Debris Entrainment Processes at Glacier Beds

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Debris entrainment at glacier beds is a fundamental geomorphic process because it provides the tools for erosional processes such as abrasion and quarrying. Nonetheless, processes of basal debris entrainment remain incompletely understood. This investigation, which focuses on these mechanisms, combines experimental studies in laboratory and field with theoretical analysis of thermal and hydrologic controls on debris entrainment. The widely accepted "Weertman-Boulton" freeze-on hypothesis of debris entrainment will be reexamined by finite-element hydrologic flow modelling. Debris entrainment by ice lensing (secondary heave) at the soles of cold glaciers may also be a very important process. The basic physics of this process will be investigated in the context of field data supporting the existence of this phenomenon. Theoretical work involving numerical simulations, to elucidate debris-entrainment rates and controls on this mechanism will be described.