Pleistocene fluvial sediments of the Northmoor Member of the Upper Thames Formation exposed at Latton, Wiltshire, record episodic deposition close to the Churn-Thames confluence possibly spanning the interval from Marine Isotope Stages (MIS) 7 to 2. The sequence is dominated by gravel facies, indicating deposition by a high-energy, gravel-bed river. A number of finegrained organic sediment bodies within the sequence have yielded palaeoenvironmental and biostratigraphical data from Mollusca, Coleoptera, vertebrates, pollen and plant macrofossils. The basal deposit (Facies Association A) contains faunal material indicating temperate conditions. Most of the palaeontological evidence including a distinctive small form of mammoth (Mammuthus cf. trogontherii), together with the U-series age estimate of >147.4 AE 20 kyr suggest correlation with MIS 7. The overlying deposits (Facies Associations B and C) represent deposition under a range of climatic conditions. Two fine-grained organic deposits occurred within Association B; one (Association Ba) in the northern part of the pit as a channel fill and the other (Association Bb) in its southern part as a scour-fill deposit. The coleopteran assemblages from Ba, indicate that it accumulated under temperate oceanic conditions, while Bb, which also yielded a radiocarbon age estimate of 39 560 AE 780 14 C yr BP, was formed under much colder and more continental climatic conditions. The sequence is considered to represent deposition within an alluvial fan formed at the Churn-Thames confluence; a depositional scenario which may account for the juxtaposition of sediments and fossils of widely differing age within the same altitudinal range.
A summary is given of the geological, faunal and archaeological information obtained during excavations in the Stanton Harcourt Channel Deposits from 1990 to 1995. The channel deposits underlie the ‘cold‐climate’ Stanton Harcourt Gravel Member of the Summertown– Radley Terrace Formation. The Channel sediments are attributed to Oxygen Isotope Stage 7, when the Thames was undergoing down‐dip migration and eroding the Weymouth Member of the Oxford Clay (Upper Jurassic), the contemporary Jurassic (Corallian) escarpment being near to Stanton Harcourt at that time. Abundant large vertebrate remains have been recovered, mainly from the base of the Channel deposits, where a cobble and boulder bed rests on thin silt or sand horizons or in scour hollows in the clay bedrock. Smaller bones occur throughout the deposits, which are mainly poorly sorted gravels, but especially at erosive horizons. Several palaeolithic artefacts have been found in the same contexts; many of the bones and some of the artefacts appear not to have been transported far. Although the artefacts cannot be linked directly with the bones, a study of them adds to our knowledge of the Middle Pleistocene human settlement of the Upper Thames Valley.
It is of interest that mammoth is abundant as part of the interglacial faunal assemblage, and the significance of this is discussed. The environment clearly included substantial areas of open grassland, although there was also some forest in the vicinity. Evidence appears to be accumulating for important faunal and floral differences between particular interglacial events during the British Middle and Late Pleistocene.
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