Coastal erosion features continued..

Wave cut platform-

Waves attack the base of a cliff processes such a hydraulic action and abrasion. Overtime this forms a wave cut notch as the cliff is undercut. The cliff collapses and retreats back leaving a wave cut platform which is exposed during low tide.

Stages of wave cut platform.

Headlands cave, stack, stumps and blowholes.

• Caves occur when waves force their way into cracks in the cliff face. The water contains sand and other materials that grind away at the rock until the cracks become a cave. Hydraulic action is the predominant process.

• If the cave is formed in a headland, it may eventually break through to the other side forming an arch.

• The arch will gradually become bigger until it can no longer support the top of the arch. When the arch collapses, it leaves the headland on one side and a stack (a tall column of rock) on the other.

• The stack will be attacked at the base in the same way that a wave-cut notch is formed. This weakens the structure and it will eventually collapseto form a stump.

• One of the best examples in Britain is Old Harry Rocks, a stack found off a headland in the Isle of Purbeck.
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Blow holes are where erosive waves blast their way through the weakness inthe cave vertically.

Blow holes