During the last glaciation the Westmorland Dales lay under a huge ice sheet hundreds of metres thick. The ice was full of boulders, gravel and sand and acted like a giant sheet of sandpaper. It streamed over the landscape, widening existing valleys, scouring the fells and scraping limestone pavements bare.
The Westmorland Dales has a complex glacial story, involving ice originating from the Lake District, Scotland and the Howgills. These different ice flows waxed and waned and at different times the ice flowed in different directions, giving rise to complex patterns of glacial features. For example, at one stage Scottish ice flowed up the Eden Valley and through the Stainmore Gap, but later, ice flowed down the Eden Valley and around the northern Lake District.