Lithological and Structural Controls on the Surface Wear Characteristics of Glaciated Metamorphic Bedrock Surfaces: Ossian Sarsfjellet, Svalbard

Abstract

Although there is an established relationship between geological structure and the morphology of certain glacial erosional landforms, the role of lithology is less clear. This is particularly true of the surface wear characteristics of glaciated bedrock. In order to examine this relationship, the surface wear characteristics of eight recently deglaciated metamorphic bedrock slabs in the Kongsfjorden area of Svalbard were mapped and recorded using detailed “micro‐maps.” Features recorded included lee‐side fracture surfaces, lee‐side cavities, and the location and depth of open joints and quartz veins. On schist, glacial erosion is favored by situations where ice movement is parallel to the trend of the bedrock foliation. In these situations, cavities may be elongated in the direction of ice flow. On more homogeneous lithologies such as marble, cavity formation is suppressed and more uniform glacially abraded rock surfaces develop. On all the metamorphic rocks examined, glacial abrasion is favored in situations where bedrock foliation is normal to ice flow. The structure of the parent bedrock, especially the orientation of foliation, exerts a strong influence on the surface wear characteristics of glaciated bedrock slabs and on the location of subglacial cavities. Geological structure therefore has the potential to influence rates of ice flow across bedrock surfaces.