Reconstructing the Last Pleistocene (Late Devensian) glaciation on the continental margin of Northwest Britain
The continental margin in the area west of Shetland was subjected to repeated and extensive ice sheet advances during the Late Pleistocene. Seabed imagery, seismic survey and borehole core data show the Late Devensian ice sheets expanded across the continental shelf three times, two of these advance...
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University of Edinburgh; College of Science and Engineering; School of GeoScience
2005
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ftunivedinburgh:oai:era.ed.ac.uk:1842/766 2023-07-30T04:04:12+02:00 Reconstructing the Last Pleistocene (Late Devensian) glaciation on the continental margin of Northwest Britain Davison, Stephen Stoker, Martyn Scrutton, Roger 2005-06 125912681 bytes application/pdf http://hdl.handle.net/1842/766 en eng University of Edinburgh; College of Science and Engineering; School of GeoScience http://hdl.handle.net/1842/766 ice sheet advance Late Pleistocene continental margin Late Devensian Thesis or Dissertation Doctoral PhD Doctor of Philosophy 2005 ftunivedinburgh 2023-07-09T20:31:03Z The continental margin in the area west of Shetland was subjected to repeated and extensive ice sheet advances during the Late Pleistocene. Seabed imagery, seismic survey and borehole core data show the Late Devensian ice sheets expanded across the continental shelf three times, two of these advances reaching the shelf edge. On the inner shelf, where present-day water depths are generally less than 100m, only thin sediments from the last retreat phase and exposed rock surfaces remain, all other deposits from earlier phases having been removed by the last advance. On the mid to outer shelf elements of all three phases are preserved, including lodgement and deformation tills, melt-out and water-lain till sheets, in-filled hollows left by stagnant ice decaying in situ and a series of large recessional and terminal moraines. In addition, there is evidence of shallow troughs and overdeepend basins which indicate preferential ice-drainage pathways across the shelf which were formerly occupied by ice streams. At the shelf edge, a thick wedge of glacigenic sediment forms a transition from the till sheets and moraines of the shelf to debris flows composed of glacigenic sediments on the upper slope. Shelf-edge moraines show an architecture indicating floating ice in modern water depths over approximately 180m, suggesting the West Shetland ice sheet was no more than about 250m thick. The upper and middle slope is dominated by glacigenic debris flows which are focused in the slope areas below the proposed ice stream discharges at the shelf edge. The mid-to-lower slope has been subjected to contour current activity which has re-worked much of the glacigenic sediment in this position. The lower slope and floor of the Faroe-Shetland Channel are marked by either large debris flow lobes of glacigenic sediment or thin glacimarine muds deposited from suspension. A conceptual model of the glacigenic development of a passive continental margin based upon the West Shetland example shows the deposited sequence for both advance and ... Doctoral or Postdoctoral Thesis Ice Sheet Edinburgh Research Archive (ERA - University of Edinburgh) |
institution |
Open Polar |
collection |
Edinburgh Research Archive (ERA - University of Edinburgh) |
op_collection_id |
ftunivedinburgh |
language |
English |
topic |
ice sheet advance Late Pleistocene continental margin Late Devensian |
spellingShingle |
ice sheet advance Late Pleistocene continental margin Late Devensian Davison, Stephen Reconstructing the Last Pleistocene (Late Devensian) glaciation on the continental margin of Northwest Britain |
topic_facet |
ice sheet advance Late Pleistocene continental margin Late Devensian |
description |
The continental margin in the area west of Shetland was subjected to repeated and extensive ice sheet advances during the Late Pleistocene. Seabed imagery, seismic survey and borehole core data show the Late Devensian ice sheets expanded across the continental shelf three times, two of these advances reaching the shelf edge. On the inner shelf, where present-day water depths are generally less than 100m, only thin sediments from the last retreat phase and exposed rock surfaces remain, all other deposits from earlier phases having been removed by the last advance. On the mid to outer shelf elements of all three phases are preserved, including lodgement and deformation tills, melt-out and water-lain till sheets, in-filled hollows left by stagnant ice decaying in situ and a series of large recessional and terminal moraines. In addition, there is evidence of shallow troughs and overdeepend basins which indicate preferential ice-drainage pathways across the shelf which were formerly occupied by ice streams. At the shelf edge, a thick wedge of glacigenic sediment forms a transition from the till sheets and moraines of the shelf to debris flows composed of glacigenic sediments on the upper slope. Shelf-edge moraines show an architecture indicating floating ice in modern water depths over approximately 180m, suggesting the West Shetland ice sheet was no more than about 250m thick. The upper and middle slope is dominated by glacigenic debris flows which are focused in the slope areas below the proposed ice stream discharges at the shelf edge. The mid-to-lower slope has been subjected to contour current activity which has re-worked much of the glacigenic sediment in this position. The lower slope and floor of the Faroe-Shetland Channel are marked by either large debris flow lobes of glacigenic sediment or thin glacimarine muds deposited from suspension. A conceptual model of the glacigenic development of a passive continental margin based upon the West Shetland example shows the deposited sequence for both advance and ... |
author2 |
Stoker, Martyn Scrutton, Roger |
format |
Doctoral or Postdoctoral Thesis |
author |
Davison, Stephen |
author_facet |
Davison, Stephen |
author_sort |
Davison, Stephen |
title |
Reconstructing the Last Pleistocene (Late Devensian) glaciation on the continental margin of Northwest Britain |
title_short |
Reconstructing the Last Pleistocene (Late Devensian) glaciation on the continental margin of Northwest Britain |
title_full |
Reconstructing the Last Pleistocene (Late Devensian) glaciation on the continental margin of Northwest Britain |
title_fullStr |
Reconstructing the Last Pleistocene (Late Devensian) glaciation on the continental margin of Northwest Britain |
title_full_unstemmed |
Reconstructing the Last Pleistocene (Late Devensian) glaciation on the continental margin of Northwest Britain |
title_sort |
reconstructing the last pleistocene (late devensian) glaciation on the continental margin of northwest britain |
publisher |
University of Edinburgh; College of Science and Engineering; School of GeoScience |
publishDate |
2005 |
url |
http://hdl.handle.net/1842/766 |
genre |
Ice Sheet |
genre_facet |
Ice Sheet |
op_relation |
http://hdl.handle.net/1842/766 |
_version_ |
1772815449697812480 |