Middle and Late Pleistocene environmental history of the Marsworth area, south-central England

Murton, J B and Bowen, D Q and Candy, I and Catt, J A and Currant, A and Evans, J G and Frogley, M R and Green, C P and Keen, D H and Kerney, M P and Parish, D and Penkman, K and Schreve, D C and Taylor, S and Toms, Phillip and Worsley, P and York, L L (2014) Middle and Late Pleistocene environmental history of the Marsworth area, south-central England. Proceedings of the Geologists' Association, 126 (1). pp. 18-49. ISSN 00167878

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Abstract

To elucidate the Middle and Late Pleistocene environmental history of south-central England, we report the stratigraphy, sedimentology, palaeoecology and geochronology of some deposits near the foot of the Chiltern Hills scarp at Marsworth, Buckinghamshire. The Marsworth site is important because its sedimentary sequences contain a rich record of warm stages and cold stages, and it lies close to the Anglian glacial limit. Critical to its history are the origin and age of a brown pebbly silty clay (diamicton) previously interpreted as weathered till. The deposits described infill a river channel incised into chalk bedrock. They comprise clayey, silty and gravelly sediments, many containing locally derived chalk and some with molluscan, ostracod and vertebrate remains. Most of the deposits are readily attributed to periglacial and fluvial processes, and some are dated by optically stimulated luminescence to Marine Isotope Stage (MIS) 6. Although our sedimentological data do not discriminate between a glacial or periglacial interpretation of the diamicton, amino-acid dating of three molluscan taxa from beneath it indicates that it is younger than MIS 9 and older than MIS 5e. This makes a glacial interpretation unlikely, and we interpret the diamicton as a periglacial slope deposit. The Pleistocene history reconstructed for Marsworth identifies four key elements: (1) Anglian glaciation during MIS 12 closely approached Marsworth, introducing far-travelled pebbles such as Rhaxella chert and possibly some fine sand minerals into the area. (2) Interglacial environments inferred from fluvial sediments during MIS 7 varied from fully interglacial conditions during sub-stages 7e and 7c, cool temperate conditions during sub-stage 7b or 7a, temperate conditions similar to those today in central England towards the end of the interglacial, and cool temperate conditions during sub-stage 7a. (3) Periglacial activity during MIS 6 involved thermal contraction cracking, permafrost development, fracturing of chalk bedrock, fluvial activity, slopewash, mass movement and deposition of loess and coversand. (4) Fully interglacial conditions during sub-stage 5e led to renewed fluvial activity, soil formation and acidic weathering.

Item Type: Article
Article Type: Article
Subjects: G Geography. Anthropology. Recreation > GB Physical geography
Divisions: Schools and Research Institutes > School of Natural & Social Sciences > Environmental Sciences
Research Priority Areas: Environmental Dynamics & Governance
Depositing User: Phillip Toms
Date Deposited: 05 May 2016 15:20
Last Modified: 27 Mar 2017 15:32
URI: http://eprints.glos.ac.uk/id/eprint/3398

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