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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Saturday, 16 January 2016

Neolithic Quarrying: conflating the issues

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.......


TonyH said...

Conflating the issues. Deflating certain over - confident archaeologists in the process. That is, if they ever step outside their ruling hypothesis bubble. Time for a Space Walk, boys (and girls)! There IS life beyond your cosy, self - congratulatory, microscopic world.

Steve Dickinson said...

The glacier boys obviously have their own Ruling Hypothesis. Glacial Entrainment reaching Somerset and Wiltshire? Where's the evidence?

BRIAN JOHN said...

Read the literature. There are scores of articles in the peer-reviewed literature about the glacial deposits in Somerset. There is doubt about how far east the ice edge extended. I have never denied this and have always admitted that the matter of Wiltshire glaciation is still being debated.

Steve Dickinson said...

You also seem to have issues regarding (1) archaeological evidence for land-based megalith transportation in the UK and Ireland, (2) megalith selection/composition, (3), Neolithic geographical, geological, technological and other knowledge (re.your posts 12.01.15, 29.01.15) - amongst others. I would be more than happy to give you some references concentrating on 1-3. I'd appreciate some recent references for the Glacial Entrainment hypothesis.

Steve Dickinson said...

You seem to have a number of issues, some of which are centred on, (1), Evidence for long-distance megalith transportation and sourcing in the Neolithic, (2), Selection of 'bluestones' for Stonehenge, (3), Evidence for Neolithic geological, geographical and other knowledges (re. posts 12 and 29.01.15). I'm happy to share some recent peer-reviewed literature references with you on these subjects. You cite 'scores of articles' in the peer-reviewed literature about glacial deposits in Somerset. (1), how recent are these, (2) do they demonstrate evidence for your Ruling Hypothesis? It seems that recent peer-reviewed literature does not support Glacial Entrainment for Wiltshire. Could you comment further on this?

BRIAN JOHN said...

You are conflating things, Steve. Are you talking about glacial entrainment, glacial transport, or glacial deposition? Start using terms more accurately, and we might have a conversation. And I don't have a ruling hypothesis. This whole blog has been devoted to a discussion of the issues and the strength of evidence from all sides -- people who have ruling hypotheses do not do that sort of thing.

Take a look at the Quaternary of SW England GCR volume -- most of the references up to 1998 are in there. Other more recent refs are in the Quaternary of Somerset Field Guide (QRA).

Steve Dickinson said...

Brian - the blog is entitled 'Stonehenge and the Ice Age'. Your 2008 book is subtitled 'Stonehenge, Preseli and the Ice Age'. I appreciate that the many posts you've put up portray opinions and speculate about various forms of evidence, but the Ruling Hypothesis you follow is evident from the titles. One of your proposals, with which you end your 'The Balance of Probabilities' chapter in your 2008 book, states that an ' "erratic train" of stones... was left in the landscape to the west of Stonehenge' (op.cit. 156). You also strongly believe that this is true (op.cit. 155), (?-hard science doesn't do belief). OK - how did those boulders get there? The geomorphological models and field evidence (obvious here in the Lake District) support the case for subglacial, englacial and supraglacial transport of such boulders. Yet JD Scourse states 'The only unequivocal evidence for the Pleistocene glaciation of southern England and adjacent shelves occurs in very localised areas of North Somerset, North Devon, the Isles of Scilly, and more extensively in the Celtic Sea... shore erratics are probably related to glacimarine rather than glacial processes.' (Scourse, J.D., 1997 Transport of the Stonehenge Bluestones: Testing the Glacial Hypothesis, in Cunliffe, B and Renfrew, C (eds.), Science and Stonehenge. British Academy, London, 271-314). No BGS or other modern map shows any Pleistocene glacier to the west of Stonehenge. No glacier - no Ice Age Stonehenge. Q.E.D.

BRIAN JOHN said...

