Holocene sea-level and environmental changes on the Isle of Mull, Scotland

Abstract

Sea-level and coastal changes are reconstructed on the Isle of Mull, western Scotland, from 10 988 to 10 507 cal BP to the present. This research has produced the first SLIP for the Isle of Mull. A multiproxy approach including pollen, spore, foraminifera and diatom analyses reveals palaeoenvironmental changes from two coastal sites. Marine phases are recorded from 10 988 to 10 507 cal BP in eastern Mull, when the relative sea level (RSL) was higher at 1.98 ± 0.15 mOD, and coinciding with the end of the Loch Lomond Stadial. The sea-level record for north-west Mull commences from 7570 to 7431 cal BP (285 cm [4.56 mOD]), showing higher RSL at 4.69 ± 0.14 mOD and approximately corresponding with the timing of the highstand recorded at nearby Arisaig. RSL is higher than present levels following marine transgression at 2273–1926 cal BP (153 cm [6.47 mOD], RSL: 3.78 ± 0.13 mOD) in north-west Mull and at 3460-2469 cal BP (317 cm [7.31 mOD, RSL: 2.39 ± 0.14 mOD]) in eastern Mull. Sea-level index points generally align well with RSL changes recorded regionally, though there is some indication that RSL was higher in north-west Mull. The data point at 10 988-10 507 cal BP can contribute to constraining the thickness of the British and Irish ice sheet as the thickest central dome of the ice sheet extended along this area of the British Isles. Coastal vegetation changes show little variation from grass-, sedge- and heather-dominated heathlands, with oak and birch shrublands throughout the Holocene. Following marine regression, there is indication of arboreal expansion in eastern areas, whilst a progressively more open environment is evident in north-west Mull. Corresponding changes in the herb pollen mosaic, NPPs and microcharcoal levels indicate a long-term anthropogenic presence on the island.