THE BOOK
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....
To order, click
HERE

Monday, 28 February 2011

Herbert Thomas and the Bluestone Heresy



Some of the points made in our recent discussions on this site got me thinking today (as I took a pleasant walk on Carningli in bright spring sunshine) about the nature and origins of the Bluestone Heresy. 

This is from a post dating from 27 march 2010:

"So what about HH Thomas and the bluestones? Well, I have suspected for some time that Thomas might have been guilty of simplification and selective citation of his samples and his rock identifications, in order to flag up the Carn Meini area as the source of the bluestones. I have also expressed my amazement in earlier posts that he "got away with murder" in that NOBODY seems to have seriously examined his evidence or questioned his wacky idea that the stones had been hauled by tribesmen all the way from Presely to Stonehenge in a totally unique feat of Stone Age long-distance transport. And why did people not scrutinize his theory more closely? Why, because there had been great discoveries about megalithic structures in Germany, and because British archaeologists were desperate to show that in these islands we had even more advanced prehistoric civilisations and even cleverer engineers and technicians.

Sounds absurd? I don't think so -- and a number of other authors have suggested that Thomas's idea was carefully put together around the time of the First World War as part of a national "feel good" strategy, and that the whole nation (and not just the archaeologists) just loved the idea when he announced it, and were disinclined to examine it carefully.

So Thomas became famous, then the bluestones became famous, and the "bluestone transport story" entered the mythology of Britain. It is still trotted out ad infinitum, even though there is even less evidence for it now than there was in 1920. And anybody who dares to question it, or to undermine our cosy assumptions about the extraordinary skills of our Neolithic ancestors, is likely to get short shrift from the archaeology establishment. Look at what happened to poor Geoffrey Kellaway......."


I was arguing at the time that Thomas might have been involved in a hoax which has fooled the archaeology establishment (and the British public) for about 90 years.  I'm not sure any longer that he deliberately conned his gullible audience or fabricated his petrography -- but we should certainly ask ourselves about the nature of the Bluestone Heresy.  The people who are currently treated as heretics are Geoffrey Kellaway, Olwen Williams-Thorpe and others (and, I suppose, myself!) who have dared to argue the case for glacial transport and who have questioned some of the assumptions underpinning the human transport hypothesis.

But hang on a moment.  Isn't this a grotesque distortion of something that should be amenable to scientific testing and debate? 

Let's imagine for a moment that Herbert Thomas had never existed.  (That is not to belittle him in any way.  He was probably a very pleasant fellow, and he was certainly a very good geologist who played a crucial role in the geological mapping of South Wales, and in other areas of geology as well).  But if he had not existed, and written that famous paper of 1923, it is perfectly likely that nobody, to this day, would be giving a moment's thought to the idea that Neolithic tribesmen went all the way to Wales to collect 80 bluestone monoliths of various shapes and sizes for use in the monument at Stonehenge.  How would we then be interpreting the current evidence that we have in the public domain? 

Well, we would be aware that there are about 30 different rock types represented in the "foreign stone assemblage" at Stonehenge.  We would also be aware that many of the rhyolites, and maybe all of the spotted dolerites, come from the eastern end of the Preseli Hills and from the outcrops of Fishguard Volcanics between there and the north Pembrokeshire coast.  We would also be aware (from abundant evidence from many different disciplines) that during the Ice Age the great Irish Sea Glacier flowed across Pembrokeshire approximately from NW towards SE, and that on at least one occasion the ice pressed all the way up the Bristol Channel to the coasts of Devon and Cornwall and into the low-lying depression of the Somerset Levels.  We would also be aware that the bluestone assemblage at Stonehenge seems to have come for the most part (with the great exception of the Altar Stone) from a very narrow band of countryside, where glaciological theory tells us that entrainment of erratics should have occurred, maybe between parallel-flowing streams of Irish sea and Welsh ice. 

The inevitable conclusion from all of that would have to be that the Stonehenge bluestone assemblage is an assemblage of glacial erratics, maybe deposited in conjunction with other glacial deposits, and maybe not.  Again, if one uses the principle of Occam's Razor, there is simply no need for any other theory, and geologists, glaciologists and geomorphologists simply need to concentrate on finding the solutions to two crucial questions: exactly when did this event occur?  and exactly where was the ice edge located when the erratics were dumped? (There are other questions as well, relating to glacial dynamics and sedimentation processes, but don't let's complicate the issue.....)

Seen in this context, and given the recent geological findings by Rob Ixer, Richard Bevins and their colleagues, if anybody was to come along today and suggest what HH Thomas suggested in 1923, he or she would simply be laughed out of court.

Back to the Bluestone Heresy.  The real heretics are not Geoffrey Kellaway and Olwen Williams-Thorpe, but Herbert Thomas, Richard Atkinson, Tim Darvill, Geoffrey Wainwright and a myriad of others who have led the world off on a wild goose chase, based upon the entirely false premise that glacial transport of the bluestones was and is impossible.  This heresy has even been perpetrated by geomorphologists including James Scourse, Chris Green and David Bowen, who should have known better. 

The real heresy is the story of the human transport of the bluestones, as a result of which the scientific community has wasted 90 years of research effort and dressed up a crazy myth as an article of faith.

The latest D/W article -- key points



Since the article by Profs Darvill and Wainwright was not refereed, here are a few points that would most probably have been raised by any referee worth his or her salt:

P 31 "... it was the bluestones that gave potency and importance to Stonehenge."  Unsupported assumption.

P 32  "The surveys and excavations we have carried out there since 2001 ......have emphasised the connections between source outcrops and water in a way that mirrors the link between Stonehenge and the Avon, formalised by the route of the Stonehenge Avenue."    What on earth is all that supposed to mean?

P 32:  "...... elaborated springheads, some associated with rock art..."  Where are the signs of elaboration, and where is the rock art?

P 32.  "....... the arrangement of bluestones at Stonehenge in the early 2nd millennium BC broadly matches the arrangement of stone outcrops in the Preseli landscape...."  That statement is so vague as to be mystical -- what are the authors trying to say?

P 32:  "Quite literally, the physical landscape of Preseli is reproduced in microcosm at Stonehenge in the disposition of a rich and varied selection of different stones..."  What are the authors trying to say here?  Are they saying that the builders of Stonehenge did not set out to collect stones from one magical place (namely Carn Meini), but actually set out to collect as many different rock types as possible so as to mimic the geology of North Pembrokeshire?  Are the authors simply trying to keep all their options open, in anticipation of further embarrassing geology?

P 33:  "The spotted dolerites occupy pride of place in the centre, and these are the largest blocks and the most intensively worked.  These in particular we argue were revered for their magic healing properties when linked with water, just as the springs and wells that issue from the Preseli Hills have been in later times."   Agreed that there is a predominance of spotted dolerites in the bluestone horseshoe, but it can be argued, perfectly reasonably, that this is because the spotted dolerite stones in the assemblage were harder and more "useful" than many of the other softer stones which were relegated to the outer circle at the time of the final adjustment of stone settings.  There is no evidence of magic healing properties associated with bluestones,  and the point about the springs and wells of the Preseli Hills is not supported either on the ground or in local folklore.

P 33:  "Ar Carn Alw... a huge block of rhyolite has been lifted out of the ground and enclosed by a low bank."  There is no evidence that the stone has been LIFTED.  Debris appears to have been excavated from around its flanks.

P 33:  "... the selection of material to be shipped across to Salisbury Plain to give meaning to Stonehenge."  That is a totally unsupportable statement, based on unproven assumptions.  It should not have got past the Editor!

P 34:  "... there are about a dozen quarries where a kind of meta-mudstone was extracrted and worked."  No evidence is provided that these are quarries rather than natural outcrops of slaty and flaky bedrock.

P 34:  ".... suggestive of an essentially ceremonial landscape south of the Preseli Ridge, around the headwaters of the Eastern Cleddau.  By contrast, the area north of the ridge contains extensive field systems and associated round-house settlements that, on visual inspection, look typically Bronze Age."   This idea -- apparently very popular in archaeology just now -- of a ceremonial landscape somehow separated from a utilitarian landscape, is not supported on the ground.  Utilitarian and "ceremonial" features are in fact mingled in the landscape.

All that having been said, the article is quite stimulating in that it brings out some things worthy of discussion -- and it is well illustrated and attractively laid out. 

I'll return to the "sacred geography" theme on another occasion.

Darvill and Wainwright reveal their secrets -- again

A subscriber to "Current Archaeology" magazine has kindly sent me a copy of the latest Darvill / Wainwright article, published in the March 2011 edition:  "The Stones of Stonehenge -- revealing secrets from the sacred circle."    The article is under the "New Research" heading -- but hardly any of it is new, since the authors have said pretty well everything already, in earlier publications and lectures.

