Glossary of geography terms - AbsoluteAstronomy.com

This is a list of geographical terms.

A

Absolute Humidity: The mass of water vapor in the atmosphere per unit of volume of space.
Absolute location: The location of a point on the Earth's surface that can be expressed by a grid reference such as latitude and longitude.
Accessibility Resource: A naturally occurring landscape feature that facilitates interaction between places.
Accessibility: A locational characteristic that permits a place to be reached by the efforts of those at other places.
Acid Rain: Rain that has become more acidic than normal (a pH below 5.0) as certain oxides present as airborne pollutants are absorbed by the water droplets. The term is often applied generically to all acidic precipitation.
Active volcano: A volcano that is currently erupting, or has erupted during recorded history.
Aerosol: Fine liquid or solid particles suspended in the atmosphere. Aerosols resulting from volcanic eruptions are tiny droplets of sulfuric acid—sulfur dioxide that has picked up oxygen and water.
Air Mass: A very large body of atmosphere defined by essentially similar horizontal air temperatures. Moisture conditions are also usually similar throughout the mass.
Alluvia: Clay, silt, gravel, or similar detrital material deposited by running water.
Alluvial Soils: Soils deposited through the action of moving water. These soils lack horizons and are usually highly fertile.
Altitude: Height of an object in the atmosphere above sea level.
Antebellum: Before the war; in the United States, belonging to the period immediately prior to the Civil War (1861–1865).
Anthracite: A hard coal containing little volatile matter.
Arete: A sharp, narrow mountain ridge. It often results from the erosive activity of alpine glaciers flowing in adjacent valleys.
Arroy: A deep gully cut by a stream that flows only part of the year; a dry gulch. A term normally used only in desert areas.
Ash: Fragments less than 2 millimeters (about 1/8 inch) in diameter of lava or rock blasted into the air by volcanic explosions.
Atlas: A bound collection of maps.
Atmosphere: The mixture of gases, aerosols, solid particles, and water vapor that envelops the Earth.

B

Badlands: Very irregular topography resulting from wind and water erosion of sedimentary rock.
Base Level: The lowest level to which a stream can erode its bed. The ultimate base level of all streams is, of course, the sea.
Batholith: A very large body of igneous rock, usually granite, which has been exposed by erosion of the overlying rock.
Bedrock: The solid rock that underlies all soil or other loose material; the rock material that breaks down eventually to form soil.
Bilingual: The ability to use either one of two languages, especially when speaking.
Biological Diversity: A concept recognizing the variety of life forms in an area of the Earth and the ecological interdependence of these life forms.
Biosphere: The realm of all living things.
Biota: The animal and plant life of a region considered as a total ecological entity.
Bituminous: A soft coal that, when heated, yields considerable volatile matter.
Boundary: A line indicating the limit of a country, state, or other political jurisdiction.
Break-in-Bulk Point: Commonly, 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.
Butte: An isolated hill or mountain with steep or precipitous sides, usually having a smaller summit area than a mesa.

C

Caprock: A stratum of erosion-resistant sedimentary rock (usually limestone) found in arid areas. Caprock forms the top layer of most mesas and buttes.
Carrying capacity: The number of people that an area can support given the quality of the natural environment and the level of technology of the population.
Cartographer: A person who draws or makes maps or charts.
CBD: The central business district of an urban area, typically containing an intense concentration of office and retail activities.
Chaparral: A dense, impenetrable thicket of shrubs or dwarf trees.
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 20C (35 to 40F) in a quarter of an hour.
Cinder cone: A steep-sided volcano formed by the explosive eruption of cinders that form around a vent. Cinders are lava fragments about 1 centimeter (about ½ inch) in diameter.
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.
Confluence: The place at which two streams flow together to form one larger stream.
Coniferous: Bearing cones; from the conifer family.
Continent: One of the large, continuous areas of the Earth into which the land surface is divided.
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.
Continental Divide: The line of high ground that separates the oceanic drainage basins of a continent; the river systems of a continent on opposite sides of a continental divide flow toward different oceans.
Continentality: The quality or state of being a continent.
Contour lines: Parallel lines used on topographic maps to show the shape and elevation of the land. They connect points of equal elevation.
Conurbation: An extensive urban area formed when two or more cities, originally separate, coalesce to form a continuous metropolitan region.
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).
Coulee: A dry canyon eroded by Pleistocene floods that cut into the lava beds of the Columbia Plateau in the western United States.
Crater: The circular depression containing a volcanic vent.
Crop-lien System: A farm financing scheme whereby money is loaned at the beginning of a growing season to pay for farming operations, with the subsequent harvest used as collateral for the loan.
Crust: The Earth's outermost layer.
Cryosphere: The ice and snow on the Earth's surface, such as glaciers; sea, lake, and river ice; snow; and permafrost.
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.
Cut-and-Sew Industry: The manufacture of basic ready-to-wear clothing. Such facilities usually have a small fixed investment in the manufacturing facility.

