Geographic Glossary

Here is a glossary of Geography terms related to landmarks. It includes natural landforms, forces that may contribute to the formation of a landform, types of geological materials, and some architectural terms.

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
A
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.
Active Volcano
A volcano that is currently erupting, or has erupted during recorded history.
Altitude
Height of an object in the atmosphere above sea level.
Archipelago
A collection of islands in a sea.
Ash
Fragments less than 2 millimeters (about 1/8 inch) in diameter of lava or rock blasted into the air by volcanic explosions.
Atlantic Seaboard Fall Line
The physiographic border between the Piedmont and Atlantic 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.
Atlas
A bound collection of maps.
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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.
Boundary
A line indicating the limit of a country, state, or other political jurisdiction.
Butte
An isolated hill or mountain with steep or precipitous sides, usually having a smaller summit area than a mesa.
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Caprock
A layer of erosion-resistant sedimentary rock (usually limestone) found in arid areas. Caprock forms the top layer of most mesas and buttes.
Cartographer
A person who draws or makes maps or charts.
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 ? inch) in diameter.
Confluence
The place at which two streams flow together to form one larger stream.
Continent
One of the large, continuous areas of the Earth into which the land surface is divided.
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.
Contour Lines
Parallel lines used on topographic maps to show the shape and elevation of the land. They connect points of equal elevation.
Coulee
A dry canyon eroded by Pleistocene floods that cut into the lava beds of the Columbia Plateau in the western United States.
Crater
A circular depression containing a volcanic vent.
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.
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Deciduous Forest
A forest in which the trees lose their leaves each year.
Dome
A steep-sided mound that forms when very thick lava is pushed out 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 at rest but is expected to erupt in the future.
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Elevation
The height above sea level of a point on the Earth's surface.
Emergent Coastline
A shoreline resulting from a rise in land surface elevation relative to sea level.
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
A lower branch of a river that meets the sea and is affected by the tides.
Exotic Stream
A stream found in an area that is too dry to be the location of the source. The source must be in an area with more moisture.
Extinct Volcano
A volcano that is not expected to erupt again.
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Fall Line
The dividing line between a mountainous or hilly region and a coastal plain. The difference in level is often marked by a line of waterfalls.
Fault
A fracture in the Earth's crust where one side of the fracture has moved in relationship to the other side.
Fault-block Mountain
A mountain mass created by either the uplift of land between faults or the land moving down 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.
Fish Ladder
A series of shallow steps down which water is allowed to flow designed to permit fish to swim around artificial barriers such as dams.
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Glacial Till
The mass of rocks and finely ground material carried by a glacier, then deposited when the ice melted. This creates an mixture made up of many different types of rocks and other materials.
Glaciation
Having been covered with a glacier or subject to glacial periods.
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.
Grid
A pattern of lines on a chart or map, such as those representing latitude and longitude, which helps determine absolute location.
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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.
Hot Spot
An area in the middle of a plate where magma rises from the mantle and erupts at the Earth's surface. Volcanoes sometimes occur above a hot spot.
Hydrography
The study of the surface waters of the Earth.
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.
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Ice Age
A time of widespread glaciation (see Pleistocene).
Igneous Rock
Rock formed when molten (melted) materials harden.
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.
Intracoastal Waterway System
A U.S. waterway channel, maintained through dredging and sheltered for the most part by a series of a line of offshore islands that extend from New York City to Florida's southern tip and from Brownsville, Texas, to the eastern end of Florida's panhandle.
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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 kilometers (68 miles).
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 where nutrients are remove from soil by the erosive movement and chemical action of water.
Leeward
The side of a land mass sheltered from the wind - the opposite of windward.
Lithosphere
The Earth's hard, outermost shell. It comprises the crust and the upper part of the mantle. It is divided into 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.)
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.
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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 2,900 kilometers (1,800 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.
Mesa
An isolated, relatively flat-topped natural elevation, usually more extensive than a butte and less extensive than a plateau.
Metamorphic Rock
Rock that has been physically altered by heat and/or pressure.
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.
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New England
The northeastern United States.
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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.
Outwash
Rocky and sandy surface material deposited by meltwater that flowed from a glacier.
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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.
Piedmont
A plateau region located in the eastern United States between the Atlantic Coastal Plain and the main Appalachian Mountains, stretching from New Jersey in the north to central Alabama in the south. The fall line marks its eastern boundary with the Coastal Plain. To the west, the Piedmont is mostly bounded by the Blue Ridge Mountains, the easternmost range of the main Appalachians. The surface of the Piedmont is characterized by relatively low, rolling hills.
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.
Precambrian Rock
The oldest rocks, generally more than 600 million years old.
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.
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Rail gauge
The distance between the two rails of a railroad.
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.
Riverine
Located on or inhabiting the banks or the area near a river or lake.
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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.
Sea Level
The ocean surface.
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.
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.
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).
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.
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.
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Taiga
A moist subarctic coniferous forest that begins where the tundra ends and is dominated by spruces and firs.
Tephra
Solid material of all sizes explosively ejected from a volcano into the atmosphere.
Topographic Map
A map that uses contour lines to represent the three-dimensional features of a landscape (elevation and shape) on a two-dimensional surface.
Topography
The physical features of a place; or the study and depiction of physical features, including terrain relief.
Tree line
The elevation (usually on a mountain or range) at which trees can no longer grow due to harsh conditions like temperature or snow.
Tundra
A treeless plain characteristic of the arctic and subarctic regions.
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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).
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.
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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.
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