1. Topic 4: Weathering, Erosion and Deposition

2. Erosion

3. deposition

4. Part 1: Weathering Weathering:
The breakdown of rocks, either chemically or physically.

5. The breakdown of rock into smaller pieces
Physical weathering
Physical Weathering:
The breakdown of rock into smaller pieces
Dominant type of
Weathering in
Cold, Damp
climates

6. Examples of physical weathering
1. Frost Action
At temperatures below freezing, water trapped in cracks expands, enlarging
cracks, eventually breaking rocks.
Many cycles of freezing and thawing will cause rock to crumble

7. Examples of physical weathering
2: Plant Action:
Roots of plants grow into cracks, widening cracks and eventually breaking rock apart.

8. Examples of physical weathering
2: Plant Action
Often begins with lichens

9. Examples of physical weathering
3: Pressure Unloading:
Earthquakes, erosion, and landslides cause overlying material to be removed from rock, allowing the rock to split along lines of weakness.

10. Examples of physical weathering
Pressure Unloading

11. Chemical Weathering
Chemical Weathering:
The breakdown of rock by changing the minerals the rock is made of. The chemical composition of the rock is changed.
Dominant type of weathering in warm and moist climates.

12. Chemical Weathering

13. Chemical Weathering Oxidation:
Chemical weathering where oxygen from the air combines with elements to form new compounds.
Example: Rust = Iron + Oxygen

14. Chemical Weathering Carbonation:
Carbon dioxide combines with WATER to form Carbonic Acid.
This acid easily dissolves limestone and marble.
This is how caves and
sinkholes form.

15. Chemical Weathering

16. Chemical Weathering

17. Water is a major agent in both physical and chemical weathering .