New constraints on post-glacial relative sea-level change around the Minch, northwest Scotland

Best, Louise ORCID: https://orcid.org/0000-0003-3731-054X, Simms, Alexander R, Lloyd, Jeremy, Bradwell, Tom, Small, David, Bradley, Sarah L and Puckette, Trap (2025) New constraints on post-glacial relative sea-level change around the Minch, northwest Scotland. In: 2025 QRA Annual Discussion Meeting, 6-8 January 2025, Newcastle Unviersity. (Unpublished)

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Abstract

Reconstructing the extent and timing of ice sheet and relative sea-level (RSL) changes provide analogues of how contemporary systems may respond under changing climate conditions. Specifically, this will help us assess the role of relative sea-level change in the marine icesheet instability (MISI) theory. This theory refers to the potential catastrophic collapse of marine based portions of contemporary ice sheets leading to significantly faster rates of sea-level rise than currently estimated. Due to the growth and demise of the British and Irish Ice Sheet and the Minch Ice Stream during and following the Last Glacial Maximum, the northwest of Scotland provides critical records for testing models of the interplay between ice-sheet retreat, glacio-isostatic adjustment (GIA), and relative sea-level changes, and can help understand the mechanisms controlling retreating ice sheet behaviour. We present a suite of new RSL constraints produced from isolation basin records from areas around the southern and western Minch, expanding the spatial and temporal resolution of RSL data for the region. Such data are key to refining GIA models, whose estimates of RSL change vary across different models during this time period in the region. From the Isle of Raasay, located in the centre of the southern Minch, a series of eight isolation basins constrain RSL fall between ~18-14 ka, and provide a marine limit at ~30 m OD at 17-18 ka. The island of Rona, immediately north of Raasay, has evidence of a RSL fall from ~28 m OD at 16-14 ka. These new constraints indicate that RSL was higher than existing records from the neighbouring Isle of Skye and Fearnmore (Applecross). Sites from near Gairloch, on the Reiff Peninsula and Isle of Ristol (Summer Isles) provide further constraints on RSL and are consistent with a northward decreasing marine limit. The ages from isolation basins also provide constraints on the timing of deglaciation, and on Raasay suggest that the area became ice-free earlier than previously published studies have reported. The new constraints suggest that the Minch Ice Stream retreated more rapidly than has been previously suggested. By improving the understanding of sea-level change along the former ice stream, we can investigate the importance of sea-level feedbacks to marine-based ice sheets during their retreat, providing insights into potential behaviours of contemporary marine-based ice sheets.

Item Type:	Conference or Workshop Item (Lecture)
Subjects:	G Geography. Anthropology. Recreation > GB Physical geography G Geography. Anthropology. Recreation > GE Environmental Sciences
Divisions:	Schools and Research Institutes > School of Arts, Culture and Environment
Depositing User:	Louise Best
Date Deposited:	18 Dec 2025 13:59
Last Modified:	18 Dec 2025 13:59
URI:	https://eprints.glos.ac.uk/id/eprint/15692

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