Precambrian[edit]
The oldest rocks found on Skye are gneisses of the Lewisian complex that were formed about 2,800 million years ago during the Archaean.[1] These gneisses outcrop on the southeastern coast of the Sleat peninsula and were originally granitic igneous rocks. Near Tarskavaig, Neoproterozoic metasediments of the Moine Supergroup are found above strongly deformed Lewisian rocks. The Lewisian and Moine sequences are thrust over another sequence of unmetamorphosed Neoproterozoic sediments, the Torridonian, along the Moine Thrust Zone. The Torridonian on Skye comprises two conformable sequences, the older Sleat Group and the younger Torridon Group. Both groups consist dominantly of sandstones and were deposited mainly by alluvial fans and rivers.