Clachtoll: the base of the Stoer Group (Torridonian)

At Clachtoll, 8 km NW of Lochinver, an irregular ancient land surface formed on Lewisian gneisses is covered by red-brown sandstones of the lower part of the Torridonian succession.

Inlet south of Clachtoll, where red-brown conglomerate and sandstone lie on an irregular surface of Lewisian gneiss. In the foreground is a conglomerate made of gneiss boulders, filling a valley in the old surface. On the right, in the middle distance, is the top of a gneiss "hill", sticking up through the conglomerate. Draped over the top of the "hill" are the red sandstones seen on the left-hand side of the inlet in the background.

A thin layer of rubble, centre right, lies on the surface of the gneiss. For some distance around this spot, erosion has stripped off almost all the Stoer Group sediments, revealing in detail the shape of the 1200 million-year-old land surface they were deposited on.

Rock types at Clachtoll

D.J. Waters, Department of Earth Sciences, May 2003