This photo is one that I took a few years ago –
you can just make out my shadow on the cliff face!
It shows a well-known example of sea stacks
caused by the erosion of chalk cliffs by the sea over a period of many
thousands of years. The foreground stacks are The Needles at the western tip of
the Isle of Wight, which is about half-way along the south coast of England.
In the very far distance you can just make
out another line of white cliffs. These culminate in another set of sea stacks,
known as the Old Harry Rocks, which are on the coast of Dorset. There was once
a continuous line of cliffs that connected The Needles to Old Harry, but the sea
has long since destroyed them and then gouged out a huge bay from the softer
deposits that were previously protected by the harder chalk.
Sea stacks form when the sea erodes the
chalk on both sides of a headland to form caves. When the caves meet
back-to-back, arches will form through which the sea can pass unhindered,
making the gap ever wider. In time the roof of each arch will collapse, and the
pillars of rock between the arches will be left isolated as stacks. Eventually
even these will go.
One can appreciate that this process must
have happened many times over to create the gap between the Isle of Wight and
Dorset, and there is nothing to suggest that it will not go on doing so into
the far distant future!
© John Welford
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