DSST Introduction to Geography key terms

The ratio between a distance measured on a map and the same distance on the ground, shown as a fraction, a written statement, or a graduated bar.

A map covering a small ground area in fine detail, such as a city plan, where the representative fraction has a large denominator relationship favoring detail over coverage.

A map showing a large ground area with little detail, such as a world or continental map, produced by a small representative fraction like 1:5,000,000.

A mathematical method for transferring positions from the curved Earth surface onto a flat sheet, always distorting some combination of shape, area, distance, or direction.

A cylindrical projection preserving compass direction and local shape but exaggerating area toward the poles, which is why Greenland looks as large as Africa on such maps.

A projection that keeps the relative sizes of regions correct at the cost of distorting shape, useful for mapping population density, land cover, or other areal data.

Any circle on the Earth's surface whose plane passes through the center, marking the shortest surface route between two points and the basis for long-distance navigation.

Angular distance north or south of the equator, measured in degrees from 0 at the equator to 90 at each pole and drawn as parallel horizontal lines.

Angular distance east or west of the Prime Meridian at Greenwich, measured from 0 to 180 degrees in each direction and drawn as converging meridians.

Collecting information about the Earth's surface from aircraft or satellites using sensors that record reflected or emitted energy, often displayed as imagery.

A computer system for storing, combining, and analyzing spatially referenced data in layers so that patterns and relationships can be mapped and queried.

A map designed to show the distribution of one particular attribute, such as rainfall, population density, or crop production, rather than general reference features.

A thematic map on which lines connect points of equal value, such as contour lines for elevation or isotherms for temperature.

A thematic map that shades whole administrative units in proportion to a measured value, giving a quick visual impression of regional variation.

A line on a topographic map joining points of equal elevation above sea level, with closely spaced lines indicating steep slopes.

The difference in elevation between the highest and lowest points of a land area, describing how rugged or flat the terrain is.

The theory that the lithosphere is broken into rigid plates that move over the asthenosphere, producing earthquakes, volcanoes, mountain belts, and ocean trenches at their boundaries.

A convergent boundary where one lithospheric plate descends beneath another, generating deep ocean trenches, volcanic arcs, and frequent powerful earthquakes.

A vent or fissure where magma, ash, and gases reach the surface, commonly arranged along plate boundaries or over mantle hot spots.

The in-place breakdown of rock by physical, chemical, or biological processes into smaller particles or dissolved material, without transporting the debris.

The removal and transport of weathered rock material by water, wind, ice, or gravity, shaping landforms such as valleys, deltas, and dunes.

The laying down of eroded sediment when transporting agents lose energy, building features such as floodplains, deltas, alluvial fans, and moraines.

A fan-shaped deposit of sediment where a river enters a standing body of water and loses velocity, often forming fertile, densely settled lowland.

The flat land bordering a river that is built of sediment and periodically inundated during high water, usually valuable for agriculture and settlement.

A vertical cross-section of soil showing distinct horizons, from surface organic litter through leached and accumulated layers down to weathered parent material.

The downward removal of dissolved minerals and organic matter by percolating water, producing leached upper horizons in humid climates.

A deeply weathered, iron- and aluminum-rich tropical soil formed by intense leaching; it hardens when exposed and is poor for most crops.

A large ecological region defined by its climate and dominant vegetation, such as tropical rainforest, savanna, desert, or tundra.

A tropical grassland with scattered trees and a pronounced dry season, found mainly in Africa, South America, and northern Australia.

The long-term average and variability of temperature, precipitation, and other atmospheric conditions at a place, distinguishing it from short-term weather.

The dry leeward side of a mountain range, where descending air has already lost its moisture on the windward slope.

Rainfall or snowfall caused when moist air is forced to rise over mountains, cooling and condensing on the windward slopes.

A seasonal reversal of prevailing winds, most famously over South and Southeast Asia, bringing a wet summer season and a dry winter season.

A periodic warming of the central and eastern equatorial Pacific that disrupts normal ocean circulation and weather patterns worldwide.

A model describing the shift of a population from high birth and death rates through declining mortality and later declining fertility to low rates.

A paired bar graph showing the age and sex structure of a population, revealing its growth stage and dependency burden.

The maximum population an environment can support indefinitely given its resources and technology without degradation.

Conditions that drive people away from a place, such as poverty or conflict, and conditions that attract them elsewhere, such as jobs or safety.

The rising share of a population living in cities, driven by rural-to-urban migration and natural growth, and accompanied by land-use change.

A city that is disproportionately larger than the second-largest city in its country and dominates national economic and political life.

A metropolitan area with more than roughly ten million residents, increasingly common in Asia, Latin America, and Africa.

A person who has fled across an international border because of persecution, war, or violence and is unable or unwilling to return home safely.

A region where a major cultural trait or complex originated and from which it later spread to other areas.

The spread of a cultural trait, idea, or technology from one place or society to another, whether by migration or by contact and communication.

An area sharing a set of related cultural traits such as language, religion, or livelihood that distinguish it from neighboring areas.

A group of languages descended from a common ancestral tongue, such as the Indo-European or Sino-Tibetan family.

Economic and social advancement that meets present needs without compromising the ability of future generations to meet their own needs.

The large-scale removal of forest cover, often for timber, ranching, or cropland, causing soil erosion, habitat loss, and carbon release.

The degradation of dryland ecosystems into desert-like conditions through drought, overgrazing, and poor irrigation practices.