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Landforms

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A basin is a depression, or dip, in the Earth's surface. Basins are shaped like bowls, with sides higher than the bottom. They can be oval or circular in shape, similar to a sink or tub you might have in your own bathroom. Some are filled with water. Others are empty.

Basins are formed by forces above the ground (like erosion) or below the ground (like earthquakes). They can be created over thousands of years or almost overnight.

The major types of basins are river drainage basins, structural basins, and ocean basins.

River Drainage Basins

A river drainage basin is an area drained by a river and all of its tributaries. A river basin is made up of many different watersheds.

A watershed is a small version of a river basin. Every stream and tributary has its own watershed, which drains to a larger stream or wetland. These streams, ponds, wetlands, and lakes are part of a river basin. The Mississippi River basin in the U.S., for instance, is made up of six major watersheds: the Missouri, Upper Mississippi, Ohio, Tennessee, Lower Mississippi, and Arkansas-Red-White Rivers.

Every river is part of a network of watersheds that make up a river system's entire drainage basin. All the water in the drainage basin flows downhill toward bigger rivers. The Pease River, in northern Texas, is part of the Arkansas-Red-White watershed. It is a tributary of the Red River. The Red River is a major tributary of the Mississippi River, which flows into the Gulf of Mexico.

The Amazon Basin, in northern South America, is the largest in the world. The Amazon River and all of its tributaries drain an area more than 7 million square kilometers (about 3 million square miles).

Structural Basins

Structural basins are formed by tectonic activity. Tectonic activity is the movement of large pieces of the Earth's crust, called tectonic plates. Tectonic activity is responsible for such phenomena as earthquakes and volcanoes. The natural processes of weathering and erosion also contribute to forming structural basins.

Structural basins form as tectonic plates shift. Rocks and other material on the floor of the basin are forced downward, while material on the sides of the basin are pushed up. This process happens over thousands of years. If a basin is shaped like a bowl, a structural basin is shaped like a series of smaller bowls, stacked inside each other. Structural basins are usually found in dry regions.

Some structural basins are known as endorheic basins. Endorheic basins have internal drainage systems. This means they don't have enough water to drain to a stream, lake, or ocean. The water that trickles into these types of basins evaporates or seeps into the ground.

When enough water collects in an endorheic basin, it can form a very salty lake, such as the Dead Sea, between Israel and Jordan. While water evaporates into the atmosphere, minerals remain. The remaining water becomes even saltier. The Dead Sea is one of the saltiest natural body of water on Earth. Its shore, about 400 meters (1,300 feet) below sea level, is Earth's lowest dry point.

Death Valley, in the U.S. state of California, is another endorheic basin. At about 86 meters (282 feet) below sea level, it is the lowest place in North America. The water draining into Death Valley from its few streams does not exit the basin to a river or estuary. It evaporates or seeps into the ground.

A lake basin is another type of structural basin. Lake basins often form in valleys blocked by rocks or other debris left by a landslide, lava flow, or glacier. The debris acts as a dam, trapping water and forming a lake. Hunza Lake in Pakistan was formed when an earthquake triggered a massive landslide in 2010. The debris dammed the Hunza River, in addition to killing 20 people and destroying the village of Attabad. The Hunza River continues to flow into the lake basin, and many geologists and villagers worry the basin won't be strong enough to hold the water.

Lake basins may also be carved out by glaciers-huge masses of ice-as they move down valleys or across the land. When the glaciers move, the basins they create remain. During the last ice age, glaciers carved the basins of the Finger Lakes, in the U.S. state of New York.

Sedimentary basins are a type of structural basin that aren't shaped like typical basins, sometimes forming long troughs. Sedimentary basins have been filled with layers of rock and organic material over millions of years. Material that fills up the basin is called sediment fill.

Sedimentary basins are key sources of petroleum and other fossil fuels. Millions of years ago, tiny sea creatures called diatoms lived and died in ocean basins. Eventually, these ancient oceans dried up, leaving dry basins. The remains of the diatoms were at the bottom of these basins. The remains were crushed under billions of tons of sediment fill, over millions of years. In the right conditions, the pressure of the sediment fill turns the diatom remains into petroleum.

The Niger Delta sedimentary basin, in the countries of Nigeria, Cameroon, and Equatorial Guinea, is one of the most productive petroleum fields in Africa. In North America, the Western Canadian Sedimentary Basin is one of the continent's largest suppliers of gas and coal.

Ocean Basins

Ocean basins are the largest depressions on Earth. Edges of the continents, called continental shelves, form the sides of ocean basins.

