1. Three Basic Definitions
Weathering + transportation = erosion 1) Weathering: Chemical and Physical processes that change the characteristics of rocks on the Earth’s surface. 2) Once a rock material has been weathered or eroded, it is ready to be transported from one location to another. 1+2 together is called erosion. 3) Deposition: Rock particles are deposited somewhere else.

3. Physical/ Mechanical Weathering
Break up of rock, no change in its composition
Active in dry and cool climates
Agents of weathering:
Rain
Wind
Heat
Cold

4. Types of Physical Weathering
Frost Shatter/Freeze-Thaw: Water enters a crack and freezes in rocks, expands, over time breaks the rock apart.

7. Exfoliation: Peeling away of large sheets of loosened materials at the surface of a rock These layers of rock may have been tightly compressed when under the surface As the overlying rock is eroded, there is less pressure holding the layers together and the layers may begin to peel apart

8. Abrasion: Occurs when some force (usually wind or water) causes two rock surfaces to come together causing mechanical wearing or grinding of their surfaces.

9. Insolation Weathering / Thermal Expansion: Caused by extreme day/night temperatures. Common in desert regions. Biological Weathering: Caused by plants or animals and breaking apart rocks.

12. Chemical Weathering
When a rock is broken down by chemical action, resulting in a change in the composition of a rock Dominant in wet areas (equator) Main agents: Oxygen, Rainwater, Carbon dioxide, and Acids produced by decaying plants and animals

13. Oxidation - When oxygen dissolved in rainwater interacts chemically with minerals [often Iron]. Process of rusting.

14. Hydrolysis: The minerals within a rock have a chemical reaction to the Hydrogen found in rainwater. Minerals are dissolved into the water and carried away. Carbonation/Solution occurs when Carbon Dioxide in rainwater reacts with the minerals in the rocks to dissolve or weaken them.

15. So those all sound similar, right. How can we remember which is which
So those all sound similar, right? How can we remember which is which? Oxidization = reaction with Oxygen Hydrolysis = reaction with Water Carbonation = reaction with Carbonic acid

17. One of the major products of weathering is soil (combination of rocks, minerals, and organic matter) that contain the necessary nutrients to support plant and animal life. We will look at soil in greater detail in Unit 4

19. Assignment
1. In your own words, explain the difference between weathering and erosion 2. Which types of physical weathering would you find in warm locations? Which would you find in cold locations? 3. Give examples of places in your life where you have seen Solution and Oxidation. 4. Read Chapter 11