Coastal processes and erosion.

Erosion

  • Corrasion (abrasion) is caused by large waves hurling beach material against a cliff.
  • Attrition is when waves cause rocks and boulders on the beach to bump into each other and to break up into small particles.
  • Corrosion (solution) is when salts and other acids in seawater slowly dissolve a cliff.
  • Hydraulic pressure is the force of waves compressing air into cracks in a cliff.

Coastal erosion is the wearing away of land and the removal of beach or dune sediments by waveaction, tidal currents, wave currents, or drainage (also beach evolution). Waves, generated by storms, wind, or fast moving boats, cause coastal erosion, which may take the form of long-term losses of sediment and rocks, or merely the temporary redistribution of coastal sediments; erosion in one location may result in accretion nearby. The study of erosion and sediment redistribution is called 'coastal morphodynamics'. It may be caused by hydraulic action, abrasion, impact and corrosion.


Primary factors

The ability of waves to cause erosion of the cliff face depends on many factors.
The hardness or ‘erodibility’ of sea-facing rocks is controlled by the rock strength and the presence of fissures, fractures, and beds of non-cohesive materials such as silt and fine sand.

Erodedcliffpacifica.jpg



Secondary factors

  • Weathering and transport slope processes
  • Slope hydrology
  • Vegetation
  • Cliff foot erosion
  • Cliff foot sediment accumulation
  • Resistance of cliff foot sediment to attrition and transport.


Animation

For an anination of wave erosion, click here.

Sean