Trimlines, blockfields and the vertical extent of the last ice sheet in southern Ireland
Trimlines separating glacially abraded lower slopes from blockfield‐covered summits on I rish mountains have traditionally been interpreted as representing the upper limit of the last ice sheet during the L ast G lacial M aximum ( LGM ). Cosmogenic 10 B e exposure ages obtained for samples from glac...
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crwiley:10.1111/bor.12109 2024-09-15T18:12:21+00:00 Trimlines, blockfields and the vertical extent of the last ice sheet in southern Ireland Ballantyne, Colin K. Stone, John O. Natural Environment Research Council 2015 http://dx.doi.org/10.1111/bor.12109 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fbor.12109 https://onlinelibrary.wiley.com/doi/pdf/10.1111/bor.12109 en eng Wiley http://creativecommons.org/licenses/by/4.0/ Boreas volume 44, issue 2, page 277-287 ISSN 0300-9483 1502-3885 journal-article 2015 crwiley https://doi.org/10.1111/bor.12109 2024-07-25T04:20:14Z Trimlines separating glacially abraded lower slopes from blockfield‐covered summits on I rish mountains have traditionally been interpreted as representing the upper limit of the last ice sheet during the L ast G lacial M aximum ( LGM ). Cosmogenic 10 B e exposure ages obtained for samples from glacially deposited perched boulders resting on blockfield debris on the summit area of S lievenamon (721 m a.s.l.) in southern I reland demonstrate emplacement by the last I rish I ce S heet ( IIS ), implying preservation of the blockfield under cold‐based ice during the LGM , and supporting the view that trimlines throughout the B ritish I sles represent former englacial thermal regime boundaries between a lower zone of warm‐based sliding ice and an upper zone of cold‐based ice. The youngest exposure age (22.6±1.1 or 21.0±0.9 ka, depending on the 10 B e production rate employed) is statistically indistinguishable from the mean age (23.4±1.2 or 21.8±0.9 ka) obtained for two samples from ice‐abraded bedrock at high ground on B lackstairs M ountain, 51 km to the east, and with published cosmogenic 36 C l ages. Collectively, these ages imply (i) early (24–21 ka) thinning of the last IIS and emergence of high ground in SE I reland; (ii) relatively brief (1–3 ka) glacial occupation of southernmost I reland during the LGM (iii) decoupling of the I rish S ea I ce S tream and ice from the I rish midlands within a similar time frame; and (iv) that the southern fringe of I reland was deglaciated before western and northern I reland. Article in Journal/Newspaper Ice Sheet Wiley Online Library Boreas 44 2 277 287 |
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Open Polar |
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Wiley Online Library |
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crwiley |
language |
English |
description |
Trimlines separating glacially abraded lower slopes from blockfield‐covered summits on I rish mountains have traditionally been interpreted as representing the upper limit of the last ice sheet during the L ast G lacial M aximum ( LGM ). Cosmogenic 10 B e exposure ages obtained for samples from glacially deposited perched boulders resting on blockfield debris on the summit area of S lievenamon (721 m a.s.l.) in southern I reland demonstrate emplacement by the last I rish I ce S heet ( IIS ), implying preservation of the blockfield under cold‐based ice during the LGM , and supporting the view that trimlines throughout the B ritish I sles represent former englacial thermal regime boundaries between a lower zone of warm‐based sliding ice and an upper zone of cold‐based ice. The youngest exposure age (22.6±1.1 or 21.0±0.9 ka, depending on the 10 B e production rate employed) is statistically indistinguishable from the mean age (23.4±1.2 or 21.8±0.9 ka) obtained for two samples from ice‐abraded bedrock at high ground on B lackstairs M ountain, 51 km to the east, and with published cosmogenic 36 C l ages. Collectively, these ages imply (i) early (24–21 ka) thinning of the last IIS and emergence of high ground in SE I reland; (ii) relatively brief (1–3 ka) glacial occupation of southernmost I reland during the LGM (iii) decoupling of the I rish S ea I ce S tream and ice from the I rish midlands within a similar time frame; and (iv) that the southern fringe of I reland was deglaciated before western and northern I reland. |
author2 |
Natural Environment Research Council |
format |
Article in Journal/Newspaper |
author |
Ballantyne, Colin K. Stone, John O. |
spellingShingle |
Ballantyne, Colin K. Stone, John O. Trimlines, blockfields and the vertical extent of the last ice sheet in southern Ireland |
author_facet |
Ballantyne, Colin K. Stone, John O. |
author_sort |
Ballantyne, Colin K. |
title |
Trimlines, blockfields and the vertical extent of the last ice sheet in southern Ireland |
title_short |
Trimlines, blockfields and the vertical extent of the last ice sheet in southern Ireland |
title_full |
Trimlines, blockfields and the vertical extent of the last ice sheet in southern Ireland |
title_fullStr |
Trimlines, blockfields and the vertical extent of the last ice sheet in southern Ireland |
title_full_unstemmed |
Trimlines, blockfields and the vertical extent of the last ice sheet in southern Ireland |
title_sort |
trimlines, blockfields and the vertical extent of the last ice sheet in southern ireland |
publisher |
Wiley |
publishDate |
2015 |
url |
http://dx.doi.org/10.1111/bor.12109 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fbor.12109 https://onlinelibrary.wiley.com/doi/pdf/10.1111/bor.12109 |
genre |
Ice Sheet |
genre_facet |
Ice Sheet |
op_source |
Boreas volume 44, issue 2, page 277-287 ISSN 0300-9483 1502-3885 |
op_rights |
http://creativecommons.org/licenses/by/4.0/ |
op_doi |
https://doi.org/10.1111/bor.12109 |
container_title |
Boreas |
container_volume |
44 |
container_issue |
2 |
container_start_page |
277 |
op_container_end_page |
287 |
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1810449940621557760 |