Mass Movement in Glaciated Landscapes

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Mass Movement

  • Mass Movement occurs when the forces acting on slope material (mainly the resultant force force of gravity) exceed the forces trying to keep the material on the slope (predominantely friction)
  • In glacial landscape systems, the most significant mass movement processes are those acting on steep slopes, which lead to the addition of material to the glacier below, loading it with debris and providing the tools for abrasion.
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Rock Falls

  • On surfaces of 40° or more, especially if the surface is bare, rocks may become detatched from the slope by physical weathering processes. These then fall to the foot of the slope under gravity. Transport processes may then remove this material, or it may accumulate as a relatively straight, lower angled scree slope.
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Slides and Slumps

  • Slides- These may be linear, with movement along a straight line slip plane, such as a fault or a bedding plane betrween rock layers, or rotational with movement taking place along a curved slip plane
  • Slumps- Rotational slides are also known as slumps. In glacial landscape systems, slides may occur due to steepening or undercutting of valley sides by erosion at the base of the slope, adding to the downslope forces. Slumps are common in weak rocks, such as clay, which also become heavier when wet, adding to the downslope forces.
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Controlling Factors

  • The angle of the slope (the gradient is the controlling factor)
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