A Re-evaluation of Glacial Lake Pickering

During the Quaternary, repeated glacial cycles left widespread deposits across Britain. These deposits hold an archive of terrestrial responses to changes in climate over the last 2.6 Ma. One such archive is the Vale of Pickering in North Yorkshire: a low-lying depression bounded on all sides save the east end by large hills comprised of Jurassic and Cretaceous bedrock. During the Late Quaternary, this natural basin was blocked by ice sheets forming large proglacial lakes. To understand the advance and retreat of the surrounding ice lobes in the Vale of York to the west and the North Sea Lobe to the east -the deposits of the Vale of Pickering are crucial; however, limited work in the area has failed to ascertain an accurate history of Lake Pickering. Using newly available high-resolution LiDAR data, field observations, historic borehole records, and optically stimulated luminescence (OSL) dating, a new chronological model for Lake Pickering has been established. This shows that 1) previously estimated lake levels are too high and that during the LGM, Lake Pickering was no more than 33 m O.D. 2) Ice invaded the eastern coast of the Vale of Pickering on more than one occasion, potentially earlier than the LGM. 3) Several iterations of Lake Pickering exist with a lake during the LGM, but at least one older than 30 ka. 4) The drainage of Lake Pickering is very complex and seaward drainage likely prevailed until the eastern end became blocked by continued deposition of glacial material. This reversed the drainage through the Kirkham Gorge. 5) The use of newer geoscientific techniques like OSL and LiDAR mapping are crucial to the understanding of the palaeoenvironment of the Vale of Pickering and the continued development of these techniques are vital to further work.

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