The altitude of the last ice sheet in Caithness and east Sutherland, northern Scotland
On the mountains of southern Caithness and east Sutherland, geomorphological evidence for the upper limit of glacial erosion implies that, at the last glacial maximum (LGM), warm-based erosive ice extended up to altitudes of 410-600 m. Above the upper limit of glacial erosion is a cover of frost-wea...
Published in: | Scottish Journal of Geology |
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Main Authors: | , |
Format: | Article in Journal/Newspaper |
Language: | English |
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2008
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Online Access: | https://risweb.st-andrews.ac.uk/portal/en/researchoutput/the-altitude-of-the-last-ice-sheet-in-caithness-and-east-sutherland-northern-scotland(e9771600-ca2b-46ef-ba6e-8122367e9ca8).html https://doi.org/10.1144/sjg44020169 http://www.landforms.eu/Caithness/library/CKB_AMH2008.pdf |
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ftunstandrewcris:oai:risweb.st-andrews.ac.uk:publications/e9771600-ca2b-46ef-ba6e-8122367e9ca8 2023-05-15T16:40:22+02:00 The altitude of the last ice sheet in Caithness and east Sutherland, northern Scotland Ballantyne, C. K. Hall, A. M. 2008 https://risweb.st-andrews.ac.uk/portal/en/researchoutput/the-altitude-of-the-last-ice-sheet-in-caithness-and-east-sutherland-northern-scotland(e9771600-ca2b-46ef-ba6e-8122367e9ca8).html https://doi.org/10.1144/sjg44020169 http://www.landforms.eu/Caithness/library/CKB_AMH2008.pdf eng eng info:eu-repo/semantics/restrictedAccess Ballantyne , C K & Hall , A M 2008 , ' The altitude of the last ice sheet in Caithness and east Sutherland, northern Scotland ' , Scottish Journal of Geology , vol. 44 , no. 2 , pp. 169-181 . https://doi.org/10.1144/sjg44020169 ET-AL. 2002 GLACIAL MAXIMUM PERIGLACIAL TRIMLINES NORTHWEST SCOTLAND COSMOGENIC BE-10 GREAT-BRITAIN BRITISH-ISLES SCOTTISH PERSPECTIVE FORMER NUNATAKS EXPOSURE AGES article 2008 ftunstandrewcris https://doi.org/10.1144/sjg44020169 2021-12-26T14:15:30Z On the mountains of southern Caithness and east Sutherland, geomorphological evidence for the upper limit of glacial erosion implies that, at the last glacial maximum (LGM), warm-based erosive ice extended up to altitudes of 410-600 m. Above the upper limit of glacial erosion is a cover of frost-weathered detritus, with tors on conglomerate bedrock. Kaolinite and gibbsite in soils on such terrain imply that it escaped significant glacial erosion at the LGM. This is confirmed by cosmogenic 10Be exposure ages of (>) 146.6±15.1 ka and (>) 178.2±18.1 ka obtained for summit tors; sites below the upper limit of glacial erosion yielded deglacial ages of 16.6±2.1 to 18.5±2.4 ka. It is unlikely that glacially unmodified summits represent LGM nunataks, as the implied ice thickness is inconsistent with an ice sheet that extended across high ground on Orkney onto the Atlantic shelf; under conservative assumptions at least 70 m of ice must have covered the highest ground in southern Caithness at the LGM. We infer that the absence of evidence for glacial erosion on some summits and plateaux reflects cover by cold-based ice, frozen to the underlying substrate, that preserved the underlying tors and blockfields. This inference calls into question the use of similar evidence in NW Scotland to identify the maximum altitude of the last ice sheet. Article in Journal/Newspaper Ice Sheet University of St Andrews: Research Portal Sutherland ENVELOPE(168.467,168.467,-77.500,-77.500) Scottish Journal of Geology 44 2 169 181 |
institution |
Open Polar |
collection |
University of St Andrews: Research Portal |
op_collection_id |
ftunstandrewcris |
language |
English |
topic |