Steve -- you fail to differentiate between a ruling hypothesis and a working hypothesis. Look at my blog carefully and you will see that we (ie the community of contributors) are constantly making adjustments to what we think, in the light of evidence that appears in print and on the web. My own ideas have changed quite a bit, as you will see. of course the blog gives a lot of prominence to Ice Age events -- do you have a problem with that?

I am of course thoroughly familiar with what James Scourse has written. His opinions are worth considering, but I do not accept that he is any more authoritative than many other people on the matters discussed, and in some respects I think that his chapter is very dodgy, as I have made clear on a number of occasions. He is wrong about the extent of evidence, and wrong about shore erratics, in my view. Any geomorphologist who uses the word "impossible" with respect to glacial transport is asking for trouble.....

"No BGS or other modern map shows any Pleistocene glacier to the west of Stonehenge." ??!!! Please go off and do some more research.

BRIAN JOHN said...

A further point of clarification. The title "Stonehenge and the Ice Age" means what it says -- it is about Stonehenge and about the changing environments of the Ice Age. That incorporates temperate, periglacial and full-glacial conditions in the southern parts of Britain. The title is NOT "Stonehenge and Glaciers"..........

chris johnson said...

Some geologists friends were golfing in Kent this Christmas and had read about the SH debate in the Times. In their opinion some of the features in the Kent area might well have been the result of glaciation although supposedly the glaciers never reached that far. They said that the amount of work done on the subject was very summary.

One might think it worthwhile for our leading universities doing the stones of stonehenge project to have some Phd students revisit the geomorphological aspects - belt and braces so to speak. Not even a nod in the direction is sloppy - the extent of many glaciations over 2 million years is not that well recorded.

BRIAN JOHN said...

I have heard rumours of some new work on Salisbury Plain by geomorphologists -- concentrating on the clay-with-flints and some of the other deposits and looking for heavy minerals and other signs of material being brought into the area from assorted compass directions....... the obvious candidate is ice incursion from the west, but we still do not have an accurate ice margin for incursion from the north either. So watch this space -- when I hear anything I'll report it.

This work will be far more reliable than the famous stone-counting exercise undertaken by Chris Green many years ago, which still gets cited. As far as I could understand it, he was looking for quartz pebbles, and counting them as "foreign" -- whereas everything else (flints, sandstones, limestones and even mysterious grey or brown pebbles) was counted as "local"...... Not surprisingly, he proposed that there was hardly any erratic material in the river gravels of the valleys he looked at.

Steve Dickinson said...

Brian - you acknowledged that your own ideas have changed as your blog has evolved. Do you then still believe, as you state on page 154 of your 2008 book, that ice was responsible for 'at least four-fifths of the [bluestone] transport...' for Stonehenge?

Useful recent references on Neolithic quarrying and long-distance stone transportation: Richards, C. (ed.) 2013. Building the Great Stone Circles of the North, (esp. Chapter 5): Windgather Press. Also, for the Neolithic passage grave sites at Bru na Boinne in Ireland: Hensey, R. 2015. First Light; The Origins of Newgrange: Oxbow Books. (Greywacke boulder quarrying and long-distance transport).

Recently published evidence for the extent of the last Pleistocene British-Irish ice sheet: Clark, C.D.,, Pattern and timing of retreat of the last British-Irish Ice Sheet, Quaternary Science Reviews (2010), doi: 10.1016/j.quascirev.2010.07.019. Also: Clark, C.D., Evans, D.J.A., Khatwa, A., Bradwell, T., Jordan, C.J., Marsh, S.H., Mitchell, W.A., and Bateman, M.D., 2004. Map and GIS database of glacial landforms and features related to the last British Ice Sheet. Boreas 33, (4), 359-375. SHERPA Archive version (open access) doi: 10.1080/03009480410001983. No glacier evident to the west of Stonehenge on these maps. Evidence refs. for southern ice extent at the so-called 'Late Glacial Maximum' to follow.


Steve Dickinson

BRIAN JOHN said...

