MATHEMATICAL SYMBOLS
ABSTRACT. We develop theoretically a description of a possible subglacial drainage mechanism for glaciers and ice sheets moving over saturated, deformable till. The model is based on the plausible assumption that flow at the ice-till interface is unstable to the formation of a channelized drainage s...
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ftciteseerx:oai:CiteSeerX.psu:10.1.1.304.5801 2023-05-15T13:58:07+02:00 MATHEMATICAL SYMBOLS Joseph S. Walder Andrew Fowler Ai Ice The Pennsylvania State University CiteSeerX Archives application/pdf http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.304.5801 http://www.maths.ox.ac.uk/%7Efowler/papers/1994.2.pdf en eng http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.304.5801 http://www.maths.ox.ac.uk/%7Efowler/papers/1994.2.pdf Metadata may be used without restrictions as long as the oai identifier remains attached to it. http://www.maths.ox.ac.uk/%7Efowler/papers/1994.2.pdf text ftciteseerx 2016-01-07T22:13:33Z ABSTRACT. We develop theoretically a description of a possible subglacial drainage mechanism for glaciers and ice sheets moving over saturated, deformable till. The model is based on the plausible assumption that flow at the ice-till interface is unstable to the formation of a channelized drainage system, and is restricted to the case in which meltwater cannot escape through the till to an underlying aquifer. In describing the physics of such channelized drainage, we have generalized and extended Rothlisberger's model of channels cut into basal ice to include "canals " cut into the till, paying particular attention to the role of sediment properties and the mechanics of sediment transport. We show that sediment-floored Rothlisberger (R) channels can exist for high effective pressures, and wide, shallow, ice-roofed canals cut into the till for low effective pressures. Canals should form a distributed, non-arborescent system, unlike R channels. For steep slopes typical of alpine glaciers, both drainage systems can exist, but with the water pressure lower in the R channels than in the canals; the canal drainage should therefore be unstable in the presence of channels. For small slopes typical of ice sheets, only canals can exist and we therefore predict that, if channelized meltwater flow occurs under ice sheets moving over deformable till, it takes the form of shallow, distributed canals at low effective pressure, similar to that measured at Ice Stream B in West Antarctica. Geologic evidence derived from land forms and deposits left by the Pleistocene ice sheets in North America and Europe is also consistent with predictions of the model. Text Antarc* Antarctica Ice Stream B West Antarctica Unknown West Antarctica |
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ABSTRACT. We develop theoretically a description of a possible subglacial drainage mechanism for glaciers and ice sheets moving over saturated, deformable till. The model is based on the plausible assumption that flow at the ice-till interface is unstable to the formation of a channelized drainage system, and is restricted to the case in which meltwater cannot escape through the till to an underlying aquifer. In describing the physics of such channelized drainage, we have generalized and extended Rothlisberger's model of channels cut into basal ice to include "canals " cut into the till, paying particular attention to the role of sediment properties and the mechanics of sediment transport. We show that sediment-floored Rothlisberger (R) channels can exist for high effective pressures, and wide, shallow, ice-roofed canals cut into the till for low effective pressures. Canals should form a distributed, non-arborescent system, unlike R channels. For steep slopes typical of alpine glaciers, both drainage systems can exist, but with the water pressure lower in the R channels than in the canals; the canal drainage should therefore be unstable in the presence of channels. For small slopes typical of ice sheets, only canals can exist and we therefore predict that, if channelized meltwater flow occurs under ice sheets moving over deformable till, it takes the form of shallow, distributed canals at low effective pressure, similar to that measured at Ice Stream B in West Antarctica. Geologic evidence derived from land forms and deposits left by the Pleistocene ice sheets in North America and Europe is also consistent with predictions of the model. |
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The Pennsylvania State University CiteSeerX Archives |
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Text |
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Joseph S. Walder Andrew Fowler Ai Ice |
spellingShingle |
Joseph S. Walder Andrew Fowler Ai Ice MATHEMATICAL SYMBOLS |
author_facet |
Joseph S. Walder Andrew Fowler Ai Ice |
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Joseph S. Walder |
title |
MATHEMATICAL SYMBOLS |
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MATHEMATICAL SYMBOLS |
title_full |
MATHEMATICAL SYMBOLS |
title_fullStr |
MATHEMATICAL SYMBOLS |
title_full_unstemmed |
MATHEMATICAL SYMBOLS |
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mathematical symbols |
url |
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.304.5801 http://www.maths.ox.ac.uk/%7Efowler/papers/1994.2.pdf |
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West Antarctica |
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West Antarctica |
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Antarc* Antarctica Ice Stream B West Antarctica |
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Antarc* Antarctica Ice Stream B West Antarctica |
op_source |
http://www.maths.ox.ac.uk/%7Efowler/papers/1994.2.pdf |
op_relation |
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.304.5801 http://www.maths.ox.ac.uk/%7Efowler/papers/1994.2.pdf |
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Metadata may be used without restrictions as long as the oai identifier remains attached to it. |
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1766266211021094912 |