2. Weathering

3. The Chemical and physical breakdown of material (rock).

4. Disintegration The breaking up of material into smaller pieces Also called Physical or Mechanical Weathering –Thermal Expansion –Frost Wedging –Plant and Animal Action –Unloading

5. Thermal Expansion Material expands when it gets warmer. The outside of a rock will get hotter than the inside during the day and colder at night, therefore the outer part expands and contracts more than the inner part. Exfoliation

6. Thermal Expansion Examples: –Expansion Joints on bridges. –Ice crackling in water –Hot water on cold glass –Cold water on hot glass

7. Frost Wedging

8. Frost or Ice Wedging What conditions would cause a lot of ice wedging?

9. How potholes form

10. Plant and Animal Action

11. Plant Roots

12. Root damage to sewer lines

13. Unloading & Jointing

15. Jointing

16. Decomposition The chemical changing of material into a new material. Most important agent involved is water. Also called Chemical Weathering –Acids –Hydrolysis –Oxidation

17. Acids Carbonic Acid or Carbonation H 2 O + CO 2 + CaCO 3 --> Ca +2 + HCO 3 -

18. Acids Organic Acids –Lichens –Plants –Animals Sweat Urine

19. Hydrolysis and Hydration Reacting with water –KAlSi 3 O 8 + H 2 0 --> Al 2 Si 2 O 5 (OH) 4 + SiO 2 + K(OH)

20. Oxidation Rust Fe +2 +O 2 --> Fe 2 O 3

21. Chemical helps Physical by making the rock weaker

22. Physical helps Chemical by increasing the surface area

23. Differential Weathering

26. Factors that Influence the Rate of Weathering

27. Rates of Weathering Rates of Weathering of Clean Rock Surfaces (micro-meters/1000years) Rock TypeCold ClimateWarm, Humid Climate Basalt10100 Granite110 Marble20200

28. 60 years of weathering

29. 60 years of weathering and plant growth.

30. Effect of humid climate on Cleopatra’s Needle.

31. Weathering Mass Wasting Erosion

32. The Result of Weathering

33. The End