D

De Facto Segregation: The spatial and social separation of populations that occurs without legal sanction.
De Jure Segregation: The spatial and social separation of populations that occurs because of legal measures.
Deciduous Forest: Forests in which the trees lose their leaves each year.
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.
Degree Day: Deviation of one-degree temperature for one day from an arbitrary standard, usually the long-term average temperature for a place.
Demography: The systematic analysis of population.
Discriminatory Shipping Rates: A transportation charge levied in a manner that is inequitable to some shippers, primarily because of those shippers' location.
Dome: A steep-sided mound that forms when very viscous lava is extruded from a volcanic vent. An uplifted area of sedimentary rocks 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.
Dormant volcano: An active volcano that is in repose (quiescence) but is expected to erupt in the future.
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.

E

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.
Economies of Scale: Savings achieved in the cost of production by larger enterprises because the cost of initial investment can be defrayed across a greater number of producing units.
Elevation: The height of a point on the Earth's surface with respect to sea level.
Emergent Coastline: A shoreline resulting from a rise in land surface elevation relative to sea level.
Enclave: A tract or territory enclosed within another state or country.
Equator: An imaginary circle around the Earth halfway between the North Pole and the South Pole; the largest circumference of the Earth.
Erratic: A boulder that has been carried from its source by a glacier and deposited as the glacier melted. Thus, the boulder is often of a different rock type from surrounding types.
Escarpment: A long cliff or steep slope separating two comparatively level or more gently sloping surfaces and resulting from erosion or faulting.
Estuary: The broad lower course of a river that is encroached on by the sea and affected by the tides.
Evapotranspiration: The water lost from an area through the combined effects of evaporation from the ground surface and transpiration from the vegetation.
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.
Extended Family: A family that includes three or more generations. Normally, that would include grandparents, their sons or daughters, and their children, as opposed to a "nuclear family," which is only a married couple and their offspring.
Extinct volcano: A volcano that is not expected to erupt again.
Exurb: A region or district that lies outside a city and usually beyond its suburbs.

F

Fall Line: The physiographic border between the piedmont and coastal plain regions. The name derives from the river rapids and falls that occur as the water flows from the hard rocks of the higher piedmont onto the softer rocks of the coastal plain.
Fallow: Agricultural land that is plowed or tilled but left unseeded during a growing season. Fallowing is usually done to conserve moisture.
Fault: A fracture in the Earth's crust accompanied by a displacement of one side of the fracture.
Fault Block Mountain: A mountain mass created by either the uplift of land between faults or the subsidence of land outside the faults.
Fault Zone: A fracture 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 fracture. A "fault zone" is an area of numerous fractures.
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.
Feral Animal: A wild or untamed animal, especially one having reverted to such a state from domestication.
Fish Ladder: A series of shallow steps down which water is allowed to flow; designed to permit salmon to circumvent artificial barriers such as power dams as the salmon swim upstream to spawn.
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 place (i.e., when the movement focuses on that location), the place is said to possess "focality."
Functional Diversity: The characteristic of a place where a variety of different activities (economic, political, or social, for example) occurs; most often associated with urban places.