Steve -- what is the point of all of this? Thank you for the references, but I am familiar with all of them, and with a great deal more besides.

If you just spend a little time on the blog, and do some searches, you will see that all of this stuff has been discussed at some length, long since.

Steve Dickinson said...

Brian - I too am familiar with many references relating to the subject of your blog, and more besides! The more one works on projects, it get less easy to see where the critical questions are. And that's the point. Critical questions about ice transporting bluestones to Salisbury Plain - not just "all this stuff" as you put it.

For me, whether you acknowledge it either as a working or as a ruling hypothesis, blog posts and book/blog titles, (minus the gateposts etc.etc.), inextricably link Stonehenge with the Ice Age. It is stated, in the initial post (above) that bluestones were gathered up on Salisbury Plain and an idea is, somehow, supported of glacier ice from the Irish Sea Glacier reaching the Plain (Bluestone Enigma, p151-2). Really? Recent published maps from peer-reviewed literature on the Quaternary do not support such a hypothesis, (e.g.: the relevant pages and maps in Ehlers, J., Gibbard, P.L., Hughes, P.D., (eds.) 2004. Quaternary Glaciation - Extent and Chronology: A Closer Look. Elsevier.) Hence my point of January 22. No modern map shows a glacier west of Stonehenge. I could call this the Glacier Myth to counter your Bluestone Myth!

BRIAN JOHN said...

"No modern map shows a glacier west of Stonehenge." Complete nonsense, Steve. That is almost as absurd a statement as that made by MPP some years ago, namely that there is no evidence of ice ever having moved eastwards in the UK. The blog is full of modern maps showing glacier ice to the west of Stonehenge. The question is this: HOW FAR to the west was the ice edge? The jury is still out, evidence is still being collected, and nothing changes. Stop wasting my time.

chris johnson said...

Successive ice ages tend to obliterate traces of the previous. The most likely candidate for SH stone moving is perhaps the Anglian, some 500k years ago and not the most recent which, as you correctly say, is much less likely to have moved the stones. As Brian says, there are a lot of previous discussions on the blog about this and references to follow.

I have not read the Colin Richards book yet. I would quite like to but it is a hefty price. My understanding is he postulates stone moving and "quarrying" over a relatively small distance of a few miles and I reckon we all accept this. After all the bluestones and sarsens would have been moved to the site and erected and this is no mean feat.

The Newgrange stones are relatively small I believe and again from the near vicinity, nothing like 150-200 miles.

My take on this currently is that the bluestones were quarried from the Prescelly outcrops by glaciers and carried some distance south-west. People then collected them and erected them at Stonehenge. The moot point is where the collection point was.

Steve Dickinson said...

Hi Chris
Gibbard and Clark (in: Ehlers, J., Gibbard, P.L., Hughes P.D. (eds) 2004. Quaternary Glaciation - Extent and Chronology: A Closer Look. Elsevier; map p77) place the Anglian ice boundary on the shorelines and slightly inland on the southern side of the mouth of the Severn. This area is 75-80km west, tending north of west, of Stonehenge. No subsequent glacier over-rode this area (re. Clark, C.D., Pattern and timing of retreat of the last British-Irish Ice Sheet, Quaternary Science Reviews (2010), doi: 10.1016/j.quascirev.2010.07.019: maps p22-24). This Anglian ice boundary, while certainly west of the Mendip Hills and the hill country to their north-east, really does not support a hypothesis of Pleistocene glacier "reaching Stonehenge" (John, B., 2008, The Bluestone Enigma. Greencroft Books, p151-2), or any area of Salisbury Plain 20-25km to its west.