There are five major ocean basins, coordinating with the major oceans of the world: the Pacific basin, the Atlantic basin, the Indian basin, the Arctic basin, and the Southern basin. Many smaller basins are often considered oceanic basins, such as the North Aleutian Basin, between the Pacific and Arctic Oceans.

Tectonic activity constantly changes ocean basins. Seafloor spreading and subduction are the most important types of tectonic activity that shape ocean basins.

Seafloor spreading happens along the boundaries of tectonic plates that are moving apart from each other. These areas are called mid-ocean ridges. New seafloor is created at the bottom, or rift, of a mid-ocean ridge. Ocean basins that have mid-ocean ridges are expanding. The Atlantic basin, for instance, is expanding because of seafloor spreading.

Subduction happens along the boundaries of tectonic plates that are crashing into each other. In these subduction zones, the heavier plate moves underneath, or subducts, the lighter one. Ocean basins that experience subduction, such as the Pacific basin, are shrinking.

Even though ocean basins make up more than 70 percent of the total land on Earth, scientists know relatively little about them. Some oceanographers (and some astronomers!) say that we know more about the surface of the moon than we do about the surface of the ocean floor.

It is very difficult to get information about landforms of the ocean basin, such as trenches and mid-ocean ridges. These landforms are thousands of feet below the surface of the water. Few instruments can endure the intense pressure, cold, and dark at the bottom of ocean basins. Occasionally, researchers themselves explore ocean basins in special submarines called submersible s.

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Writers

Kim Rutledge
Melissa McDaniel
Diane Boudreau
Tara Ramroop
Santani Teng
Erin Sprout
Hilary Costa
Hilary Hall
Jeff Hunt

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Tim Gunther
Mary Crooks, National Geographic Society

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Jeannie Evers, Emdash Editing

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Sources

Dunn, Margery G. (Editor). (1989, 1993). "Exploring Your World: The Adventure of Geography." Washington, D.C.: National Geographic Society.

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Kim Rutledge Melissa McDaniel Diane Boudreau Tara Ramroop Santani Teng Erin Sprout Hilary Costa Hilary Hall Jeff Hunt Illustrators Tim Gunther Mary Crooks

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National Geographic Society Sources Dunn

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National Geographic Society Editors Kara West Jeannie Evers

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A basin is a depression, or dip, in the Earth's surface. Basins are shaped like bowls, with sides higher than the bottom. They can be oval or circular in shape, similar to a sink or tub you might have in your own bathroom. Some are filled with water. Others are empty.

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Valley, plains, etc..

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Geography Land and Water Landform Terms Flashcards | Quizlet

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Discription of land and water landforms. Learn with flashcards, games, and more - for free.

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Exploring Landforms and Bodies of Water for Kids - FreeSchool

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Landforms, Hey!: Crash Course Kids #17.1

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Alluvial fan: land formation that occurs when sedimentary materials such as rocks, gravel, and silt, are deposited onto land as a result of decreasing or stopped water flow from a river or stream source.

Altitude (elevation): the height above sea level

Anabranch: a flowing part of the river that is separated, usually by an island, and rejoins back down stream.

Archipelago: a group of many islands.

Arête: a group sharp ridges of rocks on mountain tops usually caused by melting glaciers.

Aseismic Ridge: Chain of seamounts under the ocean created by a hotspot under the Earth's crust

Arroyo: a creek that is sometimes dry during the year from not having a constant water source such as rain.

Badlands: barren, battered and eroded land from water and shaped with the help of wearing and wind-driven sand and rain.

Barchan: is a sand dune that crescent-shape that faces the wind. The convex shape is formed by the constant blow of wind in one direction.

Barrier Island: an island or group of island, usually in the ocean, that protects the nearby mainland coast from erosion.

Basin: An area of land largely enclosed by higher land.

Bay: part of a body of salt water that reaches into the land; usually smaller than a gulf

Bayou: A slow moving body of water in a low lying area, usually near the coast, with swamp or marshland in some portions of the shoreline.

Beach: A sloping shoreline consisting of sand, gravel, soil or other sediment.

Beach Cusps: Beach formation in the form of an arc with a cusp or point at each end

Beach Ridge: Elevated formation of sand or other beach material running parallel to a shoreline

Bight: A curve like a bay landform that that has less curve than a bay.

Bluff: a cliff looking over a body of water or plain.

