Borehole video analysis of a temperate glacier's englacial and subglacial structure: implications for glacier flow models

Video observations affirm that temperate glacier ice may be reasonably represented as homogeneous in glacier flow models, but raise warnings about the complexities of basal boundary conditions and glacier sliding. Discrete englacial structures, including clear-ice layers, voids, and water conduits, compose a total of <3% of the ice mass. Planar features (clear-ice layers) are oriented near vertical and are not aligned with the sense of shear strain, meaning that the layers probably do not influence the homogeneity of the strain. Observations of the basal boundary or sliding surface indicate that there are areas of both "hard' bedrock and "soft' deformable till, which should cause spacial and temporal gradients in sliding rate. -from Authors