Glossary of Geography Terms |
ablation: All processes that that remove snow or ice from a glacier or snowfield. abrasion: A wearing of away of material by friction. Antarctica: The world's fifth largest continent. Arctic Circle: An imaginary line that encircles the North Pole at approximately latitude 66° N. It is south of the North Pole. It marks the northernmost point at which the sun is visible on the northern winter solstice and the southernmost point at which the midnight sun can be seen on the northern summer solstice. arid: Dry, having little rainfall. canopy tress: Ttrees that make up the highest layer of leaf cover in a forest. cartography: The drawing (creation) of maps. channel: The bed of a stream or waterway. climate: The weather conditions over a period of time in a particular area. Major climates include: polar, dry, mild, continental, mountain, and tropical. continent: A large landmass, as distinct from the oceans. The seven continents are: North America, South America, Europe, Asia, Africa, Australia, and Antarctica. There are also a group of islands in the Pacific ocean which geographers refer to as Oceania. (Oceania is not a continent.) continental drift: A scientific theory first put forth by Afred Wegener in 1915. The theory states that at some time in the distant geologic past, there existed one single, large "supercontinent" called Pangaea. Approximately 200 million years ago, this landmass broke up, pieces of which "drifted," forming the continents as we known them today. The idea eventually led to the today's theory of plate tectonics (see below). crust: The layer of rock on the Earth's surface. delta: A triangular feature at the mouth of a river or stream comprised of silt formed by deposited sediment. desert: An arid (dry, having little rainfall) region with little or no vegetation. earthquake: A disturbance or shaking of the Earth's surface due to underground movement. eclipse: The cutting off of light (total or partial) from one celestial body by another. ecosystem: A complex system of interaction between living organisms and their non-living environment. erosion: Wearing away of the Earth's surface by water, ice, wind. equator: An imaginary circle that goes horizontally around the middle earth at its widest point. Zero degrees latitude. It divides the northern and southern hemispheres. forest: A biological community dominated by trees and other woody plants. geographic coordinates: Imagine that lines of latitude and lines of longitude form a grid over the Earth's surface. A point (coordinate) is formed by the intersection of a latitude line and a longitude line. In this way, any location on the earth can be determined. glacier: Bodies of ice and compacted snow. Glaciers are formed with the termperature is too cold to allow accumulating snow to melt. The snow compacts and eventually the snow crystals change into granular ice crystals called firn. As the firn becomes buried under more accumulating snow, it changes into solid ice. The changes takes years to accomplish. There are two categories of glaciers: Alpine (which form on mountainsides) or ice sheets (which form on flat land). Glaciers cover approximately 10% of the Earth's land surface. gorge: A narrow, steep-sided valley or canyon. Gorges may or may not have a river at their bottom. grassland: Areas in which grass is the primary, natural vegetataion. The two main categories of grassland are: temperate grasslands and tropical grasslands. greenhouse effect: The phenomenon whereby absorbed solar radiation is re-emitted from the Earth's surface but is prevented from escaping into the atomosphere by radiatively active gases (carbon dioxide, water vapor, methane, and other trace gases). This causes a rise in the Earth's temperature. hemisphere: Half of the earth's surface. There are four hemispheres: The northern hemisphere (north of the eqautor); the southern hemisphere (south of the equator); the eastern hemisphere (east of the prime meridian); the western hemisphere (west of the prime meridian). island: A body of land completely surround by water. hurricane: A tropical cyclone with sustained winds of 74 miles per hour or greater in the North Atlantic Ocean, Caribbean Sea, Gulf of Mexico, and in the eastern North Pacific Ocean. lake: A body of water surrounded by land. latitude lines: Imaginary lines running horizontally around the globe equi-distance from one another. Zero degrees latitude is at the earth's equator. The lines increase from 0 degrees to 90 degrees north (going upward from the equator to the North Pole), and from 0 degrees to 90 degreds south (going downward to the South Pole). longitude lines: Imaginary lines running vertically around the globe. Longitude lines are not equi-distant (parallel). The lines are widest apart at the equator and eventually meet at the poles. Zero degrees longitude is called the prime meridian. Longitude lines are also called meridian lines. map projections: Two-dimensional representations of earth. See mercator projection (below) and robinson projection (below).
mercator projection: A cylindrical map projection. First introduced in 1569 by a Flemish mathematician and geographer named Gerhard Mercator. It is commonly used in navigational charts. Distortions occur as you move either far north or far south.
Mercator's Map meridian: Imaginary lines running vertically spanning the globe, passing through the Noth and South poles. Lines of longitutde. mountain: A landform that rises 1,000 or more feet above the land around it. plate tectonics: The scientific theory that the earth's lithosphere is divided into plates (or semi-rigid sections) which move horizontally and interact with one another, causing the formation of mountains, folds, faults, volcanoes, earthquakes, ocean trenches, and the mid-oceanic ridges. plates: Giant, rigid slabs of the Earth's crust. The plates "float" on a dense, fluid layer just beneath them. plateau: An elevated area of relatively level land. population: The number of people who live in a defined area. prime meridian: Zero degrees longitude. Runs through the Royal Greenwich Observatory in Greenwich, England. The prime meridian globe into the Western and Eastern hemispheres. The Earth's time zones are measured from the prime meridian. The time at 0° is called Greenwich Mean Time (GMT) or Universal Time (UT).
Richter scale: A logarithmic scale for measuring the magnitute (intensity) of earthquakes. Introduced in 1035 by Charles F. Richter. ring of fire: A zone that surrounds the land areas that ring the Pacific Ocean wherein volcanic and seismic activity occurs. (Approximately 90% of the world's earthquakes occur there.) Also called the Circum-Pacific belt. topography: The physical features of the Earth's surface such as landforms. topographic map: A map that
shows the topography of an area using contour lines to represent the size, shape, and elevation of the features. Tropic of Cancer: A latitude line that lies a quarter of the way from the equator to the North Pole. During the summer solstice, the sun is directly overhead. Tropic of Capricorn: A latitude line that lies a quarter of the way from the equator to the South Pole. During the winter solstice, the sun is directly overhead.
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