Lithosphere

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Lithosphere

• Topic 3 Slopes

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There are five main types of mass movement you
need to know

• Soil Creep
• Rock and Debris Fall
• Rock and Debris Slump
• Slump (rotational slip)
• Mudslide

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Soil Creep

• Found where the climate is damp, and occurs on
  gentle slopes where there is vegetation cover. It
  happens quite slowly and is caused in various
  ways

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Rock and Debris Fall

• Weathering of the rock face can break off
  cliff material. Also, if the lower stratum is
  weak, it can be eroded, leaving the upper stratum
  unsupported. It then collapses.
• Found in glacial and limestone scenery.

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Rock and Debris Slide

• Where strata is dipping downhill, water can
  lubricate the subsoil so that the layers of
  rock or soil slide downhill.
• Many sea cliffs are subject to such slides.

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Slump (rotational slip)

• This can occur in weak rock strata, e.g. where
  sandstone lies on top of clay. Rainwater acts
  almost as a lubricant between the surfaces
  causing them to slump.
• Common where costal erosion causes instability.

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Mudslide

• Where the subsoil is impermeable, a period of
  heavy rain will result in water being trapped in
  the soil, turning it into unstable mud.
• Steep-sided valleys often suffer mudslides.

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