Costal erosion

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  • Created by: Natalie
  • Created on: 24-03-14 19:05

1. Biological weathering

  • frequent cycle of wetting and drying are common on shore. Rocks rich in clay expand when wet and contracts when dry- causes cracks and breakdown
  • water percolates into cracks in the rock, when it freezes it expands in volume by 10%- exerting stress and forces cracks to widen. Rocks are broken away and collected at base of cliff (scree). Fragments are picked up by sea and use in further erosion
  • plant root can prise rocks apart on cliffs where they grow, creating small cracks which thicken and deepen with age. Birds, animal, and marine organisms dig burrows in cliff
  • when saltwater enter a rock, it is often evaporated, leaving behind salt crystals. These crystals grow larger and exert stress onto rock- causing it to break apart. Salt is also capable of corroding rock
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2. Soil Creep

  • individual rock fragments fall off a cliff face, due to freeze thaw
  • rapid movement of rock down a side plane
  • slow downhill movement of individual soil particles when the ground is saturated.
  • saturated soil flows downhill, triggered by heavy rain

3. Solution

  • sea water contains weak acids which work to slowly dissolve carbonated rocks such as limestone
  • the already eroded materials are eroded down further as the sediment knock together in the sea
  • breaking wave traps air as it hits cliff face. Air is forced into cracks in rock face, creating pressure at this point. As wave retreats, pressure is released. Overtime this weaken the cliff face, and huge chunks of cliff can break off due to force o
  • the sea hurls already eroded material (sand, shingle, boulders) against cliff face. This breaks down the rock on the cliff face

4. Rotational Slip

  • soft rock overlying hard rock is saturated by rain. Soft rock slumps downwards over hard rock
  • rapid movement of rock down a side plane
  • saturated soil flows downhill, triggered by heavy rain
  • movement of individual soil particles when the ground is saturated.

5. Hydraulic action

  • the already eroded materials are eroded down further as the sediment knock together in the sea
  • sea water contains weak acids which work to slowly dissolve carbonated rocks such as limestone
  • breaking wave traps air as it hits cliff face. Air is forced into cracks in rock face, creating pressure at this point. As wave retreats, pressure is released. Overtime this weaken the cliff face, and huge chunks of cliff can break off due to force o
  • the sea hurls already eroded material (sand, shingle, boulders) against cliff face. This breaks down the rock on the cliff face

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