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Saturday 6 October 2018

On the significance of Mendip for Quaternary studies


The Mendip Hills (or plateau, if we want to call it that) have been somewhat neglected by the Quaternary science community, in spite of the huge amount of work by those interested in karst landscapes and cave science.  For example, there is hardly any mention of the Mendips in the big GCR Review volume published in 1998.  The QRA Somerset Field Guide, published in 2006, gave more attention to the Mendips, but the greatest emphasis was given to the glacial and related deposits at Court Hill, Yew Tree Farm, Kenn, the Gordano Valley, Nightingale Valley and a few other locations to the west.  There are still statements in the literature to the effect that "Somerset was not glaciated" in spite of the proved existence of till at Greylake, about 12 miles inland on the Somerset Levels.

https://brian-mountainman.blogspot.com/2011/08/strange-valleys-of-mendips.html  

https://brian-mountainman.blogspot.com/2011/08/more-on-cheddar-gorge.html

https://brian-mountainman.blogspot.com/2010/08/glaciation-of-mendips.html

https://brian-mountainman.blogspot.com/2010/10/glacial-action-on-limestone-hills.html

https://brian-mountainman.blogspot.com/2011/08/cheddar-gorge-and-burrington-combe.html

https://brian-mountainman.blogspot.com/2011/08/mendip-ice-cap.html

https://brian-mountainman.blogspot.com/2018/10/was-there-proglacial-lake-on-somerset.html

And yet, as I have suggested many times on this blog, there are abundant features that point to periglacial and glacial "interference" during the Quaternary.    There is an extensive plateau that must have supported extensive snowfields, if not glacier ice, during the known glacial episodes.  There are impressive gorges (at Cheddar, Burrington Coombe and elsewhere) which are difficult to explain except by reference to vast volumes of  water that might have a snowmelt or glacial melt origin.  There are karst landscapes and limestone pavements which can be examined in detail.  There are caves and cave deposits which contain clues to Quaternary events and to human occupation history.  There are somewhat mysterious deposits around the flanks of Mendip which have not been adequately examined.  Dry valleys at Rickford and elsewhere are really quite peculiar.  And there are anomalously large valleys to the east of Mendip which are difficult to explain by normal fluvial processes -- even if operating over a long period of time.  Lake overspills and drainage directed southwards by ice?  Quite possible.


I'm intrigued that Gilbertson and Hawkins postulated a big ice lobe pushing eastwards all the way to the chalk escarpment, as suggested on the above map.  But they did not think that ice overrode the Mendips.  That conclusion needs to be tested..........

One thing is certain -- Mendip must bear the scars of the Quaternary, and they must be far easier to interpret here than in the Quantocks, Cotswolds, Brendon Hills etc, where there are no substantial cave systems, gorges, or extensive rock outcrops.

https://brian-mountainman.blogspot.com/2018/07/the-somerset-ice-lobe.html

https://brian-mountainman.blogspot.com/2015/01/glacial-confusion-in-north-somerset.html

https://brian-mountainman.blogspot.com/2018/05/glaciation-of-bristol-gloucester-region.html

https://brian-mountainman.blogspot.com/2017/01/glaciation-of-somerset.html

There are glacially derived deposits to the east of Mendip and the SE of Bath; Geoffrey Kellaway and others drew attention to these many years ago, and the BGS now assigns them to the "Kenn Formation" -- thus linking them with one of the key locations near the Bristol Channel coast. (Thanks to Alex for pointing that out to me.......)  If ice reached that far east, it is inconceivable that the Mendips were NOT affected by both periglacial and glacial processes.

My own instinct is that if Dartmoor was glaciated -- and that now looks pretty convincing -- then Mendip -- further north and close to the large Welsh Ice Cep -- must also have been glaciated.  And it needs to be examined if we are ever to find out where the Anglian ice edge may have been located.

Watch this space.......

3 comments:

TonyH said...

You mention the Glaciation of the Bristol - Gloucester region near the end of your Post. This comes from your earlier Post of 17 May 2018. The information in it is derived from the revised Earthwise [BGS] web site.

So there is growing evidence for the Anglian glaciation impinging into this region, including SE of Bath.

The study of the Anglian glaciation is an ongoing, dynamic process. Archaeologists need to be made aware of this, and to be open minded, not relying on out - of - date "received wisdom from English Heritage/ Stonehenge marketing propaganda that likes the Old, Old Story passed down from HH Thomas;s speculations. Even Richard Atkinson had the good grace to change his mind about human transport towards the end of his life. Human Transport theory is a bit like Boris Johnson - it's good selling material, but it's full of hot air and lacking in clarity or detail.

BRIAN JOHN said...

Yes, there is a gradual inching towards the truth. One of the greatest sources of confusion at the moment is summarised in the 2006 "yellow book" -- the QRA Field Guide to Somerset -- in which all the authors were thrown by the amino acid dating which was showing all sorts of things to be a great deal older than they actually are........ There are many references to the deposits at Kenn, Nightingale Valley, Court Hill being from a glacial episode well before the Anglian. All of the cockeyed dating is still to be sorted out. But whether Anglian or not, the fact of the matter is that the ice at some stage travelled quite far to the east.......

TonyH said...

I trust somebody within the Geomorphology sector of Bristol University Geography Department takes note of this - whether they be Student or Postgraduate. Surely, there will be someone there who also has an interest in prehistoric archaeology who picks up on this Post and Comment! The Ocean Liner that is the Stonehenge Marketing Machine needs to realise there is a Sea Change afoot, which requires the ship to do a full 360 degree turnabout vis a vis Glaciation and the Preselis/ Somerset/ Avon Valley and beyond.