3.6 Landforms and Landscapdw of Coastal Erosion

Question 1

How do wave cut platforms form?

Answer 1

Waves break against foot of cliff. Erosion tends to be concentrated close to the high tide line creating a wave cut notch. As the notch gets bigger, the cliff is undercut and the rock above it becomes unstable, eventually collapsing.

Question 2

Outline how caves arches and stacks are formed.

Answer 2

1. The erosion of rocks eg chalk tends to exploit the lines of weakness eg cracks.
2. When cracks are eroded by hydraulic action and abrasion, this then creates caves.
3. If the overhanging rock then collapses, a blowhole will develop.
4. If a single cave is eroded through a headland, an arch is formed. The base is widened and the gap is further enlarged by erosion and weathering.
5. Eventually the top of the arch leaves an isolated pillar of rock (stack).
6. As it continues to be eroded by the sea, the stack collapses to leave a stump, which may only appear above the surface at low tide.