Marine processes and sub-aerial processes

The marine erosion processes cause cliff retreat from the base of the cliff. Sub-aerial processes such as weathering and mass movement cause cliff retreat from the top of the cliff. Weathering and mass movement often provide the sediment for the marine erosion processes such as abrasion and attrition.

Weathering is the altercation and breakdown of rock by physical, chemical and biological processes. There are five main types of weathering including chemical, physical and biological weathering:

1. Freeze-thaw
2. Root penetration
3. Oxidation
4. Salt crystallisation
5. Raindrop action

1. Freeze-thaw is when water moves into cracks in the rock during the day. During the night, temperatures drop and the water freezes hence it expands and widens the crack in the rock. When this happens continuously, the rock weakens and begins to break apart.

2. Root penetration is the growth of roots and vegetation into cracks in the rock. They expand the cracks and cause pieces to break off.

3. Oxidation occurs when there is iron present in the rock. This process occurs and causes the rock to rust.

4. Salt crystallisation occurs when salt crystals penetrate the exposed rock face.

5. Raindrop action can affect the rock in two ways: the heavy rain can physically alter the rock's shape whilst its acidity can chemically break it down.