Category: Dictionary

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.

compass : An instrument used for navigation and orientation that indicates direction relative to the geographic cardinal directions by measuring the orientation of the Earth’s magnetic field with respect to the North Magnetic Pole. Compasses often display markings for angles or degrees, which allow them to show azimuths and bearings, in addition to a compass rose.

colony : 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.

col: Also called a gap or notch.

The lowest point on a mountain ridge between two peaks.

coast: Also coastline or seashore.

The area where land meets a sea or ocean. Coastal zones are regions where the interaction of terrestrial and marine processes occurs. Compare shore

climax vegetation : 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

cliff : Any vertical or nearly vertical rock exposure, usually formed by the processes of weathering and erosion.

city-state : A sovereign state or small independent country that usually consists of a single city and its dependent territories

city : A large human settlement, generally with extensive systems constructed for housing, transportation, sanitation, utilities, and communication.

cirque: Also corrie or cwm.

An amphitheatre-shaped valley surrounded on three or more sides by steep, cliff-like slopes and formed by glacial or fluvial erosion.

circle of latitude : See latitude.

cinder cone : 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.

choropleth : 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.

chorography : The art of establishing, describing, or mapping a geographic region or district, or more broadly, the representation of space or place.

chinook : 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 (68 °F) in a quarter of an hour.

chine : A steep-sided coastal gorge, 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.

chimney : See salient.

chart : A special-purpose map designed for navigation, especially nautical and aeronautical navigation, or to present specific data or technical information.^[

chaparral : A class of terrestrial vegetation characterized by dense, impenetrable thickets of shrubs or dwarf trees

channel: Also strait.

1.  A waterway separating two relatively close landmasses.2.  Any narrow body of water that connects two larger bodies of water.3.  The deepest part of a shallow body of water, often used as a passageway for large ships.

chain : 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”.

census-designated place (CDP) : A concentration of population identified by the United States Census Bureau for statistical purposes.

central business district : A centrally located commercial business district in an urban area, typically containing a concentration of office and retail activities.

cenote : A natural pit or sinkhole resulting from the collapse of limestone bedrock which exposes groundwater underneath.

celestial pole : 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.

cay: Also key.

A small, sandy, low-elevation island on the surface of an otherwise submerged coral reef; a type of coral island. Compare atoll.

cavern : A type of solutional cave that is formed in soluble rock with the ability to grow speleothems.

cave : Any naturally hollow underground space large enough for a person to enter.

cartogram: 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.

carrying capacity : 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

cardinal directions: The set of four primary directions used in cartography and navigation: north (N), south (S), east (E), and west (W). Together they form the primary divisions of the compass rose. They can be further subdivided into the intercardinal directions and secondary-intercardinal directions.

caprock : A stratum of erosion-resistant sedimentary rock (usually limestone) found in arid areas. Caprock forms the top layer of most mesas and buttes

cape : A large headland or promontory extending into a body of water, usually a sea or ocean.

canyon: Also gorge or cañon.

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.

canal : A navigable artificial water channel, usually built as a conduit for human activity.

caldera : A large, cauldron-shaped depression that forms through the subsidence and collapse of a ground surface following the evacuation of an underlying magma chamber.

calanque : 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.

cadastre: Also cadaster.

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.

butte : An isolated hill or mountain with steep or precipitous sides, usually having a smaller summit area than a mesa.

burgh : Scottish administrative subdivision equivalent to borough.

built environment : The human-made spaces that provide the setting for human activity, in which people live, work, and recreate on a day-to-day basis.

breakwater : 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.b