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WEATHERING AND EROSION

WEATHERING AND EROSION. Rock Cycle. 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.

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WEATHERING AND EROSION

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  1. WEATHERING AND EROSION

  2. Rock Cycle

  3. 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. ChemicalWeathering – Process by which rocks break down as a result of chemical reactions.

  4. 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

  5. ABRASION

  6. ABRASION BY WATER

  7. Abrasion – wears down or rounds

  8. ABRASION BY WIND

  9. MECHANICAL WEATHERING Was once solid rock

  10. MECHANICAL WEATHERING

  11. ICE WEDGING

  12. PLANTS

  13. EXFOLIATION

  14. Exfoliation – causes rock to sheet or flake off

  15. Barrel cactus – breaking through rock to grow

  16. EXFOLIATION

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

  18. 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

  19. CHEMICAL WEATHERING

  20. Carbonation Clip http://www.youtube.com/watch?v=Sw58a4yjFtc

  21. Details worn away by chemical weathering

  22. Acid Rain

  23. Oxidation

  24. Hydrolysis -Reaction of any substance with water

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

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

  27. Organic Weathering Lichen breaking down rock

  28. Bird dropping weathering

  29. 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

  30. http://streaming.discoveryeducation.com/search/assetDetail.cfm?guidAssetID=6B1E329E-5A77-4B36-BFA9-1D307F75441Chttp://streaming.discoveryeducation.com/search/assetDetail.cfm?guidAssetID=6B1E329E-5A77-4B36-BFA9-1D307F75441C

  31. Weathering • Get on the online book and go to chapter 14. • Select the visual concepts and watch the clips on physical and chemical weathering. http://my.hrw.com/tabnav/controller.jsp?isbn=003036339x

  32. 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

  33. 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

  34. Gullying

  35. DEFLATION

  36. Sheet Erosion

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