Sacred circle?  OK - we'll let that pass.  But what is impressive is the absolute certainty of the two professors about what is, on closer examination, a rather dodgy set of assumptions and theories.  That's strange, since these ideas have already been so energetically criticised in the media that a little more caution -- or a little more evidence -- might have been appropriate.  But no -- the two professors cannot resist getting deeper and deeper into the hole they have created for themselves.  One must, I suppose, give them due credit for perserverence and self-belief.

I'll examine some of their ideas in a future post when I've had a chance to mull over the article, but I am immediately struck by the captions to the illustrations.  An elongated bluestone monolith which looks no different to hundreds of others around Carn Meini (Menyn) is labelled as "quarried, shaped, and propped at an angle waiting to be transported."  There does not appear to be a scrap of evidence for any of that.  An exposure of slaty rock on the hillside below Carn Meini is labelled as "quarry workings".   Two small rounded or sub-angular stones are labelled as "hammerstones."  A jumble of rocks around a seepage on the hillside is referred to as an "enhanced springhead."  A broken slab of spotted dolerite is referred to as a "broken part-shaped pillar stone."  Another craggy rock outcrop is called a "stone extraction site."  If this had been a peer-reviewed article, I suspect that none of that would have got past the referee........

Another thing that strikes me immediately is that the authors, while mentioning the work of geologists Rob Ixer and Richard Bevins, have failed to take on board the main point made by geologists over the past twenty years -- namely that there are so many rock types represented in the "bluestone assemblage" and in the soil layer at Stonehenge that the assumption of Carn Meini as the focal point of Neolithic interest must be questioned if not abandoned.  But no -- on they plough, with not even the briefest mention of the glacial transport theory proposed -- and well supported by the facts -- over many decades by the likes of Judd, Jehu, Kellaway, Williams-Thorpe and her colleagues from the Open University team.

At what point, one wonders, does self-confidence turn into self-delusion?

Sunday, 27 February 2011

GLACIAL TRANSPORT OF BLUESTONES NOW CONFIRMED?

This is my current take on the situation, building on the press release from the University of Leicester.  I know this goes further than Dr Rob Ixer and Dr Richard Bevins would wish to go, but I think my main points are strongly evidence-based.

Press Notice
26 February 2011

-------------------------
STONEHENGE:  GLACIAL TRANSPORT OF BLUESTONES NOW CONFIRMED?
------------------------------------

The theory that the Stonehenge bluestones were transported by glacier ice rather than by Neolithic tribesmen has received a massive boost following recent geological work by scientists in Leicester, Cardiff and Aberystwyth.

Dr Rob Ixer, Dr Richard Bevins and Dr Nick Pearce have just published a paper (1) which confirms earlier suspicions that some of the bluestones at Stonehenge have not come from the Carn Meini area in the Preseli Hills of Pembrokeshire, but from low-lying land to the north, close to the village of Brynberian.  This follows a number of other recent geological publications from Ixer and Bevins which lead inexorably to the conclusion that the bluestones have come from many different sources, some of which are still unknown.

Recent press releases from the University of Leicester (2) and from the National Museum of Wales and Aberystwyth University (3) throw serious doubt on the long-standing theory that the bluestones were quarried from the Carn Meini area and man-handled all the way to Stonehenge as part of a great stone-collecting enterprise.  One of the geologists, Dr Rob Ixer, says that there are three key conclusions from the recent work:

1.  The  huge sandstone Altar Stone does not come from Milford Haven but from somewhere between West Wales and Herefordshire and has nothing to do with the Preseli Hills. This calls into question the proposed transport route for the Stonehenge bluestones.

2.  Much of the volcanic and sandstone Stonehenge debris does not match any standing stones.  This suggests that the stony detritus in the soil is all that is left of standing stones that have now been lost.

3. Many of the Stonehenge rocks have not come from impressive outcrops high on the hilltops of Preseli, but in less obvious places, including hollows and deep valleys.

These conclusions clearly contradict the idea that the stones were quarried and collected by tribesmen from "sacred" sites where magical or healing stones could be found.  On the contrary, they support the idea that the Stonehenge bluestones are glacial erratics, transported from West Wales towards Salisbury Plain by the huge Irish Sea Glacier maybe 450,000 years ago.

Dr Brian John, whose book The Bluestone Enigma (4) argues the case for glacial transport, says that the new work is timely and that it adds detail to the conclusions of many geologists over many decades -- conclusions that have been marginalized and even ignored by archaeologists who have been intent upon perpetrating "the Stonehenge myth" for a variety of reasons.

"We now know that the erratic or bluestone material at Stonehenge, of all shapes and sizes, has come from at least 30 different sources," he says.  "On that basis alone it is entirely logical to assume that the stones have been transported by ice for most -- but not necessarily all -- of their journey to Stonehenge.  Another fact that has been conveniently ignored by archaeologists is that the stone sources identified in the recent work are all in a narrow strip of land running approximately NW-SE across north Pembrokeshire.  That is precisely the direction followed by the ice of the Irish Sea Glacier as it crossed Pembrokeshire -- and the stones have come from exactly the right locations where one might predict glacial erosion and entrainment of rocks and smaller debris.  It is also likely that the Altar Stone is a massive glacial erratic, carried by Welsh ice flowing southwards and then eastwards towards Somerset.

"Following this new research, I do not believe that the human transport theory is still credible.  Researchers now need to address two big remaining questions:  First, exactly when did this glacial episode occur? And second, exactly where was this assemblage of bluestones and glacial erratics dumped?"


ENDS

Contact:
Dr Brian John
01239-820470
Email:  brianjohn4@mac.com

-----------------

(1)  Stonehenge rhyolitic bluestone sources and the application of zircon chemistry as a new tool for provenancing rhyolitic lithics is published in the Journal of Archaeological Science, Volume 38, Issue 3, March 2011, Pages 605-622.

(2)  http://www2.le.ac.uk/offices/press/press-releases/2011/february/new-discovery-2018will-rewrite-stonehenge2019s-history2019
New Discovery ‘will rewrite Stonehenge’s history’
Geologists question ‘sacred hills’ origins of famous bluestones (25 February 2011)

(3) http://www.museumwales.ac.uk/en/news/?article_id=642
New Discovery in Stonehenge Bluestone Mystery (22 February 2011)

(4)  The Bluestone Enigma. Stonehenge, Preseli and the Ice Age.
by Brian John.   Greencroft Books , 2008
£9.95 pp160 pb  ISBN 9780905559896.

Saturday, 26 February 2011

At last -- something sensible about the Bluestones



This press release has been issued by the University of Leicester press office. This is a hugely important story -- although readers of this blog will know it all already -- and I hope it gets picked up by media all over the world.

How much coverage will it actually get? I wonder! The media have a natural preference for wacky nonsense and fairy tales -- and this might prove to be too cool and scientific for most of them to handle.

New Discovery ‘will rewrite Stonehenge’s history’
Feb 25, 2011 11:30 AM | Permalink

Geologists question ‘sacred hills’ origins of famous bluestones

Researchers from Leicester and Wales have shed new light on the origins of bluestones at Stonehenge- long believed to have come from ‘sacred hills’ in Wales.

Geologists from the National Museum Wales, University of Leicester and Aberystwyth University, have uncovered new evidence of its origins - which brings into question how the rocks were brought to the Salisbury Plain.

One type of bluestone at Stonehenge, the so-called ‘spotted dolerite’, was convincingly traced to the Mynydd Preseli area in north Pembrokeshire in the early 1920s. However, the sources of the other bluestones - chiefly rhyolites (a type of rock) and the rare sandstones remained, until recently, unknown.

Now the team of geologists have further identified the sources of one of the rhyolite types, which also provides the opportunity for new thoughts on how the stones might have been transported to the Stonehenge area.

Their findings are published in the March 2011 edition of the Journal of Archaeological Science.

Dr Richard Bevins, Keeper of Geology at Amgueddfa Cymru, in partnership with Dr Rob Ixer, University of Leicester and Dr Nick Pearce of Aberystwyth University, have been working on the rhyolite component of the bluestones, which leads them to believe it is of Welsh origin.

Through standard petrographical techniques combined with sophisticated chemical analysis of samples from Stonehenge and north Pembrokeshire using laser ablation induction coupled mass spectrometry at Aberystwyth University, they have matched one particular rhyolite to an area north of the Mynydd Preseli range, in the vicinity of Pont Saeson.

The Bluestones are a distinctive set of stones that form the inner circle and inner horseshoe of Stonehenge. Much of the archaeology in recent years has been based upon the assumption that Neolithic Age man had a reason for transporting bluestones all the way from west Wales to Stonehenge and the technical capacity to do it.

Dr Ixer, who has been attached to the University of Leicester Department of Geology for two decades, said: “For almost 100 years the origins of the bluestones and how they got to Salisbury Plain from Southwest Wales has been matter of great debate but now due to a combination of expertise, abundant material and new techniques it is becoming possible to finally answer those questions.

