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Wednesday 8 June 2022

Salisbury Plain glaciation -- a VERY long time ago.........


After much thought, the blue line on this map shows where the outer limit of glaciation in Southern England might actually be located. Maybe this is a "composite line" showing the limits of different ice lobes of different ages, but this may also be the "Stage 16 glaciation" otherwise referred to as the Happisburgh or Cromerian glaciation, dated to c 650,000 years ago. The white line represents the outer limit of the Anglian glaciation, dated to MIS-12, around 450,000 years ago. 

Numbers identify key research areas: 1 Exmoor and the SW uplands (local ice caps and snowfields). 2 Somerset Levels. 3 Mendip. 4 Salisbury Plain. 5 North Wessex Downs. 6 Cotswold Hills. 7 Plateau drift remnants near Oxford. 8 Chilterns. 9 Chalky Till spread.


I'm increasingly convinced that the glaciation which I am suggesting for Salisbury Plain was considerably more extensive than the Anglian (c 450,000 years ago) and much older too.  I wouldn't agree with Geoffrey Kellaway that it was in the Pliocene, but the glaciation that comes into the frame was the Happisburgh (or Cromerian) glaciation currently dated at around 650,000 years ago.

This is my post in which I lay out the arguments:

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

This, I think, is one of the most important posts I have ever done, and it explains why the evidence of glaciation is very patchy and subtle -- and difficult to interpret.  After all, we are used to dealing with glacial traces in the landscape that are only 20,000 years old.  the amount of denudation / sediment destruction / sediment dispersal that happens over more than half a million years is difficult to comprehend.  And we should not be too surprised if all we can find today are some heavily weathered erratic boulders in the landscape (or in megalithic monuments like Stonehenge) and some smaller glacial erratics embedded in sediments.........

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