1. Weathering and Erosion

2. How did this happen?

3. Weathering vs. erosion Weathering Erosion
The process by which rocks on or near Earth’s surface break down and change.
Erosion
The removal and transport of weathered material from one location to another

4. Mechanical weathering
The process by which rocks and minerals break down into smaller pieces
Also called physical weathering
What two factors play a role in mechanical weathering?
Temperature
Pressure

5. Temperature
The amount of space water takes up can change due to the temperature.
Ice takes up more space than liquid water and can cause cracks to expand.
The repeated thawing and freezing of water in the cracks of rocks is called frost wedging

7. Pressure
Rocks deep below the surface are under a great deal of pressure.
When surface layers are removed, the covered layers can now expand.
The process by which outer rock layers are stripped away is called exfoliation

8. Chemical weathering
The process by which rocks and minerals undergo changes in their composition as the result of chemical reactions
What are the major factors involved in chemical weathering?
Water
Oxygen
Carbon dioxide
Acids

9. Factors affecting chemical weathering
Water
Water can dissolve many types of minerals in rocks
The reaction of water with other substances is called hydrolysis.
Oxygen
Oxygen can also react with other substances.
The chemical reaction of oxygen with other substances is called oxidation

11. Factors affecting chemical weathering
Carbon dioxide
Living organisms produce carbon dioxide when they breathe out.
Carbon dioxide combines with water to form carbonic acid and returns to the earth through precipitation.
This carbonic acid can dissolve certain minerals in rocks

12. Factors affecting chemical weathering
Acid precipitation
This is caused by pollution in the atmosphere by motor vehicles, factories etc.
Can also affect the wildlife

13. What affects the rate of weathering?
Climate
Variables of climate include:
Precipitation
Temperature
Evaporation
Rock type and composition
Surface area
Topography

14. Climate variables Where does chemical weathering occur most readily?
Climates with warm temperatures, abundant rainfall, and lush vegetation.
Lots of living organisms to produce carbon dioxide which will produce carbonic acid when mixed with water.

15. Climate variables Where does physical weathering occur most readily?
Climates that are cool and dry.
In these areas water undergoes repeated freezing and thawing.
Chemical weathering is inhibited by cool dry climates.

16. Rock type composition
A wide variety of rocks cover the earth’s surface.
Some rocks are more easily broken down than others.
Sedimentary rocks are more easily broken down than metamorphic or igneous rocks.

17. Surface Area
Mechanical weathering breaks up rocks into smaller pieces.
As the pieces get smaller, surface area increases
More surface area= more weathering that can occur

18. Topography
Topography is the study of the elevation of the earth above sea level.
Materials in level areas are more likely to stay the same
Materials on slopes are more likely to undergo change and move