Portland Raised Beach
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Portland Raised Beach refers to small raised beaches on either side of Portland Bill, on the Isle of Portland, part of the Jurassic Coast in Dorset, England. The main beach is known as the West Pleistocene Raised Beach; nearby is the East Pleistocene 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. For some depth, sandy and shelly pebbles predominate.[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.