Ice-sculpted bedrock in channels of the Canadian Arctic Archipelago

Glaciers erode bedrock at all scales, from striations of millimetres in width through to the landscape-scale of U-shaped valleys and fjords. Glacier erosion processes include fine-scale abrasion and the fracture of larger rock fragments (e.g. Iverson 1990; Harbor 1992). These processes take place especially where high stress concentrations are present below rock particles held at the glacier bed beneath actively flowing ice that is at the pressure melting point. The rate and nature of bedrock erosion by ice is also dependent on the rock type involved, its joint structure at both macro- and micro-scales and the presence of water in any joints and cavities (e.g. Iverson 1991). Multibeam sonar imagery of rocky areas of the high-latitude seafloor often reveals streamlined bedrock landforms although metre-scale and smaller features, such as striations, gouges, chattermarks and p-forms (Dahl 1965; Benn & Evans 2010), are usually below system resolution. While much of the continental shelf surrounding the Canadian Arctic Archipelago has a thick cover of predominantly glacier-derived deposits (MacLean et al. 1990), the channels between islands also have extensive areas either dominated by bedrock outcrops or where bedrock protrudes through seafloor sediments (Fig. 1a–c). Even where bedrock …