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Tuesday 27 February 2024

Was Salisbury Plain glaciated?

 


This is an  interesting "pseudo satellite"image created by Olav Odé, based on research by Kim Cohen and Marc Hijma, representing the situation in western Europe during the Elsterian glacial episode, around 470,000 - 420,000 years ago.  It's on page 38 of the Doggerland book published by Sidestone Press, and freely available for web viewing.

https://www.sidestone.com/books/doggerland-lost-world-under-the-north-sea

Forget about the artistic license employed in the portrayal of the surface morphology of the glaciated area!  The shadowed hilly areas bear no relation to reality or even glaciology.  There are some bits of the map that do not make much sense. But you have to enjoy the great slabs of broken ice shelf shown floating about off the south coast of Cornwall........

But what matters is the overall position of the ice edge, which is remarkably similar to that which Geoff Kellaway proposed many moons ago, and which I also proposed for the Anglian / Elsterian / MIS 12 glacial episode around 450,000 years ago:

https://brian-mountainman.blogspot.com/2022/02/southern-england-where-is-glacial-limit.html


This also coincides with some of the "outlier" models generated by the glaciology group from Aberystwyth University more than a decade ago.

https://brian-mountainman.blogspot.com/2012/08/where-was-somerset-gbg-limit.html

https://brian-mountainman.blogspot.com/2015/03/the-greatest-british-glaciation-gbg.html

On the Cohen / Hijma map we can see that the local ice caps on Exmoor and Dartmoor are incorporated into the "glaciated area"; that glacier ice is shown transgressing the northern coasts of Cornwall, Devon and Somerset; that the Somerset Levels are shown as glaciated; that there is an ice cover over the Mendips and the Cotswolds; and that Salisbury Plain is glaciated. 

Another interesting feature of the map is the portrayal of France as being largely covered by polar desert, with abundant small ice caps over many upland areas including the Massif central.

Yet another interesting feature --  the presence of a very substantial land bridge linking southern England to the continent.  This was important not just as a land bridge used by migrating human beings, but as a feature which must have affected local climate and precipitation patterns.  We must be careful about assuming that SW Britain was an area of temperate maritime climate characterised by relatively warm temperatures and abundant rainfall;  during this glacial episode (and maybe others) this was more likely an area of very cold and dry climate, as no doubt already identified by the new generation of ice sheet computer modellers.

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PS.  I hasten to add that when I did my 2022 post about Southern England, I had no knowledge at all of the Dutch work on ice limits that found its way into print at about the same time.......



6 comments:

Tony Hinchliffe said...

I was surprised to hear Professor Alice Roberts remark a few years ago on Radio 4's " Ramblings " that where they were walking, in the Mendips, had been glaciated. I think she was with Clare Balding.

BRIAN JOHN said...

Good God -- does she occasionally talk sense? I did once have some confidence in her abilities -- but that confidence evaporated with the broadcasting of that appalling BBC TV documentary about the "Giant Lost Circle".

Tony Hinchliffe said...

Aah, I remember that BBC programme well, unfortunately! I think Alice fell down an MPP Indiana Jones - style rabbit hole there, albeit paradoxically, on the high Preseli ground. By the way, Alice has started writing children's fiction books: I look forward to one re - imagining Conan Doyle's The Lost World, this time located in the Preselis, and featuring an archaeologist with a rather dodgy dossier inspired by an equally dubious geologist.

Tony Hinchliffe said...

We have both attempted, without success, to convince the Powers that be at the British Broadcasting Corporation that that programme ( made by a private film company) should be expunged from their archives!

BRIAN JOHN said...

The BBC is a commercial organization -- and who cares about reliability and the truth any more? The programme is a nice little earner for them, and that's all that matters.

Tony Hinchliffe said...

Well, they have wheeled out their BBC Verify and use it a great deal notably about the Russian invasion of Ukraine.