“From the 8,000 samples of rock available, the exciting part was to match the Stonehenge rocks with rocks in the field in order to find their geographical source - this was initially done microscopically. However this is difficult as rocks from every outcrop have to be described and matched and that takes detailed long term knowledge- Dr Richard Bevins from National Museum Wales has 30 years experience of sampling and collecting just these rocks in southwest Wales and once the very unusual mineralogy of some of the debitage was recognised microscopically he was able to identify the source of a major group of volcanics to Pont Season north of the Preseli Hills.

“The important and quite unexpected result based on microscopical work needed to be confirmed and this has been done recently based on very detailed mineralogical analysis with Dr Nick Pearce from the University of Aberystwyth.

“The first result was the recognition that the huge sandstone Altar stone does not come from Milford Haven but from somewhere between West Wales and Herefordshire and has nothing to do with the Preseli Hills. This calls into question the proposed transport route for the Stonehenge bluestones.

“The second unexpected result was that much of the volcanic and sandstone Stonehenge debris does not match any standing stones (so far only 2 stones out of thousands from the debris match)- it may be the debris is all that is left of lost standing stones- it is difficult to see what else it could be.

“The third is that the geographical origins for many of the Stonehenge rocks are not from impressive outcrops high on the hilltops but in less obvious places, some deep in valleys.”

Dr Ixer said that work already undertaken and more in progress suggests that, unlike the belief of the last 80 years, namely that all of the Stonehenge bluestones were from taken from the top of ‘sacred’ Preseli hills and moved southwards to the Bristol Channel and then onto Stonehenge, most or all of the volcanic and sandstone standing stones and much of the debris at Stonehenge comes from rocks in the low-lying ground to the north and northwest of the Preseli Hills and, if, they were moved by man, then they travelled initially in the Irish sea before heading south and east.

“But as ever Stonehenge asks more questions than it answers. These Stonehenge surprises will continue for a few years to come and once again the history of Stonehenge will have to be re-written.”

- Ends -

Notes for the Editor:

The original press release can be accessed here:

http://www.museumwales.ac.uk/en/news/?article_id=642

The paper Stonehenge rhyolitic bluestone sources and the application of zircon chemistry as a new tool for provenancing rhyolitic lithics is published in the Journal of Archaeological Science, Volume 38, Issue 3, March 2011, Pages 605-622.

http://www.elsevier.com/wps/find/journaldescription.cws_home/622854/description#description

------------------------------------------------

For comparison, this press release was the one issued by the National Museum and Aberystwyth University and picked up by the Western Mail and other papers. Note the differences, including the use of the MPP quote!!

News

New Discovery in Stonehenge Bluestone Mystery

The source of the bluestones at Stonehenge has long been a subject of fascination and considerable controversy. One type of bluestone, the so-called ‘spotted dolerite’, was convincingly traced to the Mynydd Preseli area in north Pembrokeshire in the early 1920s.

However, the sources of the other bluestones - chiefly rhyolites (a type of rock) and the rare sandstones remained, until recently, unknown. Now geologists at Amgueddfa Cymru – National Museum Wales have further identified the sources of one of the rhyolite types, which also provides the opportunity for new thoughts on how the stones might have been transported to the Stonehenge area.

Their findings are published in the March 2011 edition of the Journal of Archaeological Science.

Dr Richard Bevins, Keeper of Geology at Amgueddfa Cymru, in partnership with Dr Rob Ixer, University of Leicester and Dr Nick Pearce of Aberystwyth University, have been working on the rhyolite component of the bluestones, which leads them to believe it is of Welsh origin.

Through standard petrographical techniques combined with sophisticated chemical analysis of samples from Stonehenge and north Pembrokeshire using laser ablation induction coupled mass spectrometry at Aberystwyth University, they have matched one particular rhyolite to an area north of the Mynydd Preseli range, in the vicinity of Pont Saeson.

The Bluestones are a distinctive set of stones that form the inner circle and inner horseshoe of Stonehenge. Much of the archaeology in recent years has been based upon the assumption that Neolithic Age man had a reason for transporting bluestones all the way from west Wales to Stonehenge and the technical capacity to do it.

Richard Bevins said:

"This recent discovery is very significant as it potentially provides us with new clues for understanding how and possibly why the Welsh bluestones were transported to the Stonehenge area.

"It has been argued that humans transported the spotted dolerites from the high ground of Mynydd Preseli down to the coast at Milford Haven and then rafted them up the Bristol Channel and up the River Avon to the Stonehenge area. However, the outcome of our research questions that route, as it is unlikely that they would have transported the Pont Saeson stones up slope and over Mynydd Preseli to Milford Haven. If humans were responsible then an alternative route might need to be considered. However, some believe that the stones were transported by the actions of glacier sheets during the last glaciation and so the Pont Season discovery will need appraising in the context of this hypothesis.

"Matching up the rock from Stonehenge with a rock outcrop in Pembrokeshire has been a bit like looking for a needle in a haystack but I’ve looked at many if not most outcrops in the Mynydd Preseli area. We are however, confident that we have found the source of one of the rhyolites from Stonehenge because we’ve been able to make the match on a range of features not just a single characteristic. Now we are looking for the sources of the other Stonehenge volcanic and sandstone rocks".

Mike Parker Pearson, Professor of Archaeology at Sheffield University, added: "This is a hugely significant discovery which will fascinate everyone interested in Stonehenge. It forces us to re-think the route taken by the bluestones to Stonehenge and opens up the possibility of finding many of the quarries from which they came. It’s a further step towards revealing why these mysterious stones were so special to the people of the Neolithic."

Amgueddfa Cymru – National Museum Wales operates seven museums across Wales National Museum Cardiff, St Fagans: National History Museum, National Roman Legion Museum, Caerleon, Big Pit: National Coal Museum, Blaenafon, National Wool Museum, Dre-fach Felindre, National Slate Museum, Llanberis and the National Waterfront Museum, Swansea.

Entry to each Museum is free, thanks to the support of the Welsh Assembly Government.

- Ends -

For more information, please contact Lleucu Cooke, Communications Officer, Amgueddfa Cymru - National Museum Wales on 029 2057 3175 or e-mail: lleucu.cooke@museumwales.ac.uk

Arthur Dafis, Communications and Public Affairs Officer, Aberystwyth University 01970 621763 / 07841 979 452 / aid@aber.ac.uk

Notes for the Editor:

The paper Stonehenge rhyolitic bluestone sources and the application of zircon chemistry as a new tool for provenancing rhyolitic lithics is published in the Journal of Archaeological Science, Volume 38, Issue 3, March 2011, Pages 605-622.

http://www.elsevier.com/wps/find/journaldescription.cws_home/622854/description#description

Date: 22 February 2011

Friday, 25 February 2011

Now for some self-defence



A couple of posts ago I posted Rob Ixer's review published in Wiltshire Studies 2011.  I'm grateful for any review that might come along......

But just a few comments:

"Dr John, however, suggests this dearth of sarsens in Salisbury Plain around Stonehenge is due to their incorporation into the monument as “a truly motley collection of all shapes and sizes” or as ”simply a collection of stones from the neighbourhood.”"  I'm not the first to suggest this -- Prof Andrew Goudie and various others who have done intensive research on Salisbury Plain have suggested it before -- so I lay no claim to originality here.

Re glacial theory and the explanations of entrainment, transport and deposition by ice:  "Both his expertise and experience in this very specialised  field (that has very little to do with geomorphology!) means that this chapter deserves careful reading."  Actually this all has a great deal to do with geomorphology.  I'm a geomorphologist by training, and almost everything I say about glaciers comes from my knowledge of glaciated landscapes and how they were formed.

"........ this independently-produced and excellently-illustrated little book has problems. There is too much 19th century-style political tract and not enough nice Victorian scholarship."  Fair enough, Rob, but if I had wanted to write a learned paper I would have done that (and I have one in draft form right now). I wanted to write a popular book for the layman, and I also wanted to address the question of why it is that "establishment" views and ruling hypotheses are so remarkably difficult to shift.  So I thought -- and still think -- that a certain amount of politics and polemics was in order!

"Being partisan does not mean taking pot shots at the enemy; Profs. Darvill and Wainwright especially, must feel peppered, and this is a dis-service to them and to Dr John. It is a great pity when the lasting impression of this book is not its salutary nod to the power of glaciers but its grimace at archaeologists."  This is a fair point, and we can debate it at length.  But if I had concentrated on the glaciers and the geology, would anybody have bought the book?  I doubt it.  And it would have been dismissed by certain influential individuals as irrelevant and naive, in that it had not got stuck in to the meat of the ARCHAEOLOGICAL debate.  A book on the bluestones, without any consideration of current archaeological ideas, would have been a cop-out.  OK -- Profs D&W might feel a bit peppered, but I feel no responsibility to protect them from the real world, and in any case they are probably quite thick-skinned after the welter of criticism their healing stones / sacred springs / Neolithic hospital ideas attracted in the media -- particularly in discussion forums and Stonehenge blogs other than mine.  Those gentlemen have done a fair bit of peppering in their time -- and they have done no credit to their cause by ignoring or dismissing out of hand the ideas of Kellaway, Williams-Thorpe and others.    If they want to dish it out, they must also be prepared to take it.

