EROSION PROCESSES´╗┐Erosion is the wearing away of the land by material carried by rivers, glaciers, waves and the wind.external image Coastal_Erosion.gif

external image Rate_of_erosion.gif

There are 4 types of erosion:

1) Hydraulic action:

Hydraulic action is a form of erosion caused by the force of moving water currents rushing into a crack in the rock face. It is strong enough to loosen sediment along the river bed and banks. The water compresses the air in the crack, pushing it right to the back. As the wave retreats, the highly pressurised air is suddenly released with explosive force, capable of chipping away the rockface over time.
external image wlp_coast1.gif
2) Abrasion:

Abrasion occurs when waves break on cliff faces and slowly erode it. As the sea pounds cliff faces it also uses the scree from other wave actions to batter and break off pieces of rock from higher up the cliff face which can be used for this same wave action and attrition.

cliff.jpg
cliff.jpg


3) Attrition:

Attrition occurs when waves causes loose pieces of rock debris to collide with each other, grinding and chipping each other, progressively becoming smaller, smoother and rounder. Scree also collides with the base of the cliff face, chipping small pieces of rock from the cliff or have a abrasion effect, similar to sandpapering.


4) Solution:

Solution weathering occurs when the sea's pH corrodes rocks on a cliff face. Limestone cliff faces, which have a high pH, are particularly affected in this way. Wave action also increases the rate of reaction by removing the reacted material.


external image Bays_Headlands.png
http://www.bbc.co.uk/schools/gcsebitesize/geography/coastal/coastalprocessesrev3.shtml
http://cgz.e2bn.net/e2bn/leas/c99/schools/cgz/accounts/staff/rchambers/GeoBytes/GCSE%20Revision/Unit%201/Coasts/Coastal%20Erosion/CoastalErosion.htm
http://en.wikipedia.org/wiki/Coastal_erosion#Hydraulic_action