Reference Work Entry

Encyclopedia of Snow, Ice and Glaciers

Part of the series Encyclopedia of Earth Sciences Series pp 85-90


Basal Sediment Evacuation by Subglacial Drainage Systems

  • Darrel A. SwiftAffiliated withDepartment of Geography, University of Sheffield Email author 


Basal sediment: The debris layer that exists at the ice–bedrock interface of a glacier or ice sheet and that is produced by glacial erosion of the underlying bedrock.

Basal sediment evacuation: The removal of basal sediment from the ice–bed interface by glacial and/or glaciofluvial sediment transport; most frequently used to describe the flushing of basal sediment from the ice–bedrock interface by subglacial water.

Subglacial drainage system: The network of drainage pathways at the ice–bed interface that convey water to the glacier margin or terminus.


Contemporary observations and theoretical analyses demonstrate that, for Temperate Glaciers (qv), the entrainment and transport of basal sediment by fluvial processes dominates all other glacial sediment transport (Sediment Entrainment, Transport, and Deposition, qv) processes (see Hallet et al., 1996; Alley et al., 1997). Basal sediment evacuation by the

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