Erosion and Deposition

What is Erosion?

• Erosion is the carrying away of pieces of weathered rock.

• Rock is carried away by– Gravity– Water– Wind and– Ice

• Water is the GREATEST cause of erosion.

When and How does Erosion Occur?

• Erosion occurs the moment the first drop of water falls from the sky.

• Changes may not occur over night but over time obvious changes occur.

• Once water hits the ground it begins to flow downhill.

• Moving water is very powerful and can push and carry things along.– The faster the water is moving, the bigger rocks it can

move.

Erosion at work.

• The steeper the slope the more erosion occurs.

• http://www.glencoe.com/sites/common_assets/science/virtual_labs/ES08/ES08.html

Humans and Erosion

• We have an affect on erosion and the land around us.

• Clear cutting and planting are just some of the ways humans can affect erosion.

• Clear cutting is the stripping away of trees and other vegetation of a mountain.

• Planting vegetation helps stabilize the land.

Positive

Negative

Wind and Erosion • Wind is moving air and can push things along,

like water.• Wind is not as powerful as water so it erodes

smaller pieces of rock, like sand.

Ice and Erosion

• Ice also causes erosion. • Glaciers are an example of ice that is effected by

erosion.• Ice does not move as quickly as water but it is still

very powerful.• When the ice of a glacier freezes onto rocks and

then the glacier moves downhill, the rock is torn right out of the ground.

• Glaciers can move rocks bigger than your house!

Deposition

• Deposition is the rocks that are dropped off into streams, lakes and oceans because of erosion.

• When the wind slows down, the ice melts and the water slows down deposition occurs.

• Rocks that are deposited by water, wind and ice build up earth’s surface.