Wave-cut platform formation

• What is our example

  Selwicks Bay
• What happens at the wave cut notch

  When high and steep waves break the foot of a cliff their energy and erosive action is concentrated into a small area of the rock face. Its a small indent at the base of a cliff formed when a cliff is undercut by the sea
• The development of the wave cut notch

  When a wave breaks on a cliff, all the wave energy is concentrated on one specific point and this section of the cliff experiences more rapid erosion via abrasion
• Recession of the cliff

  A gently sloping (less than 4 degrees) relatively smooth rock platform at the base of cliffs
• Why is the length of the platform limited

  The platform continues to grow and as it does, the waves break further and further out to sea, and they have to travel across more platform before it reaches the cliff line. This dissipates the wave energy, reducing the rate of erosion of the cliffs
• Inputs of sediment and energy

  Wind and waves:

  The waves that affect this stretch of coastline are often driven by northern Atlantic storms that pass into the Northern sea.
• Controls on the coastline

  Selwicks bay coastline is made up of resistant chalk which forms steep cliffs and slows erosion. However, cracks in the chalk allow water to infiltrate making it vulnerable to weathering and erosion along weak points.
• Wave-cut platform formation


  - Marine process of erosion including is concentrated at the base of a cliff between the mean high tide and low tide.

  - This results in undercutting of the cliff to form wave cut notch. Over time the continual undercutting causes increased stress and tension in the cliff until eventually it collapses.

  - The sediment at the base of the cliff is eroded by attrition and transported away by marine processes of transport.

  - As these processes are repeated, the cliff retreats leaving at its base a gently sloping wave cut platform.

  - As the cliff continues to retreat the widening platform means that the incoming waves break further out to sea.

  - This will reduce the amount of energy in the waves and there will be less erosion of the cliffs, for this reason it is thought that wave cut platforms cannot extend beyond 500m out to sea.