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Abstract Abrasion acts to smooth glacial terrains and leaves behind linear scratch-like features (striations) on bedrock landscapes. Striations are often used as measures of glacier flow directions, but their morphology can also provide information about the subglacial stress conditions that produced the features. While striations are often abundant in the field, the processes that create them can be opaque and hard to examine in situ because they occur under thick layers of flowing ice. To alleviate that difficulty and provide information for interpretation of the populations of striations that are observed in the field, we conducted a set of laboratory experiments in which a ring of temperate debris-laden ice was slid atop a planar marble bed under various contact force conditions that led to the creation of hundreds of striations. During the experiment, numerous glaciological properties were continuously measured, including the resistive drag. Following the completion of the experiments, the marble beds were extracted, and the striations were measured for length and categorized by morphological type, and a subset was measured using a high-resolution white-light profilometer. These experiments showed that, similar to field observations, type 2 striations were initially the most abundant; however, we found that type 3 striations became the most abundant at large displacements. We found good correlation between the abundance of striations as a function of displacement and measured drag as a function of displacement. When taken together, these results suggest that, in natural settings, ice flow around small roughness elements in glacier beds can “reset” the basal debris field, causing striations to become more abundant in their wake. As roughness is linked to quarrying, abrasion rates may increase in areas of increased quarrying. 

Abstract Subglacial abrasion drives erosion for many glaciers, inundating forefields and proglacial marine environments with glaciogenic sediments. Theoretical treatments of this process suggest that bedrock abrasion rates scale linearly with the energy expended through rock-on-rock friction during slip, but this assumption lacks an empirical basis for general implementation. To test this approach, we simulated abrasion by sliding debris-laden ice over rock beds under subglacial conditions in a cryo-ring shear and a direct shear device. Miniscule volumes of erosion that occurred during each run were mapped with a white-light profilometer, and we measured the rock mechanical properties needed to constrain the energy expended through abrasion. We find that abraded volume per unit area increases linearly with average shear force at the bed and that abrasion rates increase linearly with basal power for plane beds. Lastly, only a small percentage (1%) of the energy partitioned to basal slip is dissipated by abrasion. These results confirm the basal-power abrasion rule is viable to implement in landscape evolution models.