- A -
Absolute Humidity:
The mass of water vapor in the atmosphere per unit of volume of space.

Accessibility:
A locational characteristic that permits a place to be reached by the efforts of those at other places.

Accessibility Resource:
A naturally occurring landscape feature that facilitates interaction between 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.

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.

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.

- 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, that 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 to eventually 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.

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.

Boll Weevil:
A small, greyish beetle of the southeastern United States with destructive larvae that hatch in and damage cotton bolls.

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 strata 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.

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.

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.

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.

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

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).

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.

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.

Culture Hearth:
The area from which the culture of a group diffused (see Hearth).

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 -
Deciduous Forest:
Forests in which the trees lose their leaves each year.

De Facto Segregation:
The spatial and social separation of populations that occurs without legal sanction.

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

De Jure Segregation:
The spatial and social separation of populations that occurs as a consequence of legal measures.

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:
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.

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.

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.

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.

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 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 either by 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, social) occur; 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.

Ghetto:
Originally, the section of a European city to which Jews were restricted. Today, 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. Creates an unstratified material of varying composition.

Glaciation:
Having been covered with a glacier or subject to glacial epochs.

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.

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 -
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).

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.

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.

- 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.

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 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 lake bed.

Latitude:
A measure of distance north or south of the equator. One degree of latitude equals approximately 110 kilometers (69 miles).

Leaching:
A process of soil nutrient removal through the erosive movement and chemical action of water.

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.

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.

- M -
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.

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 -
Nodal Region:
A region characterized by a set of places connected to another place by lines of communication or movement.

New England:
The northeastern United States.

Nuclear Family:
See Extended Family.

- O -
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.

Physiographic Region:
A portion of the Earth's surface with a basically 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.

Plural Society:
A situation in which two or more culture groups occupy the same territory but maintain their separate cultural identities.

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:
Period in geologic history (basically the last one million years) when ice sheets covered large sections of the Earth's land surface not now covered by glaciers.

Polynodal:
Many-centered.

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).

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).

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. 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 of interest to people and 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 water course or lake.

Riverine:
Located on or inhabiting the banks or the area near a river or lake.

- S -
Scarp:
Also "escarpment." A steep cliff or steep slope, formed either as a result 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 1600s.

Secondary Sector:
That portion of a region's economy devoted to the processing of basic materials extracted by the primary sector.

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.

Sedimentary Rock:
Rock formed by the hardening of material deposited in some process; most commonly sandstone, shale, and limestone.

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 with a cash rent.

Shield:
A broad area of very old rocks above sea level. Usually characterized by thin, poor soils and low population densities.

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. A reflection of urbanization.

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.

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).

Sustainable Yield:
The amount of a naturally self-reproducing community, such as trees or fish, that 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.

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., transportation, retail and wholesale operations, 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?).

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 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.

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 to be 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.

- 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.

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

United States Geography

Source: U.S. Department of State