"Thomas (who first realised the ultimate origin of the spotted dolerites from Stonehenge was the Preseli Hills) was not ‘distasteful of Judd’s (petrographical) work of 1902’ --  indeed he called the work  ‘excellent’."  That isn't what I said on p 96.  Thomas may well have said that Judd's petrography was excellent, but he still treated it with disdain by ignoring or dismissing his conclusions about glacial transport.

"The recent history of the Boles Barrow spotted dolerite, an important dolerite found in Wessex outside of Stonehenge and its environs and a cornerstone in the man versus ice argument is not as Dr John’s (p140) and almost all the post 1980 literature suggest, secure in its Boles Barrow provenance -- the primary literature is ambiguous."  What the hell -- I'll defend myself here as well!  Yes, the provenance of the Boles Barrow bluestone is ambiguous -- but only because archaeologists refuse to believe that it can have been in place well before the stone settings at Stonehenge were created.  It is the ultimate "inconvenient" piece of evidence.  And the post-1980 literature is all bandwaggon stuff -- written by people who are intent in holding the party line.

"Despite web-based assertions, Drs Ixer and Turner have not suggested the Altar Stone came from the Brecon Beacons, they merely state it is not from Milford Haven."  That's a bit unfair, Rob --  I don't say that at all.  On pp 104-5 I report faithfully what you guys said -- that the stone was probably from the Senni Beds, somewhere to the east.

"Almost every sentence about the Great Cursus and its associated lithics (pp 68, 69, 77, 103, 108) is incorrect --- once again these errors, missing from the original papers, are found on-line."  Hang on a bit -- I was reporting as accurately as I could on what MPP and others had put into their early field reports and statements to the press.  I think I'm right in saying that in 2008 (when the book was written) the detailed petrography had not been published --  it's not very fair to expect me to have known about stuff that was not yet in print!

"..........there are dozens of different rock-types recorded, granite, gabbro, slate and limestone; brick, cement and burned coal and these days sacred crystals and ‘magnetic haematite’ (look anytime beneath the Altar Stone to see a selection of these) but have they any (non-sociological) significance?"  I would agree with that word of caution.  Extraneous or adventitious stones brought in by accident must always be looked for -- I have been used to doing that on the Pembrokeshire coast, where ballast brought in by ships is often found in close vicinity to glacial deposits!

"The meaning of ‘bluestone’ already endlessly argued over should be re-defined once more as ‘any non-sarsen lithology employed as a Stonehenge orthostat’."  I don't think I would agree with that.  If we just concentrate on the  standing and fallen bluestones, and maybe the stumps, we lose sight of maybe hugely significant "debitage" or debris and smaller stones that might well have a glacial origin -- and we could end up no closer to the truth.  Erratics are not all large -- very many of them are very small.

Apart from those small points I'm happy to accept Rob's points in what I thought was a perfectly fair review.  If you write things and get them into print, you have to accept both the kind words and those that are not so kind!

Neil explains the bluestones

Neil explains the bluestones?  Well, actually he doesn't.........

I managed to watch the latest episode (Part 2) of the BBC series on the History of Ancient Britain, this time without that additional soundtrack.  I thought it was quite good -- a nice tour, with wonderful images, of some of the key Neolithic sites of Britain and Ireland.  I particularly liked his reference to the "Stalinist-style reconstruction of Newgrange" !!

On the matter of Stonehenge and the bluestones, we learned nothing new, and simply got a faithful rendering of the MPP version of events -- Stonehenge as a place of the dead, built by a highly organized tribal people with great leaders and priests, who had the resources to fetch 200 tonnes of bluestones from Preseli and to haul them to Stonehenge.  According to Neil, these great leaders occasionally pottered off on various perambulations of Britain, in much the same way that the gentry did in the days of Jane Austen and Co.  There was no questioning, and no trace of doubt or dispute in any of the commentary.  Not even any mention of the Darvill-Wainwright hypothesis.  And I do find that intensely irritating.  Why is it that TV presenters have to demonstrate COMPLETE CERTAINTY about everything?  Do they think that a mention of alternative theories will somehow lower the esteem of the viewers?  Do they think that we are too stupid to cope with the occasional use of the words "perhaps", "possibly" or "maybe" ???

A little less pontification and a bit less arrogance from the producers of programmes like this would not come amiss -- particularly in something that purports to be an educational series, with the heavy involvement of the Open University.

New review of the book


The Bluestone Enigma. Stonehenge, Preseli and the Ice Age.
by Brian John   Greencroft Books Nov 3 2008
£9.95 pp160 pb  ISBN 9780905559896.
published in Wiltshire Archaeological & Natural History Magazine, "Wiltshire Studies" 2011

Here is a review by Rob Ixer  -- needless to say, I have a few ripostes!  Watch this space...

I have always believed that everyone should have a little Stonehenge paper (pace Jean Muir) and this is Dr John’s contribution and, like Ms Muir’s dress, the intention here is to draw attention, cause comment and, perhaps, be provocative. 
Dr John is a glaciologist by profession, Pembrokeshire native by persuasion and a passionate –sometimes strident - advocate of his main cause namely that Stonehenge is an incomplete monument erected from locally/regionally available stones.
Few, if any, dispute the regional (defined here as more than a day but less than week’s walk) nature of the large, sandstone sarsens used in the Stonehenge Sarsen Circle and Sarsen Horseshoe, but most workers suggest that their origin is 30km or so to the north on Marlborough Downs and that Stonehenge itself sits in an area that was originally devoid of sarsens. Dr John, however, suggests this dearth of sarsens in Salisbury Plain around Stonehenge is due to their incorporation into the monument as “a truly motley collection of all shapes and sizes” or as ”simply a collection of stones from the neighbourhood.”
Whatever the truth, it is clear that the sarsens remain in the role of Cinders in Stonehenge lithic studies (unlike the bluestone lavas and ashes) and that all aspects of them should be re-examined.
However, as the book title suggests, it is the eponymous rocks and their mode/modes of transport to Stonehenge that mainly exercise the author. He totally rejects the idea that the bluestones (here, defined as any non-sarsen, Stonehenge-related rock), whose ultimate origins are, with the exception of the Altar Stone, southwest Wales, were trans-shipped 230kms from the Preseli Hills by man and so uses chapter 3 ‘The Bluestone Myth’ to some effect. Rather, he suggests that an Irish Sea glacier moving eastwards along the Bristol Channel moved the varied bluestones to Somerset and perhaps even closer, to Stonehenge. Hence the Welsh Preseli bluestones were collected by the monument makers from no further than Somerset. This suggestion, that nature is largely responsible for the movement of the bluestones, historically favoured by geologists rather than archaeologists and geomorphologists is, of course, not new. Dr John gives full credit to the Open University (and colleagues) team who closely argued this position in 1991. What is new and what demands serious attention is the author’s discussion given in chapter 7 ‘The Irish Sea Glacier’, on the possible natural mechanisms of rock selection, rock movement and finally deposition, by glaciers. It appears that nature can be as careful or as capricious as mankind in selecting rock for transport.
Both his expertise and experience in this very specialised field (that has very little to do with geomorphology!) means that this chapter deserves careful reading. It is easily the author’s most successful and is, and should remain, a significant contribution to Stonehenge studies. A visit to Dr John’s blog, where he continues his campaign, shows that recent Pleistocene studies confirm his views rather than counter them- still, as ever, it is early days.
But, but, but, this independently-produced and excellently-illustrated little book has problems. There is too much 19th century-style political tract and not enough nice Victorian scholarship.
The author has a sub-theme namely that the (archaeological) establishment has deliberately suppressed the truth partly for national and personal aggrandisement, partly out of inertia and, I wonder, even plain naughtiness. This is wearing, well before the end of the first quarter of the book, progressively becoming predictable, tedious and counter productive. The book without this might have been less enjoyable and cathartic to write but would have been far, far more persuasive. Being partisan does not mean taking pot shots at the enemy; Profs. Darvill and Wainwright especially, must feel peppered, and this is a dis-service to them and to Dr John. It is a great pity when the lasting impression of this book is not its salutary nod to the power of glaciers but its grimace at archaeologists. A second edition and I really hope and feel there should be one, can soften this so easily.
There are minor errors, some trivial like references incorrectly cited in the text, others
suggest that some of the text is moulded from secondary/tertiary sources and so perpetuates archaeo-urban myths (Stonehenge is as cursed by as many of these as the Egyptian Pyramids). ‘Facts’ from a web-site, however Pagan, are not and
cannot be treated as the equal to peer-reviewed data from Antiquity. A few examples:-
Thomas (who first realised the ultimate origin of the spotted dolerites from Stonehenge was the Preseli Hills) was not ‘distasteful of Judd’s (petrographical) work of 1902’ indeed he called the work  ‘excellent’. The recent history of the Boles Barrow spotted dolerite, an important dolerite found in Wessex outside of Stonehenge and its environs and a cornerstone in the man versus ice argument is not as Dr John’s (p140) and almost all the post 1980 literature suggest, secure in its Boles Barrow provenance-the primary literature is ambiguous. Despite web-based assertions, Drs Ixer and Turner have not suggested the Altar Stone came from the Brecon Beacons, they merely state it is not from Milford Haven. Almost every sentence about the Great Cursus and its associated lithics (pp 68, 69, 77, 103, 108) is incorrect-once again these errors, missing from the original papers, are found on-line. A second edition can correct these simply and the missed Pitts-Howard lithological contribution of the early 1980s can be incorporated alongside more recent petrographical work (often published in Wiltshire Studies).
Then there is emphasis; “the sheer number of rock types (at Stonehenge) is a grave inconvenience to many who write about Stonehenge; and so they conveniently fail to mention it” (p8), for Dr John the dozens of rock types are important as they show the haphazard collection/deposition-strategy of ice, for some archaeologists they suggest the number of collectives contributing to the manufacture of the monument and for others, Dr John is probably correct, they have failed to find/understand their import. The reasons for the large number of Stonehenge-associated rock types are as varied and numerous as its summer visitors, for there are dozens of different rock-types recorded, granite, gabbro, slate and limestone; brick, cement and burned coal and these days sacred crystals and ‘magnetic haematite’ (look anytime beneath the Altar Stone to see a selection of these) but have they any (non-sociological) significance? To the question how were the bluestone orthostats moved to Stonehenge, probably not. The meaning of ‘bluestone’ already endlessly argued over should be re-defined once more as ‘any non-sarsen lithology employed as a Stonehenge orthostat’. This would reduce the origin/transport problem to a few lithologies and their geological provenances. If, as seems likely, these lithologies have multiple sources then speculation can recommence but with much of the rock clutter removed.
Enough, now for a final verdict on the book - set aside the polemics, forgive the factual errors and unsafe excursions into TAG-territory and enjoy the splendid photographs, for this is a cheap but valuable book that should sit alongside (even, forgive the ironic pun) complement the many recent Stonehenge books written by archaeologists. Dismissing/ignoring its central theme, that glaciers have a role in Stonehenge stone transport studies might just turn out to be a Michael Fish hurricane/what hurricane? moment.

