Coastal Processes and Landforms

Erosion at the coast
This section will go into greater depth about the processes affecting coastal environments, and what landforms occur because of it. First, I'll look at erosion at the coast.

Erosion can be seen in action on cliff coastlines. It is most rapid on soft rock coastlines. The processes responsible for cliff erosion can be classified into two types:

*Those active at base of cliff (cliff-foot or marine processes, including hydraulic action, corrasion and attrition

*Those active on the cliff face (sub-aerial processes, involving the action of weathering

The patterns of erosion are influenced by a wide range of factors including:

*rock type- its resistance to wave action, its resistance to sub-aerial processes (landslides, gulleying), and its solubility.

*rock structure- the way the rock is divided by joints, bedding planes, and faults. Erosion takes place in joints, cracks and bedding planes.

*beach character- a wide beach may be protective and halt erosion even on weak cliffs. The size of the beach may vary with the seasons. The beach may shrink if erosion and sediment supply is reduced 'updrift' by sea walls or groynes. Offshore dredging may remove beach material from the coast zone.

Hydraulic Action
This is the action of breaking waves on cliffs. A storm may throw hundreds of tonnes of water against a cliff face with every breaker. The shock of the impact can loosen rocks and air trapped in joints and faults can blast the rock with extreme pressure.


Corrasion
This is the process by which pebbles and sand forced against cliffs succeed in wearing away new rock. Corrasion (sometimes referred to as abrasion) produces wave-cut notches under cliffs and, eventually, wave-cut platforms. For corrasion to continue, attrition must be effective.

Attrition
This is the process by which erosion continues to operate by grinding down cliff fall material. After hydraulic action and corrasion have eroded cliffs,the eroded material lies at the base of the cliff, forming a protective armour which is often too large for the sea to move. By grinding smaller particles against these large block, the size is eventually reduced until the sea can move them away.


Solution can also cause coastal erosion as acids in the water dissolve rock particles and minerals.