Which marine processes shape our coastline?

Step 1: Read the key terms list below. Make sure that you understand and could give a definition to somebody else.

Step 2: Read the information in Section 1. Answer the exam questions here 7.3 exam questions and complete the short quiz below

Coastal unit key terms

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Key terms:

Hydraulic action, corrasion, abrasion, solution, attrition – Below.

Longshore drift – The process of transporting sediment along a coastline in a zig zag pattern. Caused by waves approaching the beach at an angle.

Section 1: Coastal erosion – Use this information for Questions 2, 3, 6

Destructive waves wear away the coast. There are 5 main processes of coastal erosion:

  1. Hydraulic action – This is where the sheer force of the wave power causes trapped air into holes and cracks in the rock. This eventually causes the rock to break apart.
  2. Corrasion – This is where small pieces of rock are picked up and thrown against the cliffs by the sea. They scrape and gouge the rock.
  3. Abrasion – Pebbles have a sand papering effect, grinding over rocks, causing them to become smooth.
  4. Solution – Rocks such as chalk and limestone are vulnerable to being dissolved by seawater.
  5. Attrition – This is where rock fragments carried by the sea collide with one other,


Coastal erosion results in various landforms which you can find out more about here

Section 1: Coastal transportation – Use this information for Question 1

The size and amount of sediment transported by the sea depends on the strength of waves and tidal currents.

4 types of coastal transportation:

  1. Solution – material is dissolved and carried by the water.
  2. Traction – Large pebbles and rock fragments are rolled along the sea bed,
  3. Suspension – Sediment that does not dissolve is suspended within the water and carried.
  4. Saltation – Particles that are too heavy to be transported through suspension bounce or hop along the sea bed.


Longshore drift – Use this information for Questions 4, 7

Longshore drift diagram

Longshore drift diagram

  1. Beach
  2. Sea
  3. Current direction
  4. Incoming waves
  5. Swash
  6. Backwash

Longshore drift is the process of sediment movement along a beach in a zig-zag pattern. Waves approach at an angle causing the zig zag pattern.


Section 1: Coastal deposition – Use this information for Question 5

Coastal deposition happens in areas along the coast where the flow of water has slowed down. The water does not have enough energy to transport or carry the sediment and so it is deposited (dropped). Coastal deposition results in various landforms which you can find out more about here