Erosion is the carrying away of weathered rock pieces by gravity, water, wind, and ice. Water is the greatest cause of erosion, as it begins eroding land from the first drop of rain and carries larger rocks faster. Erosion occurs over time through water flowing downhill, with steeper slopes experiencing more erosion. Humans can impact erosion through activities like clear cutting vegetation or planting plants to stabilize soil. Wind and ice also cause erosion, but to a lesser extent than water. Deposition occurs when erosion stops depositing rocks in streams, lakes, oceans and on land, building up the Earth's surface over time.

1. Erosion and Deposition

2. 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.

5. 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.

6. 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

7. 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.

8. Negative
Positive

9. 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.

10. 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!

13. 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.