Category: Dictionary

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.

crater : Any large, roughly circular depression, pit, or hole in the Earth’s surface. Craters can be classified into different types based on their ultimate causes; see impact crater, volcanic crater, and pit crater.

cove : 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.

course :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.

county : A type of subnational division of a country or federal state used for administrative or other purposes.

country : A region identified as a distinct national entity in political geography. Compare state.

couloir : 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.

coulee : A dry canyon eroded by Pleistocene floods that cut into the lava beds of the Columbia Plateau in the western United States.

corrasion : 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.

core area : The portion of a country that contains its economic, political, intellectual, and cultural focus. It is often the center of creativity and change. See hearth.

conurbation : An extensive urban area formed when two or more initially separate cities coalesce to form a continuous metropolitan area.

contour interval : The difference in elevation between any two adjacent contour lines as depicted on a particular topographic map

contour line: Also isoline or isopleth.

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.

continentality : The quality of being located on a continent.

continental shelf : 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.

continental divide : 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.^[

continental climate : 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.

continent : 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.

contiguity : 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.

coniferous : Bearing cones; from the conifer family

confluence : The place at which two or more rivers or other watercourses flow together to form one larger river or watercourse.^[

compass rose : 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.