G

Geomorphology: 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.
Geosphere: The nonliving parts of the Earth: the lithosphere, the atmosphere, the cryosphere, and the hydrosphere.
Ghetto: Originally, the section of a European city to which Jews were restricted. Today, this is commonly defined as a section of a city occupied by members of a minority group who live there because of social restrictions on their residential choice.
Glacial Till: The mass of rocks and finely ground material carried by a glacier, then deposited when the ice melted. This creates an unstratified material of varying composition.
Glaciation: Having been covered with a glacier or subject to glacial epochs.
Glacier: A thick mass of ice resulting from compacted snow that forms when more snow accumulates than melts annually.
Globe: A true-to-scale map of the Earth that duplicates its round shape and correctly represents areas, relative size, and shape of physical features, distances, and directions.
Great Circle Route: The shortest distance between two places on the Earth's surface. The route follows a line described by the intersection of the surface with an imaginary plane passing through the Earth's center.
Grid: A pattern of lines on a chart or map, such as those representing latitude and longitude, which helps determine absolute location.
Growing Season: The period from the average date of the last frost (in the United States, this occurs in the spring) to the first frost in the fall.

H

Harmonic tremor: Continuous rhythmic earthquakes in the Earth's upper lithosphere that can be detected by seismographs. Harmonic tremors often precede or accompany volcanic eruptions.
Hazardous Waste: Unwanted by-products remaining in the environment and posing an immediate potential hazard to human life.
Hearth: The source area of any innovation. The source area from which an idea, crop, artifact, or good is diffused to other areas.
Heavy Industry: Manufacturing activities engaged in the conversion of large volumes of raw materials and partially processed materials into products of higher value; hallmarks of this form of industry are considerable capital investment in large machinery, heavy energy consumption, and final products of relatively low value per unit weight (see Light Industry).
Hemisphere: 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.
Hinterland: The area tributary to a place and linked to that place through lines of exchange, or interaction.
Horizon: A distinct layer of soil encountered in vertical section.
Hot spot: An area in the middle of a lithospheric plate where magma rises from the mantle and erupts at the Earth's surface. Volcanoes sometimes occur above a hot spot.
Humus: Partially decomposed organic soil material.
Hydrography: The study of the surface waters of the Earth.
Hydroponics: The growing of plants, especially vegetables, in water containing essential mineral nutrients rather than in soil.
Hydrosphere: The water that covers 71 percent of the Earth's surface as oceans, lakes, rivers, and streams. The hydrosphere also includes ground water, water that circulates below the Earth's surface in the upper part of the lithosphere.

I

Ice Age: A time of widespread glaciation (see Pleistocene).
Igneous Rock: Rock formed when molten (melted) materials harden.
Indentured Labor: Work performed according to a binding contract between two parties. During the early colonial period in America, this often involved long periods of time and a total work commitment.
Indigo: A plant that yields a blue vat dye.
Inertia Costs of Location: Costs borne by an activity because it remains located at its original site, even though the distributions of supply and demand have changed.
Insular: Either of an island, or suggestive of the isolated condition of an island.
International Date Line: A line of longitude generally 180 degrees east and west of the prime meridian. The date is one day earlier to the east of the line.
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.
Intracoastal Waterway System: A U.S. waterway channel, maintained through dredging and sheltered for the most part by a series of linear offshore islands, that extends from New York City to Florida's southern tip and from Brownsville, Texas, to the eastern end of Florida's panhandle.
Isohyet: A line on a map connecting points that receive equal precipitation.

J

Jurisdiction: The right and power to apply the law; the territorial range of legal authority or control.

K

Karst: An area possessing surface topography resulting from the underground solution of subsurface limestone or dolomite.
Kudzu: A vine, native to China and Japan but imported into the United States; originally planted for decoration, for forage, or as a ground cover to control erosion. It now grows wild in many parts of the southeastern United States.