Bornhardt: a rock formation with steep or vertical sides and a round or dome-shaped top usually with little or no vegetation.

branch (tributary)
a river or stream that flows into a larger river or stream

Blowhole: a hole connected to a cave that is attached to a water system that builds up pressure through waves, current or wind. When the pressure is great enough, water is release, usually in a spouting manner.

Blowout: A depression or a major loss in vegetation in the ground where the wind has blown away sand or topsoil.

Braided River: A river that has three or move channels that come back together or drain into the same body of water.

Butte: A rock formation with vertical or nearly vertical sides that is flat on top and taller than it is wide

Canal: a man-made waterway connecting two bodies of water and is designed to shorten travel time or irrigate

Canyon: narrow valley with steep sides; usually created by erosion

Cape: a curved or hooked piece of land extending into a body of water

Cave: a hallow space in the ground or mountain with an opening to enter.

Cenote: a collapsed are, usually limestone, with exposed water.

Channel: a narrow deep waterway connecting two larger bodies of water; the deepest part of the waterway.

climate
the pattern of weather conditions (temperature, precipitation) over a long period of time

Cliff: A high, steep slope of rock or soil

coast
land along the sea or ocean

Confluence: Two or more bodies of water meet and their waters mix.

Continent: one of the seven largest bodies of land on earth

Continental shelf: plateau of land surface into the ocean but underwater extending from a continent.

Cove: a small bay with a restricted entrance.

Crater Lake: is a crater or caldera filled with water caused by a volcano eruption or meteor impact.

Crevasse: is a large crack in a glacier that can be seen from the surface.

Cuspate Foreland: a triangular extension from the coast

Cuesta: a gentle ground slope with a cliff.

Current: the flow of a stream of water

Dam: a wall built across a stream or river to hold back water

Dell: a valley with trees.

Delta: land built up by deposits of sand and silt at the mouth of some rivers

Dirt Cone: Done shape deposit of dirt caused by a glacier.

Desert: dry, barren region usually sandy and without trees, little rainfall or practical use of land unless irrigated

Divide: the highest ridge of land separating river basins

Dome: Oval or round land formation that is elevated from the surrounding areas.

downstream
the direction of a river's flow; toward the mouth of the river

Drainage Basin: All the water in the river exiting at a point usually into another water system like the ocean, lake or another river.

Dry Lake: a lake that is dry all year or most of the year with the dry layer being mud or salt.

Dune: a pile of sand created by wind or waves (underwater dunes)

Erg: a group of sand dunes usually found in a desert.

Estuary: where a river runs into the ocean or other types of salt water.

Escarpment: The edge of a cliff with a steep slope

fault
a fracture in the rocks along which there has been movement

fjord: a narrow inlet of the sea between high banks or cliffs created by glaciers

Flats or flat: a floodplain or former floodplain that has a flat ground surface.

Floodplain: a flat are of land around a river that floods when the river gets high.

Forest: a large tract of land covered with trees and underbrush; extensive wooded area

Fork: The place where a stream or tributary joins a river

Geo: a narrow inlet in a cliff usually caused by waves or glaciers.

Geyser: An opening in the ground that ejects hot water and steam due to volcanic activity.

Glacier: a large body of slow moving ice which alters the land around it through displacement

Glacier Caves: A cave at the bottom of a glacier.

Glen: a long and deep valley usually with steep sides. See also dale and valley.

Gully: a channel cut in the hillside or mountainside from

Gulf: part of a sea or ocean that reaches into land; usually larger than a bay.

Gorge: a deep valley with steep rocks on each side. Also referred to as a valley or canyon.

Graben: a ground depression between two faults.

Guyot: is a flat top seamount that is or once had volcanic activity.

Hanging Valley: A valley that is above another valley usually separated by a cliff.

harbor
a sheltered area of water where ships may anchor safely

Headland: a large area of land extending into a large area of water

hemisphere: half of the earth usually referred to as eastern or western; northern or southern

highland
an area of hills, plateaus, and mountains

hill: a raised part of the earth's surface with sloping sides; old mountain which because of erosion has become rounder and shorter

Hogback: an exposed rock range caused by erosion

Hoodoo: A irregular shaped rock formation that is tall and pillar-like

Iceberg: a large mass of floating ice that has broken off from a glacier, most of this is underwater

Inlet: a small part of a body of water that reaches into a coast

Island: an are of land completely surrounded by water

Islet: A island, usually all rock with little vegetation, that is uninhabitable.

isthmus: narrow strip of land with water on both sides connecting two larger pieces of land.

