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This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
© 2018 The Authors. Journal of Quaternary Science Published by John Wiley & Sons Ltd.The Welsh Ice Cap was a dynamic component of the last British–Irish Ice Sheet at the Last Glacial Maximum, but there are few chronological constraints on the pace and timing of deglaciation. This paper presents new geomorphological and geochronological evidence that constrains the timing of the separation of the Welsh Ice Cap from the Irish Sea Ice Stream and the subsequent deglaciation of south-west Wales; and allow these to be assessed in the context of late Pleistocene climatic events. Luminescence ages from glacial outwash sediments south of Cardigan demonstrate that the Irish Sea Ice Stream was receding by ∼26.7 ka. The subsequent recession of the Welsh Ice Cap is documented by cosmogenic ages from landforms and sediments in the Aeron and Teifi valleys and upland areas. Deglaciation of the Cambrian Mountains was underway by ∼19.6 ka. Cross-valley moraines and associated deglaciation deposits show that minor re-advances interrupted the recession of the Aeron Glacier twice, and the Teifi Glacier on at least 12 occasions. By ∼14.9 ka, the Aeron valley was probably ice-free, but the northwards withdrawal of the Teifi glacier had halted in the Tregaron area. The final rapid recession of this glacier into the uplands of central Wales was completed during the Windermere Interstadial (13.5 cal ka BP) when, in common with much of the UK, the whole of Wales is believed to have become ice-free. There is no evidence that the Cambrian Mountains contained ice-free enclaves at the Last Glacial Maximum, as has been previously suggested. The new ages presented here support suggestions that there was rapid change in the configuration of the Welsh Ice Cap between 20 and 17 ka as upland areas became exposed and there was increasing topographic control on patterns of ice discharge.
Author(s): Glasser NF, Davies JR, Hambrey MJ, Davies BJ, Gheorghiu DM, Balfour J, Smedley RK, Duller GAT
Publication type: Article
Publication status: Published
Journal: Journal of Quaternary Science
Year: 2018
Volume: 33
Issue: 7
Pages: 804-818
Print publication date: 01/10/2018
Online publication date: 13/08/2018
Acceptance date: 12/07/2018
Date deposited: 16/08/2022
ISSN (print): 0267-8179
ISSN (electronic): 1099-1417
Publisher: John Wiley and Sons Ltd
URL: https://doi.org/10.1002/jqs.3061
DOI: 10.1002/jqs.3061
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