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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

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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 • Organic activity- plants and animals (Plant roots, Animal activity burrowing, moving soil) • Abrasion • Exfoliation

  4. Ice Wedging

  5. Plant Roots (organic activity)

  6. Animal Activity (Organic activity)

  7. AbrasionThe scraping of materials together

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

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

  10. Hydrolysis • The interaction of water with other substances to weather rock- important in soil formation

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

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

  13. Carbonation, Continued • Chemical weathering of limestone, breakdown of calcite • Results in Karst Topography - A type of landscape characterized by caves and sinkholes.

  14. Features of Karst: Sinkholes

  15. Features of Karst: Caves

  16. Features of Karst: Disappearing Streams

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

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

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

  24. 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.

  25. Climate

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

  27. 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

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

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