Late Pleistocene temperate deposits in Lincolnshire, England and their implication for the history of the River Trent system

Abstract

This article examines the interpretation and implications of Ipswichian (Eemian) Stage temperate deposits discovered by the British Geological Survey east of the Lincoln Gap in eastern England. The fluvial deposits underlie the Southrey Terrace at Coronation Farm, Southrey and The Hermitage, Stainfield in the River Witham valley. Previously unpublished palynological analyses indicate that the temperate deposits compliment published pollen, mollusc and coleopteran assemblages from the same localities. The deposit at Southrey represents Ipswichian (=Eemian) substages Ip IIb and III, whilst that at Stainfield represents the Ip IIb Substage. The combined sequences are compared to those at neighbouring localities in the Witham and Bain-tributary valleys at Tattershall Castle and Tattershall Thorpe. The implications of the correlation of the interglacial deposits provide a re-evaluation of the River Trent-Witham terrace sequence, demonstrating that the Southrey Terrace deposits are not the equivalent of the Late Wolstonian (=Saalian) Balderton Member, but the Middle Devensian (=Weichselian) Substage Fulbeck Member, upstream of Lincoln. This implies that the River Trent was potentially aligned northwards towards the Humber before the Ipswichian Stage interglacial. The revised correlation indicates that glaciation of the region did not occur in the Middle Wolstonian (MIS 8) but during the Late Wolstonian (MIS 6) Substage.