The Chesil Bank is formed from gravels washed down from the top of Golden Cap – the conspicuous hill about 20 miles to the NW along the cost from Abbotsbury. It gets its name from the exposed beds at the top. As the sea washes away the bottom, a steady stream of material falls down onto the beach and is slowly washed along the coast to the SE. As is well known the larger stones move faster so the beach at Portland, where the Chesil Bank ends, is made of stones about 9" to a foot across.

No-one knows why the bank has formed and naturally there is occasional concern that it might be swept away. It is certainly dynamic – the shingle of summer is usually swept away in winter to reveal sand, or the underling rock or clay. This is the time when metal detectorists find gold and silver coins from the inumerable ships which have been wrecked on the beach over the centuries. Lyme Bay is the archetypical ‘lee shore’. A square rigged ship caught in a SW gale would be trapped in it, unable to beat to windward. If the gale lasted long enough, she would inevitably be driven ashore and beaten to pieces.

We can report that the Chesil’s size has not changed noticeably since 1947. We overlaid vertical aerial survey photographs from 1947 (RAF), 1980 (Indian Navy?) and 2002 (Dorset CC) over the Ordnance Survey map. It was clear that the beach, at least in the neighbourhood of the Abbotsbury Swannery, had not altered materially over 55 years.