LITHOLOGICAL AND STRUCTURAL CONTROLS ON THE SURFACE WEAR CHARACTERISTICS OF GLACIATED METAMORPHIC BEDROCK SURFACES - OSSIAN SARSFJELLET, SVALBARD

Although there is an established relationship between geological struc ture and the morphology of certain glacial erosional landforms, the ro le of lithology is less clear. This is particularly true of the surfac e wear characteristics of glaciated bedrock. In order to examine this relationship, the surface wear characteristics of eight recently degla ciated metamorphic bedrock slabs in the Kongsfjorden area of Svalbard were mapped and recorded using detailed ''micromaps.'' Features record ed included lee-side fracture surfaces, lee-side cavities, and the loc ation and depth of open joints and quartz veins. On schist, glacial er osion is favored by situations where ice movement is parallel to the t rend of the bedrock foliation. In these situations, cavities may be el ongated in the direction of ice flow. On more homogeneous lithologies such as marble, cavity formation is suppressed and more uniform glacia lly abraded rock surfaces develop. On all the metamorphic rocks examin ed, 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 surfac e wear characteristics of glaciated bedrock slabs and on the location of subglacial cavities. Geological structure therefore has the potenti al to influence rates of ice flow across bedrock surfaces.