1. Types of Weathering
© Copyright   M. J. Krech. All rights reserved.

2. Mechanical Weathering

3. Disintegration – breaks down into smaller pieces, no new substance

4. Frost Action or Ice Wedging

5. Frost Action Ice expands when frozen and cracks rocks
Causes pot holes in winter
Happens where the temperature goes both above and below the freezing point of water
Called Ice Wedging

7. Abrasion

8. Wind blows sand which wears away cliffs
Wind Abrasion
Wind blows sand which wears away cliffs

9. Water Abrasion
Water carries rocks along in streams & rivers which collide and become smoothed into rounded river rocks

10. Gravity

12. Landslides Gravity pulls rocks loose
They break apart as they fall downhill

13. Organic Activity: Root Pry

14. Root Pry Roots expand as they grow and crack rocks.
Other organic activity
Ants, woodchucks, and worms dig holes that let in water that causes weathering.

17. Wetting and Drying

18. Rocks that contain CLAY swell and shrink as they absorb water then dry out, thus cracking the rocks

20. Joint Sheeting

21. As top soil erodes, rock layers below expand and crack into layers
Called EXFOLIATION when large sheets of rock break away at the surface

23. Chemical Weathering

24. Decomposition – breakdown into new substances

25. Hydrolysis

26. The chemical action of water with other substances
Example: Feldspar turns into clay

27. Feldspar +Water = Clay
Feldspar
A Clay Cliff

28. Plant Acids

29. Acids given off by lichens and mosses eat at rocks

31. Sulfuric Acid

32. ACID RAIN: Sulfuric acid causes blurred words on gravestones and monuments

33. Photo taken 100 years ago
Photo taken recently

34. Both of these are Civil War headstones.
Why has one weathered more?
1865
1862

35. Oxidation

36. RUST caused by oxygen combining with iron-bearing minerals in rocks causes red bands on limestone cliffs

39. Carbonation

40. Carbon dioxide combines with water to form carbonic acid which eats away layers of limestone rock
Forms CAVES; KARST TOPOGRAPHY

43. Karst Topography
A type of landscape in rainy regions where there is limestone near the surface, characterized by caves, sinkholes, and disappearing streams.
Created by chemical weathering of limestone

44. Features of Karst: Sinkholes

45. Features of Karst: Caves

46. Features of Karst: Disappearing Streams

47. The end.
© Copyright   M. J. Krech. All rights reserved.