One of the reasons why the archaeologists at Rhosyfelin and Carn Goedog have gone so seriously astray is that they have conflated, in a manner which is scientifically indefensible, three very different issues.
In the "Stonehenge bluestone debate" there are three essential problems that have to be addressed:
1. In the bluestone source areas: what were the mechanisms of entrainment / quarrying / stone collection?
2. En route: what were the transport mechanisms?
3. At the bluestone destination area around Stonehenge: how were the monoliths and other stones deposited and then used?
For many years now, bits and pieces of progress on one or another of these issues have been used to inform or influence opinions and pronouncements on one or another of the other issues. One can understand how and why this has happened, but one can, I hope, also see the dangers. For example, right through the literature on Stonehenge we see this sort of argument: "Since the builders of Stonehenge were clearly very clever at measuring things and aligning things and moving very heavy stones into and onto complex structures, they were clearly also smart enough to quarry the stones from West Wales if they had wanted to, and smart enough to carry 80 large monoliths on rafts or rollers from Pembrokeshire to Stonehenge, if they had wanted to......" There is a certain logic in all of that, but none of it is based on actual scientific evidence, and it is based upon speculation rather than observation.
Similarly we see this sort of argument -- from geologists as well as from archaeologists: "Because there are no known moraines or scattered bluestone erratics on Salisbury plain, this shows that the glacial transport hypothesis is indefensible, and this shows that there must have been human transport of the stones, and this in turn shows that the stones must have been quarried in their source areas." Now that is a pretty convoluted and cockeyed piece of twisted logic -- but it has been subscribed to with all seriousness by scores of researchers and writers ever since the days of HH Thomas. All of the recent work at Rhosyfelin and Carn Goedog is predicated upon the assumption that glacial transport of the bluestones was impossible, and that the human transport hypothesis (being the only alternative hypothesis in town) must be true and verifiable.
So the hypothesis has turned into a ruling hypothesis, and the field research programme by Mike Parker Pearson and his colleagues has turned into an exercise in ruling hypothesis validation or confirmation.
So opinions relating to bluestone transport and deposition / use have been been called up in aid of an answer to a quite different question -- namely that of "how were the stones removed from their source or provenance sites?" So instead of moving in on these sites with a view to describing what is there to be seen, the archaeologists have moved in on them with the express purpose of finding "engineering installations" and other traces of quarrying -- in other words, with the purpose of finding and describing what they wanted to find. Biased, unscientific, unprofessional, irrational, naive -- or deliberately manipulative and designed to misrepresent the features on the ground? Take your pick as to the words you want to use. John, Dyfed and myself have already accused the archaeologists of creating "archaeological artifices" in the pursuit of their dream.
Let's not forget that as soon as the archaeologists had started digging at Rhosyfelin they were describing it in the most colourful terms as a "Neolithic bluestone quarry". The process of reinforcing the myth has continued, at an accelerating pace, ever since, culminating in the publication of three highly contentious and poorly presented papers in recent months, in "Antiquity", "British Archaeology" and "Current Archaeology". No doubt the big "National Geographic" feature article is still to come.........
It was because of our concerns about the cockeyed logic and the inbuilt bias in the archaeological digs that we three earth scientists decided to look very carefully at what was on the ground and to describe it as dispassionately as we could, without any assumptions relating to the likelihood of human or glacial transport of the stones. (Question number two, in my list of three, deserves separate consideration, in a separate paper currently in the pipeline.) Our conclusions, as described in two peer-reviewed papers, are that the landforms and deposits at Rhosyfelin and Carn Goedog are entirely natural and unspectacular, and that they owe nothing whatsoever to prehistoric human quarrying activities.
In conclusion, let's look at these three questions in reverse order.
3. At the bluestone destination area around Stonehenge: how were the monoliths and other stones deposited and then used?
There is really no disagreement about this -- we are all agreed that the stones were gathered up from a larger or smaller area on Salisbury Plain, moved into position by human agency, and then placed into various settings a over a long history of occupation in the Late Neolithic / Bronze Age period. Nobody knows how many stones were used, either sarsens or bluestones. As far as the bluestone monoliths are concerned, there were at least 43 of them, of many shapes, sizes and lithologies. So -- essentially, abundant evidence and broad agreement.
