Glacial erosion in an ice-divide zone

It is widely accepted that glacial erosion, and therefore deposition, are insignificant at the centres of ice-sheets^1-4, although a few authors have argued for extensive glacial erosion in those areas^5,6. Here I argue from the detailed study of erratics trains from three distinctive bedrock sources, from striae and from ice-moulded landforms that the two views need not be mutually exclusive. The presence of large quantities of lodgement till in the vicinity of a former ice-divide in south-west Scotland is explained by debris emplacement during ice-sheet build-up, when conditions for erosion obtained. The till was protected from subsequent removal by the superimposition of an ice-divide across the area. © 1983 Nature Publishing Group.