Portland Raised Beach

[1] They exhibit multi-type erosion and deposition during a warm spell in the last Ice Age in the inter-tidal zone show signs of tide and wave impact during more recent millennia.

[2][3] A factor in the higher than average speed shore erosion is the weight of the ice which covered the north of Britain and beyond in the colder spells that caused the British Isles landmass to tilt (see post-glacial rebound) and prevailing south-west currents and breeze, a pace which results in the relatively little water-eroded cliff-based fossils, stones and pebbles along Chesil Beach.

[4] Tidally caught fine material (sand) is deposited on most great bays facing the deeper western half or so of the English Channel and only at narrowings along the increasingly shallow eastern half.

[7] The beach is about 125,000 years old and has abundant mollusc shells such as species of Patella and Littorina and small bivalves that lived on seaweed.

It has been much disturbed by cryoturbation (freezing and thawing) during the late Pleistocene ice age.