More on ice-free corridors

A couple of years ago I did a post on the glaciation of the Oxford area and the Thames Valley, and featured this publication jacket from the Oxford Geology Group.  On chancing upon it again, I was struck by the absurdity of the "ice-free corridor" shown extending from the Bristol Channel and north-westwards to incorporate central and SE Pembrokeshire.

I think I have now finally disposed of this ice-free corridor or enclave in my field research culminating in my latest QN publication:

https://www.qra.org.uk/mp-files/qn158_1_late-devensian-ice-free-corridor-in-pembrokshire.pdf/

Citation:
John, B.S. 2023. Was there a Late Devensian ice-free corridor in Pembrokeshire? Quaternary Newsletter 158, pp 5-16.
==================

As I have mentioned before. this sup[posed LGM ice-free corridor has been built into numerous ice sheet modelling exercises and has caused chaos by leaving model segments that are seriously absurd from a glaciological point of view and that are out of step with field evidence.

But there may still be some who say "Ah yes, but look at the similarities with the ice-free corridor shown in NE England!  If such a thing existed there, why not something similar in West Wales?"

Well, there vis one fundamental difference.  In NE England the ice free corridor was maintained because high ground -- namely the Yorkshire Wolds and North York Moors -- were enough of an obstacle to force the ice to flow around them rather than over them.  So a long ice lobe from the north filled the Vale of York and flowed as far south as the inner reaches of the Humber Estuary.  There was also a very complex pattern -- and history -- of glacial lake development in the area, which is still being unravelled by glacial geomorphologists.  So there were two main factors -- the relative weakness of the ice incursion from the North Sea, and topographic controls.

In Pembrokeshire the ice-free corridor as portrayed in countless publications is, by comparison, nonsensical because it supposedly existed in an area of lowland, almost surrounded by flowing ice which somehow miraculously left it alone............. also, there is no trace of an ice dam or of glacio-lacustrine deposits covering parts of the supposedly ice-free area. And the field evidence, as detailed in my QN article, shows scattered glacial and fluvioglacial deposits across south and central Pembrokeshire, just as in west and north Pembrokeshire --  indicating a common glacial history.

==========================

https://www.semanticscholar.org/paper/The-%E2%80%98Lindholme-Advance%E2%80%99-and-the-extent-of-the-Last-Friend-Buckland/9bd44c6e4c81e0b24a93f64020620ac7cb556772

https://www.pure.ed.ac.uk/ws/portalfiles/portal/22211677/22198376.pdf

Quote:

Another BIIS example of glacier lobe interactions is thought to have existed within the Yorkshire/Lincolnshire region. Here, a 125 km long ice lobe (Vale of York lobe) is known to have flowed from the Stainmore Gap south-eastward into the southern part of the Vale of York (Boulton et al., 1985; Clark et al., 2004). Further east, an approximately 400 km long ice lobe (North Sea lobe) advanced from southern Scotland (Catt and Penny, 1966; Boulton et al., 1985; Busfield et al., 2015) southwards down the eastern margins of the

North Sea basin (Eyles et al., 1994; Clark et al., 2004; Boston et al., 2010; Evans and Thomson, 2010), as far south as north Norfolk (Pawley et al., 2006; Moorlock et al., 2008). These lobes, if they were coeval, will have moved within 10 km of each other either side of the chalk escarpment in East Yorkshire and Lincolnshire, thereby forming ice dams and a series of proglacial lakes in the lowland terrain of eastern England (e.g. Livingstone et al., 2012).