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.