The highly dissected terrain indicates great differences in rock resistance. The mountain on the right, towering above the exhumed SubTorridonian surface of low relief, is an erosional remnant, an outlier of the Moine thrust. Bare rock is common, with a cover of forests, heath, and brush. Rounded knobby hills and monadnocks and mountain ranges above 1000 m alternate with low moors. The land was largely covered by Late Pleistocene glacial ice.
Many valleys are ice-sculptured weak zones along faults.