Surface profiles of the laurentide ice sheet in its marginal areas
Surface slopes of ice lobes can be estimated from the gradients of their margins as shown by ice limits, by contemporaneous recessional moraines, or by lateral melt-water channels, with allowance being made for the dip of an ice lobe laterally, as well as forward, toward its extremities. Profiles ca...
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Language: | English |
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Cambridge University Press (CUP)
1974
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Online Access: | http://dx.doi.org/10.1017/s0022143000023352 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000023352 |
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crcambridgeupr:10.1017/s0022143000023352 2024-09-15T17:43:45+00:00 Surface profiles of the laurentide ice sheet in its marginal areas Mathews, W. H. 1974 http://dx.doi.org/10.1017/s0022143000023352 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000023352 en eng Cambridge University Press (CUP) Journal of Glaciology volume 13, issue 67, page 37-43 ISSN 0022-1430 1727-5652 journal-article 1974 crcambridgeupr https://doi.org/10.1017/s0022143000023352 2024-07-24T04:03:42Z Surface slopes of ice lobes can be estimated from the gradients of their margins as shown by ice limits, by contemporaneous recessional moraines, or by lateral melt-water channels, with allowance being made for the dip of an ice lobe laterally, as well as forward, toward its extremities. Profiles can be fitted approximately to a parabola with the equation in which h is the height above and x the distance up-stream from the terminus, in the same units, and A is a coefficient which varies from glacier to glacier. The coefficient A has a value of 4.7 m 1 for both the Antarctic ice sheet inland from Mirny and the west central Greenland ice sheet. Several examples of late Pleistocene ice lobes within mountainous terrain of North America and New Zealand have values of A ranging from 2.9 m l to about 4.1 m 1 . For several ice lobes in the south-western part of the late Pleistocene Laurentide ice sheet, however, values are from about 0.3 to 1.0 m 1 , corresponding to basal shear stress of from about 0.07 to 0.22 bar. A major problem exists in accounting for the active movement of ice here under such low surface gradients and basal shear stresses. Evidence of basal slip, aided by high subglacial water pressure, should be looked for in the field. Alternatively, other possibilities for the explanation of such low surface gradients should be sought. Article in Journal/Newspaper Antarc* Antarctic glacier Greenland Ice Sheet Journal of Glaciology Cambridge University Press Journal of Glaciology 13 67 37 43 |
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Open Polar |
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Cambridge University Press |
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crcambridgeupr |
language |
English |
description |
Surface slopes of ice lobes can be estimated from the gradients of their margins as shown by ice limits, by contemporaneous recessional moraines, or by lateral melt-water channels, with allowance being made for the dip of an ice lobe laterally, as well as forward, toward its extremities. Profiles can be fitted approximately to a parabola with the equation in which h is the height above and x the distance up-stream from the terminus, in the same units, and A is a coefficient which varies from glacier to glacier. The coefficient A has a value of 4.7 m 1 for both the Antarctic ice sheet inland from Mirny and the west central Greenland ice sheet. Several examples of late Pleistocene ice lobes within mountainous terrain of North America and New Zealand have values of A ranging from 2.9 m l to about 4.1 m 1 . For several ice lobes in the south-western part of the late Pleistocene Laurentide ice sheet, however, values are from about 0.3 to 1.0 m 1 , corresponding to basal shear stress of from about 0.07 to 0.22 bar. A major problem exists in accounting for the active movement of ice here under such low surface gradients and basal shear stresses. Evidence of basal slip, aided by high subglacial water pressure, should be looked for in the field. Alternatively, other possibilities for the explanation of such low surface gradients should be sought. |
format |
Article in Journal/Newspaper |
author |
Mathews, W. H. |
spellingShingle |
Mathews, W. H. Surface profiles of the laurentide ice sheet in its marginal areas |
author_facet |
Mathews, W. H. |
author_sort |
Mathews, W. H. |
title |
Surface profiles of the laurentide ice sheet in its marginal areas |
title_short |
Surface profiles of the laurentide ice sheet in its marginal areas |
title_full |
Surface profiles of the laurentide ice sheet in its marginal areas |
title_fullStr |
Surface profiles of the laurentide ice sheet in its marginal areas |
title_full_unstemmed |
Surface profiles of the laurentide ice sheet in its marginal areas |
title_sort |
surface profiles of the laurentide ice sheet in its marginal areas |
publisher |
Cambridge University Press (CUP) |
publishDate |
1974 |
url |
http://dx.doi.org/10.1017/s0022143000023352 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000023352 |
genre |
Antarc* Antarctic glacier Greenland Ice Sheet Journal of Glaciology |
genre_facet |
Antarc* Antarctic glacier Greenland Ice Sheet Journal of Glaciology |
op_source |
Journal of Glaciology volume 13, issue 67, page 37-43 ISSN 0022-1430 1727-5652 |
op_doi |
https://doi.org/10.1017/s0022143000023352 |
container_title |
Journal of Glaciology |
container_volume |
13 |
container_issue |
67 |
container_start_page |
37 |
op_container_end_page |
43 |
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1810490907104903168 |