Chesil Beach is a 30 km long barrier beach, which formed as sea level rose at the end of the last ice age. It connects the Isle of Portland to the mainland and is sometimes, inaccurately, described as a tombolo. The beach is composed of shingle and is up to 200 metres wide and 15 metres high.
The pebbles are larger at the eastern end than the western end, so removing the possibility that it has been formed by Longshore Drift.
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SY6774 : Chesil Beach (Southern end) For any like me puzzled by the name Chesil it means gravel or shingle according to the OED, being derived from the German word Kies.