A report has appeared in SALON, and while not so biased and garbled as some others in the media, the author (Chris Catling, the Editor?) cannot resist referring to "the probable quarry site." Further, if Ixer and Bevins are correctly quoted, they cannot resist suggesting that the new work now tips the balance towards the "human transport theory" and away from the glacial transport theory.
I do find it rather wearying that archaeologists and geologists persist in the belief that a narrow range of stones at Stonehenge would support the human transport thesis, whereas "the use of different rock types from disparate parts of Wales to create the first stone circle at Stonehenge would support the thesis that the stones were carried by natural means, such as the Irish Sea Glacier." How many times do I have to repeat that that is not how glaciers work? Glaciers do not simply collect up stones from here, there and everywhere, mix them up and then dump them in one place. Glaciers entrain, transport and deposit debris on streamlines, and if stones from disparate sources are entrained and carried they can only come from a narrow band of country coinciding with the streamlines themselves. We know pretty accurately what the streamlines of the Irish Sea Glacier looked like. It is not at all unusual (as I have shown many times on this blog) for glaciers to entrain clusters of boulders from one very limited location and to dump those boulders tens or even hundreds of kilometres away, in another location --- with or without an erratic train joining the two points together. How many times do I have to repeat that, in order for people to understand it?
Stonehenge bluestones: natural or human transport?
SALON - the Society of Antiquaries of London Online Newsletter
Salon 268: 3 January 2012
In an important new paper published in the journal Archaeology in Wales, our Fellows Rob Ixer, of Leicester University, and Richard Bevins, of Amgueddfa Cymru — National Museum Wales, report on the latest stage in their work to pin down the precise origin of the rhyolitic bluestones that formed the first stone circle at Stonehenge. Having already published a paper in the Journal of Archaeological Science suggesting that the crags of the Pont Saeson area of Pembrokeshire (on the northern flank of the Preseli hills, some 6.5km from Newport) were the likely source, they have now refined their chemical and petrographical techniques to the extent that they have been able to identify a specific outcrop as the probable quarry site.
‘We assumed that we might be able to pin down the source to an area of several hundreds of square metres’, Rob Ixer said, ‘but we can now pin it down unequivocally to an area of a few square metres, namely to a small single outcrop or couple of outcrops at Craig Rhos-y-felin’. The outcrop is some 70m long and has many tall, narrow slabs up to 2m high as the dominant feature, splitting off from the parent rock in blocks that are reminiscent of the Stonehenge bluestones.
The site was found by comparing the chemical properties of stone taken from outcrops in Wales and the west of England with the distinctive bluestone debitage (the waste created by shaping and dressing the stones) excavated in 1947 and subsequently stored in a box at Salisbury Museum. ‘I have always wanted’, Rob Ixer told our Fellow Norman Hammond, Archaeological Correspondent of The Times, ‘to tell this story under the tabloid heading “Old shoebox held key to Stonehenge mystery”.’
Drs Ixer and Bevins also say that their recent work is tipping the balance in the debate about whether or not the stones are glacial erratics. In the ‘nature versus human transport debate’, the higher the number of stones that can be demonstrated to have come from one site, and not from any other, the more likely it is that human agency accounts for their quarrying and transport to Stonehenge. Vice versa, the use of different rock types from disparate parts of Wales to create the first stone circle at Stonehenge would support the thesis that the stones were carried by natural means, such as the Irish Sea Glacier.
Rob Ixer told Current Archaeology magazine that ‘this is the first time that any lithics from Stonehenge have been so clearly provenanced but it will not be the last’. Meanwhile, the hunt continues for the source of four standing Stonehenge orthostats (SH38, SH40, SH46 and SH48) that have been tested and found not to have any petrographical match for any rhyolitic lithology at Pont Saeson — so the story of how and from where the bluestones got to Stonehenge still has some way to run.