The Living World
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Coastal Processes: Erosion

Erosion is probably the most influential process that changes our coastline. It is best defined as ‘the wearing away of rock along the coastline and the transportation of this material by natural forces’. The eroded material is typically carried away by destructive waves.

  • Destructive waves have a strong backwash which contributes to erosion

However, erosion can devastate coastal regions, wearing away at cliff faces and damaging coastal habitats that wildlife depend on. Properties positioned on eroding coastlines are at risk and will ultimately have to be relocated or removed from the coastline.

Erosion is also responsible for the creation of coastal features such as bays which remain distinctive aspects of coastlines around the UK.

There are four types of erosion to consider, and it’s important that you’re aware of the distinction between them:

  • Hydraulic Action
  • Abrasion
  • Attrition
  • Solution

Hydraulic Action

Hydraulic action is the power of destructive waves, which smash into the rock. The waves come with a long fetch, and a high height. They build up a great deal of energy on their journey to the coast. As the waves smash against the cliff, air becomes compressed in the cracks of the rock, causing the rock to break apart.

Abrasion

Abrasion is the process of material grinding along the rock like sandpaper, which smooths the rock over time. The material is carried by the waves and hurled at the rock face.

Attrition

Attrition primarily occurs within the body of the sea rather than directly against cliff faces. However, it plays a significant role in coastal erosion.

As waves carry rocks and pebbles, they knock against each other, causing them to break apart and become progressively smaller, rounder and smoother over time.

This process reduces the size of the material, which can decrease the abrasive force that such materials exert on the cliffs when propelled by waves. Therefore, although attrition happens away from the cliff face, it indirectly influences the rate of coastal erosion by changing the characteristics of the sediment that interacts with the coastline.

  • Attrition contributes to the formation of sand

Solution

Solution, also known as chemical weathering, is the dissolving of certain types of rocks by seawater. Weaker rocks, such as limestone, are vulnerable to this, whereas other rocks are stronger and will resist solution far better.

Key Terms

TermDefinition
Destructive WavesWaves that remove material from the beach due to their weak wash and stronger backwash. 
BaysAn inlet of coastline where the land curves inwards. The land has recessed due to erosion of weaker, vulnerable rock. 
LimestoneA hard sedimentary rock that has chemical reactions with water and carbon dioxide, which wear the rock away. 

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