Repository data of striation scans

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 provide information about the subglacial stress conditions that produced them. While striations are often abundant in the field, the processes that create them can be opaque and hard to examine in situ as they occur under thick layers of flowing ice. To alleviate that difficulty and provide information about how to interpret 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 lead 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, categorized by morphological type, and a subset were measured using a high-resolution white light profilometer. These experiments show that, similar to field observations, type 2 striations are initially the most abundant, however, we find that at large displacements type 3 striations become the most abundant. We find 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 suggests 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.