10 research outputs found
Holocene relative sea level changes in a glacio-isostatic area: new data from south-west Scotland, United Kingdom
This paper contributes to knowledge of Holocene relative sea level change along the mainland Ayrshire coast and offshore Isle of Bute, SW Scotland, UK, where few such studies have previously been undertaken. Morphological studies (mapping and altitude survey), together with stratigraphical and biostratigraphical studies (pollen and diatom analyses and radiocarbon dating) disclose evidence for mid and late Holocene relative sea level changes. The Main Postglacial and Blairdrummond displaced shorelines, previously identified widely in mainland Scotland, are dated in the area at c. 6800 calibrated years (c. 6000 C-14 years) and c. 4200 calibrated years (c. 3800 14C years) BP respectively. This information is compared with previously published information for Scotland against the classical theoretical model of relative sea level change in areas of glacio-isostasy. For the mid and late Holocene, in conformity with the model, a falling sequence of relative sea level changes near the centre of uplift is replaced by a rising sequence towards the periphery, in which later shorelines overlap earlier ones. In particular, the Blairdrummond Shoreline, which overlaps the earlier Main Postglacial Shoreline, is identified as the highest Holocene shoreline over much of the coastline of Scotland
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The Holocene Storegga Slide tsunami in the United Kingdom
All currently known sites in the United Kingdom with evidence for the Holocene Storegga Slide tsunami are described. Information on the altitude, distribution, stratigraphical context, age, particle size profile and microfossil characteristics of the deposits is presented. The tsunami involved a greater area than previously described, reaching a coastline over 600km long. The ubiquitous sand layer which forms the main deposit associated with the event is shown to exhibit a consistent morphology and a particle size profile marked by fining-upwards sequences. An analysis of new and previously published radiocarbon dates indicates that from evidence in the United Kingdom, the event took place sometime around 7100 radiocarbon years BP (7900 calibrated years BP). A new isobase model for mainland Scotland and adjacent areas, providing a preliminary estimate of land uplift since the tsunami, is presented. The model estimates contemporary sea surface level offshore at 14m below the present day mean high water spring tides. Tsunami sediment run-up is greatest in inlets, where it reaches at least 25m on Shetland and at least 5m along the mainland coastline to the south, and run-up of the tsunami would have exceeded these values. The tsunami sediments identified here are considered particularly valuable as a synchronous marker horizon