2009 Portland GSA Annual Meeting (18-21 October 2009)

Paper No. 12
Presentation Time: 9:00 AM-6:00 PM


FORD, Jon1, PRICE, Simon2, BURKE, Helen2, KESSLER, Holger2, COOPER, Anthony3 and FARRELL, Rolf4, (1)British Geological Survey, Kingsley Dunham Centre, Keyworth, Nottingham NG12 5GG, Nottingham, NG12 5GG, United Kingdom, (2)British Geological Survey, Kingsley Dunham Centre, Keyworth, Nottingham, NG12 5GG, United Kingdom, (3)British Geological Survey, Kingsley Dunham Centre, Keyworth, Nottingham, NG112 5GG, United Kingdom, (4)Water Resources Technical Services, Environment Agency of England and Wales, Rivers House, 21 Park Square South, Leeds, LS1 2QG, United Kingdom, hke@bgs.ac.uk

During the Devensian glaciation the Vale of York was glaciated with ice moving south-eastwards and ploughing into a large proglacial lake (Lake Humber) impounded by North Sea ice blocking the Humber Gap. Laminated clays forming the Hemingbrough Glaciolacustrine Formation were deposited here. The ice then overrode the lake deposits forming a terminal moraine at Escrick which is now confirmed as the last glacial maximum limit (LGM). The ice then wasted back forming another moraine complex at York, then others further to the north-west. Long-lived drainage routes in the ice resulted in linear esker belts and the impounding of proglacial meltwater resulted in several glacial lakes in front, between and behind the moraines.

The increased geological understanding of the Quaternary history of the Vale of York has been built up from numerous datasets. It has been aided by interpretation of digital elevation models (DEMs), allied with air photograph interpretation and a detailed 1:10 000 scale field survey. The survey involved extensive hand augering, percussion drilling and the examination of many thousands of boreholes held by the British Geological Survey. These were used to generate a 3D fence diagram and calculate a block model for the York area.

By combining 3D data with detailed geological mapping and by utilising DEM interpretations it has been concluded that the last glacial maximum (LGM) limit of the Devensian ice was at the Escrick Moraine. No evidence of glacial till deposits has been found in the proglacial lake deposits to the south. This integrated survey has given new insight into the glacial and pro-glacial processes that affected this area during the Devensian glaciation in the Vale of York and can be used as a model for other quaternary studies.