Coastal Erosion Processes      Back

Types of coastal erosion                    Factors affecting the rates of coastal erosion

Types of Coastal Erosion

There are 6 main types of erosion processes in action at the coast

1. Abrasion (corrasion) - this is where breaking waves hurl rock fragments against the cliffs gradually wearing away the cliff material.

2. Hydraulic Pressure - this is where erosion occurs due to the pressures exerted by breaking waves as air trapped in cracks in the cliff is compressed by the water. This compression and sudden release gradually forces the cracks apart.

3. Solution (corrosion) - this is where salt water can act to dissolve some chemicals in the rocks, for example in limestone, calcium carbonate is dissolved, weakening the rock.

4. Attrition - as rock fragments are swirled around by waves they are gradually broken down as they hit against each other.

5. Wave scouring - waves breaking at the base of the cliffs swirl around the base and result in the removal of loose rock.

6. Wave Pounding - breaking down of the cliff face due to the sheer force of the wave which can exert upwards of 30 tonnes / m2 when crashing on the cliffs. 

As well as the action of the sea causing the erosion of the cliffs, weathering processes and human activity can also be responsible for affecting the wearing away of the rock.

Weathering Processes Human Activity
Freeze-thaw processes (as water freezes and thaws in cracks in cliffs, the expansion and contraction forces the rock open, making them more susceptible to the action of waves).
Surface runoff / Rainfall - water running down the face of cliffs, either from surface runoff from above or from rainfall can result in solution
Biological weathering - burrowing organisms and roots of vegetation forces open cracks, making them more susceptible to wave erosion)
Pressure on cliffs (construction work)

 

Sea Defences (although designed to reduce erosion - in some instances (e.g. the use of groynes) can increase erosion by starving down stream areas of sediment)

 

Factors affecting the rate of coastal erosion

 

Remember:

Erosion is the breakdown and removal of rock

Weathering is the break down of rock (which can make it more susceptible to erosion)

 

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