THE BOOK
Some of the ideas discussed in this blog are published in my new book called "The Stonehenge Bluestones" -- available by post and through good bookshops everywhere. Bad bookshops might not have it....
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Monday 8 April 2024

What did HH Thomas know about the extent of glaciation?

I have been digging up some more info about what HH Thomas knew or did not know when he presented his controversial views on the transport of the bluestones in 1923.  (And in 1921, actually......)  

Let's take 1910 as a reasonable date to look at.  The "state of play" was determined at the time by such senior geologists and "glacialists" as James Geikie (far more important than his older brother Sir Archibald), Carvill Lewis, Frederick Wright,  Thomas Jehu and John Wesley Judd. 


Henry Carvill Lewis (1853-1888) , an American who did much fieldwork in the British Isles.  He proposed that the edge of the great Ice Age glaciation in Britain  coincided with a line of prominent moraines and other features which could be traces across country.  At first he found it difficult to accept that traces (such as erratic boulders) south of his limit were genuinely related to the presence of glacier ice, and he initially assigned them to some great Ice Age Flood. But later in his all-too-short life he fell into line with Geikie and others and did accept that the maximum position of the ice edge in the Ice Age was well to the south of his hypothetical line. 

 


Prof James Geikie (1839-1915), a Scottish geologist who was convinced that there was very extensive glaciation in the Ice Age, and that the ice limit in SW England lay somewhere off the Cornish coast. he was also active in promoting the idea that there had been several glaciations, separated by warmer intervals or interglacials.


Frederick Wright’s map of 1895, showing a strange ice limit across South Wales, based in part on Carvill Lewis’s identification of assumed terminal moraines. Wright ignored the abundant records of far-travelled erratics to the south of this line.


Europe and the greatest extent of glaciation during the Ice Age. From “Prehistoric Europe - A Geological Sketch”, by James Geikie (Edward Stanford, London, 1881). Note that Geikie incorporates the whole of the Bristol Channel area into the glaciated area, with an ice edge on or near Salisbury Plain……..


In this map, also from Wright (1895) a highly generalised line, based on the work of James Geikie, is drawn well to the south of the “moraines” identified by Carvill Lewis. Geikie recognised that the abundance of glacial erratics around the Bristol Channel coasts indicated extensive glaciation, at least as far south as the Cornish coast.


Extract from Harmer’s “erratic map” of 1928, showing erratic boulders and ”drift” exposures in abundant locations including South Pembrokeshire, Gower, Glamorgan and the Ilfracombe district — all to the south of the “moraines” mapped by Carvill Lewis. The work on this map was done between 1902 and 1913, and it must have been known to HH Thomas.





Prof Thomas Jehu (1871-1943) was born in Wales and later spent most of his working career in Scotland. As a young man he studied the glacial deposits of North Pembrokeshire, and published his findings in a highly regarded article in 1904. He recognized a tripartite succession in the drift sequence of Pembrokeshire -- namely Lower boulder clay, Middle sands and gravels, and Upper boulder-clay.  He characterised the latter deposit as a "rubbly drift" -- this is now recognized as a mixed deposit of melt-out till, flowtill and ablation till, rearranged and redeposited in a chaotic ice wastage environment.  Jehu agreed with Hicks that the Irish Sea ice that affected North Pembrokeshire flowed across the county from NW towards SE -- thus contradicting Geikie who had earlier portrayed the ice as having travelled from NE towards SW,


 Prof John Wesley Judd (1940-1916) was a prominent geologist who specialised in petrology.  He was Professor of Geology in the Royal College of Science and at Imperial College, and also President of the Geological Society.  Because he was London-based, he was right at the centre of things, and knew all about what was going on in assorted disputes and areas of progress.  He participated actively in the Stonehenge bluestone debate, and provided comments or additional material to some of the prominent archaeologists includingGowland and Hawley.  In 1901, Judd suggested that the bluestones at Stonehenge were erratics of glacial origin. He argued that the debris at Stonehenge had come from North Pembrokeshire or North Wales. He also observed that in areas affected by very ancient glaciations, most of the till had been eroded away by natural processes, leaving only a thin scatter of erratics here and there. Further, he observed that hard stones (including bluestones) left behind on Salisbury Plain would have been targetted down through the centuries for building purposes simply because neither chalk nor flint makes good building material.  Intriguingly, Judd concentrated not on the 43 known bluestone monoliths or orthostats themselves, but on the Stonehenge debitage. He found an extraordinary assortment of soft or fragile stones.  He made the point specifically that this material did not seem to be very closely related to the remaining standing bluestones -- so he concluded that only the hardest stones had survived, with all the other material breaking down and becoming incorporated into the soil layer over many thousands of years.  Judd suggested the presence of a “Stonehenge moraine” incorporating an abundance of foreign stones which would have been readily available to the builders of Stonehenge. He also argued -- perfectly plausibly -- that “stone availability” (of both bluestones and the larger sarsens) might have actually determined the precise position of the monument. 

