Processes affecting river valleys

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  • Created by: Niamh
  • Created on: 29-04-14 08:56
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  • Processes affecting river valleys
    • Erosion is the wearing away of the banks and bed of a river. These processes help remove material
      • A river can erode laterally or vertically
    • Weathering is the wearing away of the river valley sides
      • Takes place in situ but the weathered material may move due to gravity and form scree slopes
      • Examples
        • 1. Physical - Freeze-thaw - water freezes and the crack is widened
        • 2. Chemical - Acid Rain - rain water is slightly acidic, the acid reacts with minerals in the rocks and dissolves them
        • 3. Biological - roots grow into cracks and split rocks apart
    • Mass movement
      • Over time the sides of a river valley become less steep as material is moved from the top to the bottom
        • 1. Soil creep - soil particles move down the slope under influence of gravity
        • 2. Slumping - the river erodes the bottom of the valley slope making it steeper. Material above slides downwards, particularly if it is saturated with rain water
        • 3. Rock fall - rocks at the top of valley are affected by freeze-thaw. Parts of the rock break off and move down the slope

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