Dr Rob Ixer FSA 27th August 2010.

Thursday, 24 February 2011

The Suppression of Dissent



I am often asked when the second (improved!) edition of "The Bluestone Enigma" will be published.  Rob has asked me about this several times, and now so has Tony, in his response to my latest post.  So a word about the realities of radical publishing is in order.  Since I published the book myself, I was able to keep costs (and the cover price) down, and on balance I'm quite pleased with sales, having sold maybe 1200 copies thus far.  The print run was 2,000 -- so I have to sell another 800 copies before I think seriously about a new edition.  I have covered my printing costs, of course, but not much more.

I'm not complaining (I knew the score before I published the book) -- but it is INCREDIBLY difficult to sell a book of this type, aimed at a non-specialist readership, which questions and even challenges the establishment.  In spite of sending review copies out in all directions the book has had very few reviews, and my offers to key journals to write articles explaining the "glacial transport hypothesis" have simply been ignored.  In this field dissent is not dealt with by sending in the tanks and aircraft, but simply by pretending it does not exist!  After a long struggle, I managed to get the book into the Stonehenge Visitor Centre, but I have not had a repeat order from EH for some months now -- and I suspect the book might have been taken off the shelves.  I hope I'm wrong -- but I'm trying to find out.  There are of course many other EH and museum outlets (and even college and university bookshops) where the book SHOULD be on sale -- but again it may be that the august organizations which promote and protect our cultural heritage, and which teach the next generation of archaeologists,  themselves feel threatened when their belief systems are subjected to careful scrutiny.

Is there a cunning plan, involving the forces of darkness, to suppress my book?  I doubt it -- but I think it's fair to assume that certain organizations have no particular desire to see my ideas being examined by the masses and turned into common currency........

So I continue to have fun, asking questions where appropriate, examining evidence from fields that might have a bearing on Stonehenge and the bluestones, and throwing new ideas into the public domain.  Nobody can sack me, or withdraw my research funding; and I don't need to protect my standing amongst my peers.  So I feel quite privileged to be an entirely free agent!

Wednesday, 23 February 2011

My conclusions.......


Almost 3 years have elapsed since I was hard at work on the text for The Bluestone Enigma. So what has changed during that time? Not a lot, to be honest, except that more evidence has stacked up in support of what I suggested. I have added some notes below, in red.

================================

These were my conclusions in The Bluestone Enigma, published in 2008:

** The bluestones have come from at least fifteen different localities in West and South Wales, and other areas as yet unidentified. It is inconceivable that a series of Neolithic "stone collecting expeditions" can have collected all these stones, of many shapes and sizes, from so many different (and geologically unrelated) locations.

Having gone through the literature, ancient and modern, I am now quite sure that the foreign material at Stonehenge has come from at least 30 different locations, including Pont Saeson and other locations within the outcrop area of the Fishguard Volcanics in North Pembs.

** There is no evidence for any cultural, political or economic motive which would have driven Early Neolithic man to undertake any “bluestone collecting expeditions” in the far west of Wales.

This is still true.

** No cultural links have ever been established between West Wales and Wessex that might demonstrate any affinity or preferred trading contact between the two areas. Their tombs, stone settings and tools show that Pembrokeshire had strong links with tribes around the Irish Sea and St George’s Channel, but not with tribes in England.

This is still true.

** It has never been demonstrated that the Neolithic tribes had the technical ability or the mental maps which would have enabled them to undertake the proposed stone collection enterprise.

Still no evidence to contradict my statement on this.

** The bluestones were present on or near Salisbury Plain at least a thousand years before the first stone monument was built at Stonehenge.

People still go on about the provenance of the Boles Barrow bluestone, but I see no reason to doubt its authenticity.

** Some of the bluestones at Stonehenge (for example, those made of volcanic ash) are "rubbish stones" which would never have been selected for incorporation into a megalithic monument. They were used simply because they were conveniently located close to the building site.

The new geology on the rhyolite orthostats and debris (by Rob Ixer, Richard Bevins and colleagues) confirms this, although they do not address this issue directly.

** There is no evidence that the "spotted dolerite" so beloved of archaeologists was ever viewed as sacred or magical. It was never used preferentially, either in Wales or Wiltshire, in megalithic structures.

I have confirmed this by further research in the literature -- the spotted dolerite was NOT a special stone.

** It follows that if spotted dolerite was not viewed as a healing or magical rock, the idea of healing springs associated with spotted dolerite outcrops is equally fanciful.

I still think this -- although certain senior professors keep on claiming (on the basis of NO hard evidence) that there were assumed healing properties.

** The idea that the bluestones at Stonehenge were carried to the site as “petrified embodiments” of the ancestors of Neolithic people is also fanciful, and smacks of attempting to justify an unproven assumption.

This might be a fine theory in Madagascar, but there is nothing to support it in the UK.

** Studies of axe-heads made of spotted dolerite and found in England suggest that they were actually made from the same group of stones that were built into the monument. In other words, Stonehenge was probably at one time the site of an axe-head factory.

This idea might need some revising, when we know more about the distribution of rock types through the Stonehenge layer and in other detritus.

** None of the stone settings at Stonehenge was ever finished. Whatever might have been the grand designs of the "architects", the builders never had enough stones to finish the job.


Nobody has come up with any evidence to contradict this. And my YouTube Video called "Stonehenge Unhinged" is thus far unchallenged except by those who are outraged by the very thought of such sacrilege!

** The ice of the great Irish Sea Glacier came in from the west and reached at least as far east as Bath, the Mendip Hills and Glastonbury. It is still uncertain whether the ice covered Salisbury Plain.

These statements still stand -- but I am tending towards the idea that the ice edge may have been somewhere near the chalk scarp.

** An "erratic train" of stones of all shapes and sizes was left in the landscape to the west of Stonehenge. It was an easy matter for the Stonehenge builders to follow this trail westwards, and to collect up one stone after another, until they were all gone.

This idea, which I developed in the EARTH article with Lionel Jackson, is still a good working hypothesis.

** It follows that the Neolithic builders of Stonehenge had no idea where the stones had come from. They had no need to know. They may have revered them because they were “different” from the sarsens, but not because of any association with a “sacred place.”

This is still perfectly reasonable, and I still believe this.

