Glacier flow at a former ice-divide in SW Scotland

Abstract

AbstractLate Devensian ice-sheet movement in the western Southern Uplands of Scotland is demonstrated by the distribution of erratics from four different bedrock sources and by glacial striae and ice-moulded landforms. This evidence shows an almost radial movement of ice from an ice-divide zone. The control of relief over ice flow and the distribution of erratics is emphasised. The distribution of erratics from two of the sources, however, shows that debris in the ice was transported only a very short distance in certain places. Abundant deposits of lodgement till occur in the vicinity of the former ice-divide. Although it is generally considered that glacial erosion, and therefore deposition, are insignificant at the centre of ice-sheets, this study suggests otherwise. It is inferred that till and erratics may be emplaced during ice-sheet build-up when conditions for erosion obtained, these deposits being protected from subsequent removal by the establishment of an ice-divide across the area. The implications for high rates of erosion in ice-sheet source areas are examined.