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New age constraints for the limit of the British–Irish Ice Sheet on the Isles of Scilly

New age constraints for the limit of the British–Irish Ice Sheet on the Isles of Scilly Thumbnail


Abstract

The southernmost terrestrial extent of the Irish Sea Ice Stream (ISIS), which drained a large proportion of the last British–Irish Ice Sheet, impinged on to the Isles of Scilly during Marine Isotope Stage 2. However, the age of this ice limit has been contested and the interpretation that this occurred during the Last Glacial Maximum (LGM) remains controversial. This study reports new ages using optically stimulated luminescence (OSL) dating of outwash sediments at Battery, Tresco (25.5 +/- 1.5 ka), and terrestrial cosmogenic nuclide exposure dating of boulders overlying till on Scilly Rock (25.9 1.6 ka), which confirm that the ISIS reached the Isles of Scilly during the LGM. The ages demonstrate this ice advance on to the northern Isles of Scilly occurred at ~26 ka around the time of increased ice-rafted debris in the adjacent marine record from the continental margin, which coincided with Heinrich Event 2 at ~24 ka. OSL dating (19.6 +/- 1.5 ka) of the post-glacial Hell Bay Gravel at Battery suggests there was then an ~5-ka delay between primary deposition and aeolian reworking of the glacigenic sediment, during a time when the ISIS ice front was oscillating on and around the Llyn Peninsula, ~390km to the north.

Acceptance Date Nov 4, 2016
Publication Date Jan 9, 2017
Publicly Available Date Mar 29, 2024
Journal Journal of Quaternary Science
Print ISSN 0267-8179
Publisher Wiley
Pages 48 -62
DOI https://doi.org/10.1002/jqs.2922
Keywords British–Irish Ice Sheet, ice stream, Last Glacial Maximum, OSL,TCN
Publisher URL http://dx.doi.org/10.1002/jqs.2922

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