Coastal rock platforms and cliffs are the product of wave erosion
“Coastal rock platforms and cliffs are the product of wave erosion”. Wave erosion is the process where by the actions and movement of the sea causes a reduction to sediment or rock. Examples of wave erosion will vary from shoreline to shoreline examples of erosion techniques though can be: Æ Wave pounding- waves breaking at the foot of the cliff or shoreline can generate shockwaves upto 30 tonnes per sq m, which can cause the gradual destabilisation of the cliff. Æ Hydraulic pressure- this is when a parcel of air is trapped and compressed either in a crack within the cliff or between a breaking wave and a cliff. Then the resultant increase and change within pressure can over time weaken and break off pieces of rock or damage sea defences. Æ Abrasion/ corrasion- this is the wearing away of the cliffs by sand, shingle and boulders hurled against the cliffs by the wave movement. This is the most effective erosion process and is most rapid on coasts exposed to storms waves. Æ Attrition- rocks and boulders already eroded from the cliffs are broken down into smaller more rounded particles Æ Corrosion/solution- this is the dissolving of limestone in particular, by the chemical compound of the sea (carbonic acid) There are also many factors which can effect the rate of erosion; Æ Rock type- the type of rock and structure does differ greatly the erosion process. A soft rock at the base of a cliff will erode faster and will cause wave cut notches which will under stress collapse. Also bays are formed by the deposition of soft rock between hard rock. The soft rock erodes quicker than the hard rock so forms a bay which is then protected by the hard rock acting as a headland ÆWave steepness- very steep waves are more destructive than gentle constructive waves. Æ Depth of sea and length of fetch- a steep shelving beach creates steeper more destructive waves, equally the longer the fetch the more energy a wave can pick up from the wind so too increasing the potential energy released.