Controls on subglacial bedrock erosion and morphology near Drumnadrochit, Scotland

Abstract

Abrasion and plucking are important subglacial erosional processes that create different landforms. This study shows that properties of bedrock control subglacial erosion and bedrock morphology. Softer and less-jointed bedrock favours abrasion, while denser-jointed bedrock and harder bedrock do not. Field work for this study was carried out near Drumnadrochit in Inverness-shire, where the lithology, geology and morphology of rôches moutonnées and crag-and-tails were examined. In this area, the rôches moutonnées, which have an abraded stoss side, are only shaped out of a relatively soft, biotite-rich gneiss, with not much jointing. The crag-and-tails have more densely jointed stoss sides and are shaped out of serpentinite or a harder, more felsic gneiss. Foliation appears not to influence subglacial erosion, since the foliation in rôches moutonnées and crag-and-tails in the study area is similar. Thematic collection: This article is part of the Early Career Research collection available at: https://www.lyellcollection.org/cc/SJG-early-career-research