Assynt, Sutherland. A basal breccia is present in many areas with large clasts derived from the underlying Lewisian. The breccia passes up into muddy sandstones, often with well-preserved desiccation structures, and into deposits of a braided river system, trough cross-bedded sandstones and conglomerates. A thin sequence of siltstones and fine sandstones alternate with muddy sandstones, suggesting deposition in a lacustrine environment. The uppermost part of the sequence consists of trough cross-bedded sandstones thought to have been deposited by braided rivers. Sleat Group The Sleat Group, which outcrops on the Sleat peninsula on Skye, underlies the Torridon Group conformably, but the relationship with the Stoer Group is nowhere exposed. It is presumed to have been in deposited later that the Stoer Group, but possibly in a separate sub-basin. It is metamorphosed to greenschist facies and sits within the Kishorn Nappe, part of the Caledonian thrust belt, making its exact relationship to the other outcrops difficult to assess. The sequence consists of mainly coarse-grained feldspathic sandstones deposited in a fluvial environment with some less common grey shales, probably deposited in a lacustrine environment. Torridon Group The Torridon Group infills an irregular land surface with up to 600 m of topography locally, cutting down through the previously deposited Stoer group sediments, resting in many areas directly on the Lewisian. The lowest part of this group consists of a basal breccia passing up into sandstones and subordinate shales deposited as alluvial fans building out into ephemeral lakes. The upper parts of the group consist of an overall fining-upward sequence of sandstones, interpreted to have been deposited in a bajada environment. Cambro-Ordovician sediments This thin strip of Lower Paleozoic strata lie unconformably on both the Lewisian complex and the Torridonian. The sequence is divided into the lower Cambrian Ardvreck Group overlain by the Durness Group of Cambrian to lower Ordovician age. Ardvreck Group The ca. 200 m thick lower Cambrian Ardvreck Group consists of two formations, the basal Eriboll Formation and the overlying An-t-Sron Formation. The Eriboll Formation contains the Basal Quartzite member, with a basal conglomerate overlain by the heavily bioturbated Pipe Rock member with its distinctive skolithos trace fossils. The An-t-Sron Formation consists of calcareous siltstones of the Fucoid Beds and overlying sandstone of the Salterella Grit. Durness Group The Durness group lies conformably on the Ardvreck Group. It consists of several hundred metres of mainly dolomites with some limestones and cherts, although