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Weathering Soils Mass Movement

Weathering Soils Mass Movement. Chapter 8. TOPIC 1. Weathering - The break-up of rock due to exposure to the atmosphere. Depth of rock a factor. GRANITE - Formed deep in Earth Factors on rock - Rain, wind, gravity, Erosion - Agents also include glaciers, waves, currents. Mechanical

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Weathering Soils Mass Movement

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  1. WeatheringSoilsMass Movement Chapter 8

  2. TOPIC 1 • Weathering- The break-up of rock due to exposure to the atmosphere. • Depth of rock a factor. • GRANITE - Formed deep in Earth • Factors on rock - • Rain, wind, gravity, • Erosion - Agents also include glaciers, waves, currents.

  3. Mechanical Break or split; No composition change “Disintegration” Chemical Water & water Vapor important agents. Substances changed “Decomposition” Weathering Types

  4. Mechanical Weathering • Frost Action - • Wetting & Drying - • Plant/Animal Actions- • Overlying rock layer loss

  5. Mechanical Weathering • Frost Action - • Water takes up 10% more space when frozen. • “Frozen Pop” • “Ice Wedging” - Northern United States • Occurs in porous rocks. • Bare mountain tops (FIGURE 8.1) • Potholes (roads) • Ice Heaving

  6. Mechanical Weathering • Wetting & Drying • Break up rocks that contain CLAY • Swelling & Shrinking • Shale an example

  7. Mechanical Weathering • Plants/Animal Actions • Lichens - Figure 8.2 • Roots wedge cracks apart • Digging Animals • Holes allow access for water to erode bedrock

  8. Mechanical Weathering • Rock Layer Loss • Exfoliation • (Figure 8.3)

  9. Chemical Weathering • Hydrolysis- Minerals unite with water • CLAY a product of hydrolysis. • Oxidation - Oxygen and other substances Chemically Combine. • Carbonic Acid- CO2 dissolved in water • Erodes Calcite • Limestone Caverns • Gypsum & Halite are eroded by this too.

  10. Weathering Rate • Rock Types • Climate where rock is located. • Wet Climates • Dry Climates • Variable Climates

  11. Earth MattersAcid Weathering • Marble statues • Increased rusting & corrosion • Why would National Park Service people be interested in studying the effects of Acid rain?

  12. Soil Conservation Topic II

  13. Weathering Results • Soil Formation • Sand, Clay, Silt known ingredients • Parent Material • Residual Soil - bedrock as parent material. • Transported soils- Caused by what?

  14. SOIL PROFILE • A, B, C, Bedrock layer. • Horizons • Topsoil - “A Horizon” • Gray to black in color • Humus from decaying of plants • B Horizon - Clay is washed to this level • Red / Brown from iron oxides • C Horizon - Rock fragments

  15. Factors on Soil • Climate • Mature soils in Wet Tropical places similar. • Tropical Soil - Formed in constant high temp. and heavy rainfall. Chemical weathering faster. • Grassland Soil - Profile > 1 meter thick • Very Fertile due to Organic material. Figure 8.12

  16. Factors On Soil • Forest Soils - Cool season, hardwoods / evergreens. NOT very fertile. • Desert Soil - Profile seldom over 3cm. CALCIUM RICH. Fertile when watered!!! • Arctic Soils - High elevations/latitudes, boggy, PermaFrost

  17. Mass Movement • Steep slopes weathering > gentle slopes • Creep - Noticed by its effects. Fence posts • Talus - Rock slope at cliff base. 40 deg.or < • Avalanche - Landslide of rock, snow, soil. • Slumps - Cliffs, steep hills, roadsides • Collbran area • Mudflow - Water saturated Clay & Silt

  18. Soil Conservation • Windbreaks • Contour Farming • Strip Cropping Figure 8.15 page 143 • No-till - All processes done at once

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