Glacial Lake Pickering: stratigraphy and chronology of a proglacial lake dammed by the North Sea Lobe of the British–Irish Ice Sheet

David J A Evans,David H Roberts,Geoff A T Duller,Alicia Medialdea,Derek Fabel,Chris D Clark,Laura Hayes,Mark D Bateman

doi:10.1002/jqs.2833

Abstract

ABSTRACTWe report the first chronology, using four new optically stimulated luminescence dates, on the sedimentary record of Glacial Lake Pickering, dammed by the North Sea Lobe of the British–Irish Ice Sheet during the Dimlington Stadial (24–11 ka cal BP). Dates range from 17.6 ± 1.0 to 15.8 ± 0.9 ka for the sedimentation of the Sherburn Sands at East Heslerton, which were formed by multiple coalescing alluvial fans prograding into the falling water levels of the lake and fed by progressively larger volumes of debris from the Wolds. Fan formation ceased ∼15.8 ka, at a time when permafrost was degrading and nival‐fed streams were no longer capable of supplying sediment to the fans. A further age of 10.1 ± 0.7 ka dates the reworking of coversand into the early part of the Holocene, immediately post‐dating Younger Dryas periglacial structures. A 45‐m lake level dates to ∼17.6 ka, when the North Sea Lobe was already in retreat, having moved eastward of the Wykeham Moraine; it stood further east at the Flamborough Moraine by ∼17.3 ka. The highest (70 m) lake level and the occupation of the Wykeham Moraine date to an earlier phase of the North Sea Lobe occupation of the Vale of Pickering.

Highlights

This paper reports on the first attempt to provide a chronology on the sedimentary record pertaining to the operation of Glacial Lake Pickering during the Dimlington Stadial (24–11 ka cal BP), on the sedimentation recorded on the south side of the vale in the Sherburn Sands at East Heslerton (Fig. 1)
LF1b, the East Heslerton deposits predominantly record subaerial fan aggradation. Because they lie below 45 m OD, they must have aggraded to a lake level no higher than that altitude and probably to the lowest Glacial Lake Pickering shoreline indicated by the Pickering delta at 30 m OD
The maximum extent of the North Sea lobe is unknown but the Pickering/ Thornton-le-Dale limit could be related to the early stages of the 70-m lake level

Summary

Introduction to Glacial Lake Pickering

The sedimentary and stratigraphic record of the recession of the North Sea Lobe of the British–Irish Ice Sheet (BIIS) is best documented along the coast of eastern England, in the tills and associated glacilacustrine deposits of Holderness (Catt, 1991, 2007; Evans et al, 1995; Boston et al, 2010; Evans and Thomson, 2010) and the Humber Estuary and North Lincolnshire (Straw, 1961, 1979; Gaunt, 1981; Bateman et al, 2008, 2015). Exposures through the stratigraphic sequence at East Heslerton have been logged previously by Foster (1985, 1987a), who proposed a glacial outwash origin, with the deposits grading distally into the Slingsby Sands at the west end of the Vale of Pickering and interdigitating in the east with the glacier-proximal Seamer Gravels at the Wykeham and Flamborough moraines. The subaerial nature of LF2, as indicated by the fluvial bedforms and intraformational ice wedge development at East Heslerton, indicates that lake water levels had fallen to below 34 m OD by the time it was deposited This must have taken place sometime after the 45-m shoreline phase of the Cayton–Speeton Stage (Penny and Rawson, 1969) and a lower lake stand is recorded by the Pickering delta at 30 m OD (Kendall, 1902), potentially recording a later incision level at the intake of the Kirkham Priory spillway. Further age determinations on the uppermost facies of the Sherburn Sands are warranted

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Discussion

Conclusions