Erosion and Deposition

Erosion wears away surface materials and moves them from one location to another.

Agents of erosion are: gravity, glaciers, wind, and water.

Deposition is the dropping of sediments.

Erosion and Deposition by Gravity Mass Movement: when gravity alone

causes materials to move down-slope. Slump Creep Rockslide Mudflow

Slump

A mass movement that happens when loose materials or rock layers slip down a slope.

Happen most frequently after earthquakes or heavy rain

WINTER PARK, FL, SINKHOLE

Creep

Sediments slowly inch their way down a hill.

Common in areas of freezing and thawing.

Rockslide

Large blocks of rock break loose from a steep slope and start tumbling.

Happen most often after earthquakes or heavy rain, but can happen at anytime without warning.

SHALLOW SOIL SLIP

Mudflows

A thick mixture of sediments and water flowing down a slope.

Happen in dry areas where sediments have accumulated and heavy rain begins to fall.

LANDSLIDE BLOCKSTHE CANYONFLOODING COMMUNITY OF THISTLE, UTAH BY CREATING ANATURAL DAM.

VAIONT DAM IN ITALY, 2600 LIVES WERE LOSTWORLD’S WORST DAM DISASTER, OCTOBER 9, 1963

Glaciers A moving mass of ice. Continental and Valley Continental glaciers cover large

amounts of land. Valley glaciers are found in high

mountains where average temperatures keep the ice and snow from melting in the summer.

Valley Glaciers

As the ice moves it pushes loose materials out of its path.

Plucking is when boulders, gavel, and sand are added to the bottom of the glacial ice.

The glacier leaves behind distinctive features: arete, cirque, striations, moraines, U-shaped vallies. Fig 7-12

Glacial Deposition

Till- a mixture of different sized sediments dropped from a glacier.

Fig. 7-3 p. 184 shows various features of glacial deposition and outwash plain.

ARETE

MORAINE

Wind

Deflation, is the removal of finer particles by the wind. Sand, silt, and clay are blown away leaving larger size particles behind.

Abrasion, is the wearing of other rocks by the wind carried particles such as sand.

Sand and Dust Storms

Sand storms occur in the desert and at the beach.

Dust storms occur when very dry soil is blow away by the wind.

Reducing Wind Erosion

Windbreaks made of plants prevent reduces the wind energy.

Roots help hold soil together.

Loess

Fine-grained wind deposits.

Dunes

A mound of sand drifted by the wind. Dunes are constantly moving, one sand

grain at a time. Fig. 7-21, p. 195, illustrates the

migration of a dune.