The Pleistocene glaciations of eastern Yorkshire: a review

摘要

The Pleistocene deposits of eastern Yorkshire and adjacent areas have been studied intensively for about 150 years, but numerous problems of dating and correlation remain. Holderness provides the British type site for deposits of the Last Glacial Maximum (the Dimlington Stadial, part of Marine Isotope Stage 2) here dated to between 18,500 and 13,000 radiocarbon years (c. 23,000-15,000 calendar years) BP, but older glacial deposits are still very difficult to date precisely. An earlier Devensian glaciation of east Lincolnshire and south-west Yorkshire has been suggested, but remains uncertain. The most extensive pre-Devensian glacial deposit is the Basement Till of Holderness and other eastern coastal areas. This is overlain by the raised beach of the Ipswichian Stage (MIS 5e; 128,000-117,000 years ago) at Sewerby, by the pre-Ipswichian Calcethorpe Till at Welton-le-Wold, Lincolnshire, and by boulders weathered in interglacial conditions at Warren House Gill, Durham, so it was deposited during MIS 6 or an earlier cold stage. Late Devensian (MIS 2) amino-acid dates for marine shells from the Basement Till at Dimlington may be explained by intrusion during subglacial disturbance of the till's upper layers by the Late Devensian glacier. In coastal areas of east Yorkshire, the Skipsea and Withernsea tills and their equivalents between Flamborough Head and the Tees Estuary are attributed to the Dimlington Stadial, and there is considerable evidence that they were deposited by a single surge of a two-tiered ice sheet. The lower (Skipsea) tier originated in south-east Scotland and north-east England, and the upper (Withernsea) tier from Lake District ice that crossed the Pennines via the Stainmore Gap and overrode the Skipsea Till glacier in the Lower Tees Valley area. Stainmore ice was also diverted southwards into the Vale of York. The patchy 'Older Drift' in the Vale of York (mainly grey till with Permian, Carboniferous and Lake District erratics) was also deposited by Stainmore ice flowing southwards, probably in MIS 12.