The generalised pattern of flow of the last ice sheet to cross Orkney has been known for over a century. The orientation of striae, distribution of erratics and the presence of shelly till leave no doubt that ice has moved from the bed of the North Sea across Orkney and out towards the Atlantic continental shelf.

Evidence of events before the last ice sheet is almost absent from Orkney. The sediments of the outer Moray Firth basin and from the continental shelf west of the islands do, however, provide a long record of the Quaternary history of Orkney.