Dimensions and deglacial chronology of the Outer Hebrides Ice Cap, northwest Scotland: implications of cosmic ray exposure dating
Cosmic ray exposure ages of frost-weathered bedrock from mountain summits in the Outer Hebrides exceed the age of Late Devensian glaciation. Exposure ages of most glacially-abraded bedrock Surfaces at low and intermediate elevations are younger than the age of maximum Late Devensian glaciation. Thes...
Published in: | Journal of Quaternary Science |
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Online Access: | https://research-portal.st-andrews.ac.uk/en/researchoutput/dimensions-and-deglacial-chronology-of-the-outer-hebrides-ice-cap-northwest-scotland-implications-of-cosmic-ray-exposure-dating(225d1142-b1c5-448b-824a-dd6ce8bf6098).html https://doi.org/10.1002/jqs.933 http://www.scopus.com/inward/record.url?scp=31344446870&partnerID=8YFLogxK |
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ftunstandrewcris:oai:research-portal.st-andrews.ac.uk:publications/225d1142-b1c5-448b-824a-dd6ce8bf6098 2024-06-23T07:53:41+00:00 Dimensions and deglacial chronology of the Outer Hebrides Ice Cap, northwest Scotland: implications of cosmic ray exposure dating Stone, J O Ballantyne, C K 2006-01 https://research-portal.st-andrews.ac.uk/en/researchoutput/dimensions-and-deglacial-chronology-of-the-outer-hebrides-ice-cap-northwest-scotland-implications-of-cosmic-ray-exposure-dating(225d1142-b1c5-448b-824a-dd6ce8bf6098).html https://doi.org/10.1002/jqs.933 http://www.scopus.com/inward/record.url?scp=31344446870&partnerID=8YFLogxK eng eng https://research-portal.st-andrews.ac.uk/en/researchoutput/dimensions-and-deglacial-chronology-of-the-outer-hebrides-ice-cap-northwest-scotland-implications-of-cosmic-ray-exposure-dating(225d1142-b1c5-448b-824a-dd6ce8bf6098).html info:eu-repo/semantics/restrictedAccess Stone , J O & Ballantyne , C K 2006 , ' Dimensions and deglacial chronology of the Outer Hebrides Ice Cap, northwest Scotland: implications of cosmic ray exposure dating ' , Journal of Quaternary Science , vol. 21 , no. 1 , pp. 75-84 . https://doi.org/10.1002/jqs.933 cosmogenic isotope exposure dating periglacial trimlines deglaciation chronology Outer Hebrides LATE DEVENSIAN GLACIATION MAXIMUM ALTITUDE SHEET RECONSTRUCTION ISLE LEWIS SURFACES HARRIS LIMITS RATES WEST article 2006 ftunstandrewcris https://doi.org/10.1002/jqs.933 2024-06-13T00:25:25Z Cosmic ray exposure ages of frost-weathered bedrock from mountain summits in the Outer Hebrides exceed the age of Late Devensian glaciation. Exposure ages of most glacially-abraded bedrock Surfaces at low and intermediate elevations are younger than the age of maximum Late Devensian glaciation. These results confirm that previously mapped periglacial trimlines in the Outer Hebrides define the upper limit of bedrock erosion by Late Devensian ice. They are consistent with the interpretation, based on geomorphological evidence, that the trimlines mark the approximate upper limit of a Late Devensian Outer Hebrides Ice Cap. A postglacial exposure age from the summit of Oreval (662 m) Suggests that this mountain was overrun during the last glaciation, indicating thicker ice cover and a lower Surface gradient west of the ice-cap divide than previously inferred. Although bedrock Surfaces below the trimlines are strongly ice-moulded, some show evidence of prior cosmic ray exposure, which we attribute to limited erosion during Late Devensian glaciation. If this interpretation is correct, the Youngest apparent ages from these surfaces give the most reliable dates for deglaciation, at ca. 14.5-14 ka. This implies that ice persisted at favourable sites through the warm opening phase of the Windermere Interstade. Comparison with radiocarbon-dated evidence from offshore cores Suggests net ice margin retreat of similar to 74 km eastwards across the adjacent shelf in > 2.3 +/- 1.0 ka. The dating evidence is consistent with relatively rapid retreat of calving margins to the coast, then slower withdrawal of ice margins to high ground. Copyright (c) 2005 John Wiley & Sons, Ltd. Article in Journal/Newspaper Ice cap University of St Andrews: Research Portal Journal of Quaternary Science 21 1 75 84 |
institution |
Open Polar |
collection |
University of St Andrews: Research Portal |
op_collection_id |
ftunstandrewcris |
language |
English |
topic |
cosmogenic isotope exposure dating periglacial trimlines deglaciation chronology Outer Hebrides LATE DEVENSIAN GLACIATION MAXIMUM ALTITUDE SHEET RECONSTRUCTION ISLE LEWIS SURFACES HARRIS LIMITS RATES WEST |
spellingShingle |