** The larger erratics were used as monoliths in stone settings while smaller stones were used as packing stones, mauls and hammers, and for the manufacture of hand axes. The evidence of glaciation on Salisbury Plain is not missing or destroyed; it has simply been moved from one place to another through a stupendous human effort.

Nobody has seriously disputed this.

** This is all entirely consistent with what we know of Neolithic monuments, whose locations were always determined by the availability of nearby raw materials. So far from Stonehenge being “the grand exception to the rule”, it conformed to the rule in all important respects.

This still stands, and is backed up in the literature.

=======================

And from the point of view of the glaciology and geomorphology, recent literature has confirmed that in the earlier glacial episodes (if not in the Devensian) the Irish Sea Glacier (or ice stream) behaved more or less as described, sweeping across Pembrokeshire and the Presely Hills, moving eastwards up the Bristol Channel, and pushing inland into Somerset and Avon. Nobody -- not even James Scourse or David Bowen) has suggested otherwise. This MUST have happened if we are to explain the existence of glacial deposits in Somerset, Devon and Cornwall. The BRITICE models support the idea of a very extensive glaciation at this time, including small ice caps over the uplands of SW England. And my investigations of isostatic / eustatic interactions lead inexorably to the conclusion that the giant erratics of the Channel coasts can only be explained by a BIG glaciation which included isostatic depression of the crust in Southern England......

The more we know about the sources of the rhyolites and dolerites which have ended up at Stonehenge, the more confirmation there is for the entrainment of glacial erratics by ice moving upslope on the northern flank of Presely, in a "contact zone" between Welsh ice and Irish Sea ice. The band was a remarkably narrow one -- and explains the petrology of the Stonehenge bluestone orthostats quite neatly. Nobody has thus far come up with anything from glaciology to contradict my conclusions on bluestone entrainment, transport and deposition. It all fits.

That piedmont glacier........

On doing some more research on ice directions etc at the peak of the Devensian (ie at the time of the LGM) I came across this map in Greenwood and Clark 2009 -- after McCabe 2008.  Interesting -- because it shows ice streaming off the south coast of Ireland, derived from the Irish Midlands.  The portrayal of the Irish Sea ice stream is speculative, and of course there is no ground evidence south of the Wicklows to support it.  (If there is evidence for this phase of activity involving the Irish Sea ice stream around 22,000 years ago, it is on the bed of St George's Channel, and is thus a bit difficult to get at.....)
If we wipe off the Irish Sea ice stream arrow from this map, and assume that the Southern Irish piedmont glacier went into a phase of rapid expansion or surging behaviour, at the same time as a reduction in the power of ice flowing through St George's Channel from the north, we have the scenario on which I speculated a few days ago.

On with the mad Quarry Hunt?



Now the BBC and assorted other media outlets have also homed in on the Pont Saeson story -- all using identical words, presumably taken from the press release.

What's going on here?  If we look at the words used by RB and MPP, they both seem to be suggesting that what is now needed is a grand Quarry Hunt.  Are we going to find that  taxpayers money is going to be expended on this absurd exercise,  justified only by the assumption that however the stones got from Wales to Stonehenge, and however many sources may now be identified, they MUST have been transported by our heroic Neolithic ancestors?   Sorry, but I have nightmares about blinkered ostriches, disguised as archaeologists, with their heads buried in the sand........

Why, oh why, are archaeologists so completely convinced that the glacial transport of erratics from Wales to Somerset or Wiltshire, during one of the big glaciations, was utterly and incontrovertibly impossible?  Because James Scourse, Chris Green and David Bowen told them it was impossible?  As I have said before, anybody in the field of geomorphology who uses the word "impossible" with respect to something which is eminently possible is asking for trouble.

More media hype










There's a piece in today's Western Mail which is typical of the garbled hype that passes for journalism these days. Journalists half-understand things, and never actually get as far as completing their education before rushing into print...... rather sad, really.

Quote:
Dr Bevins added: “Theoretically if we could trace the source of the other rhyolites (rock types) we could create a map with six or more locations pinpointing where each stone was sourced. Archeologists could then essentially see the route that was taken by these people, they could re-trace those steps, set up archaeological digs and make who knows how many new discoveries."
Did Richard really say that? Hmm -- sound to me like a rather dodgy presumption of the correctness of the human transport, in spite of the fact that the new evidence points clearly to a non-human agency in the transport of the stones.

Quote:
Mike Parker Pearson, Professor of Archaeology at Sheffield University, added: “This is a hugely significant discovery which will fascinate everyone interested in Stonehenge.
It forces us to re-think the route taken by the bluestones to Stonehenge and opens up the possibility of finding many of the quarries from which they came. It’s a further step towards revealing why these mysterious stones were so special to the people of the Neolithic.”

Now that, if I may say so, is illogical and unscientific. If MPP really did say that (which, given the propensity of journalists to invent quotations, he might not have done) I find that disappointing. The obvious conclusion arising from the Point Saeson discoveries is that the stones from an increasing number of locations were NOT quarried and carried by human beings at all, but were quarried and carried by glacier ice. The human transport theory is entirely unnecessary. Why are the archaeologists so reluctant to accept the blindingly obvious? Don't ask me -- ask them...........
--------------------------------------
Scientists ‘step closer’ to solving Stonehenge mystery

• by Sion Morgan, Western Mail
• Feb 23 2011

IT is a mystery that has baffled geologists and historians for centuries... how were the Stonehenge rocks transported from Wales’ Preseli mountains to their resting place 120 miles away.
Scientists are today one step closer to solving the 4,000-year- old mystery after making their most significant discovery in 15 years.

Of the six to eight different bluestone types found in the inner circle of rocks on Salisbury Plain, only one, the so- called “spotted dolerite”, was convincingly traced to the Mynydd Preseli area in north Pembrokeshire in the early 1920s.

But modern technology has now assisted geologists at Amgueddfa Cymru – National Museum Wales – in creating a “fingerprint” for one of the other rock types found in Wiltshire.

And that “fingerprint” has been identically matched to stones found in an area north of the Mynydd Preseli range, in the vicinity of Pont Saeson.

The discovery means archaeologists are now a step closer to retracing the footsteps of Neolithic engineers who moved the stones in the first place.

Dr Richard Bevins, Keeper of Geology at Amgueddfa Cymru, said: “The outer circle of Stonehenge is made up from stones sourced locally in Salisbury Plain but it is the mismatch of rocks found in the inner circle that have caused so much mystery.

“We have known for some time that spotted dolerite came from Preseli but of those remaining stones we think that six to eight more may have come from Pembrokeshire, until now though we haven’t been able to be sure because the stones are very fragile and we didn’t previously have the technology to extract their DNA.”

Dr Bevins added: “Theoretically if we could trace the source of the other rhyolites (rock types) we could create a map with six or more locations pinpointing where each stone was sourced.

“Archeologists could then essentially see the route that was taken by these people, they could re-trace those steps, set up archaeological digs and make who knows how many new discoveries.

“In terms of looking at where the stones came from this is the most important discovery we’ve made regarding Stonehenge in 10 or 15 years.”

Dr Bevins, in partnership with Dr Rob Ixer at the University of Leicester and Dr Nick Pearce of Aberystwyth University, made the discovery by analysing microscopic crystals found in the rock, vaporising them and analysing the gases found as a result.

The composite of gases makes up the rock’s DNA which can then be matched to other rock forms.

Sourcing the rhyolites also provides the opportunity for new thoughts on how the stones might have been transported to the Stonehenge area.

Much of the archaeology in recent years has been based on the assumption that Neolithic Age man had a reason to transport bluestones all the way from West Wales to Stonehenge and the technical capacity to do it.

Dr Bevins said: “It has been argued that humans transported the spotted dolerites from the high ground of Mynydd Preseli down to the coast at Milford Haven and then rafted them up the Bristol Channel and River Avon to the Stonehenge area.

“However, the outcome of our research questions that route, as it is unlikely that they would have transported the Pont Saeson stones up slopes and over Mynydd Preseli to Milford Haven, we would assume that they would not carry the rocks up and over a steep mountain range.

“If humans were responsible then an alternative route might need to be considered.”

Some believe that the stones were transported by the actions of glacier sheets during the last glaciation and so the Pont Season discovery will need appraising in the context of this hypothesis.

Mike Parker Pearson, Professor of Archaeology at Sheffield University, added: “This is a hugely significant discovery which will fascinate everyone interested in Stonehenge.

“It forces us to re-think the route taken by the bluestones to Stonehenge and opens up the possibility of finding many of the quarries from which they came.

“It’s a further step towards revealing why these mysterious stones were so special to the people of the Neolithic.”


