The Stonehenge bluestones look like a mottley collection of glacial erratics -- heavily battered and weathered -- that were collected up from the area around Stonehenge.
But let's get one thing straight. There is no "killer fact" that demonstrates that Salisbury Plain was directly affected by glacier ice. It's broadly agreed that nowhere in the literature is there a clear description of either glacial erratics or unequivocal glacial deposits on the chalk downs. That does not mean that such things have never been observed -- lack of evidence is not evidence that something didn't happen -- but it simply means that field workers have not interpreted the things that they have seen in a particular way. We can cite various described exposures of "clay-with-flints" as being open to alternative explanations, and we can also quote all those packing stones turned up in Stonehenge digs which have simply been ignored as irrelevances......
That having been said, the inexorable decline of the human transport hypothesis and the bluestone quarrying hypothesis over the past few months leads us to ask why senior archaeologists (and two senior geologists) base all of their writings on the bluestones of Stonehenge on the assumption that glacial transport was "impossible". Over and again we see definitive statements to the effect that glacial transport has been "comprehensively rejected" or "definitively dismissed" by glaciologists and other senior experts. End of story. But is it?
I have tackled this issue of bias and selective citation many times before on this blog.
This extract from the big chapter by Darvill and Wainwright in the Pembrokeshire County History can be taken as representative of the "archaeology establishment" view:
"Although it still has vocal supporters, eminent geologists and glaciologists have dismissed the glacial theory (Bowen 2005; Green 1997; Scourse 1997) and concur with Thomas's original suggestion that the stones "were transported by human agency, in all probability by an overland route (Thomas, 1923, 259)."
There are four names in there -- Bowen, Green, Scourse and Thomas. These are the villains of the piece. No doubt they are very eminent, but not one of them is an eminent glaciologist. And only Thomas was an eminent geologist, who was busy, one hundred years ago, in formulating his famous ideas about the bluestones while ignoring the opinions of his colleagues who were specialists in the effects of glaciation. Thomas knew neither Preseli nor Salisbury Plain particularly well. Bowen, Green and Scourse are geomorphologists like myself, but as far as I know only Chris Green has actually done fieldwork on Salisbury Plain, and he would not refer to himself as a glacial geomorphologist. His thesis was on the long-term evolution of the landscape, and his "relevant studies" (ie relevant to the glacial transport debate) relate to pebble counts in river terraces in the Salisbury area -- some distance from Stonehenge. He has drawn certain conclusions on the basis of these studies, as mentioned in posts like this one:
My point is that no systematic research has ever been conducted on Salisbury Plain by a glacial geomorphologist looking at erratics, landforms or sediments. That is rather an important point!
And as for "the weight of expert opinion", let's remind ourselves that even in Thomas's time, in the first decades of the twentieth century, senior geologists (and archaeologists) were perfectly happy with the idea of glacial transport. Judd, Jehu, Gowland, Geikie, and many others had no problem with the thought that a great glacier might have carried assorted erratics from West Wales to Salisbury Plain -- but their voices were drowned out in all the noise surrounding the "exciting discoveries" of HH Thomas. It would be interesting to know what discussions went on behind the scenes -- but for better or for worse, Thomas argued his case for the human transport of the bluestones with great vigour, and the others backed off, presumably mindful of the fact that there was very little evidence that could be cited one way or the other.
When it comes to the weight of modern opinion among specialists, we know that Hubbard, Patton and other modelling specialists working on the BRITICE-CHRONO project have shown that glacier ice -- even in the smaller Devensian glaciation -- could have extended as far east as Wiltshire:
Quote:
"The experiments presented also indicate significant excursions of wet-based ice into areas of southern England, where little evidence of recent glaciation has been found. This may not present such a major problem given that our model indicates ice was at this extended limit for less than 1 ka. The experiments also provide support for a possible glacial mechanism for the movement of Preseli erratics as a transport trajectory which overrides parts of northern Pembrokeshire and was subsequently deflected south-eastwards across the Bristol Channel into SW England, cannot be completely discounted."
'Dynamic cycles, ice streams and their impact on the extent, chronology and deglaciation of the British–Irish ice sheet.'
Alun Hubbard, Tom Bradwell, Nicholas Golledge, Adrian Hall, Henry Patton, David Sugden, Rhys Cooper, Martyn Stoker
Quaternary Science Reviews 28 (2009) 759–777
Let's not forget too that the OU team which researched the bluestones in the late 1980's -- including Richard Thorpe, Olwen Williams-Thorpe, Richard Thomas and even Rob Ixer, actually did some work on Salisbury Plain and came down strongly in favour of the glacial transport hypothesis. Then we can mention Geoffrey Kellaway, Prof Danny McCarroll, myself, Dyfed Elis-Gruffydd, John Downes -- all quite eminent people who presumably know what they are talking about --arguing for glacial transport as not only possible but probable.
Even Prof Richard Atkinson, towards the end of his life, accepted that the human transport of the bluestones would have been vanishingly improbable, and that glacial transport had to be the favoured option.
No matter what spin might have been given to the issue by a handful of senior archaeologists with powerful vested interests, there is no doubt at all that the weight of expert opinion is, and always was, that the bluestones were probably transported by glacier ice. James Scourse should have been much more careful when he used the word "impossible".........
Clearly stated and argued, Brian. You give the debate a good objective overall perspective. This Post should be recommended/essential reading for anyone interested in the bluestones and archaeology.
ReplyDeleteShouldn't we call the subject of the overall debate, Humans v Glaciation, BLEXIT??
With apologies for changing the subject to the Stonehenge sarsen stones, today's news that a core sample taken in 1958 has been returned so that Brighton University can now analyse its geochemical composition with the fond hope that this may provide some indication of its original provenance, reminds us that similar core sampling of a few of the Stonehenge bluestones would go a long way to resolving their provenance too, as has been discussed and promoted in several Posts here over the years.
ReplyDeleteVested interests? Now, you have my conspiracy radar twitching. I do have to wonder how this fairy story got so out of hand. For MPP a little more TV celebrity. Some summers spent with friends on paid holiday in West Wales, adoration in hushed pub presentations. Phone calls from fellow conspirators bending the story on isotopes... Spreading throughout the world's news media...
ReplyDeleteHow did it get so mad?
How did it get so mad? I lay the blame at that Bristol - based Welshman - Hubris.
ReplyDelete