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All things considered, the accumulated evidence shows that by 1910 the broad outlines of glaciation in the Bristol Channel / Celtic Sea arena were already established, involving thick and active ice carrying erratics and other glacial materials from the NW across Pembrokeshire and up the Bristol Channel, affecting the coasts of South Wales and the South-West Peninsula. In making his claims about the impossibility of bluestone transport towards Stonehenge HH Thomas wilfully ignored a great amount of evidence in the printed literature, and wilfully misrepresented the opinions of senior "glacialists". It is quite extraordinary that he got away with it -- but that, maybe, was because he was a geologist talking to archaeologists or antiquarians. If he had been a geologist talking to other geologists, he would certainly not have got away with it.  They would have had his guts for garters. 

Interestingly enough, the great majority of the articles published by Ixer and Bevins in recent years have also been published in archaeological journals -- and presumably they have been refereed for the most part by archaeologists. What a strange coincidence........!!






Saturday 6 April 2024

HH Thomas knowingly misrepresented the glacial erratic transport evidence in the Bristol Channel

I have been looking again at the manner in which, in 1923, HH Thomas informed the world that the glacial transport of bluestones from west to east (up the Bristol Channel) would have been impossible.  Here is an earlier post of mine:

https://brian-mountainman.blogspot.com/2019/10/hh-thomas-and-his-glacial-blind-spot.html

Thomas was guilty of over-simplification and selective citation of his samples (there were very few anyway) and his rock identifications, in order to flag up the idea that there were just two main sources for the bluestones. It's interesting that in 2018 Bevins and Ixer attacked Thomas's slapdash methods, his sharp practices and his reputation pretty enthusiastically, but they restricted their scrutiny to his geological analyses, and criticised him for homing in on Carn Meini and Carn Alw as the main source locations for the Stonehenge bluestones.

https://brian-mountainman.blogspot.com/2018/06/herbert-thomas-scrutinized.html
https://brian-mountainman.blogspot.com/2022/06/dale-judd-and-engleheart-versus-thomas.html

Retracing the footsteps of H.H. Thomas: a review of his Stonehenge bluestone provenancing study.
Richard Bevins and Rob Ixer
Antiquity, May 2018.
https://doi.org/10.15184/aqy.2018.10
Published online: 31 May 2018

Bevins and Ixer later (in the magazine called Liver Science) went off on a tangent and tried to demonstrate (without any evidence at at all)  that the bluestones were transported by land instead of by sea.  That was a serious waste of time and effort, especially since HHT did not try to promote the idea of sea transport either.  That came later, with the involvement of Atkinson and other archaeologists.


Also, it's rather ironic that in attacking HHT for concentrating on the "wrong" two tors, they then concentrated on trying to convince the rest of us that two other tors or rock outcrops (Carn Goedog and Rhosyfelin) were key to the understanding of what went on  -- while admitting in other papers that the bluestone monoliths and fragments at Stonehenge have come from multiple locations.  Not for the first time, pots and kettles come to mind!

B and I  also declined to comment on the most influential part of the HHT paper -- namely the section dealing with the bluestone "mode of transport."  But the section in the 1923 paper on the "ice transport option" is truly awful, misrepresenting all sorts of things and including many statements that HHT must have known were untrue -- even allowing for the fact that he was writing a century ago. That section should have been scrutinized.   Below I reproduce the key part of the infamous paper, with some comments of my own.

