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_asse ts/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.
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.