Read More http://www.walesonline.co.uk/news/wales-news/2011/02/23/scientists-step-closer-to-solving-stonehenge-mystery-91466-28216698/#ixzz1ElyMTwqb

Sunday, 20 February 2011

The Teifi Varve dilemma



The top photo shows the Swedish aristocrat and geologist De Geer, who pioneered the science of interpreting varve sequences, examining exposures in a clay pit.  The map below shows the "Swedish varve chronology" -- successive ice edge positions during the wastage of the Scandinavian ice sheet.  Much of this chronology (established eventually by many geologists over many years) was based upon the early observations of De Geer, and his recognition that characteristic sequences could be traced across country, from one exposure to another,  until a more or less complete story could be recreated -- from places that were inundated by fresh of brackish water, in vast lakes, as the ice melted.

In the top photo we can see that the varves vary quite considerably in thickness -- but the basic principle is that the light coloured layers are summer layers, when the sediment load in lakes was high, with sandy and silty layers settling on the lake bed relatively quickly.  The dark layers (generally much thinner) are the winter layers, comprised of much finer silt and clay particles, that settled out during the winter, very slowly and probably under a seasonal ice layer.  Many of the lakes concerned were more than 100m deep.

Back to Lake Teifi and the other lakes.  If anybody out there knows how many annual varve layers have been counted thus far in the cores and exposures examined in the course of research, I'd be pleased to hear about it.  How much time elapsed between the initial ice advance across the coastline from Cardigan Bay and the eventual collapse of the ice sheet edge?  Shall we assume for the moment that we are talking about a period of c 1,000 years?

Friday, 18 February 2011

Glacial Lake Teifi


The recent work on Glacial Lake Teifi and the other temporary lakes formed during the advance and retreat of the Devensian Irish Sea Glacier onto the North Pembs - South Cardiganshire coast is interesting in several respects. One of the most interesting is the presence of varves and rhythmites in the lower deposits on the lake beds, some of which were laid down in water up to 100m deep. These rhythmites are described in some detail, but the two key papers about them fail -- as far as I can see -- to address the question of the length of time that elapsed from the beginning to the end of the glacial episode in this area. Are we talking about decades or centuries?

In Sweden it was established long ago that many of the varves in clay deposits had annual layers in them, so that they could be counted -- and matched up across many sites (like tree rings) until a comprehensive chronology of deglaciation and varve deposition was worked out. Are the rhythmites real annual layers in these Teifi Valley lakes, or are the rhythms related more to oscillations of melting and water flow into the big bodies of standing water? I'll try to get some answers....

-------------------------------------

Development of glacial Llyn Teifi, west Wales: Evidence for lake-level fluctuations at the margins of the Irish Sea ice sheet, by Fletcher, C J N, Siddle, H J , Journal of the Geological Society, Mar 1998.
Palaeoenvironmental interpretation of an ice-contact glacial lake succession: an example from the late Devensian of southwest Wales, UK.
by James L. Etienne, Krister N. Jansson, Neil F. Glasser, Michael J. Hambrey, Jeremy R. Davies, Richard A. Waters, Alex J. Maltman and Philip R. Wilby,
Quaternary Science Reviews, Volume 25, Issues 7-8, April 2006, Pages 739-762

Ring out wild bells

 I came across this the other day, in a very ancient (pre-1900) copy of "Boy's Own Paper".  I thought it rather splendid -- and although it is not New Year's Eve  (maybe in the Chinese calendar it is?) it's a nice reminder that we should always be prepared to ditch old ideas and take on new ones.  All quite relevant to my earlier posts about Occam's Razor,  Karl Popper and the matter of falsification in science.....

Click for an enlargement.

Searching the Blog

With several hundred posts on this blog, and many quite protracted (and generally amiable!) discussions over the last year or so, this is just a reminder that the search facility on the site actually works rather well.  I have covered a vast range of topics, ranging from specifically Stonehenge issues to Bluehenge and the Cursus, to geology and petrology, to sea-level change (isostasy and eustasy), to glacier behaviour, chronology and ice margin positions.......

Thanks to the wonders of Blogger, it's possible to type in almost anything in the search box on the site, and you will get a list of links that are easy to use.  I use it a lot myself, since I have completely forgotten most of what I have posted in the past!

And by the way, another nice thing about Blogger is that you can click on almost any of the illustrations, to bring up an enlarged version.  Some will even enlarge click by click until they almost fill your screen.  Happy browsing!  And comments are always welcome.

Why Stonehenge was never finished

Thanks to Merlin and the Stonehenge News for this one.  I have argued on this site many times that Stonehenge was never finished, and that the builders walked away from the site in disgust for some reason or other.....

Well, now we have confirmation for that.  Click to enlarge the picture above.  Clearly, the giants employed by Merlin the magician (in an earlier incarnation, long long ago) were too stupid to be able to read the Ikea instructions!

Wednesday, 16 February 2011

Who's for the chop?

Watched this evening's episode of the History of Ancient Britain.  Actually it was quite interesting and informative, and they still haven't reached Stonehenge and Carn Meini, but in some ways it was the most incompetent programme ever -- somebody (who is probably for the chop) forgot to wipe off the extra editorial sound track, presumably with the editor's or director's voice.  That gave an idiot's guide to what each scene was all about -- "Neil sits on a rock", "Helicopter flies off into the distance" and such like, as if we didn't know it already from looking at the screen.  Oh dear oh dear.  Maybe they just finished the programme five minutes before it went on air, and never got round to finishing the editing........

The Irish Sea Glacier -- fact or fantasy?

http://en.wikipedia.org/wiki/Irish_Sea_Glacier

The classic picture of the Irish Sea Glacier -- described in the Wikipedia entry linked above -- is one of a great glacier or ice stream supplied from extensive icefields across the Irish Sea, Northern Ireland and the SW of Scotland, squeezed through St George's Channel and then expanding in a great lobe out into the Celtic Sea and the SW approaches.  I still think this picture is valid for the Anglian and possibly other early glaciations -- and indeed we need such a glacier if we are to explain all the evidence on the ground.

But it now looks as if the Devensian picture was very different.  As shown in the map above, if the Irish Sea Glacier had a "normal" long profile, the ice over St George's Channel must have had a surface altitude around 2,000m, with even higher ice domes to west and east -- this means ice surfaces at c 2,500m over Ireland and Wales.  These altitudes can be reduced somewhat if the passage of ice across the Celtic Sea was facilitated by a saturated substrate of marine muds and a highly deformable and unfrozen bed -- leading to rapid ice movement and surging or "purging" behaviour.  in those circumstances, forward glacier movement can be maintained -- at least for a short period of time -- by ice which has a much shallower surface gradient.  The extent to which we revise these ice surface contours downwards is something for the BRITICE and other modellers to work out!

As suggested in the last few posts, this model may only be applicable to the early glacial phases to have affected the British Isles.  In the Devensian something very strange seems to have happened -- in that the major areas of supply for this glacier seem to have been cut off and displaced by a large snow dome over the Midlands of Ireland.  Can we find an explanation for that in climate modelling?  Time will tell...

Perhaps we should not be too surprised if there were vastly different glacier dynamics and ice limits in the different glacial episodes on the west side of the country.  In eastern England (and to some extent in the Midlands) the pattern of glaciation between one glaciation and the next  did vary enormously, with the Devensian ice edge some 200 km further north than the Anglian ice limit, which was not far from London.

More on the Celtic Sea Piedmont Glacier

On looking back over some earlier references on this, I rediscovered this:

 Quote from Hubbard et al 2009:

"Without preconditioning certain large but critically limited zones
of the Irish Basin to a priori streaming, it is difficult to achieve
a single ‘surge-advance’ south to the Scilly Isles without a broad
piedmont type-lobe impinging onshore across much of SW
England. The reconstruction inferred in the E109b2 experiment
with a high precipitation scenario across western Britain may be
exaggerating the case somewhat but this simulation does tantalisingly
still meet all of the available ice-directional and RSL
constraints. Further enhancing precipitation rates across SW Eire
up to and exceeding present day values would yield a considerably
more western dominated Irish Sea ice-mass that would bring
modelled ice limits, especially those associated with the ISIS in SW
England, into line. However, there is little palaeo-climatic evidence
nor GCM modelling to support a wetter LGM than present across
southern Eire. Within the limitations of this study, we do not
pursue this though further investigation is clearly required."


So what evidence is there for a big ice dome over Southern Ireland around 23,000 - 20,000 years ago?   Work on the south coast of Ireland by O'Cofaigh and Evans (2007), backed up by many radiocarbon dates, shows that there was an incursion by the Irish Sea Glacier which was pushing westwards after passing through St George's Channel.  However, after that the irish Sea Glacier was displaced by ice pouring out from the Irish Midlands and the SW mountain areas, leading to the deposition of local tills (which go by a variety of local names) on top of classic Irish Sea till.  What we do not know is how protracted this "Irish Ice" episode might have been.

