Is the Basal Ice of a Temperate Glacier at the Pressure Melting Point?
Abstract Certain aspects of the flow of glaciers suggest that molecular adhesion contributes to basal friction of glaciers sliding at speeds below those of surging glaciers. Laboratory experiments indicate that this will only occur if some part of the ice-rock contact is “cold”, that is below the pr...
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Cambridge University Press (CUP)
1976
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Online Access: | http://dx.doi.org/10.1017/s002214300003152x https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S002214300003152X |
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crcambridgeupr:10.1017/s002214300003152x 2024-03-03T08:46:08+00:00 Is the Basal Ice of a Temperate Glacier at the Pressure Melting Point? Robin, G. de.Q. 1976 http://dx.doi.org/10.1017/s002214300003152x https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S002214300003152X en eng Cambridge University Press (CUP) Journal of Glaciology volume 16, issue 74, page 183-196 ISSN 0022-1430 1727-5652 Earth-Surface Processes journal-article 1976 crcambridgeupr https://doi.org/10.1017/s002214300003152x 2024-02-08T08:36:10Z Abstract Certain aspects of the flow of glaciers suggest that molecular adhesion contributes to basal friction of glaciers sliding at speeds below those of surging glaciers. Laboratory experiments indicate that this will only occur if some part of the ice-rock contact is “cold”, that is below the pressure melting point (p.m.p.), a few tenths of a degree being sufficient. Field evidence is scanty, but suggests that such cold patches may exist at the base of a temperate glacier. Discussion of pressure-melting within the basal ice mass, as distinct from processes at the ice-rock contact, indicate that excess water is formed in zones of high-pressure ice up-stream of obstacles. If this water is squeezed out of the ice by the pressure, we have a simple heat pump that will tend to cool the basal ice. The ice will warm again as the result of thermal conduction and internal friction, but before reaching the p.m.p. it can produce "cold" patches of the ice-rock contact, roughly estimated to be from 0. 1 to 1.0 m in extent. Another factor that could cause intermittent cold patches at the ice-rock interface arises from changes of basal water pressures with time beneath a glacier. If a major part of the weight of a glacier is supported by a thin water film at a relatively low pressure and by a small proportion of water film in which pressures are high, then over a large area the water pressures must balance the weight of ice. If however the pressure in the low-pressure film rises, the smaller high-pressure areas of stress concentration will suffer a proportionately greater decrease of pressure to maintain the total balance between pressure and weight, If changes take place rapidly, in a matter of hours, then in areas of stress concentration of the order of a metre or more across, the water film will freeze to the bed as stresses are relieved. This could cause stick-slip motion in a temperate glacier. Pressure-temperature effects at the ice-rock interface can help to explain certain features of glacial erosion, such as ... Article in Journal/Newspaper Journal of Glaciology Cambridge University Press Journal of Glaciology 16 74 183 196 |
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Open Polar |
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Cambridge University Press |
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crcambridgeupr |
language |
English |
topic |
Earth-Surface Processes |
spellingShingle |
Earth-Surface Processes Robin, G. de.Q. Is the Basal Ice of a Temperate Glacier at the Pressure Melting Point? |
topic_facet |
Earth-Surface Processes |
description |
Abstract Certain aspects of the flow of glaciers suggest that molecular adhesion contributes to basal friction of glaciers sliding at speeds below those of surging glaciers. Laboratory experiments indicate that this will only occur if some part of the ice-rock contact is “cold”, that is below the pressure melting point (p.m.p.), a few tenths of a degree being sufficient. Field evidence is scanty, but suggests that such cold patches may exist at the base of a temperate glacier. Discussion of pressure-melting within the basal ice mass, as distinct from processes at the ice-rock contact, indicate that excess water is formed in zones of high-pressure ice up-stream of obstacles. If this water is squeezed out of the ice by the pressure, we have a simple heat pump that will tend to cool the basal ice. The ice will warm again as the result of thermal conduction and internal friction, but before reaching the p.m.p. it can produce "cold" patches of the ice-rock contact, roughly estimated to be from 0. 1 to 1.0 m in extent. Another factor that could cause intermittent cold patches at the ice-rock interface arises from changes of basal water pressures with time beneath a glacier. If a major part of the weight of a glacier is supported by a thin water film at a relatively low pressure and by a small proportion of water film in which pressures are high, then over a large area the water pressures must balance the weight of ice. If however the pressure in the low-pressure film rises, the smaller high-pressure areas of stress concentration will suffer a proportionately greater decrease of pressure to maintain the total balance between pressure and weight, If changes take place rapidly, in a matter of hours, then in areas of stress concentration of the order of a metre or more across, the water film will freeze to the bed as stresses are relieved. This could cause stick-slip motion in a temperate glacier. Pressure-temperature effects at the ice-rock interface can help to explain certain features of glacial erosion, such as ... |
format |
Article in Journal/Newspaper |
author |
Robin, G. de.Q. |
author_facet |
Robin, G. de.Q. |
author_sort |
Robin, G. de.Q. |
title |
Is the Basal Ice of a Temperate Glacier at the Pressure Melting Point? |
title_short |
Is the Basal Ice of a Temperate Glacier at the Pressure Melting Point? |
title_full |
Is the Basal Ice of a Temperate Glacier at the Pressure Melting Point? |
title_fullStr |
Is the Basal Ice of a Temperate Glacier at the Pressure Melting Point? |
title_full_unstemmed |
Is the Basal Ice of a Temperate Glacier at the Pressure Melting Point? |
title_sort |
is the basal ice of a temperate glacier at the pressure melting point? |
publisher |
Cambridge University Press (CUP) |
publishDate |
1976 |
url |
http://dx.doi.org/10.1017/s002214300003152x https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S002214300003152X |
genre |
Journal of Glaciology |
genre_facet |
Journal of Glaciology |
op_source |
Journal of Glaciology volume 16, issue 74, page 183-196 ISSN 0022-1430 1727-5652 |
op_doi |
https://doi.org/10.1017/s002214300003152x |
container_title |
Journal of Glaciology |
container_volume |
16 |
container_issue |
74 |
container_start_page |
183 |
op_container_end_page |
196 |
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1792502063648735232 |