The Pleistocene succession of the Severn Estuary: a revised model based upon amino acid racemization studies

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Abstract
This paper reports the results and stratigraphic implications of amino acid racemization studies of fresh- and/or inter-tidal molluscs from: (i) the important Pleistocene sequences of Kenn Church, New Blind Yeo Drain, Yew Tree Farm and Kenn Pier (Avon County); (ii) the previously undescribed Pleistocene beach deposits beneath the Llanwern steel mill, South Wales; and (iii) re-prepared and re-analysed shells from the Th/U-series dated beach deposits in Belle Houge Cave, Jersey, Channel Islands. These studies indicate the complexity of sea level change in the area. In amino acid Group II (Oxygen isotope stage 5e; 120,000–130,000 years BP) sea level reached 4–5 m OD and possibly 12 m OD. This episode is correlated with similar Group II beach deposits on the Gower coast, and freshwater deposits in SW and SE Britain. The data suggest these Group II deposits are different in age from the Ipswichian interglacial, inter-tidal deposits at Selsey. A Group IV age is attributed to freshwater deposits at Yew Tree Farm and Kenn Pier which collected just above a contemporary sea level or included re-worked earlier inter-tidal rocky shore faunas. These are provisionally correlated with the Group IV deposits in the Thames Estuary at Purfleet ( c. 400,000–600,000 years BP). Since these deposits are thought at post-date glacial deposits previously identified at Kenn and Court Hill, Avon, this glacial episode is now regarded as being much older than the Wolstonian glacial stage with which it had been correlated previously.