Colin Richards and his team found evidence that stones of at least 9 tonnes weight were quarried from Vestra Fiold, 10km NW of the Ring of Brodgar and Stones of Stenness (Richards, C., (ed.) 2013. Building the Great Stone Circles of the North. Windgather Press; map p.124, quarrying details; ps 132-143). In 1986 George Eogan estimated that some 2000 boulders and slabs were used as kerb and other major features in the passage tombs of Newgrange, Knowth and Dowth (Eogan, G., 1986. Knowth and the passage-tombs of Ireland. Thames and Hudson; p 113). The major kerb stones of the tombs weigh up to 4 tonnes - and some are much larger. In the 1980's it was considered that the stone source material was a Lower Palaeozoic Silurian zone 5km N and E of Knowth. More recent work indicates that a coastal quarry (or quarries) form the stone source; some 20km to the NE of the sites (Phillips, A., Corcoran, M. and Eogan, G. 2001. Derivation of the source localities for the kerb, orthostat and standing stones of the Neolithic passage graves of the Boyne Valley, Co. Meath. Dept. of Geology, Trinity College, Dublin.) This isn't the 'near vicinity' of the Bru na Boinne.

Whilst I can appreciate that the blog ranges widely, and has considered and speculated in many directions, I understand that contributions from archaeologists to it are rare. It would be considered constructive if one such was not thought to be taking up someone else's valuable time !

BRIAN JOHN said...

So Gibbard and Clark et al are assumed to be in possession of the truth? Come along Steve -- you must know that those cited articles contain interpretations and citations that are inherently no more reliable than mine. They are also contradicted by other articles in the peer-reviewed literature. Glacial modelling suggests that it was perfectly feasible for ice to have extended as far as Salisbury Plain at some stage: Hubbard, A., Bradwell, T., Golledge, N., Adrian Hall, A., Patton, H., Sugden, D., Cooper, R., Martyn Stoker, M. 2009. Dynamic cycles, ice streams and their impact on the extent, chronology and deglaciation of the British–Irish ice sheet.' Quaternary Science Reviews 28 (2009) 759–777. I have devoted plenty of space to this issue. There are what appear to be glacial deposits at Greylake and at other sites in Somerset, and my assertion that "the Pleistocene geology and geomorphology of S Britain supports the idea of ice reaching Stonehenge" is still sound -- based on my interpretation of the climatic and glacial conditions that must have prevailed during the Anglian. I happen to think that we are looking at an erratic assemblage at Stonehenge, and if that is not how you choose to interpret those 43 bluestones of all shapes, lithologies and sizes, that's your privilege. There is no "smoking gun", and we are all seeking the make the best of the small amount of evidence we have on the ground. However flimsy my evidence of glaciation may be, it is still a good deal stronger than that of the opposition!

We have dealt with Vestra Fiold and Newgrange before, and I don't think there is anything new to report.

chris johnson said...

I was not clear on Newgrange so sorry for that. I thought there was a working hypothesis, no more than that, that some big curbstones had come from Clogerhead some 16 kilometres away. Is this what you are referring to?

My mind was focussed at the time of writing on the smaller stones which come from different places 50-75 kilometres away. This gives an indication of the size of the area the monuments were serving and transporting the stones would have been inconvenient but easily manageable by one person or small group because they are small.

Do you know whether the 16 kilometres for the curbstones is now proven with the same level of certainty as the debitage at Stonehenge is provenanced to Prescelli?

BRIAN JOHN said...

Newgrange is a nightmare to work out, because the distribution of glacial erratics in that part of Ireland is very complex indeed. During parts of the Ice Age the ice moved from the NE, on other occasions from the NW -- and it is possible that there might even have been erratic transport northwards into the Boyne valley from the Wicklows, when there was a local ice cap there. There are lots of papers in which Irish ice movement directions are reconstructed. We have to be very careful indeed about any assumptions re the "quarrying" of stones used at Newgrange......

TonyH said...


Good to read your contributions recently, Steve. We get very few comments from archaeologists and it is interesting to find you have done a great deal within the Lake District, a landscape much glaciated. Few of us are experts in glacial geomorphology, many of us are very curious.

Keep contributing! I hope you receive a generally courteous and non - crabby reception from us all as we try and explore how the bluestones eventually ended up being utilised at what is now "The Old Ruin" on Salisbury Plain.