Karst: A soluble rock landscape shaped through erosion.

lake: a large body of water surrounded by land

Latitude: imaginary lines on a globe or map used to measure distance from the equator; parallel lines running east and west

Lava Dome: a rise in the ground or volcano caused by lava going through vents in the earth.

Lava Field: area of land covered by lava flow.

Lava Lake: molten lava in a crater or vent. (Like a lake filled with lava)

Lava Spine: vertical flowing lava that grows, usually in a sharp tower like shape.

Lava Tube: a sold cave tube caused by lava

Longitude: imaginary lines on a globe or map used to measure distance from the Prime Meridian; lines running from pole to pole.

Lowland: an area of low and usually level land

Marsh: a wetland with grasses and little or no trees

Meander: a major bend in a river or stream

Mesa: a land formation having a relatively flat top and steep rock walls

Moraine: deposits of rock and sediment left from a former or receding glacier

Mountain: high, rocky land, usually with steep sides and a pointed or rounded top, higher than a hill

Mountain Pass: the highest point in a mountain range that is passable by foot.

Mountain Range: a long chain of mountains; a row of connected mountains

Mouth (of a river): place where a river empties into a larger body of water; the end of a river

Mud Volcano: geothermal heated mud that bubbles like lava in a volcano.

Natural Arch: rock that forms together with a natural rock bridge usually caused by erosion.

Nunatak: Rocks coming from a glacier

Oasis: a fertile place in the desert where there is water and some vegetation

ocean: largest body of salt water; these cover 3/4 of the earth's surface.

Ocean Range or Mid-Ocean Range: two separating underwater tectonic plates separating with magma expelling creating mountain ranges.

Oceanic Basin: All the land in each specific ocean.

Oceanic Plateau: an elevated area of the seafloor that is higher than the surrounding area.

Oxbow Lake: a former meander of a river that has separated into a curved lake.

Peninsula: piece of land that extends into a body of water and is surrounded on three sides by water.

Pit Crater: a hole or crater with steep sides caused by volcanic activity.

Plain: a broad, flat or gently rolling area; usually low in elevation.

Plateau: flat highland area with one steep face; elevated plain.

Plunge Pool: a deep area of water under the waterfall.

Pond: a small body of water surrounded by land.

Port: man-made place along the coastline where ships can load and unload cargo; not a natural harbor.

Pothole: A hole in an exposed layer of rock that created by a river's flowing water.

Prairie: a large plains region with tall grass.

Proglacial Lake: a freshwater lake that forms behind a glacier.

Pyramidal Peak: Is where two or more arêtes meet and form a pyramid shape on top of a mountain.

Raised Beach: an area of land above the shore that is higher than high tide.

Rapids: a part of a river, generally shallow, where the currents move swiftly over rocks.

Ravine: a smaller form of a valley with steep sides.

Reef: a ridge of rock or sand at or near the surface of the water.

Reservoir: a lake where water is collected and stored for future use.

Ria: a valley that flows into a coastline's water and gets submerged.

Riffle: a shallow area of a river, lake or stream that has ripples caused usually by a rocky surface.

Rift Valley: two separating tectonic plates forming a valley by the land falling.

River: a large stream of water flowing through the land into a lake, ocean, or other body of water.

River Delta: a branching river extending into another body of water.

River Island: an island in a river.

Sea: a large body of water, usually salt water, partly or completely surrounded by land.

Sound: a wide channel connecting two bodies of water or an inlet between the mainland and islands

Source (of a river): the place where a river or stream begins.

Strait: a narrow waterway connecting two larger bodies of water.

Sandbar: an area of sand or sentiment that has been collecting and rises above or just below the water.

Sinkhole: Collapsed limestone or other softrock that forms a hole on the earth's surface.

Swamp: an area of land that is always soaked with water; low, wet land that supports grass and trees.

Terrace: a flat area of land like a step on landforms like a mountain, valley or beach.

Tide: the regular rising and falling of the water of the oceans and waters connected to the ocean.

Upstream: the direction toward a river's source; opposite to the rivers' flow.

Valley: low land between hills or mountains.

Volcano: a cone shaped mountain formed out of rock or ash thrown up from inside the arth, frequently with an opening or depression at the top.

Waterfall: place where running water makes a sheer drop, usually over a cliff.

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Alluvial fan: land formation that occurs when sedimentary materials such as rocks, gravel, and silt, are deposited onto land as a result of decreasing or stopped water flow from a river or stream source. Altitude (elevation): the height above sea level Anabranch: a flowing part of the river that is separated, usually by an island, and rejoins back down stream.