Holocene relative sea-level changes on the margin of a glacio-isostatically uplifted area: an example from northern Caithness, Scotland

Abstract

Evidence is presented for Holocene relative sea-level changes on the margin of a glacio-isostatically uplifted area: the lower Wick River valley, northern Caithness, Scotland. Lithostratigraphic, biostratigraphic and chronostratigraphic analyses of intercalated clastic and organic sediments disclose evidence for a rapid rise of relative sea level from at least as low as -3.6 m to +1.5 m O.D. during the mid-Holocene, culminating between c. 6900 and c. 5900 BP. This is correlated with the Main Postglacial Transgression, identified widely in eastern Scotland. Following a subsequent regression, the sediments record two further marine transgressions beginning at c. 4400 and c. 1200 BP. The presence of late-Holocene estuarine deposits as the highest Holocene marine sediments is a situation only recorded to date at one other site in mainland Scotland. The coastal sediment sequence also indicates evidence for a palaeotsunami that occurred at between c. 7300 and c. 7000 BP and was associated with the Second Storegga Slide, one of the world's largest submarine sediment slides, located on the continental slope west of Norway.