Sediment entrainment by a soft-bedded glacier: a model based on regelation into the bed
Article first published online: 3 JUL 2000
Copyright © 2000 John Wiley & Sons, Ltd.
Earth Surface Processes and Landforms
Volume 25, Issue 8, pages 881–893, August 2000
How to Cite
Iverson, N. R. (2000), Sediment entrainment by a soft-bedded glacier: a model based on regelation into the bed. Earth Surf. Process. Landforms, 25: 881–893. doi: 10.1002/1096-9837(200008)25:8<881::AID-ESP105>3.0.CO;2-Y
- Issue published online: 3 JUL 2000
- Article first published online: 3 JUL 2000
- Manuscript Accepted: 9 FEB 2000
- Manuscript Revised: 30 DEC 1999
- Manuscript Received: 8 JUN 1999
- US National Science Foundation. Grant Number: EAR-9418671
- effective pressure;
- basal melt rate;
Experimental results indicate that wet-based, soft-bedded glaciers may penetrate their substrates by regelation (melting and refreezing) and thereby entrain sediment. In principle, there should be a steady depth of penetration at which the downward regelation speed, driven by the interfacial effective pressure, equals the basal melt rate. Herein, the magnitude and distribution of penetration are estimated for the case of a glacier resting on a deformable bed with channelized basal drainage. The distance between channels and the distribution of effective pressure across the bed are calculated, and special attention is paid to the interdependence of the basal melt rate and effective pressure. A major uncertainty is whether fine-grained tills may impede or prevent regelation as a result of high surface tension at the ice/water interface.
Predicted penetration depths range from millimetres to a few decimetres, and thus, dirty basal ice layers of such thicknesses might be expected. Predicted distances between channels agree well with those indicated by borehole measurements at Ice Stream B, West Antarctica. Effective pressures, and hence penetration depths, increase toward channels. Therefore, the edges of interfluves, bounded by anastomosing subglacial channels, should be eroded preferentially. This motivates the testable hypothesis that such erosion contributes to the formation of streamlined landforms, such as drumlins. Copyright © 2000 John Wiley & Sons, Ltd.