2. En route: what were the transport mechanisms?
On this, we know that the ice of the Irish Sea Glacier flowed across West Wales, up the Bristol Channel and into Somerset on at least one occasion. The evidence is on the ground, and is described in the peer-reviewed literature, so there is really no dispute about it. The dispute relates to a different question: how far to the east did the glacier ice progress? In other words, did it reach Salisbury Plain? On that one, the jury is still out. But only the most foolhardy of glaciologists or geomorphologists would use the word "impossible" as part of an answer. On the human transport mechanism, we know even less, since no evidence on the ground has ever been found to reinforce the assumptions made about trackways, rafts, rollers, sledges, ropes and a host of other issues -- including motivations. I have highlighted the problems associated with the human transport hypothesis on many occasions, as follows:
1. There is no sound evidence from anywhere in the British Neolithic / Bronze Age record of large stones being hauled over long distances (more than 5 km or so) for incorporation in a megalithic monument. The builders of Neolithic monuments across the UK simply used whatever large stones were at hand.
2. If ancestor or tribute stones were being transported to Stonehenge, why have all of the known bluestones come from the west, and not from any other points of the compass? Were belief systems and "local politics" quite different to the north, east and south?
3. There is no evidence either from West Wales or from anywhere else of bluestones (or spotted dolerite or Rhosyfelin rhyolite in particular) being used preferentially in megalithic monuments, or revered in any way. The builders always used whatever was available to them in the vicinity, and it can be argued that stone availability was a prime locational determinant for stone settings.
4. If long-distance stone haulage was "the great thing" for the builders of Stonehenge, why is there no evidence of the development of the appropriate haulage technology leading up to the late Neolithic, and a decline afterwards? It is a complete technological aberration.
5. The evidence for Neolithic quarrying activity in key locations is questionable. No physical evidence has ever been found of ropes, rollers, trackways, sledges, abandoned stones, quarrymen's camps, or anything else that might bolster the hypothesis.
6. The sheer variety of bluestone types (near 30 when one includes packing stones and debris) argues against selection and human transport. There cannot possibly have been ten or more "bluestone quarries" scattered across West Wales.
7. Bits and pieces of experimental archaeology on stone haulage techniques (normally in "ideal" conditions) have done nothing to show that our ancestors could cope with the sheer physical difficulty of stone haulage across the heavily-wooded Neolithic terrain of West Wales (characterised by bogs, cataracts, steep slopes and very few clearings) or around the rocky coast.
8. Neither has it been shown that the Stonehenge builders had the geographical awareness and navigational ability to undertake long and highly complex journeys with very heavy loads.
9. And if there was a "proto-Stonehenge" somewhere, built of assorted local stones and then dismantled and taken off to Stonehenge, where was it? The mooted "Preselite" axe factory has never been found, and neither has the mythical Stonehenge precursor.
10. Analyses of bluestone monolith stone shapes does not suggest that elongated “pillars” were preferred. Slabs, stumps and boulders of all shapes and sizes are highly suggestive of a glacial erratic assemblage.
At the end of all of this, let's be charitable and say that the jury is still out on how an ill-assorted collection of stones of all shapes and sizes travelled from West Wales to Salisbury Plain.
1. In the bluestone source areas: what were the mechanisms of entrainment / quarrying / stone collection?
If we are trying to employ any sort of scientific logic in finding an answer to this question, we need to undertake research in those areas which seem to be the source areas of some of the Stonehenge monoliths, and describe what we see. Dyfed, John and I have done just that, and have discovered some interesting things which incline us towards the suggestion that glacial entrainment of stones of all shapes and sizes would have been possible during at least two different glacial episodes. We would put things no more strongly than that.
As an interesting aside, one of the referees who reported on one of our papers (we assume he/she must have been an archaeologist) submitted to the editor a set of comments that had nothing whatsoever to do with our paper as written, but concentrated entirely on the perceived shortcomings of the glacial transport thesis. Naturally enough, both the journal editor and we three authors entirely ignored the comments.
In contrast to the earth science approach, the archaeologists have moved in on two sites with all trumpets blaring, with the intention of describing what they wanted to see, predicated upon unreliable answers to questions that were irrelevant to the matter in hand. How on earth did they manage to ditch so comprehensively the scientific method and to leave themselves so vulnerable to scientific scrutiny? Answers on a postcard please.......