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The nature of sea cliff erosion
The principle causes of erosion of cliffs can be related to at least four stages
in slope failure and movement of the material namely:
Some of the processes involved at each stage include:
DETACHMENT - Sub-surface weathering (water seepage, alternative freezing
and thawing of water in the ground or between joints in the rock), erosion of
underlying rocks, chemical weathering (including the action of salt spray);
TRANSPORT - lubrication between geological layers (through the liquefaction
of clays and other easily mobilised material), erosion by rainwater (along streams
and gullies);
DEPOSITION ON THE FORESHORE - mass movement by slumping and sliding,
rock fall;
REMOVAL OF DEBRIS - long shore drift, wave and tidal action, storms
(Lee et al. 2001).
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Guidance: The erosion described above represents the main processes
taking place that cause major changes to cliff morphology. Much smaller
scale processes including 'soil creep' are also important on steeper rock
slopes. These help to maintain an open vegetation mosaic on an essentially
stable geological structure.
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References
Lee, E.M., Brunsden, D., Roberts, H., Jewell, S. & McInnes, R.
2001.
Restoring biodiversity to soft cliffs.
English Nature Research Report, 398
English Nature.
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