1. WEATHERING, EROSION & DEPOSITION Advanced Earth Science VA SOL ES. 7(a)

2. Weathering, erosion and deposition are all INTER-RELATED processes. A good analogy for this would be eating. Chewing and breaking down food is weathering Moving the food down your throat and through your body is erosion Excreting your waste is deposition It is not very common to have one without the other

3. Two Types of Weathering PHYSICAL / MECHANICAL CHEMICAL

4. Physical/Mechanical Weathering Physical weathering occurs when a rock is broken into smaller pieces without a change in composition. The most common physical/mechanical weathering is: Abrasion Frost Wedging Exfoliation Plant Activity

5. Abrasion Abrasion makes rocks smoother and rounder by rubbing them together, and this commonly happens in streams. The longer a rock is in a stream, the rounder it gets. Abrasion also happens when glaciers move over the land, during landslides, and in windy deserts where rocks get sand blasted

6. Frost Wedging Frost wedging splits apart when water seeps into cracks and then freezes. When water freezes it expands and this forces the rock apart

7. Exfoliation Exfoliation happens when overlying layers of rock or soil are removed, and the rock underneath expands as the pressure is released. These tend to make rounded domes. Half dome in Yosemite is an exfoliation dome.

8. Plants Plants can seriously break down rocks. They start out small but as they grow they relentlessly pry the rocks apart.

9. Chemical Weathering Chemical weathering occurs when a rock’s composition is changed by chemical reactions. The most common ways rocks are chemically weathered are by: Water Oxygen Carbon Dioxide

10. Water Most powerful agent of weathering Process is known as HYDROLYSIS

11. Oxygen Most commonly see as RUST Process called OXIDATION

12. Carbon Dioxide CO 2 + H 2 O = Carbonic Acid Commonly known as acid rain Groundwater is naturally acidic and this acid is what dissolves limestone to form karst features such as caves and sinkholes

13. Other Factors that Affect Weathering Weather (climate) Surface area exposed to weathering The more of the rock that is exposed, the most weathered the rock will be Rock type Some rocks break down easier than others Topography “shape” of the land

14. Erosion Erosion is the movement of weathered material As a material is moved (eroded) it is also being weathered. However, weathering and erosion and NOT THE SAME THING! Weathering = breakdown Erosion = moving

15. Deposition Weathered materials STOP moving. Materials settle on land or in water.