The stability of a viscous till sheet coupled with ice flow, considered at wavelengths less than the ice thickness

• Published in: Journal of Glaciology
• Main Author: Hindmarsh, Richard C. A.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 1998
• Subjects: Ice Sheet; Journal of Glaciology
• Online Access: http://dx.doi.org/10.1017/s0022143000002628; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000002628

Abstract A perturbation method is used to analyse the stability of a thin till layer overlain by a deep ice layer. Ice is modelled as a linearly viscous fluid, while the till viscosity has power-law dependence on stress and effective pressure. A linearized set of equations yields descriptions of the coupling of the ice flow with the sediment flow and reveals parameter ranges where the till-perturbation amplitude can grow. This sheet-flow instability is an essential part of any theory of drumlin formation and shows that viscous models of till have the ability to explain typical deforming-bed features. This is of great significance for large-scale ice-sheet modelling.