Holocene alluvial environments at Barking, Lower Thames Valley (London, UK) C.P. Green a , C.R. Batchelor a, *, P.J. Austin b , A.D. Brown a , N.G. Cameron c , D.S. Young a a School of Archaeology, Geography and Environmental Science, University of Reading, Whiteknights, Reading RG6 6AB, UK b 81 Church Street, Leighton Buzzard, Bedfordshire LU7 1BS, UK c Environmental Change Research Centre, Department of Geography, University College London, Pearson Building, Gower Street, London WC1E 6BT, UK 1. Introduction For the Lower Thames Valley there are many unpublished records of the Holocene deposits underlying the floodplain. Much of the information is accessible in the borehole archive of the British Geological Survey (BGS; NERC) or in the so-called ‘grey literature’ – the geological and archaeological reports arising from commercial site investigations. Despite this profusion of site-specific information, there are surprisingly few published accounts of the floodplain deposits, especially downstream from Greenwich; and few attempts to assess the quality of the available data, or to explore the factors that shaped the sedimentary environments and landforms of the Holocene valley floor. These broader problems have been considered in the lower Lea valley by Corcoran et al. (2011) and highlighted by Bates and Whittaker (2004) for the Lower Thames Valley. Investigation of two sites on the floodplain at Barking (Fig. 1) has provided the opportunity to describe and explain the Holocene alluvial record in the Barking Reach of the Lower Thames Valley through the application of deposit modelling to archived borehole data, supplemented by data from a small number of targeted boreholes. The aim of the present paper is to reconstruct the relief of the valley floor at each stage in its development during the Holocene and to explore the origin of this relief and the way in which it may have influenced the accumulation of alluvial sediments. The sites, at Barking Riverside, and Renwick Road, together with the immedi- ately adjoining land (an area referred to throughout this paper as ‘Barking’), cover an area of 277 Ha, occupying c. 1.5 km of the north bank the Thames and extending inland c. 1.7 km to include an area of Taplow Gravel and the bluff separating the Taplow Gravel from the floodplain. The present ground surface is between 4.0 m and 13.5 m OD, but is entirely artificial, reflecting the presence of variable Proceedings of the Geologists’ Association 125 (2014) 279–295 A R T I C L E I N F O Article history: Received 8 November 2013 Received in revised form 12 May 2014 Accepted 18 May 2014 Available online 24 June 2014 Keywords: Deposit modelling Lower Thames Shepperton Gravel Environmental change Peat Holocene A B S T R A C T Deposit modelling based on archived borehole logs supplemented by a small number of dedicated boreholes is used to reconstruct the main boundary surfaces and the thickness of the main sediment units within the succession of Holocene alluvial deposits underlying the floodplain in the Barking Reach of the Lower Thames Valley. The basis of the modelling exercise is discussed and the models are used to assess the significance of floodplain relief in determining patterns of sedimentation. This evidence is combined with the results of biostratigraphical and geochronological investigations to reconstruct the environmental conditions associated with each successive stage of floodplain aggradation. The two main factors affecting the history and spatial pattern of Holocene sedimentation are shown to be the regional behaviour of relative sea level and the pattern of relief on the surface of the sub-alluvial, Late Devensian Shepperton Gravel. As is generally the case in the Lower Thames Valley, three main stratigraphic units are recognised, the Lower Alluvium, a peat bed broadly equivalent to the Tilbury III peat of Devoy (1979) and an Upper Alluvium. There is no evidence to suggest that the floodplain was substantially re-shaped by erosion during the Holocene. Instead, the relief inherited from the Shepperton Gravel surface was gradually buried either by the accumulation of peat or by deposition of fine-grained sediment from suspension in standing or slow-moving water. The palaeoenvironmental record from Barking confirms important details of the Holocene record observed elsewhere in the Lower Thames Valley, including the presence of Taxus in the valley-floor fen carr woodland between about 5000 and 4000 cal BP, and the subsequent growth of Ulmus on the peat surface. ß 2014 The Geologists’ Association. Published by Elsevier Ltd. All rights reserved. * Corresponding author. Tel.: +44 1183788941. E-mail address: c.r.batchelor@reading.ac.uk (C.R. Batchelor). Contents lists available at ScienceDirect Proceedings of the Geologists’ Association jo ur n al ho m ep ag e: www .els evier .c om /lo cat e/p g eo la http://dx.doi.org/10.1016/j.pgeola.2014.05.001 0016-7878/ß 2014 The Geologists’ Association. Published by Elsevier Ltd. All rights reserved.