Thames interglacial sites, Ipswichian sea levels and Antarctic ice surges |
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| Authors: | JOHN T HOLLIN |
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| Institution: | c/o Environmental Research Laboratories, National Oceanic and Atmospheric Administration, Boulder, Colorado, 80302, 11th June 1976 |
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| Abstract: | New and old, pollen and other studies are summarized for seven sites in the Thames estuary, all of them most probably of last (Ipswichian) interglacial age. Early in the interglacial, at Crayford, Little Thurrock, and Purfleet, there was an aggradation of laminated (3 mm/pair) 'brickearth' (clay, with silt and sand), to above +11 m O.D. Observations in modern estuaries suggest that the laminations were of tidal origin, and related to a sea stand at +7 m, represented on the coast by e.g. the raised cliff at Brighton. In the middle of the Ipswichian, freshwater fossils at West Thurrock and Wretton (Norfolk) suggest that the sea fell below 0 m. Late in the Ipswichian, arguably at the break of climate, at Crayford, Ilford, Aveley, West Thurrock, Stutton (Suffolk) and probably Little Thurrock, there was an aggradation of massive brickearth (famous for its mammal remains) grading up into sand, to above + 14 m. The possibility is discussed that this second aggradation reflects a second rise of sea level, to +16 m, represented by e.g. the raised beach at Portland, and caused by an Antarctic 'surge'. According to A. T. Wilson, this surge triggered the last (Devensian) ice age. |
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