Blog for Mr Wilkinson's History and Geography classes at Haileybury Almaty. Posts by Mr Wilkinson and his students.

Sunday 11 June 2017

How caves, arches and stacks form - Form 4 Playdoh explanations

Winner of best Geographical explanation
In this diagram Leia demonstrates that headlands are not only eroded from the furthest seaward point backwards, but also from the sides due to wave refraction. There is also a good use of key terminology such as corrasion. Corrasion is where sediment within the sea are thrown against the cliff by waves, helping to accelerate erosion.

Runner up
Deen's explanation of how a headland is eroded is very clear, showing the sequence of erosion from a fault to the stump. He also mentions key types of erosion such as hydraulic action, where the force of the wave compresses air inside the cracks of the rock. This form of erosion helps to deepen and widen points of weakness in the rock forming arches such as Piercy Rock in New Zealand's Bay of Islands.

The only minor criticism is that his explanation of a blowhole would have been better located under the heading for a fault.

Winner of most artistic headland
Although there is not much in the way of explanation about how these features are formed, this model of a headland by Macy is very clear. You can see the clear progression of erosion from sea cave, to arch, collapsed arch and then stump. It is also very artistic with her use of rocks, sand, plants an cellophane sea - great improvisation and a step above what I expected when I handed out Playdoh.

Other honorable mentions....

Below, Rachel shows well the action of refracted waves and the low and high tide mark.

Adam shows how sediment in the sea helps to erode the headland.

Brittany clearly shows the direction of retreat.


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