HOW GLACIERS ENTRAIN AND TRANSPORT BASAL SEDIMENT - PHYSICAL CONSTRAINTS

Simple insights from the physics of ice, water and sediment place cons traints on the possible sediment-transport behavior of glaciers and ic e sheets. Because glaciers concentrate runoff, streams generated by gl aciers transport much sediment and may erode bedrock rapidly. Deformin g glacier beds also can transport much sediment, particularly in margi nal regions. Rapid sediment entrainment producing thick debris-rich ba sal zones may occur by regelation into subglacial materials, and by fr eeze-on from rising supercooled waters. Numerous other mechanisms may be important but primarily near ice margins, especially those of advan cing or fluctuating glaciers. Several sediment-entrainment mechanisms may be active beneath a single glacier, but one process is likely to b e dominant at any place and time. Copyright (C) 1998 Elsevier Science Ltd.