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Extract from HH Thomas, 1923 Antiquaries Journal

MODE OF TRANSPORT

Having in a great measure solved the problem of the source of the Foreign Stones, we must consider carefully the possible and probable modes of transport of the stones from Pembrokeshire to Salisbury Plain. Two modes of transport have been suggested : one natural, by ice during the great Ice Age ; the other, by human agency at, of course, a later period.

The Hypothesis of Ice-transport. 

Professor Judd in 1901 put forward the hypothesis that the Foreign Stones of Stonehenge had been transported to the Plain by ice during the Pleistocene Glacial Period, and this view seems to have found favour and acceptance in many quarters.

We have, of late years, considerably advanced our knowledge of the distribution and extent of the British Ice-fields, and also accumulated much information concerning the directions and limits of dispersal of erratic boulders. The geological evidence is such that the idea of a glacial origin for the Foreign Stones will not bear investigation.

((Comment:  Perhaps not a good idea to get your conclusion in first, before considering the evidence.........))

Let us consider critically this hypothesis of glacial transport as suggested by Professor Judd. First, there is no evidence of glacial drift on Salisbury Plain such as would of necessity have been left by any ice-sheet capable of transporting the masses of rock in question. Isolated masses of rocks foreign to the district, other than those used in the fabric of Stonehenge are entirely wanting, as also are small pebbles of such rocks from the gravels of the neighbourhood. It has been claimed, without producing any evidence in support of the statement, that such masses did exist but that they have all been collected to make walls, gateposts, millstones, etc. But, as Mr. Stevens of Salisbury has cogently stated, no one can point to a single rock-mass like any of those used at Stonehenge having been put to any such purpose. Mr. Stevens says ' There are many millstones and gateposts in Wiltshire, but where is there one which corresponds in any way to the upright Foreign Stones of Stonehenge ? Unhappily this tangible evidence is wanting ; so, alluring as the Glacial Drift Theory may appear, it must reluctantly be set aside for want of convincing evidence.'

((Comment: It's disingenuous of Thomas to pretend that substantial "rock masses" of exactly the right type on Salisbury Plain are required in order to demonstrate that glacial entrainment and transport might have occurred. There are erratic stones in the records of work prior to 1923, and the Boles Barrow bluestone was already on the record following its discovery by Cunnington in 1801.  If you want to wear rose-tinted spectacles rather than dark sunglasses, you might wish to count the Stonehenge bluestone assemblage as quite valid evidence of glacial transport and dumping, and Thomas should have acknowledged this.))

To transport glacially a series of igneous boulders of great size from Pembrokeshire to Wiltshire postulates the existence of an ice-sheet of unbroken character occupying the whole of the intervening country ; and with the ice moving in a direction a little south of east. We have, fortunately, good evidence of the extent of glaciation of Pembrokeshire, and we find that this county was crossed in a south-easterly direction by an ice-sheet that moved down the Irish Sea. This ice-sheet carrying Scottish
boulders, crossed the low plateau of Anglesey and Carnarvon, gathering fresh material as it went, but was kept from passing far inland by the local Welsh ice-sheet that had its centre of dispersal in the highlands of Snowdon, The Arenigs and Cader Idris, and was pressing outwards towards the coast. On reaching the latitude of Pembrokeshire, far removed from the main centre of Welsh glaciation, the Irish Sea ice-sheet was allowed to spread fanwise and to override the plateau-regions of Pembrokeshire and Southern Ireland which offered relatively little opposition. In spite of this there is the clearest evidence, from the distribution of Pembrokeshire and Scottish boulders that the ice-front lay only just south 
of the present coast-line of Pembrokeshire, and that the ice as a solid mass neither crossed the Bristol Channel to Devon and Cornwall, nor passed in an easterly direction beyond the coastal regions of Pembrokeshire

((Comment: This is utter nonsense, and Thomas must have known it.  We are talking here of the maximum known glaciation in the region.  To claim that the glacier ice front lay just to the south of the Pembrokeshire coast, and to claim that the ice progressed no further up the Bristol Channel,  is to fly in the face of the evidence that had been in the public domain for more than 20 years.  Jehu and many other professional geologists must have been appalled by Thomas's claims.  Judd, who died in 1916, would have turned in his grave.  Glacial deposits were already known, and described in the literature, from the Bridgend - Pencoed area, from Fremington, Trebetherick and the Isles of Scilly -- all attesting to a very extensive glaciation  that could, even according to the thinking of geologists in 1923, have extended to Somerset and Salisbury Plain. Thomas must have known of the Pentre, Newton and St Athan erratic boulders in the Vale of Glamorgan, all three almost certainly from Pembrokeshire.  And far-travelled glacial erratics were already described from the coasts of Devon and Cornwall.))