Tuesday, 15 February 2011

A Glaciological Dilemma


Following on from my last post, this map (from Hambrey et al 2001) is important because it shows that at the time of the last glacial (Devensian) maximum in West Wales, the ice edge on the Pembrokeshire coast was approximately at the altitude of present sea-level.  (Let's forget about eustatic and isostatic variations for the moment.)  The ice surface in North Pembrokeshire might have been as high as 200m -- but it was probably no higher than that.

The directions of ice movement picked up from striations and other traces were from the NW (in western Pembrokeshire) and NNW in north Pembrokeshire.  This is consistent with the position of the ice edge.

However, we now have the problem of the so-called "Scilly Isles Surge" which carried ice all the way to the Isles of Scilly some time between 23,000 and 20,000 BP.  Moraines were laid down there just a little above present sea-level.  How can that have happened if the surging glacier responsible was the Irish Sea Glacier?  Over a distance of 200 km, the "surging glacier" must -- according to the hypothesis of James Scourse and others -- have had a long profile which was totally flat or a gradient of zero.  I don't like to use the word "impossible" -- but I hope that all who know even a little about glaciology might agree that whatever the ground sliding conditions and deformable bed characteristics might have been in the dry Celtic Sea at the time, this scenario is vanishingly improbable........

Things get even more improbable when we realise that there is a deep trench in the middle of St George's Channel which must have forced basal ice to flow UPHILL on its passage towards the south and south-west.  Glacier ice can only flow uphill when there is a sufficiently steep surface gradient, and a sufficient thickness of ice, to maintain forward momentum -- one again, if we are talking about the Irish Sea Glacier, that argues for thick ice in the channel, and not ice just 200-300m thick.

To return to the models in the literature that seek to explain the presence of Devensian ice in the Scilly Isles.  These three will illustrate what is in the literature:



The top diagram is from O'Cofaigh and Evans 2007, and the second and third come from Clark et al 2010.  The precise date for this "surge" is immaterial -- but it was probably sometime between 23,000 and 20,000 years BP.

So if these models are inherently improbable, what model will more reasonably explain the evidence on the ground, at least on the eastern flanks of the glacier involved?  Here is my suggestion:

The only scenario that seems to be consistent with the facts is one in which the Irish Sea Glacier builds up in an early phase of the glaciation but is then suddenly starved of its supply, and is replaced in St George's Channel and the Celtic Sea by a Celtic Sea Piedmont Glacier supplied by ice from the uplands of Southern Ireland.  There may have been a substantial ice dome there, with an ice surface altitude in excess of 600m.  This explains both the onshore ice directions in Pembrokeshire, and the presence of the glacier terminus at near present sea-level both in the Scillies and in West Wales.  What I am less sure about is the glacial sediment sequence in SE Ireland; and I also wonder whether a reconstructed piedmont glacier of this sort, when we work out its surface contours, will make sense with respect to glacier modelling and "ground truthing."

To the best of my knowledge, this is the first time that a piedmont glacier of this sort, in the Celtic Sea, has been proposed.  OK-- all you geomorphologists and glaciologists out there who are working on the LGM,  let's have your opinions!



Monday, 14 February 2011

The Devensian Ice Edge in Pembrokeshire

The map above is based on one drawn by Prof David Bowen which I was previously unconvinced by, but which on consideration I now think is more or less correct.  But it does need some tweaking, and the revised version below is about as accurate as we can get for the time being.

The main difference is that I am convinced that the coast of St Bride's Bay was glaciated, as we can see from glacial deposits at Druidston, little Haven, West Dale etc.  The kame terrace at Mullock Bridge, near Dale, has ice contact materials in it, so the ice must have crossed the mouth of Milford Haven.  It also affected the South Pembrokeshire coast in the area around West Angle Bay -- there are ice contact deposits here, including flowtills.

There are a number of distinct zones shown on the map.

A = the South Wales End Moraine zone, incorporating a number of glacial lakes formed for the most part during the period of ice advance, and with pre-existing (Anglian?) meltwater channels in the Gwaun-Jordanston area re-used by marginal and sub-marginal meltwater streams, sometimes as lake overflows.  The till on the coast is Irish Sea till.  Extensive spreads and hummocks of fluvio-glacial materials, including eskers and kames.  Varved lake deposits in Lakes Teifi and Nevern, and elsewhere, sometimes overlain by glacial materials.

B=  St Davids Peninsula.  Irish Sea till on the north coast and local tills further inland and on the south coast of the peninsula.  Tors and rocky hillocks all glaciated and moulded by overriding ice.

C=  SW coastal areas.  Irish Sea till and local tills in isolated coastal pockets, and some fluvio-glacial materials further inland.

SE Pembrokeshire borders =  Mostly fluvio-glacial materials derived from Welsh Ice which has moved broadly westwards from the ice streams in the Tywi and Taf catchments.  Some mounds, but for the most part the gravels are in valley sandurs.

Ice-free Central Pembrokeshire = The tors of Treffgarne Gorge were unaffected by glacier ice.  Valley sandurs in the Western Cleddau catchment, and the Treffgarne Gorge may have been modified by vast torrents of glacial meltwater flowing south towards Milford Haven.  Great thicknesses of fluvio-glacial gravels -- some terraces up to 30m above the present floodplain of the Western Cleddau river.

That's the best I can do for now -- I think ALL the evidence accords with the glacial limit shown here.

Sunday, 13 February 2011

The North Pembrokeshire Devensian Trimline

I've been pondering on this matter lately, after another walk on Carningli yesterday.  I'm still investigating where the trimline might be along the north Pembrokeshire coast which shows us the maximum elevation of Devensian glacier ice coming in from Cardigan Bay and St George's Channel.

 The zone referred to as being occupied by the "The South Wales End Moraine" -- characterized by extensive glacial deposits, fluvio-glacial landforms and deposits, and pro-glacial lakes. Click to enlarge.

Many years ago Charlesworth identified the "South Wales End Moraine" as marking the maximum extent of glacier ice during the last glacial episode.  It consists of a scattered assemblage of mounds and terraces of fluvio-glacial material, located for the most part between Fishguard and Cardigan.  I spent years studying this "moraine" and it's not really a line at all, since the sands and gravels (including some patches of ice-contact materials) are in a band of country some 15 km long and 8 km wide.  I have always thought that the ice progressed well beyond this "zone of deposits" and that it should therefore not be referred to as an end moraine.  But how much further?  Danny McCarroll and others think that the north coast was glaciated because the tors and craggy hills on Pencaer and along the coast between Fishguard and Dinas are rounded or ice moulded, whereas  those further inland, on Dinas Mountain and on the Carningli upland, are frequently delicate, with steep crags and balanced boulders etc.  They appear to have been affected by frost action but not by overriding ice.

So somewhere there is a trimline...........  as I have suggested, the ice appears to have affected Carningli up to an altitude of c 300m, possibly leaving behind the Pont Ceunant moraine after a retreat downslope on the north-facing mountainside.  I have found more evidence of overriding ice almost as high as the summit crags.


Evidence of ice action on Carningli.  Top and bottom photos:  ice smoothed undulating rock slabs near the summit.  Middle photo: smoothed rock slabs with crescentic gouges, on the south side of the mountain near the western summit.  If these really are Devensian features, there must have been ice at least 30 metres thick.....

Other evidence comes in the form of perched blocks.  There are two spectacular ones in the area -- one on Carn Edward (alt 280m), to the west of Carningli, and the other on one of the four tors which are called Carnedd Meibion Owen (alt 240m).  These blocks are extremely unlikely to have been emplaced by periglacial action or any other mode of tor formation;  they must have been stranded or let down by melting glacier ice.


Yet more evidence coming into the frame is that relating to the pro-glacial lakes referred to as Llyn Teifi and Llyn Nevern -- occupying the lower parts of those two valley systems.  Charlesworth (see above maps) was the first one to refer to these lakes, in 1929 -- but he thought that they formed during ice retreat or deglaciation, which is when we would expect vast quantities of meltwater to be pouring off the wasting ice.  New work, however, suggests that the lakes were impounded by ADVANCING glacier ice, since lake deposits including fine silts and clays with varved sequences are overlain by coarser stream sediments and even by till.  So the glacier coming in from the coast rode over these lake sediments and passed further inland.  Etienne and others (2006) think that the ice eventually flowed right over the Carningli upland and blocked off the whole of Cwm Gwaun, with lakes flowing over a succession of cols to cut overflow channels in the vicinity of the ice edge.  They think that the overflowing water utilized the older and larger channels of the Gwaun-Jordanston channel system -- which were inherited from earlier glacial episodes.  I think I would agree with much of that, although I won't be entirely convinced about all those lakes until we have varved sediments to look at.

So if the ice margin pressed as far inland as Eglwyswrw and Brynberian, with meltwater impounded up against the north face of Mynydd Presely, we can set the altitude of the ice edge at somewhere around 200m.  Now that is very important indeed, as we shall see.......

http://brian-mountainman.blogspot.com/2010/06/new-dates-shed-light-on-old-ice-limits.html