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Weathering and Erosion

Weathering and Erosion. Weathering. The breakdown of the materials of Earth’s crust into smaller pieces. Mechanical Weathering. Process by which rocks are broken down into smaller pieces by physical means. Types of Physical weathering Ice wedging Plant roots

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Weathering and Erosion

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  1. Weathering and Erosion

  2. Weathering • The breakdown of the materials of Earth’s crust into smaller pieces.

  3. Mechanical Weathering • Process by which rocks are broken down into smaller pieces by physical means. • Types of Physical weathering • Ice wedging • Plant roots • Animal activity (burrowing, moving soil) • Abrasion • Exfoliation

  4. Ice Wedging

  5. Ice Wedging

  6. Plant Roots

  7. Animal Activity

  8. AbrasionThe scraping of materials together

  9. Exfoliation • As pressure reduces on exposed rock, the granite expands, resulting in long curved cracks and layers that peel away from the rock

  10. Chemical Weathering • The process that breaks down rock through chemical changes. • The types of chemical weathering • Carbonation • Hydrolysis • Oxidation

  11. Hydrolysis • The interaction of water with other substances to weather rock

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

  13. Carbonation • CO2 dissolves in rain water and creates carbonic acid • Carbonic acid easily weathers limestone and marble

  14. Carbonation, Continued • Chemical weathering of limestone, breakdown of calcite • Results in Karst Topography - A type of landscape in rainy regions where there is limestone near the surface, characterized by caves, sinkholes, and disappearing streams.

  15. Features of Karst: Sinkholes

  16. Features of Karst: Caves

  17. Features of Karst: Disappearing Streams

  18. Living Organisms

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

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

  21. Water Erosion • Rivers, streams, and runoff

  22. Ice Erosion • Glaciers

  23. Wind Erosion

  24. Mass Movements (Gravity) • Landslides, mudslides, slump and creep, talus landslide clip.mpeg

  25. Talus • Rocks at the base of a slope deposited by gravity

  26. Rates of Weathering How quickly or slowly a rock weathers and erodes depends on several factors: Rock Composition Exposure Climate Topography Human Activity

  27. Rock Composition Some rocks are more resistant to weathering. For example, rocks comprised of quartz are more resistant to weathering since quartz is so stable, having crystallized last from the magma chamber.

  28. Climate

  29. Human Activity Mining, Construction, Transportation, Recreational activities all contribute to wearing away and eroding rocks

  30. Topography The elevation and slope of the land surface affects its rate of weathering, for example: • Colder temperatures at higher elevations, more ice wedging • Low elevations – more erosion by wave action • Steep slopes more affected by gravity

  31. Exposure • The more rock exposed, the more weathering can occur, so the rate of weathering increases.

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