Some of the ideas discussed in this blog are published in my book called "The Bluestone Enigma" -- available by post and through good bookshops everywhere. Bad bookshops might not have it....
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Friday, 4 December 2009

Glaciation "impossible" on the Wiltshire Downs?

Crusoe Glacier, Axel Heiberg Island, N Canada. I visited this glacier more than 40 years ago -- very impressive, with relatively clean ice, and in places a vertical ice cliff simply sitting on the tundra (which of course is permanently frozen).

I have been looking again, in the big Cunliffe/Renfrew "Science and Stonehenge" book (1997), at the chapters written by Jim Scourse and Chris Green. I am still amazed, as I was when I first read them. Seldom have I encountered such certainty, and without accusing them of pandering to the wishes of their sponsors and most influential readers (ie the archaeology establishment) I wonder why and how they can have brought themselves to the point of using the word "impossible" with respect to the glaciation of Salisbury Plain, or even a part of it. These chapters, which we might call "the Gospels according to St James and St Christopher", have of course been heavily cited by the likes of Darvill, Wainwright, Parker-Pearson and Pitts -- who say, repeatedly, that if "their experts" tell them that glaciation this far east was impossible, then it WAS impossible. My two learned friends are frequently referred to as either geologists or glaciologists -- they are neither, since (like me) they are geomorphologists. Their opinions are no more reliable than mine...........

What I find intriguing -- and somewhat irritating -- is the manner in which they waste a great deal of time going after some of the extreme and peripheral issues raised in the writings of Geoff Kellaway -- and spend very little time addressing the key issues:

1. Why is there no evidence in support of the human transport hypothesis?
2. Why are there so many rock-types represented at Stonehenge, and so many variations in "bluestone" size and shape, varying from substantial monoliths down to small stones and fragments?
3. If you are looking for "evidence of glaciation" as a geomorphologist, surely it is there, before your very eyes, in this complex and varied assemblage of "foreign stones"?
4. If the ice of the Irish Sea Glacier did (as they admit) extend across the Bristol Channel coast and into Somerset, would it not be more logical to assume that the "foreign" stones at Stonehenge (and elsewhere) were erratics, dumped somewhere to the west of Stonehenge?

They seem to have major problems on these points, and they do not address them properly. I'm not saying they are wrong in everything they say -- but I do challenge some of their assumptions. They say that if the Plain was glaciated, there should be glacial sediment sequences and "depositional landforms." I disagree. They say that if the chalk scarp had been overridden by ice from the west, there would be "glacio-tectonic structures." I disagree. They say that glaciological theory makes it impossible for glacier ice to have carried erratics from Preseli to Stonehenge. I disagree. They say there is an inconsistency between "observational and theoretical data.... and the regional geological data." I disagree.

The answer, when it comes (and it will come) will be partly down to the collection of field data and partly down to a better understanding of what happens on a chalk downland when it is affected by cold-based dry ice. It is patently obvious that Salisbury Plain was not affected by warm-based and "wet" ice carrying huge amounts of debris; if it had been, there would be glacial sediment sequences, moraines and other features all over the place. But I prefer to look, for my parallels or analogies, at the northern parts of Canada, the Dry Valleys of Antarctica, and maybe parts of North Greenland, where polar-based ice affected the landscape without doing very much to it at all. This is where our debate should concentrate...... and all contributions will be gratefully received!

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