Holocene Coastal Barrier Development at Bay of Carness, Mainland Island, Orkney, Scotland

Abstract

A coarse clastic barrier and backing lagoon at Bay of Carness, Orkney, Scotland, United Kingdom, are examined. Mapping and survey of the landforms and sediments associated with the barrier and lagoon, followed by stratigraphical investigation and laboratory analyses including pollen analysis, plant macrofossil analysis, diatom analysis and radiocarbon dating are described. The earliest dated event recorded is the development of a saltmarsh across fluvial sands as relative sea level was rising at 6560±50 radiocarbon years before present (BP). At this time, the barrier had begun to develop. By 5470±210 BP, the saltmarsh was replaced by largely freshwater lagoonal silts, reflecting the isolation of the head of the bay when the barrier formed across the bay as a swash aligned feature. As the lagoonal sediments continued to accumulate, barrier rollover was probably occurring, and both lagoonal and underlying saltmarsh sediments were either obscured or eroded at their seaward margins. At a time unknown, barrier movement landward ceased and the barrier stabilised, although there is some evidence that it might become unstable in the future. Pollen and plant macrofossil analysis from the saltmarsh and lagoonal sediments record the changing vegetation dynamics and pollen analysis reflects the impact of Neolithic activity after 4860±120 BP. The available evidence for relative sea level change at Bay of Carness is compared with evidence from Wick, to the south, and with a recent model of glacio-isostatic uplift which includes the area.

Key Words:

• Orkney
• barrier
• relative sea level
• diatoms
• pollen
• radiocarbon dating

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Corrigendum

Acknowledgements

This work was supported by the European Commission under the project Impacts of climate change and relative sea-level rise on the environmental resources of European coasts (Contract Number: EV5V CT92 0175); the Centre for Quaternary Science, Coventry University; and the Leverhulme Foundation. The authors thank Dr Mike Field, University of Leiden, for plant macrofossil analysis at core 69; Dr Tim Mighall, University of Aberdeen, for advice on several aspects of this work; Dr Sue Dawson, University of Dundee, for help in the field; and Stuart Gill, of SCG Cartographics, for drawing work. The authors would also like to thank the referees for their constructive comments on the manuscript.