'Pipe Rock' at Skiag Bridge, Loch Assynt, Sutherland.

This is the classic exposure of the Pipe Rock Member of the Eriboll Formation (early Cambrian) at Skiag Bridge, Loch Assynt, Sutherland, Scotland.

Cross-bedded pale grey quartzitic/feldspathic marine sandstones deposited as sand bars in a near-shoreline environment are stained purplish-red and penetrated by Skolithos burrows infilled with creamy grey sandstone.

This indicates that there was periodic halting of sedimentation and near, or actual emergence, so that oxidation of the iron and manganese minerals in the sediments could occur and the top part of the sediments colonised by burrowing organisms, probably worm-like animals.