ET-AL. 2002 GLACIAL MAXIMUM PERIGLACIAL TRIMLINES NORTHWEST SCOTLAND COSMOGENIC BE-10 GREAT-BRITAIN BRITISH-ISLES SCOTTISH PERSPECTIVE FORMER NUNATAKS EXPOSURE AGES |
spellingShingle |
ET-AL. 2002 GLACIAL MAXIMUM PERIGLACIAL TRIMLINES NORTHWEST SCOTLAND COSMOGENIC BE-10 GREAT-BRITAIN BRITISH-ISLES SCOTTISH PERSPECTIVE FORMER NUNATAKS EXPOSURE AGES Ballantyne, C. K. Hall, A. M. The altitude of the last ice sheet in Caithness and east Sutherland, northern Scotland |
topic_facet |
ET-AL. 2002 GLACIAL MAXIMUM PERIGLACIAL TRIMLINES NORTHWEST SCOTLAND COSMOGENIC BE-10 GREAT-BRITAIN BRITISH-ISLES SCOTTISH PERSPECTIVE FORMER NUNATAKS EXPOSURE AGES |
description |
On the mountains of southern Caithness and east Sutherland, geomorphological evidence for the upper limit of glacial erosion implies that, at the last glacial maximum (LGM), warm-based erosive ice extended up to altitudes of 410-600 m. Above the upper limit of glacial erosion is a cover of frost-weathered detritus, with tors on conglomerate bedrock. Kaolinite and gibbsite in soils on such terrain imply that it escaped significant glacial erosion at the LGM. This is confirmed by cosmogenic 10Be exposure ages of (>) 146.6±15.1 ka and (>) 178.2±18.1 ka obtained for summit tors; sites below the upper limit of glacial erosion yielded deglacial ages of 16.6±2.1 to 18.5±2.4 ka. It is unlikely that glacially unmodified summits represent LGM nunataks, as the implied ice thickness is inconsistent with an ice sheet that extended across high ground on Orkney onto the Atlantic shelf; under conservative assumptions at least 70 m of ice must have covered the highest ground in southern Caithness at the LGM. We infer that the absence of evidence for glacial erosion on some summits and plateaux reflects cover by cold-based ice, frozen to the underlying substrate, that preserved the underlying tors and blockfields. This inference calls into question the use of similar evidence in NW Scotland to identify the maximum altitude of the last ice sheet. |
format |
Article in Journal/Newspaper |
author |
Ballantyne, C. K. Hall, A. M. |
author_facet |
Ballantyne, C. K. Hall, A. M. |
author_sort |
Ballantyne, C. K. |
title |
The altitude of the last ice sheet in Caithness and east Sutherland, northern Scotland |
title_short |
The altitude of the last ice sheet in Caithness and east Sutherland, northern Scotland |
title_full |
The altitude of the last ice sheet in Caithness and east Sutherland, northern Scotland |
title_fullStr |
The altitude of the last ice sheet in Caithness and east Sutherland, northern Scotland |
title_full_unstemmed |
The altitude of the last ice sheet in Caithness and east Sutherland, northern Scotland |
title_sort |
altitude of the last ice sheet in caithness and east sutherland, northern scotland |
publishDate |
2008 |
url |
https://risweb.st-andrews.ac.uk/portal/en/researchoutput/the-altitude-of-the-last-ice-sheet-in-caithness-and-east-sutherland-northern-scotland(e9771600-ca2b-46ef-ba6e-8122367e9ca8).html https://doi.org/10.1144/sjg44020169 http://www.landforms.eu/Caithness/library/CKB_AMH2008.pdf |
long_lat |
ENVELOPE(168.467,168.467,-77.500,-77.500) |
geographic |
Sutherland |
geographic_facet |
Sutherland |
genre |
Ice Sheet |
genre_facet |
Ice Sheet |
op_source |
Ballantyne , C K & Hall , A M 2008 , ' The altitude of the last ice sheet in Caithness and east Sutherland, northern Scotland ' , Scottish Journal of Geology , vol. 44 , no. 2 , pp. 169-181 . https://doi.org/10.1144/sjg44020169 |
op_rights |
info:eu-repo/semantics/restrictedAccess |
op_doi |
https://doi.org/10.1144/sjg44020169 |
container_title |
Scottish Journal of Geology |
container_volume |
44 |
container_issue |
2 |
container_start_page |
169 |
op_container_end_page |
181 |
_version_ |
1766030758257885184 |