L

Lacustrine Plain: A nearly level land area that was formed as a lakebed.
Lateral blast: A sideways-directed explosion from the side or summit of a volcano.
Latitude: A measure of distance north or south of the equator. One degree of latitude equals approximately 110 kilometres (68.4 mi). Imaginary lines that cross the surface of the Earth parallel to the Equator, measuring how far north or south of the Equator a place is located.
Lava: The term used for magma once it has erupted onto the Earth's surface.
Leaching: A process of soil nutrient removal through the erosive movement and chemical action of water.
Leeward: The side of a land mass sheltered from the wind—the opposite of windward.
Legend: A key to what the symbols or pictures in a map mean.
Legume: A plant, such as the soybean, that bears nitrogen-fixing bacteria on its roots, and thereby increases soil nitrogen content.
Life Cycle Stage: A period of uneven length in which the relative dependence of an individual on others helps define a complex of basic social relations that remains relatively consistent throughout the period.
Light Industry: Manufacturing activities that use moderate amounts of partially processed materials to produce items of relatively high value per unit weight (see Heavy Industry).
Lignite: A low-grade brownish coal of relatively poor heat-generating capacity.
Lithosphere: 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.
Lithospheric plates: 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. (Also called tectonic plates.)
Loess: A soil made up of small particles that were transported by the wind to their present location.
Longitude: A measure of distance east and west of a line drawn between the North and South Poles and passing through the Royal Observatory at Greenwich, England. : Imaginary lines that cross the surface of the Earth, running from north to south, measuring how far east or west of the prime meridian a place is located.

M

Magma: 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.
Mantle: A zone in the Earth's interior between the crust and the core that is 2900 kilometres (1,802 mi) thick. (The lithosphere is composed of the topmost 65-70 kilometers (39–42 miles) of the mantle and the crust.)
Map: A picture of a place that is usually drawn to scale on a flat surface.
Maritime Climate: A climate strongly influenced by an oceanic environment, found on islands and the windward shores of continents. It is characterized by small daily and yearly temperature ranges and high relative humidity.
Mediterranean Climate: A climate characterized by moist, mild winters and hot, dry summers.
Mesa: An isolated, relatively flat-topped natural elevation, usually more extensive than a butte and less extensive than a plateau.
Mesquite: A spiny deep-rooted leguminous tree or shrub that forms extensive thickets in the southwestern United States.
Metamorphic Rock: Rock that has been physically altered by heat and/or pressure.
Metes and Bounds: A system of land survey that defines land parcels according to visible natural landscape features and distance. The resultant field pattern is usually very irregular in shape.
Metropolitan Coalescence: The merging of the urbanized areas of separate metropolitan regions; Megalopolis is an example of this process.
Monadnock: An isolated hill or mountain of resistant rock rising above an eroded lowland.
Moraine: The rocks and soil carried and deposited by a glacier. An "end moraine," either a ridge or low hill running perpendicular to the direction of ice movement, forms at the end of a glacier when the ice is melting.
Mudflow: A flowing mixture of water and debris (intermediate between a volcanic avalanche and a water flood) that forms on the slopes of a volcano. Sometimes called a debris flow or lahar, a term from Indonesia where volcanic mudflows are a major hazard.
Multilingual: The ability to use more than one language when speaking or writing (see Bilingual). 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.
Municipal Waste: Unwanted by-products of modern life generated by people living in an urban area.

N

New England: The northeastern United States.
Nodal Region: A region characterized by a set of places connected to another place by lines of communication or movement.
Nuclear Family: See Extended Family.

O

Ocean: The salt water surrounding the great land masses, and divided by the land masses into several distinct portions, each of which is called an ocean.
Open Range: A cattle- or sheep-ranching area characterized by a general absence of fences.
Orographic Rainfall: Precipitation that results when moist air is lifted over a topographic barrier such as a mountain range.
Outwash: Rocky and sandy surface material deposited by meltwater that flowed from a glacier.
Overburden: Material covering a mineral seam or bed that must be removed before the mineral can be removed in strip mining.

P

Palisades: A line of bold cliffs.
Panhandle: A narrow projection of a larger territory (as a state).
Permafrost: A permanently frozen layer of soil. ; permanently frozen ground at high latitude and high elevation.
Physiographic Region: A portion of the Earth's surface with a common topography and common morphology.
Physiography: Physical geography.
Piedmont: Lying or formed at the base of mountains; in the United States, an area in the southern states at the base of the Blue Ridge Mountains.
Plate Tectonics: Geologic theory that the bending (folding) and breaking (faulting) of the solid surface of the earth results from the slow movement of large sections (plates) of that surface.
Platted Land: Land that has been divided into surveyed lots.
Pleistocene: The period the last one million years in geologic history when ice sheets covered large sections of the Earth's land surface not now covered by glaciers.
Plural Society: A situation in which two or more culture groups occupy the same territory but maintain their separate cultural identities.
Polynodal: Many-centered.
Populated place
Populated place
A populated place is a place or area with clustered or scattered buildings and a permanent human population referenced with geographic coordinates...

