SEDIMENT DEFORMATION BENEATH GLACIERS - RHEOLOGY AND GEOLOGICAL CONSEQUENCES

Experiments beneath Breidamerkurjokull in Iceland have led to development of flow laws for the subglacial till, relating strain rate to shear stress and effective pressure and assuming either Bingham fluid or nonlinearly viscous fluid behaviour. A one-dimensional theory of subglacial deformation is developed in which the empirical flow law is coupled with a model of subglacial hydrology and consolidation. Tunnel valleys can be regarded as the equivalent in soft sediment areas of eskers in bedrock areas. -from Authors