1. World Geography Unit 1: Physical Geography Land and Water Forms. Physical and Chemical Weathering

2. Weathering  Earth’s largest landforms, and highest peaks are constantly being torn down by physical and chemical means. Physical Weathering: Involves the use of physical elements of the environment Chemical Weathering: Uses chemicals to change the composition of rocks.

3. Physical Weathering  Physical Weathering can occur in many forms Frost Fracture: occurs from repetitive freezing and thawing of water that seeps into cracks in rocks. Exfoliation: Internal pressure from the earth causes rock to expand and fracture. Plant Growth: Roots of plants can pry rock apart Burrowing Animals: As animals dig burrows they expose more rock surface, and expand cracks in the rock

4. Frost Fracture

5. Exfoliation

6. Plant Growth

7. Burrowing Animals

8. Chemical Weathering  Chemical weathering occurs when rock minerals are broken down in chemical reactions Solution: By absorbing chemicals from the atmosphere rain becomes acidic and reacts with certain rock minerals which leads to their decay Hydrolysis: Minerals are carried away in solution when carbonic acid reacts with minerals known as silicate. Oxidation: Metallic minerals in rocks react to the oxygen in water. As a result of this reaction a new mineral, oxide is formed.

9. Solution

10. Hydrolysis

11. Oxidation

12. Weathering and the Environment  Weathering does not occur in all places equally. Weathering tends to happen quicker in moist places that experience a great range of temperatures Can you think of some places in your community were weathering may occur?