: place or area with clustered or scattered buildings and a permanent human population (city, settlement, town, or village) referenced with geographic coordinates. (USGS)
Post-industrial: An economy that gains its basic character from economic activities developed primarily after manufacturing grew to predominance. Most notable would be quaternary economic patterns.
Precambrian Rock: The oldest rocks, generally more than 600 million years old.
Presidio: A military post (Spanish).
Prevailing winds: The direction from which winds most frequently blow at a specific geographic location.
Primary Product: A product that is important as a raw material in developed economies; a product consumed in its primary (i.e., unprocessed) state (see Staple Product).
Primary Sector: That portion of a region's economy devoted to the extraction of basic materials (e.g., mining, lumbering, agriculture).
Prime Meridian: An imaginary line running from north to south through Greenwich, England, used as the reference point for longitude.
Pueblo: A type of Indian village constructed by some tribes in the southwestern United States. A large community dwelling, divided into many rooms, up to five stories high, and usually made of adobe. This is also a Spanish word for town or village.

Q

Quaternary Sector: That portion of a region's economy devoted to informational and idea-generating activities (e.g., basic research, universities and colleges, and news media).

R

Rail Gauge: The distance between the two rails of a railroad.
Rainshadow: An area of diminished precipitation on the lee (downwind) side of a mountain or mountain range.
Region: An area having some characteristic or characteristics that distinguish it from other areas. A territory that is of interest to people, for which one or more distinctive traits are used as the basis for its identity.
Resource: Anything that is both naturally occurring and of use to humans.
Riparian Rights: The rights of water use possessed by a person owning land containing or bordering a watercourse or lake.
Riverine: Located on or inhabiting the banks or the area near a river or lake.

S

Scale: The proportional relationship between a linear measurement on a map and the distance it represents on the Earth's surface.
Scarp: Also "escarpment." A steep cliff or steep slope, formed either because of faulting or by the erosion of inclined rock strata.
Scots-Irish: The North American descendants of Protestants from Scotland who migrated to Northern Ireland in the 17th century.
Sea level: The ocean surface.
Second Home: A seasonally occupied dwelling that is not the primary residence of the owner. Such residences are usually found in areas with substantial opportunities for recreation or tourist activity.
Secondary Sector: That portion of a region's economy devoted to the processing of basic materials extracted by the primary sector.
Sedimentary Rock: Rock formed by the hardening of material deposited in some process; most commonly sandstone, shale, and limestone.
Seismograph: A scientific instrument that detects and records vibrations (seismic waves) produced by earthquakes.
Sharecropping: A form of agricultural tenancy in which the tenant pays for use of the land with a predetermined share of his crop rather than by paying rent in cash.
Shield: A broad area of very old rocks above sea level that is usually characterized by thin, poor soils and low population densities.
Shield volcano: A volcano that resembles an inverted warrior's shield. It has long gentle slopes produced by multiple eruptions of fluid lava flows.
Silage: Fodder (livestock feed) prepared by storing and fermenting green forage plants in a silo.
Silo: Usually a tall, cylindrical structure in which fodder (animal feed) is stored; may be a pit dug for the same purpose.
Sinkhole: Crater formed when the roof of a cavern collapses; usually found in areas of limestone rock.
Site: Features of a place related to the immediate environment on which the place is located (e.g., terrain, soil, subsurface, geology, ground water).
Situation: Features of a place related to its location relative to other places (e.g., accessibility, hinterland quality).
Smog: Mixture of particulate matter and chemical pollutants in the lower atmosphere, usually over urban areas.
SMSA - Standard Metropolitan Statistical Area: A statistical unit of one or more counties that focus on one or more central cities larger than a specified size, or with a total population larger than a specified size. This is a reflection of urbanization.
Snowline: The lowest elevation at which snow remains from year to year and does not melt during the summer.
Soluble: Capable of being dissolved; in this case, the characteristic of soil minerals that leads them to be carried away in solution by water (see Leaching).
Space Economy: The locational pattern of economic activities and their interconnecting linkages.
Spatial Complementarity: The occurrence of location pairing such that items demanded by one place can be supplied by another.
Spatial Interaction: Movement between locationally separate places.
Spreading ridges: Places on the ocean floor where lithospheric plates separate and magma erupts. About 80 percent of the Earth's volcanic activity occurs on the ocean floor.
Staple Product: A product that becomes a major component in trade because it is in steady demand; thus, a product that is basic to the economies of one or more major consuming populations (see Primary Product).
Stratovolcano: A steep-sided volcano built by lava flows and tephra deposits. (Also called composite volcano.)
Subduction zone: The place where two lithospheric plates come together, one riding over the other. Most volcanoes on land occur parallel to and inland from the boundary between the two plates.
Sustainable Yield: The amount of a naturally self-reproducing community, such as trees or fish, which can be harvested without diminishing the ability of the community to sustain itself.