cosmogenic isotope exposure dating periglacial trimlines deglaciation chronology Outer Hebrides LATE DEVENSIAN GLACIATION MAXIMUM ALTITUDE SHEET RECONSTRUCTION ISLE LEWIS SURFACES HARRIS LIMITS RATES WEST Stone, J O Ballantyne, C K Dimensions and deglacial chronology of the Outer Hebrides Ice Cap, northwest Scotland: implications of cosmic ray exposure dating |
topic_facet |
cosmogenic isotope exposure dating periglacial trimlines deglaciation chronology Outer Hebrides LATE DEVENSIAN GLACIATION MAXIMUM ALTITUDE SHEET RECONSTRUCTION ISLE LEWIS SURFACES HARRIS LIMITS RATES WEST |
description |
Cosmic ray exposure ages of frost-weathered bedrock from mountain summits in the Outer Hebrides exceed the age of Late Devensian glaciation. Exposure ages of most glacially-abraded bedrock Surfaces at low and intermediate elevations are younger than the age of maximum Late Devensian glaciation. These results confirm that previously mapped periglacial trimlines in the Outer Hebrides define the upper limit of bedrock erosion by Late Devensian ice. They are consistent with the interpretation, based on geomorphological evidence, that the trimlines mark the approximate upper limit of a Late Devensian Outer Hebrides Ice Cap. A postglacial exposure age from the summit of Oreval (662 m) Suggests that this mountain was overrun during the last glaciation, indicating thicker ice cover and a lower Surface gradient west of the ice-cap divide than previously inferred. Although bedrock Surfaces below the trimlines are strongly ice-moulded, some show evidence of prior cosmic ray exposure, which we attribute to limited erosion during Late Devensian glaciation. If this interpretation is correct, the Youngest apparent ages from these surfaces give the most reliable dates for deglaciation, at ca. 14.5-14 ka. This implies that ice persisted at favourable sites through the warm opening phase of the Windermere Interstade. Comparison with radiocarbon-dated evidence from offshore cores Suggests net ice margin retreat of similar to 74 km eastwards across the adjacent shelf in > 2.3 +/- 1.0 ka. The dating evidence is consistent with relatively rapid retreat of calving margins to the coast, then slower withdrawal of ice margins to high ground. Copyright (c) 2005 John Wiley & Sons, Ltd. |
format |
Article in Journal/Newspaper |
author |
Stone, J O Ballantyne, C K |
author_facet |
Stone, J O Ballantyne, C K |
author_sort |
Stone, J O |
title |
Dimensions and deglacial chronology of the Outer Hebrides Ice Cap, northwest Scotland: implications of cosmic ray exposure dating |
title_short |
Dimensions and deglacial chronology of the Outer Hebrides Ice Cap, northwest Scotland: implications of cosmic ray exposure dating |
title_full |
Dimensions and deglacial chronology of the Outer Hebrides Ice Cap, northwest Scotland: implications of cosmic ray exposure dating |
title_fullStr |
Dimensions and deglacial chronology of the Outer Hebrides Ice Cap, northwest Scotland: implications of cosmic ray exposure dating |
title_full_unstemmed |
Dimensions and deglacial chronology of the Outer Hebrides Ice Cap, northwest Scotland: implications of cosmic ray exposure dating |
title_sort |
dimensions and deglacial chronology of the outer hebrides ice cap, northwest scotland: implications of cosmic ray exposure dating |
publishDate |
2006 |
url |
https://research-portal.st-andrews.ac.uk/en/researchoutput/dimensions-and-deglacial-chronology-of-the-outer-hebrides-ice-cap-northwest-scotland-implications-of-cosmic-ray-exposure-dating(225d1142-b1c5-448b-824a-dd6ce8bf6098).html https://doi.org/10.1002/jqs.933 http://www.scopus.com/inward/record.url?scp=31344446870&partnerID=8YFLogxK |
genre |
Ice cap |
genre_facet |
Ice cap |
op_source |
Stone , J O & Ballantyne , C K 2006 , ' Dimensions and deglacial chronology of the Outer Hebrides Ice Cap, northwest Scotland: implications of cosmic ray exposure dating ' , Journal of Quaternary Science , vol. 21 , no. 1 , pp. 75-84 . https://doi.org/10.1002/jqs.933 |
op_relation |
https://research-portal.st-andrews.ac.uk/en/researchoutput/dimensions-and-deglacial-chronology-of-the-outer-hebrides-ice-cap-northwest-scotland-implications-of-cosmic-ray-exposure-dating(225d1142-b1c5-448b-824a-dd6ce8bf6098).html |
op_rights |
info:eu-repo/semantics/restrictedAccess |
op_doi |
https://doi.org/10.1002/jqs.933 |
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Journal of Quaternary Science |
container_volume |
21 |
container_issue |
1 |
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75 |
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