Energy Dissipation During Subglacial Abrasion at Nisqually Glacier, Washington, U.S.A.
Abstract This study examines the effect of subglacial abrasion on the basal sliding term of the gravitational energy balance of the dynamic, temperate Nisqually Glacier on Mount Rainier, Washington, U.S.A. Subglacial water flux is estimated as 3 × 10 7 m 3 a –1 and suspended sediment flux as 3 × 10...
| Published in: | Journal of Glaciology |
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| Main Author: | |
| Format: | Article in Journal/Newspaper |
| Language: | English |
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Cambridge University Press (CUP)
1979
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| Online Access: | http://dx.doi.org/10.1017/s0022143000029865 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000029865 |
| Summary: | Abstract This study examines the effect of subglacial abrasion on the basal sliding term of the gravitational energy balance of the dynamic, temperate Nisqually Glacier on Mount Rainier, Washington, U.S.A. Subglacial water flux is estimated as 3 × 10 7 m 3 a –1 and suspended sediment flux as 3 × 10 7 kg a –1 . Suspended-sediment flux is assumed to represent, within an order of magnitude, the annual mass eroded by subglacial abrasion. Subglacial abrasion involves both brittle fracture and plastic deformation. Field observations of bas-relief and grooved depression striations appear to have exact counterparts in rock mechanics experiments approximating subglacial velocities and normal stresses. Boulton's ([ C l974]) abrasion model and a new attritivity model proposed herein are shown to predict subglacial abrasion-rates within the limits of natural variability and the error range of measurements. The first crude gravitational energy balance for lower Nisqually Glacier (1.96 km 2 ) is attempted and probably has only order-of-magnitude accuracy. The importance of subglacial abrasion in dissipating basal sliding energy at Nisqually Glacier is confirmed. |
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