No boulders of Pembrokeshire rocks, such as would of necessity be carried by any extension of this icesheet, have ever been found either on the north coast of Devon, Cornwall or Somerset, or on the south coast of Wales east of the estuary of the River Towy.

((Comment:  That is not correct. The Pembrokeshire erratics in the Storrie Collection, from the till at Pencoed in Glamorgan, were well known by 1923. Indeed, Thomas himself was one member of the Geological Survey team that described the erratics in the Bridgend GS Memoir of 1904.))

Scottish boulders, however, occur on the north coast of Devon and on the coast of Glamorganshire where their presence, unmixed with Pembrokeshire boulders, indicates that they were not carried by that portion of the ice-sheet which had crossed Pembrokeshire but had been borne by the portion that came down the central region of the Irish Sea. The ice-sheet would probably have a crescentic front and the medial portion would have the furthest southerly extension. It is to be noticed that all the occurrences of Scottish boulders outside Pembrokeshire and its adjacent islands lie at raised-beach level, as at Croyde Bay and in Glamorganshire. There is no evidence of the erratic material mounting the cliffs or extending inland. The inference is, therefore, that these Scottish boulders were deposited from icebergs that had broken away from the central portion of the main ice-front and were stranded on relatively distant shores. The geological evidence proves conclusively that although Pembrokeshire was crossed in a south-easterly direction by a lobe of the Irish Sea ice-sheet the front of this ice-sheet never reached across or far up the Bristol Channel.

((Comment:  Thomas gets himself into a frightful tangle over the shape, thickness and  movement of  "the ice sheet" -- and although he may be right to assume that Scottish erratic boulders were constrained within a segment of the ice stream, he must have known the evidence on the file that Pembrokeshire erratics were in fact transported much further east than the Towy estuary.))

Passing to the country intervening between Pembrokeshire and Wiltshire, we find nowhere along the line that an ice-sheet would have to traverse in order to transport Pembrokeshire boulders to Salisbury Plain, any evidence of glaciation of an intense character. 

((Comment:  This is a somewhat absurd statement, given that most of this territory is currently under water.  And what sort of glaciation is to be counted as "of an intense character" as distinct from one that is not intense?))

There are no trains of far-travelled boulders, no ice-scratching and polishing of outstanding rocks, and no thick accumulations of boulder-clay. As has been pointed out in a previous communication such a hypothetical ice-sheet, in order to account for the Foreign Stones of Stonehenge would have to gather from Pembrokeshire blocks all of about the same size and mainly of two rock-types. It would have to carry them all that distance without dropping any by the way. 

((Comment:  Here, Thomas raises the nonsensical idea that ice cannot possibly have delivered to Stonehenge exactly the right number of bluestones, of the right colour and lithology, to satisfy the designers and the builders of the monument.  This has, of course, been repeated many times since.  So many unsupported assumptions are built into that it is really not worth wasting time on them.))

Further, it would have to pass over all kinds of rocky obstacles without gathering to itself any of the various materials over which it was forced to ride. Such in itself, without the additional positive evidence that is forthcoming as to the extent of the glaciation of Pembrokeshire and adjoining counties, permanently disposes of the idea of glacial transport for the Foreign Stones of Stonehenge.

((Comment:  Thomas must have known, from his work with the Geological Survey including Cantrill, Strahan, Dixon and Jones, that glacial entrainment, transport and deposition are complex matters which are difficult to predict and which constantly throw up surprises in the field.  The apparent absence of erratics from all upglacier outcrops does not (and did not in 1923) demonstrate the absence of glaciation.))

Note: The rocks of the Western Isles, Ailsa Craig, and Galloway are fairly common as erratics. They occur on the Cardigan coast, on the plateau-region of Pembrokeshire and its outlying islands (Skomer, Skokholm, etc.), and on the Glamorganshire coastal regions of the Bristol Channel.