T

Taiga: A moist subarctic coniferous forest that begins where the tundra ends and is dominated by spruces and firs.
Temperature Inversion: An increase in temperature with height above the Earth's surface, a reversal of the normal pattern.
Tephra: Solid material of all sizes explosively ejected from a volcano into the atmosphere.
Territory: A specific area or portion of the Earth's surface; not to be confused with region.
Tertiary Sector: That portion of a region's economy devoted to service activities (e.g., retail and wholesale operations, transportation, insurance).
Threshold: The minimum-sized market for an economic activity. The activity will not be successful until it can reach a population larger than this threshold size.
Time-distance: A time measure of how far apart places are (how long does it take to travel from place A to place B?). This may be contrasted with other distance metrics such as geographic distance (how far is it?) and cost-distance (how much will it cost to get there?).
Topographic map: A map that uses contour lines to represent the three-dimensional features of a landscape on a two-dimensional surface.
Topography: The physical features of a place; or the study and depiction of physical features, including terrain relief.
Township and Range: The rectangular system of land subdivision of much of the agriculturally settled United States west of the Appalachian Mountains; established by the Land Ordinance of 1785.
Transferability: The extent to which a good or service can be moved from one location to another; the relative capacity for spatial interaction.
Transhumance: The seasonal movement of people and animals in search of pasture. Commonly, winters are spent in snow-free lowlands and summers in the cooler uplands.
Tree Line: Either the latitudinal or the elevational limit of normal tree growth. Beyond this limit, closer to the poles or at higher or lower elevations, climatic conditions are too severe for such growth.
Tree Rings: Concentric rings formed annually as a tree grows.
Tropics: Technically, the area between the Tropic of Cancer (21-1/2 N latitude) and the Tropic of Capricorn (21-1/2 S latitude), characterized by the absence of a cold season. Often used to describe any area possessing what is considered a hot, humid climate.
Tundra: A treeless plain characteristic of the arctic and subarctic regions.

U

Underemployment: A condition among a labor force such that a portion of the labor force could be eliminated without reducing the total output. Some individuals are working less than they are able or want to, or they are engaged in tasks that are not entirely productive.
Underpopulation: Economically, a situation in which an increase in the size of the labor force will result in an increase in per worker productivity.
Uniform Region: A territory with one or more features present throughout and absent or unimportant elsewhere.

V

Vent: The opening at the Earth's surface through which volcanic materials (lava, tephra, and gases) erupt. Vents can be at a volcano's summit or on its slopes; they can be circular (craters) or linear (fissures).
Viscosity: Measure of the fluidity of a substance. Taffy and molasses are very viscous; water has low viscosity.
Volcanic avalanche: A large, chaotic mass of soil, rock, and volcanic debris moving swiftly down the slopes of a volcano. Volcanic avalanches can also occur without an eruption due to an earthquake; heavy rainfall; or unstable soil, rock, and volcanic debris. (Also called debris avalanche.)
Volcano: A vent (opening) in the Earth's surface through which magma erupts; also the landform that is constructed by eruptive material.

W

Water Table: The level below the land surface at which the subsurface material is fully saturated with water. The depth of the water table reflects the minimum level to which wells must be drilled for water extraction.
Windward: The side of a land mass facing the direction from which the wind is blowing—the opposite of leeward.

Z

Zoning: The public regulation of land and building use to control the character of a place.

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See also