internal structure while being displaced as a whole.
2. A single large
mountain mass or compact group of connected mountains forming an independent portion of a
mountain 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 average
sea level of one or more of the Earth's coastal bodies of water, such as
oceans and
seas, or at a particular location, from which heights such as
elevation and
altitude are measured.
One of a series of regular
sinuous curves, bends, loops, turns, or windings in the
main channel of a
river,
stream, or other
watercourse. 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 a
valley or
floodplain.
The process by which the
strip of land separating the two closest parts of a
meandering river or stream
channel 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 a
slackwater or an
oxbow lake, or becomes loaded with sediment and dries up entirely, leaving
visible traces of the former channel.
meander neck
The narrow strip of land separating the river on each side of a well-developed
meander.[4] If this strip is completely eroded away, a
cutoff occurs. See also neck.
A branch of
human 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 large
city, 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 large
alluvial 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).
Also equatorial cylindrical orthomorphic map projection.
A
conformalcylindricalmap projection in which the
equator is represented by a straight line true to scale and
meridians 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.[14] The standard Mercator projection has long been popular in
navigation 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 shallow
pond,
lake, or
wetland. The term is used primarily in Great Britain and other parts of Western Europe.
mereing
A type of
surveying 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. a
metes and bounds survey.[9]
A line of
longitude, i.e. any imaginary line connecting points of equal longitude and running perpendicular to all
lines 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 the
geographic poles. Each meridian is half of a
great circle drawn on the Earth's surface; the other half, connecting all of the meridian's
antipodes, is termed an
antimeridian. Meridians are numbered according to their longitudinal measure in angular
degrees (further subdivided into
minutes and
seconds) up to 180 degrees east or west of an arbitrarily designated zero or
prime meridian, by convention the
International 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] Contrast septentrional.
A system of
land 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 large
city or
conurbation which is considered a significant economic, political, or cultural center for a
country or geographic region and/or an important hub for regional or international connections and communications.
A region consisting of one or more densely populated
urban cores (often a
metropolis) and its less populous surrounding territories, including satellite
cities,
towns, and intervening
rural areas, all of which are socioeconomically tied to the core as typically measured by
commuting patterns. A metropolitan area usually comprises multiple
neighborhoods,
jurisdictions, and
municipalities, with its inhabitants sharing industry, housing, and many other forms of infrastructure.
An isolated, rounded, steep-sided
hill composed of either limestone, marble, or dolomite and surrounded by nearly flat
alluvial plains, especially as found in
tropical regions.
The boundary between the Earth's
crust and the
mantle, as defined by the abrupt change in velocity of seismic
P waves traveling across this boundary, which occurs as the waves pass through different densities of rock.[10]
A long, massive, man-made stone or earthen structure used as a
pier or
breakwater, or as a
causeway between places separated by water, but designed to prevent the free movement of water underneath it (unlike a true pier).
Of or pertaining to a
mountain or mountains; mountainous; occurring at high
elevation. The term is used in particular to describe
biomes or ecological communities occupying cool, humid zones at or near
timberline.[17] See also alpine.
monticule
A secondary
cone on the side of a larger
volcano, or any small mountain or large hill.[17]
An upland habitat and
ecoregion characterized by low-growing vegetation on acidic soils and generally referring to uncultivated
hills but also including low-lying
wetlands.
The rocks and soil carried and deposited by a
glacier. A
terminal 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 surface
meltwater flows into a
glacier, usually formed at lines of structural weakness in the ice.[13]
Any heaped pile of earth, gravel, sand, rocks, or debris, typically with a rounded top and of topographically higher
elevation than its immediate surroundings.
A large
landform that rises prominently above the surrounding land in a limited area, usually in the form of a rocky peak with great vertical
relief; a mountain is generally considered steeper than a
hill. Mountains are formed by
volcanic or
tectonic forces and erode slowly through the actions of rivers, glaciers, and
weathering. Most exist within extensive
mountain ranges.
A series of neighboring
mountains or
hills, often closely arranged in a line and connected by high ground. Individual mountains within the same mountain range are usually the result of the same
orogeny, and often (though not always) share a common form, alignment, and geology.
1. The place where a
river or
stream flows into another body of water, such as a
lake or another river but especially a
sea or
ocean.
Deltas and
estuaries occur near the mouths of rivers.
2. The lower or downstream end or the most accessible entrance of a
valley,
canyon,
ravine, or
cave.
A type of coastal
wetland consisting of exposed layers of
bay mud formed by the deposition of silts, clays, and marine animal
detritus by
tides or
rivers. Mudflats usually form within the
intertidal zone of relatively sheltered areas such as
bays and
lagoons.
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-purpose
urbanadministrative subdivision having
corporate status and powers of self-government or
jurisdiction 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 as
counties, though the nature of their territorial boundaries and political jurisdictions can vary considerably in different parts of the world.
^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.
^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, retrieved October 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)