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Warm-up

Warm-up. Soil and Weathering Test Review. Weathering and Erosion. Order Weathering Erosion Deposition. Weathering breaks down the rocks, erosion moves the particles, and deposition drops the sediments in another location. Badlands National Park, South Dakota. Weathering.

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Warm-up

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  1. Warm-up

  2. Soil and Weathering Test Review

  3. Weathering and Erosion Order • Weathering • Erosion • Deposition Weathering breaks down the rocks, erosion moves the particles, and deposition drops the sediments in another location. Badlands National Park, South Dakota

  4. Weathering The process in which water, ice, and heat break down rock into smaller pieces, called sediments. Arches National Park, Utah

  5. Mechanical (physical) Weathering Physical Weathering – the breakdown of rocks and minerals into smaller pieces without a change in chemical composition. • Frost Wedging and Root/Plant Wedging • Exfoliation • Abrasion

  6. Mechanical (physical) Weathering Frost Wedging - alternate freezing & thawing of water Root/plant wedging– plant roots growing into existing joints and fractures.

  7. Exfoliation- outer layers of rock get stripped away over time Abrasion- when rocks rub against each other

  8. Chemical Weathering • The breakdown of rocks and minerals into smaller pieces by chemical action. Badlands National Park, South Dakota 7 Colors Hill, Argentina

  9. Chemical Weathering • Oxidation- when oxygen unites chemically with a mineral. Ex. Rust (iron oxide) • Hydration- when water unites chemically with minerals.

  10. Rates of Weathering Climate- the average weather of a location over time (precipitation and temperature) • Surface area - If particle size goes down then weathering rate goes up

  11. Rates of Weathering Rock type and composition • Different minerals weather at different rates. • Hard rocks weather slowly • Soft rocks weather quickly

  12. Erosion – the removal and transport of weathered material by: • Wind • Gravity • Glaciers • Running water • Living Things Erosion and Deposition Deposition –The process in which sediment is dropped and comes to rest

  13. Wind Erosion– hot and dry areas especially Erosion Glacial Erosion– scrape and gouge, carry debris

  14. Erosion Rill erosion – caused when water runoff is heavy (after rainfall) Gully Erosion – removal of large amounts of soil by heavy rainfall

  15. Soil • Soil- made primarily of particles of rocks, minerals, and humus – decaying organic matter. • Horizons- The layers of soil

  16. Residual soil - Soil formed from the rock material beneath the soil. Transported soil - Soil that has been moved from its place of origin.

  17. Soil Horizons • Topsoil- (A horizon) the top layer of mature soil containing organic matter and the most weathered rock. • Subsoil - (B horizon) the layer below the topsoil made of partly weathered rock, clay sized particles, and very little organic matter. • Bedrock- (C horizon) rock layer underneath useable soil Parent Material

  18. Humus- (O horizon) dead material on top of the soil column. Rich in nutrients. Not all horizons may be present!

  19. Soil Profile: The vertical sequence of soil layers. • Soil is the result of weathering and biological activities. • Humus “improves” the soil texture and helps it to hold water. • Can take 100 years for 1 cm of soil to form!

  20. Soil Texture: classified according to % of the various sized grains: clay, silt, and sand. • Sand- any rock particle less than 2 mm but more than 0.05 mm • Silt - any rock particle less than 0.05 mm but more than .002 mm • Clay- any rock particle smaller than .002 mm

  21. 30% Clay 20% Silt 50% Sand

  22. Soil Type: Sandy clay loam

  23. Soil Types • Often classified based on climate: • polar • temperate • desert • tropical • other • Climatic conditions are the main influence on soil development

  24. Mass Movements • Creep - Slow, steady, downhill flow of loose materials – 3 cm/year • Slides - Rapid, downslope movement of layer of loose material • Mudflow - Swiftly moving mixtures of mud and water • Slump - Landslide along a curved surface • Avalanche - Landslides of snow All mass movements occur on a slope!

  25. Glacial Erosion • Glacier: large, moving mass of ice • Weight of top layers exerts downward pressure forcing snow below to recrystallize into ice

  26. If Formed in Valley: • Snow accumulation causes glacier to become heavy and to flow downhill, due to gravity • Speed affected by slope, temperature, thickness of ice and valley shape – 1mm/day

  27. Valley Glaciers • Carve out U-shaped valleys from bedrock • The deep depressions where carved out from valley called a cirques More rounded – U Shape

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