Geomorphological signature and flow dynamics of The Minch palaeo-ice stream, NW Scotland

Large-scale streamlined glacial landforms are identified in 11 areas of northwest Scotland, from the Isle of Skye in the south to the Butt of Lewis in the north. These ice-directional features occur in bedrock and superficial deposits, generally below 350 m above sea level, and where best developed have elongation ratios of >20:1. Sidescan sonar and multibeam echo-sounding data from The Minch show elongate streamlined ridges and grooves on the seabed, with elongation ratios of up to 70:1. These bedforms are interpreted as mega-scale glacial lineations. All the features identified formed beneath The Minch palaeo-ice stream which was ca. 200 km long, up to 50 km wide and drained ca. 15 000 km2 of the northwest sector of the last British-Irish Ice Sheet (Late Devensian Glaciation). Nine ice-stream tributaries and palaeo-onset zones are also identified, on the basis of geomorphological evidence. The spatial distribution and pattern of streamlined bedforms around The Minch has enabled the catchment, flow paths and basal shear stresses of the palaeo-ice stream and its tributaries to be tentatively reconstructed.