Lateglacial and Holocene relative sea-level changes and first evidence for the Storegga tsunami in Sutherland, Scotland.

Abstract

We reconstruct one of the longest relative sea-level (RSL) records in northwest Europe from the north coast of mainland Scotland, using data collected from three sites in Loch Eriboll (Sutherland) that we combine with other studies from the region. Following deglaciation, RSL fell from a Late Glacial highstand of +6-8 m OD (Ordnance Datum = c. mean sea level) at c. 15 k cal a BP to below present, then rose to an early Holocene highstand and remained at c. +1 m OD between c. 7 and 3 k cal a BP, before falling to present. We find no evidence for significant differential Holocene glacio-isostatic adjustment between sites on the northwest (Lochinver, Loch Laxford), north (Loch Eriboll) and northeast (Wick) coast of mainland Scotland. This suggests that the region was rapidly deglaciated and there was little difference in ice loads across the region. From one site at the head of Loch Eriboll we report the most westerly sedimentary evidence for the early Holocene Storegga tsunami on the Scottish mainland. The presence of the Storegga tsunami in Loch Eriboll is predicted by a tsunami wave model, which suggests that the tsunami impacted the entire north coast of Scotland and likely also the Atlantic coastline of northwest Scotland.