A research campaign into the scarcely known history and prehistoric origins of Scottish West Highland and Island settlement, has located an area of ‘fossil’ landscape at Coileagan an Udail (the Udal), N. Uist. The completion of a first stage of 14 years excavation (155 weeks) has provided detailed evidence of continuous occupation from the Iron Age to the eighteenth century AD. Sampling has shown positive indications of a similar picture back through much of prehistory at least as far as the Beaker period and is the basis for the proposed second stage of excavations. This remarkably long (by European standards) sequence of deposition has had its coherence confirmed by a first series of radiocarbon dates. The calibration of these dates and their relationship to crucial artifacts is considered. This article is by Iain Crawford, who has just completed two years as Senior Visiting Research Fellow at The Queen's University of Belfast, and Dr Roy Switsur, Head of the Radiocarbon Dating Research Laboratory University of Cambridge.