Major ConceptsLandforms are features that make up the Earth's surface. There

are many kinds of landforms.

Some landforms are created by the action of wind, water, and ice. This action physically changes the Earth's surface by carving and eroding land surfaces, carrying and depositing soil, sand and other debris.

Crustal movement and other tectonic activity inside Earth create landforms; mountains, faults, sinks, and volcanos.

Topographic maps and models are used to represent landforms and help scientists better understand objects and processes.

RELIEF MAP OF THE US

Basic Landform TypesMountains- high, steeply sloped areas of the Earth's surface formed

by the upward movement of rock. Mountains are found on land and on the ocean floor.

Plains - low areas of the earth that have been eroded nearly level or formed of flat-lying sediments.

Glacial Plains - The Great Plains of the central United States were formed from glacial action during the Ice Age.

Coastal Plains - located along the Atlantic Ocean and Gulf of Mexico in the U.S.

Plateaus - high, nearly level uplifted areas composed of horizontal layers of rocks.

Colorado Plateau - formed from crustal uplift.

Columbia- formed from lava flow.

MOUNTAINS

ROCKY MOUNTAINS Most of this map covers western

Montana, though there are parts of Idaho to the SW and of Canada to the north.

At the bottom right is the very northern edge of Yellowstone National Park. The mountains in the SE corner of the map are the Absaroka Range. The Yellowstone River flows through the SW/NE trending, deeply shadowed valley to the west of the Absarokas, then turns east, flowing off the map to join the Missouri in North Dakota.

AndesMountains

Space borne Imaging Radar of Andes Mountains:

Patagonian Ice Fields

Land forms caused by erosion or deposition:

Alluvial Fan-fan shaped deposit of earth material from where a stream flows from a steep slope onto flatter land.

Canyon-A narrow, deep, steep-sided opening in the earth's surface with steep cliff walls, cut into the earth by running water; a gorge.

Delta-a fan shaped deposit of earth materials at the mouth of a stream.

ALLUVIAL FAN

Intermittent streams, resulting mostly from bursts of infrequent rain, rush down steep canyons scouring boulders, soil and other debris. The flood of water carries the whole mass with it and deposits it on the valley floor at the canyon's mouth.

GRAND CANYON These images give different

perspectives on the Grand Canyon, a famous landform.

The Colorado River is the cause of changes past and present. The river cuts through rocks exposing walls of Grand Canyon.

The Colorado River has carved out the Grand Canyon by carrying away the rock and soil that were once there.

GRAND CANYON

This image is from the Landsat satellite, a remote-sensed image.

This image is processed using remote-sensed data to produce a 3-d image

DELTA

Delta-a fan shaped deposit of earth materials at the mouth of a stream.

FLOODPLAIN

Floodplain land that gets covered with water during a flood. This picture is of the Willamete River in Oregon, spring, 1996.

FLOODPLAIN

Columbia River flooding Portland Oregon, during the flood of 1996.

HILL

Hill-an isolated elevation in the land, usually no more than 30 meters from base to peak.

MEANDER

Meander-a curve or loop in a river.

Land forms caused by erosion or deposition:

Mesa - a broad, flat-topped elevation with one or more clifflike sides, common in the southwest United States

Mouth - a natural opening, as the part of a stream or river that empties into a larger body of water or the entrance to a harbor, canyon, valley, or cave.

Valley - a low area between hills and mountains where a stream often flows

V-shaped Valleys - Formed from the Action of Rivers

Valleys formed from the action of rivers tend to have steep sides,

resulting in a V-shape.

U-shaped Valleys - Formed from the Action of Glaciers

Valleys formed from the action of glaciers tend to have slower

sloping sides, resulting in a U-shape.

WATERFALLS

MORRAINES

Glacial morraines are large accumulations of rock debris piled up by glaciers

Sand Dunes

These are images of sand dunes, resulting from the action of wind on stretches of sand.

This image is taken from the Space Shuttle of sand dunes in the Peruvian Andes.

SAND DUNES

This photo is from Great Sand Dune National Monument, Colorado.

Landforms caused by movement of the Earth's crust

Fault - a fracture, or crack, in rocks along which movement has taken place.

Death Valley is an example of an area on the Earth that

is slowly sinking. The large block of rock that makes up

the floor of Death Valley is slowly tilting as one end

sinks, resulting in the lowest place in the Western Hemisphere.

SAN ANDREAS FAULT

Aerial view of the San Andreas fault slicing through the Carrizo Plain in the Temblor Range east of the city of San Luis Obispo.

This image shows San Andreas Lake and Crystal Springs reservoir from the air. The highway paralleling the lakes to the left is Interstate 280.

This valley is remarkably straight because the San Andreas fault runs down its center. The San Andreas is a classic ``Strike Slip'' fault: the two sides (for the most part) move past each other horizontally. The vegetation and terrain on either side of the lakes look different partly because the underlying rock IS geologically very different. The rock on the right came from the Southern Sierra Nevada mountains, and has been transported from several hundred miles to the South by motion along the fault. With each San Andreas earthquake, it continues a few more feet (or tens of feet) on its long slow journey.

DEATH VALLEY

The left view is a radar image overlaid upon a topographic model of Death Valley. The right view is a camera photo from approximately the same vantage point.