Category: Geography Dictionary

geography : The scientific study of the lands, features, inhabitants, and phenomena of Earth.

geographical mile : 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.

Geographic Names Information System (GNIS) : 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.

geographic information system (GIS): 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.

geographic information science (GIS): Also GIScience.

The scientific study of data structures and computational techniques for capturing, representing, processing, and analyzing geographic information.

geographic coordinate system: 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.

geodynamics: A subfield of geophysics and Earth science that studies the physical dynamics of the Earth by applying physics, chemistry, and mathematics to the understanding of how mantle convection and other internal processes lead to plate tectonics and geological phenomena such as mountain formation, volcanism, earthquakes, and faulting, among others.

geodetic datum: 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.

geodetic control network: Also geodetic network, reference network, or control point network.

geodesy: Also geodetics.

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.

gazetteer : 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.

functional diversity : The characteristic of a place where a variety of different activities (economic, political, or social) occur, most often associated with urban places.

fresh water : Any naturally occurring water characterized by low concentrations (typically less than 0.05% by volume) of dissolved salts and other solids relative to either salt water or brackish water. Sources of fresh water on Earth include glaciers, ice caps, icebergs, bogs, lakes, rivers, streams, and most groundwater.

forest : Any extensive area dominated by communities of trees.

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).

foothills : A geographic transition zone defined by gradual increases in elevation between plains or low-relief hills and adjacent topographically higher hills, mountains, or uplands.

focus: Also hypocenter.

The point inside the Earth’s crust from which an earthquake originates.

fluvial : Of or pertaining to rivers or streams; produced by the action of a river or stream

focality : 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.

floodplain: Also bottomland.

A broad, flat area of land adjacent to a river or stream which is leveled by annual flooding and by the lateral and downstream movement of meanders.

fjord: Also fiord.

A long, narrow marine inlet with steep sides or cliffs created by glacial erosion.

fissure : A long, narrow opening or line of breakage made by cracking or splitting, especially in rock or earth

fish ladder : 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

firth : 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.

firn : 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.

figure of the Earth : 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.

field: Also spatially dependent variable.

A quantity or observation, such as temperature, soil moisture, or population density, that can be theoretically assigned to any point of space. Both scalar and vector fields are found in GIS applications, although the former is more common.

federation : 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.

fault zone : 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

fault-block mountain : A mountain mass created by either the uplift of land between faults or the subsidence of land outside the faults.

fault : A fracture in the Earth’s crust accompanied by a displacement of one side of the fracture

fallow : Agricultural land that is plowed or tilled but left unseeded during a growing season. Fallowing is usually done to conserve moisture and soil nutrients

fall line : A geomorphologic unconformity between an upland region of relatively hard crystalline basement rock and a coastal plain of softer sedimentary rock.

exurban : 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

extinct volcano: A volcano that is not expected to erupt again.

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.

exclave : 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.

evorsion : See pothole.

evapotranspiration : The process by which water is lost from an area through the combined effects of evaporation from the ground surface and transpiration from vegetation.

etchplain : 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.

estuary : The broad lower course of a river where it enters the ocean and is affected by the tides. Compare delta

esker: Also called an os or spelled eskar or eschar.

A long, winding ridge of stratified sand and gravel, usually occurring in glaciated or formerly glaciated areas.

escarpment : A long cliff or steep slope separating two comparatively level or more gently sloping surfaces and resulting from erosion or faulting.

erratic : A boulder that has been carried from its source by a glacier and deposited as the glacier melted. Such boulders are often of different rock types than the surrounding rocks.

Equator : The imaginary circle around the Earth halfway between the geographic poles which is assigned a latitude of zero degrees and is therefore used as a reference point for all other lines of latitude. It is the largest circumference of the Earth

epicenter : 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.Equator

endorheic 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.

enclave : A tract or territory completely surrounded by and enclosed within the territory of one other state, country, or other political entity. Unlike enclaves, exclaves can be surrounded by more than one other state

emergent coastline : A coast or shoreline resulting from a rise in land surface elevation relative to sea level

ekistics: 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.

elevation : The height of a point on the Earth’s surface with respect to sea level. Compare altitude.

edgelands : 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.

edge city : 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.

ecoregion: Also called an ecological region.

