Reconstructing past glacier dynamics and erosion from glacial geomorphic evidence: Snowdon, North Wales
Abstract Bedrock surfaces exposed around Llyn Llydaw, North Wales demonstrate contrasting styles of erosion beneath a Late Devensian ice sheet and a Loch Lomond Stadial (LLS) valley glacier. Ice sheet erosion involved lee‐side fracturing, surface fracture wear and abrasive wear, while LLS erosion wa...
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crwiley:10.1002/jqs.3390040203 2024-06-02T08:08:11+00:00 Reconstructing past glacier dynamics and erosion from glacial geomorphic evidence: Snowdon, North Wales Sharp, Martin Dowdeswell, Julian A. Gemmell, J. Campbell 1989 http://dx.doi.org/10.1002/jqs.3390040203 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fjqs.3390040203 https://onlinelibrary.wiley.com/doi/pdf/10.1002/jqs.3390040203 en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor Journal of Quaternary Science volume 4, issue 2, page 115-130 ISSN 0267-8179 1099-1417 journal-article 1989 crwiley https://doi.org/10.1002/jqs.3390040203 2024-05-03T12:03:05Z Abstract Bedrock surfaces exposed around Llyn Llydaw, North Wales demonstrate contrasting styles of erosion beneath a Late Devensian ice sheet and a Loch Lomond Stadial (LLS) valley glacier. Ice sheet erosion involved lee‐side fracturing, surface fracture wear and abrasive wear, while LLS erosion was primarily by abrasive wear. Preservation of ice sheet erosional features indicates limited rates of erosion during the LLS. Analysis of the geometry and distribution of erosional markings suggests that the low erosional capacity of the LLS glacier was due to a low basal sliding velocity. This prevented the formation of lee‐side cavities, reduced the debris flux over the bed and minimised particle‐bed contact loads. Reconstructions of the mass balance and geometry of the LLS glacier indicate that most of its balance velocity could be achieved by internal deformation alone. A combination of low subglacial water pressures and an unusually rough substrate explain the low sliding velocities. High bed roughness is due to the absence of leeside cavities and a change in flow orientation between ice sheet and LLS times, which meant that the LLS glacier was in contact with roughness elements which were generated in cavities beneath the ice sheet. Article in Journal/Newspaper Ice Sheet Wiley Online Library Loch Lomond ENVELOPE(-125.746,-125.746,54.239,54.239) Journal of Quaternary Science 4 2 115 130 |
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Open Polar |
collection |
Wiley Online Library |
op_collection_id |
crwiley |
language |
English |
description |
Abstract Bedrock surfaces exposed around Llyn Llydaw, North Wales demonstrate contrasting styles of erosion beneath a Late Devensian ice sheet and a Loch Lomond Stadial (LLS) valley glacier. Ice sheet erosion involved lee‐side fracturing, surface fracture wear and abrasive wear, while LLS erosion was primarily by abrasive wear. Preservation of ice sheet erosional features indicates limited rates of erosion during the LLS. Analysis of the geometry and distribution of erosional markings suggests that the low erosional capacity of the LLS glacier was due to a low basal sliding velocity. This prevented the formation of lee‐side cavities, reduced the debris flux over the bed and minimised particle‐bed contact loads. Reconstructions of the mass balance and geometry of the LLS glacier indicate that most of its balance velocity could be achieved by internal deformation alone. A combination of low subglacial water pressures and an unusually rough substrate explain the low sliding velocities. High bed roughness is due to the absence of leeside cavities and a change in flow orientation between ice sheet and LLS times, which meant that the LLS glacier was in contact with roughness elements which were generated in cavities beneath the ice sheet. |
format |
Article in Journal/Newspaper |
author |
Sharp, Martin Dowdeswell, Julian A. Gemmell, J. Campbell |
spellingShingle |
Sharp, Martin Dowdeswell, Julian A. Gemmell, J. Campbell Reconstructing past glacier dynamics and erosion from glacial geomorphic evidence: Snowdon, North Wales |
author_facet |
Sharp, Martin Dowdeswell, Julian A. Gemmell, J. Campbell |
author_sort |
Sharp, Martin |
title |
Reconstructing past glacier dynamics and erosion from glacial geomorphic evidence: Snowdon, North Wales |
title_short |
Reconstructing past glacier dynamics and erosion from glacial geomorphic evidence: Snowdon, North Wales |
title_full |
Reconstructing past glacier dynamics and erosion from glacial geomorphic evidence: Snowdon, North Wales |
title_fullStr |
Reconstructing past glacier dynamics and erosion from glacial geomorphic evidence: Snowdon, North Wales |
title_full_unstemmed |
Reconstructing past glacier dynamics and erosion from glacial geomorphic evidence: Snowdon, North Wales |
title_sort |
reconstructing past glacier dynamics and erosion from glacial geomorphic evidence: snowdon, north wales |
publisher |
Wiley |
publishDate |
1989 |
url |
http://dx.doi.org/10.1002/jqs.3390040203 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fjqs.3390040203 https://onlinelibrary.wiley.com/doi/pdf/10.1002/jqs.3390040203 |
long_lat |
ENVELOPE(-125.746,-125.746,54.239,54.239) |
geographic |
Loch Lomond |
geographic_facet |
Loch Lomond |
genre |
Ice Sheet |
genre_facet |
Ice Sheet |
op_source |
Journal of Quaternary Science volume 4, issue 2, page 115-130 ISSN 0267-8179 1099-1417 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1002/jqs.3390040203 |
container_title |
Journal of Quaternary Science |
container_volume |
4 |
container_issue |
2 |
container_start_page |
115 |
op_container_end_page |
130 |
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1800753381002706944 |