1. WEATHERING AND EROSION

2. Rock Cycle

4. WEATHERING
I. Weathering - The breakdown of rock due to exposure to the atmosphere, weather, plants, and animals.
A. Mechanical Weathering (Physical Weathering) - Rock is split or broken into smaller material without changing its composition.
B. Chemical Weathering – Process by which rocks break down as a result of chemical reactions.

5. Mechanical (Physical)Weathering
1. Ice wedging (Porus, rocks with cracks (ice heaving/Frost Action)
2. Wetting and drying (for clay containing rocks)
3. Plants (lichens, mosses, shrubs, trees)
4. Exfoliation (the peeling away of surface layers) due to the relief of pressure from rocks above it.
5, Expansion / Contraction (Temperature)
6. Abrasion- process of breaking down by means of friction

6. ABRASION

7. ABRASION BY WATER

8. Abrasion – wears down or rounds

9. ABRASION BY WIND

10. MECHANICAL WEATHERING
Was once solid rock

11. MECHANICAL WEATHERING

12. ICE WEDGING

16. PLANTS

17. EXFOLIATION

18. Exfoliation – causes rock to sheet or flake off

19. Barrel cactus – breaking through rock to grow

20. EXFOLIATION

21. WEATHERING
B. Chemical Weathering - Break down of rocks when the rock minerals are changed to different substances.

22. Chemical Weathering
1. Hydrolysis - chemical reaction with water and other substances (feldspar, hornblende, augite) these combine to form clay.
2. Oxidation - chemical reaction with oxygen and other substances. (Iron bearing substances) , (red soil in Carolina & Virgina)
3. Carbonic acid/Carbonation - Carbon dioxide dissolves in H2O to form carbonic acid. (found in soda), P,Na,Mg and Ca (forms caves)
4. Acid Rain - sulfur from cars and coal/oil plants
5. Plants/Animals (Lichens) - produce rock dissolving acids

24. CHEMICAL WEATHERING

25. Carbonation Clip

26. Details worn away by chemical weathering

27. Acid Rain

28. Oxidation

29. Hydrolysis -Reaction of any substance with water

30. Chemical Weathering- Water molecules "pull" apart a mineral (dissolve it)

31. Plants can grow on rocks and produce weak acids that can break down rock.

32. Organic Weathering
Lichen breaking down rock

33. Bird dropping weathering

34. RATES OF WEATHERING II. Rates of Weathering
1. The rocks themselves - Igneous and metamorphic most resistant, sedimentary least resistant because of pores.
2. Surface Area – More surface area = faster weathering
3. Climate - Warm and wet = chemical weathering
Cold and Dry = mechanical weathering
4. Topography

42. http://streaming. discoveryeducation. com/search/assetDetail. cfm

43. Weathering Get on the online book and go to chapter 14.
Select the visual concepts and watch the clips on physical and chemical weathering.

45. EROSION
IV. EROSION - The breakup and removal of rock by moving natural agents (gravity, glaciers, wind, water)
A. Water Erosion
1. Rain
a. Sheet wash - thin sheets of soil removed prevent by - grass, continued plowing, crop rotation, strip crop, terraces
b.Gullying - valleys in sloped land - farms
2. Running water - most effective agent of erosion
a. stream, river, creek
b. Stream abrasion - grinding away of rock from bed or bank.
c. The faster the river moves = more “stuff” it can carry

46. EROSION B. Wind Erosion - just as water; only less powerful
1. Abrasion - wearing down of particles
2.Deflation - removal of loose particles by wind - the most important effect by wind
3. Dunes - sand piled up, moved by wind
C. Glaciers – most powerful agent of erosion

47. Gullying

48. DEFLATION

50. Sheet Erosion

51. DUNES

52. Arches National Park
Wind abrasion

53. EROSION
IV. EROSION - The breakup and removal of rock by moving natural agents (rivers, glaciers, wind, water)
A. Mass movements - Earth material down a slope caused by gravity.
1. Creep - Very, Very slow down slope movement of soil. (water in soil adds to it)
a. Talus - Loose rock fragments at base of cliffs
2. Landslides - sudden movement of bedrock or loose rocks down a cliff.
3. Slumps - small landslides on hills
4. Mudflow - fast movement of water saturated clay and silt.
5. Avalanche

54. TALUS

57. Landslide – mass movement

59. What happened?
mudflow

60. LANDSLIDE

62. LANDSLIDE

63. Landslide – mass movement

64. CREEP

65. Creep

68. SLUMPS

69. SLUMPS

70. SLUMP

71. MUDFLOW

81. The Colorado River weather and eroded way for 1,000s of years

82. Brought to us by the Colorado River