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.

economies of agglomeration : The economic advantages that accrue to an activity by locating close to other activities; benefits that follow from complementarity or shared public services

economic geography : A sub-discipline of geography which studies the location, distribution, and spatial organization of economic activities across the world.

Eastern Hemisphere : The half sphere of the Earth that is east of the Prime Meridian and west of the antimeridian. It is opposite the Western Hemisphere.

earthquake : The sudden and intense shaking of the ground due to tectonic activity.

Earth science: Also called the Earth sciences or geoscience.

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.

dune : A hill of loose sand built by the movements and erosional and depositional processes of wind or water, often occurring in deserts and coastal areas.

dry point : An area of firm or dry ground in a wetland, marsh, or floodplain, often capable of supporting a human settlement.

dry farming : A type of farming practiced in semi-arid or dry grassland areas without irrigation using such approaches as fallowing, maintaining a finely broken surface, and growing drought-tolerant crops.

drumlin : 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.

draw: Also re-entrant.

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.^[

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.

drainage basin: Also catchment area, drainage area, river basin, water basin, or watershed.

Any area of land where precipitation collects and drains into a common outlet, such as a river, lake, ocean, or any other body of water. The drainage basin 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.

drift ice: Also brash ice.

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.

dormant volcano : An active volcano that is in repose (quiescence) but is expected to erupt in the future

dome : 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.

district : 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.

distributary : A stream or river that branches off and flows away from a main channel. Distributaries are common near river deltas. Contrast tributary.

dissected plateau : 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 level of the summit; much of the area instead occurs as eroded hills or badlands.

diocese : A type of administrative division used by certain Christian churches for religious purposes.

dike See levee.

desert : 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.

depression: Any landform that is sunken or depressed below the surrounding area. Depressions include an enormous variety of landforms and can form by a number of different mechanisms, including erosion, ground collapse, tectonic activity, volcanism, and meteorite impacts.

delta : A landform at the mouth of a river where the main stem splits up into several distriutaries. It is formed from the deposition of the sediment carried by the river as the flow leaves the mouth of the river. Compare estuary.

dell : A small, secluded hollow, usually within a grassy, park-like, partially wooded valley.

degree day : Deviation of one-degree temperature for one day from an arbitrary standard, usually the long-term average temperature for a place

degree : A unit of angular measure. A circle is divided into 360 degrees, represented by the º symbol. Degrees are used to divide the roughly spherical shape of the Earth for geographic and cartographic purposes

defile : A narrow pass or gorge between mountains or hills.

deciduous forest : A forest composed of trees which lose their leaves each year.

debouch: Also debouche.

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.

de jure segregation : The spatial and social separation of populations that occurs because of legal measures.

de facto segregation : The spatial and social separation of populations that occurs without legal sanction.

dam: Also impoundment.

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).

dale: Another name for a valley.

Cyclopean stairs : A term referring to the longitudinal profile of some glaciated valleys which have been eroded into a series of consecutive hanging valleys resembling stairs.

cwm : See cirque.

cutoff : The new channel formed when a meandering stream erodes through a narrow strip of land and thereby shortens the length of the main channel.

cut bank : A continually eroding bank along a meandering river or stream channel, 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.

culture hearth : The area from which the culture of a group diffused. See hearth.

culture : 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

cultural geography : 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.

cuesta : A long, low ridge with a steep scarp slope and a gentle backslope (dip slope).

cryoturbation: Also frost churning.

The mixing of materials from various horizons of the soil down to the bedrock due to freezing and thawing.

cryosphere : 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.

crust : 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.

creek : 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.^[

crater lake : A lake that forms in a volcanic crater or caldera (such as a maar), an impact crater left by a meteorite, or a crater resulting from a man-made explosion.