Coastal Processes
The main coastal processes are erosion, transportation and deposition. These processes work together to shape the coastline, creating a variety of momentous landforms. This section will explore exactly what these processes are and how they work with each other.
Erosion
The term erosion means the wearing away and breaking up of material. There are four main types of erosion by wave action which are explained below:
As you can see, the synonym used is CASH can be a useful way of remember all four processes.
The following diagram shows how these processes work:
- Corrasion/Abrasion - particles are thrown against the cliff face in the wave spray which wears it away
- Attrition - waves for pieces of rock to bump against each other at the shoreline making them rounder and smaller
- Solution/Corrosion - acidic sea water dissolves certain types of rock, such as chalk and limestone
- Hydraulic Action - air is forced and compressed into cracks and joints in the cliff when the wave breaks. This exerts pressure which causes the rock to become weaker and break away
As you can see, the synonym used is CASH can be a useful way of remember all four processes.
The following diagram shows how these processes work:
Erosion - Weathering
Weathering is the wearing away or breaking down of material in situ. By this, we mean that nothing is removed or taken away. Weathering of a cliff is above sea level and happens without the sea. It is referred to as sub-aerial weathering and takes several main forms:
Freeze-thaw - water resides in cracks and joints in the cliff. When the water freezes it expands, which exerts pressure on the surrounding rock. This weakens the rock, and will eventually cause material to break away
Biological weathering - animals and plant roots burrow into the rock, causing it to become weaker. People walking on top of the cliff can also cause footpath erosion
Carbonation -
The following diagram shows how these processes can work together alongside erosion to break down the cliff.
Both these processes can lead to cliff retreat and the formation of erosional landforms.
Freeze-thaw - water resides in cracks and joints in the cliff. When the water freezes it expands, which exerts pressure on the surrounding rock. This weakens the rock, and will eventually cause material to break away
Biological weathering - animals and plant roots burrow into the rock, causing it to become weaker. People walking on top of the cliff can also cause footpath erosion
Carbonation -
The following diagram shows how these processes can work together alongside erosion to break down the cliff.
Both these processes can lead to cliff retreat and the formation of erosional landforms.