EGU2020-9438
https://doi.org/10.5194/egusphere-egu2020-9438
EGU General Assembly 2020
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

The evolution of the terrestrial-terminating Irish Sea glacier during the last glaciation

Richard Chiverrell1, Geoff Thomas, Matthew Burke1, Alicia Medialdea2, Rachel Smedley1, Mark Bateman3, Chris Clark3, Geoff Duller4, Derek Fabel5, Geraint Jenkins4, Xianjiao Ou4, Helen Roberts4, and James Scourse6
Richard Chiverrell et al.
  • 1University of Liverpool, Environmental Sciences, Geography and Planning, Liverpool, United Kingdom of Great Britain and Northern Ireland (rchiv@liv.ac.uk)
  • 2Institute of Geography, University of Cologne, Cologne, Germany
  • 3Department of Geography, University of Sheffield, Sheffield, UK
  • 4Department of Geography and Earth Sciences, Aberystwyth University, Ceredigion, UK
  • 5Scottish Universities Environmental Research Centre, Rankine Avenue, Scottish Enterprise Technology Park, East Kilbride
  • 6Centre for Geography and Environmental Science, College of Life and Environmental Sciences, University of Exeter

Comprehensive mapping and the Briticechrono geochronology provides a reconstruction of the last advance and retreat of the only land-terminating ice lobe of the western British Irish Ice Sheet. The Irish Sea Glacier was fed by ice from Lake District, Irish Sea and Wales, and extended to maximum limits in the English Midlands. During ice retreat after 27 kyrs, a series of reverse bedrock slopes rendered proglacial lakes endemic in the land-system. Not resembling the more extensive definitions of the classical ‘Glacial Lake Lapworth’, these ice contact lakes were smaller time transgressive moraine- and bedrock-dammed basins that evolved with ice marginal retreat. Combining, for the first time on glacial sediments, OSL bleaching profiles for cobbles with single grain and small aliquot OSL measurements on sands, has produced a coherent chronology from these heterogeneously bleached samples, and constrained for the Irish Sea Glacier a post 30ka ice maximum advance, 26.5±1.8ka maximum extent, and 25.3±1.6 to 20.6±2.2ka retreat vacating the region. With retreat of the Irish Sea Glacier an opportunistic Welsh re-advance 19.7±2.5ka took advantage of the vacated space and rode over Irish Sea Glacier moraines. Our geomorphological chronosequence shows a glacial system forced by climate, but mediated by piracy of ice sources shared with the larger and marine terminating Irish Sea Ice Stream to the west. The Irish Sea Glacier underwent changes flow regime and fronting environments driven by stagnation and decline as the primary impetus to advance was diverted. Ultimately, the glacier of the English Midlands display complex uncoupling and realignment during deglaciation and ice margin retreat towards upland hinterlands ~17.8 kyrs (Lake District and Pennines) and asynchronous behaviour as individual adjacent ice lobes became increasingly important in driving the landform record.

How to cite: Chiverrell, R., Thomas, G., Burke, M., Medialdea, A., Smedley, R., Bateman, M., Clark, C., Duller, G., Fabel, D., Jenkins, G., Ou, X., Roberts, H., and Scourse, J.: The evolution of the terrestrial-terminating Irish Sea glacier during the last glaciation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9438, https://doi.org/10.5194/egusphere-egu2020-9438, 2020

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