1. Weathering and Erosion

2. Weathering
The breakdown of the materials of the Earth’s crust into smaller pieces, due to exposure to the atmosphere

3. Mechanical (Physical) Weathering
The process by which rocks are broken down into smaller pieces, without changing its composition.
Types of mechanical weathering:
Frost (ice) heaving and frost (ice) wedging
Plant roots
Wetting and drying (swelling/shrinking)
Friction and impact
Burrowing of animals

4. Frost (Ice) Wedging

5. Frost (Ice) Heaving

6. Plant Roots

7. Friction and Repeated Impact

8. Burrowing of Animals

9. Chemical Weathering
The process that breaks down rock through chemical changes.
The agents of chemical weathering
Water
Oxygen
Carbon dioxide
Living organisms
Acid rain

10. Water Water weathers rock by dissolving it
Water combines with some minerals (eg. Feldspar) to produce clay
Chemical reaction of water with other substances is called hydrolysis

11. Oxygen
Iron combines with oxygen in the presence of water in a processes called oxidation
The product of oxidation is rust

12. Carbon Dioxide CO2 dissolves in rain water and creates carbonic acid
Carbonic acid easily weathers limestone and marble

13. Living Organisms
Lichens that grow on rocks produce weak acids that chemically weather rock
Acids are formed when plants and animals decay

14. Acid Rain
Compounds from burning coal, oil and gas react chemically with water forming acids.
Acid rain causes very rapid chemical weathering

15. Rate of Weathering
Several factors determine the rate at which rock weathers:
Wet vs. dry climates
The composition of the rock (what minerals it contains)
The amount of surface area exposed

16. Bryce Canyon (Utah)
-rocks of different resistance weather at different rates.

17. Erosion
The process by which water, ice, wind or gravity moves fragments of rock and soil.

18. Water Erosion
Rivers, streams, and runoff

19. Ice Erosion
Glaciers

20. Wind Erosion

21. Mass Movements Landslides, mudslides, slump and creep
landslide clip.mpeg