Ice-carved landscapes

Under the right conditions, glaciers can be very effective agents of erosion. In the uplands, powerful ice streams carved deep glacial troughs from the existing valleys (e.g. Glen Clova and Glen Docherty) and sometimes formed deep rock basins on their floors (e.g. Loch Ness and Loch Monar). Elsewhere, they breached watersheds, cutting new glens that now form important transport routes (e.g. Glencoe and Glen Shiel).

Scouring the landscape

In some areas, the effects of the glaciers were 'selective', where pre-existing glens were deepened but adjacent plateau surfaces were little altered, as in the Cairngorms. In others, the glaciers extensively scraped, scoured and roughened the bedrock, often up to the summits, forming landscapes of 'areal scouring', as in the Western Isles, Sutherland and Ardgour.

Eastern lowlands

In the lowlands of eastern Scotland, the landscape was moulded and streamlined by the glaciers, producing crag-and -tail landforms such as Edinburgh Castle Rock and the Royal Mile. Individual rock outcrops were often shaped into 'roches moutonnées', with smoothed upstream sides and quarried downstream sides; good examples occur in upper Deeside, south of Aviemore and at Dulnain Bridge.

West and Northwest Highlands

By far the greatest impact was in the West and Northwest Highlands, illustrated by the fact that 90% of the corries and more than 90% of the rock basins are in westerly flowing river catchments. There, snowfall was greater, the ice thicker and the glaciers steeper and faster flowing and hence capable of more effective erosion.

Unchanged in the northeast

In contrast, the glaciers had a relatively benign effect on the landscape in some areas, especially in Northeast Scotland. Many of the features of the pre-glacial period, especially gently rolling slopes and weathered bedrock, remain little modified (as in Buchan), tors have been uncovered but not destroyed (as on Bennachie) and river systems remain largely intact.