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Weathering and Erosion

Weathering and Erosion. Weathering. The breakdown of the materials of the Earth’s crust into smaller pieces, due to exposure to the atmosphere. Mechanical (Physical) Weathering. The process by which rocks are broken down into smaller pieces, without changing its composition.

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Weathering and Erosion

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  1. Weathering and Erosion

  2. Weathering • The breakdown of the materials of the Earth’s crust into smaller pieces, due to exposure to the atmosphere

  3. Mechanical (Physical) Weathering • The process by which rocks are broken down into smaller pieces, without changing its composition. • Types of mechanical weathering: • Frost (ice) heaving and frost (ice) wedging • Plant roots • Wetting and drying (swelling/shrinking) • Friction and impact • Burrowing of animals

  4. Frost (Ice) Wedging

  5. Frost (Ice) Heaving

  6. Plant Roots

  7. Friction and Repeated Impact

  8. Burrowing of Animals

  9. Chemical Weathering • The process that breaks down rock through chemical changes. • The agents of chemical weathering • Water • Oxygen • Carbon dioxide • Living organisms • Acid rain

  10. Water • Water weathers rock by dissolving it • Water combines with some minerals (eg. Feldspar) to produce clay • Chemical reaction of water with other substances is called hydrolysis

  11. Oxygen • Iron combines with oxygen in the presence of water in a processes called oxidation • The product of oxidation is rust

  12. Carbon Dioxide • CO2 dissolves in rain water and creates carbonic acid • Carbonic acid easily weathers limestone and marble

  13. Living Organisms • Lichens that grow on rocks produce weak acids that chemically weather rock • Acids are formed when plants and animals decay

  14. Acid Rain • Compounds from burning coal, oil and gas react chemically with water forming acids. • Acid rain causes very rapid chemical weathering

  15. Rate of Weathering Several factors determine the rate at which rock weathers: • Wet vs. dry climates • The composition of the rock (what minerals it contains) • The amount of surface area exposed

  16. Bryce Canyon (Utah) -rocks of different resistance weather at different rates.

  17. Erosion • The process by which water, ice, wind or gravity moves fragments of rock and soil.

  18. Water Erosion • Rivers, streams, and runoff

  19. Ice Erosion • Glaciers

  20. Wind Erosion

  21. Mass Movements • Landslides, mudslides, slump and creep landslide clip.mpeg

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