1. Rock Cycle Unit 3 – 2. 1. 3 What is weathering
Rock Cycle Unit 3 – What is weathering? Explain how weathering can lead to soil formation.

2. Weathering Chapter 7 – Pg.152--

3. Weathering Definition
A constant process of breaking down objects on the Earth’s surface.

4. Mechanical Weathering
Breaking rock into smaller and smaller pieces.

5. 1. Abrasion - physical grinding of rock fragments

6. 2. Frost Wedging Water expands when frozen in cracks of rocks causing them to break.

7. 3. Organic Activity- plants grow through rocks and cause them to break.

8. 4. Thermal Expansion
Warming causes the rock to expand and when it is cooled it contracts and breaks.

9. Chemical Weathering
Changes in the mineral composition or chemical make up.

10. 1. Oxidation – Iron + Oxygen = Rust

11. Gets into the soil dissolves the rocks beneath.
2. Carbonation Carbon Dioxide + Water = Carbonic Acid
Gets into the soil dissolves the rocks beneath.

12. 3. Sulfuric Acid Sulfur oxides + Rain = Acid Rain

13. 4. Hydrolysis
Water + feldspar = clay
Water can dissolve minerals or form a new mineral.

14. Factors that Affect the Rate of Weathering

15. 1. Composition of the Rock
Example - Sandstone is easily weathered.
Rocks that resist weathering are called stable rocks Ex: Granite (most common igneous rock)
Sandstone Swirl – Arizona

16. 2. Climate
The more moisture the faster the rocks weather.

17. 3. The Amount of the Rock Exposed to the Surface

18. Weathering Animation
Brain pop