Mechanical (physical) Weathering

2. Mechanical (physical) Weathering • The process of breaking down sediment without changing the rocks chemical composition. • Frost wedging

3. Physical Weathering

4. Biological activity (Mechanical Weathering) –(sometimes chemical) Tree roots splitting rock

5. Biological activity

6. Exfoliation (Mechanical Weathering) • Uplift of under rock causes the top hard rock, like granite, to split into layers.

7. Thermal Heating & Contraction

8. Chemical Weathering • The transformation of rock into one or more new substances.

9. Oxidation

10. Chemical Weathering • Oxidation : Elements reacting with Oxygen ex. (Rust)

12. Hydrolysis

13. Feldspar +Water = Clay Feldspar A Clay Cliff

14. Acids

15. Lichen – Plant Acid

16. Sulfuric Acid & Carbonic Acid

17. Acids (chemical weathering) • Old tombstones made of marble will weather due to the Carbonic Acid that is in rainwater.

18. Dissolution • Dissolving a rock in water

19. Carbonation

21. What can affect Mechanical and Chemical Weathering? Dissolving candy!!!! – I need a volunteer

22. Where does chemical weathering occur the fastest???????????? • Warm and Moist!!!!!! • Tropical rainforest

23. Where does mechanical weathering occur the fastest??? • Wet & temperate(warm day / cold night) • Frost Wedging!!!!! Buffalo, NY

24. Erosion – The process of moving weathered sediments from one location to another.

25. The four major Agents of Erosion are:

26. Gravity (Mass Movement)

28. Running Water

31. Wind

33. Glaciers

34. Types of Mass Movement (Gravity)

35. Water erodes more sediments than any other agent of erosion, due to its great energy of motion.

36. Deposition When water flows downhill or wind slows down it loses energy of motion, & drops its sediments. Large Sediment Med Sediment Small Sediment http://www.classzone.com/books/earth_science/terc/content/visualizations/es1303/es1303page01.cfm?chapter_no=visualization

37. Mass Movement • Gravity causes loose materials to move down a slope. When gravity alone causes materials to move down slope this erosion is called Mass Movement.

38. Mass Movements: Five Main Types

39. Slump • occurs when loose materials or rock layers slip downward as one large mass. It happens because the material under the slump weakens.

41. Creep • occurs when sediments slowly move downhill. As the ground freezes, small sediments are pushed up by the expanding water in the soil. As it thaws, the sediments fall down slope, often less than a millimeter at a time.

42. Rockslides • occur when large blocks of rock break loose from steep slopes and tumble quickly to the bottom. • Fastest form of Mass Movement Talus

43. Mudflows • usually occur in relatively dry areas where weathering forms thick layers of dry sediments. When heavy rains or rapid ice thawing happens, water mixes w/ the sediments & forms a thick mud. Gravity causes this mud to flow downhill.

44. All types of Mass Movement happen where there are slopes. All are more likely to happen after a heavy rain because water makes the sediments heavier & slippery.

45. Wind Erosion

46. Areas most prone to wind Erosion

47. Deflation • wind picking up and moving small sediments such as clay, silt, and sand.

48. Sediment Transport by Wind

49. Abrasion • wind making sand grains roll and skip, bumping into other grains and rocks. The surfaces they strike become pitted and polished when small fragments are broken off. (sandblasting) Glen Canyon, AZ