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  • Sarah Louise Callard
    Durham University
  • Colm O'Cofaigh
    Durham University
  • Sara Benetti
    Ulster University
  • Richard Chiverrell
    University of Liverpool
  • Katrien Van Landeghem
  • Margot Saher
  • S.J. Livingstone
  • Chris Clark
    University of Sheffield
  • David Small
    Durham University
  • Derek Fabel
    Scottish Universities Environmental Research Centre
  • Steven Moreton
    Natural Environment Research Council, Radiocarbon Facility, East Kilbride, Scotland, G75 OQF, UK
During the Last Glacial Maximum, the British-Irish Ice Sheet extended across the continental shelf offshore of Galway Bay, western Ireland, and reached a maximum westward extent on the Porcupine Bank. New marine geophysical data, sediment cores and radiocarbon dates are used to constrain the style and timing of ice
-sheet retreat across the mid to inner-shelf. Radiocarbon dated shell fragments in subglacial till on the mid-shelf constrains ice advance to after 26.4 ka BP. Initial retreat was underway before 24.4 ka BP, significantly earlier than previous reconstructions. Grounding-line retreat was accompanied by stillstands and/or localised readvances of the grounding -line. A large composite Mid-Shelf Grounding Zone Complex marks a major grounding-line position, with the ice grounded and the margin oscillating at this position by, and probably after, 23 ka BP. The continental shelf was ice-free by 17.1 cal. ka BP, but the ice sheet may have retained a marine margin until c. 15.3 ka BP. Retreat occurred in a glacimarine setting and the ice sheet was fringed by a floating ice-shelf.
Collectively, this evidence indicates a dynamic and oscillatory marine-terminating ice sheet offshore of western Ireland during the last deglaciation.


  • Grounding Zone Wedges, British -Irish Ice Sheet, Ice Shelf, Glacimarine, Last Glacial Maximum, Ice -Sheet Retreat, Continental Shelf
Original languageEnglish
Article number106087
JournalMarine Geology
Early online date26 Nov 2019
Publication statusPublished - Feb 2020
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