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I'm still staggered that Thomas was allowed to get away with all of this, and to make such definitive statements on the record.  We know that a few people -- including Engleheart and Dale -- were sceptical, but where were all the geologists who knew that he was talking nonsense?  Was he such a forceful character that nobody had the guts to challenge him?  Or was the establishment view already established -- namely that the human transport of the bluestones was a matter of national pride, meaning that anybody who challenged the idea could be charged with being unpatriotic?



Wednesday 3 April 2024

The unhealthy obsession with bluestone tors




One of the "high crags" of Preseli -- this one is on Foel Drygarn

As a result of some interesting recent correspondence with a knowledgeable reader of my latest article in "The Holocene",  I have been thinking afresh about the manner in which the bluestone tors of Preseli don't just dominate the upland landscape, but also dominate the debate about Stonehenge.  Ever since 1923, when HH Thomas homed in on the tors of Preseli as the likely sources of most of the bluestone monoliths at Stonehenge,  it has been assumed that the monoliths were taken from the most prominent places in the landscape -- the high crags.  Literally thousands of learned academic papers, book chapters, journal articles, popular magazine features, news reports, TV programmes etc have unknowingly and unthinkingly signed up to the same assumption.  Did the spotted dolerite monoliths (and fragments in the debitage) come from Carn Meini or Carn Goedog, Cerrig Marchogion or Carn Alw, Carn Ddafad-las or Carn Gyfrwy?  Acres of newsprint and millions of words devoted to the question "Here, or there?", "This tor or that tor?"

It's actually quite intriguing.  I have got caught up in it myself, what with my blog posts extolling the virtues of the Preseli and Carningli tors and trying to encourage the general public to visit them and value them:

https://brian-mountainman.blogspot.com/2021/01/the-tors-of-carningli-and-mynydd-dinas.html 

https://brian-mountainman.blogspot.com/2016/12/the-preseli-tors.html

Because they are so beautiful and impressive, it is easy to attach to the tors some sort of spiritual or sacred quality, and to say that "they have always been worshipped" or that they have always been deemed to be associated with the gods. In the Christian era some tors at least must have been invested with significance: Carningli summit was the place where St Brynach "communed with the angels", and the Bronze Age burial mounds on the summit of Foeldrygarn must indicate a reverence for the place............

Then it's very easy to slip into the habit of linking these high rocky places with power or territorial control. The hillforts on Foel Drygarn, Carn Alw, Carningli and Carnffoi must have been built not just because these were good defensive sites but because they were statements of power: this is my territory -- keep away, or stray into it at your peril.......It's not much of a leap from there to assume (as the archaeologists have done) that since Stonehenge was as much a political statement as anything else, its component stones must have been sacred or powerful in themselves, so they must have come from sacred places, so they must have come from "the high places" that dominated the Preseli skyline, so they must have been quarried. We are of course now into circular reasoning, but that hasn't bothered anybody very much.

But hang on. Is there actually any evidence in West Wales that these "high rocky places" were valued by our prehistoric ancestors, and that the stones that came from the tors were especially sacred or special? Interestingly enough, there isn't. Let's look at the big and famous megalithic structures of West Wales. Pentre Ifan cromlech was not made from stones imported from a tor or high point in the landscape; the stones used were taken from a litter of largely local erratics. At Bedd yr Afanc the stones used are of several types, picked up locally and apparently used randomly. Carreg Samson has nothing to do with a prominent rock outcrop, and neither does Gors Fawr, and neither does King's Quoit, Coetan Arthur, Carreg Coetan Arthur, Bedd Arthur, or any of the other stone settings of West Wales. As pointed out by Nora Figgis, Steve Burrow, Stephen Briggs, Olwen Williams-Thorpe, Nikki Cook and many others, the Neolithic and Bronze Age monuments are all built of boulders, pillars and slabs of rock found locally and used more or less where found.  The three Bronze Age burial mounds on Foel Drygarn are made of local bedrock slabs, not because they were sacred but because they were easily collected from adjacent outcrops.

Now let's think about geology. In his original work on the provenancing of the bluestones, HH Thomas was completely dependent for his analysis on samples taken from the crags. He did not do his own sample collecting, but depended upon samples collected by his BGS colleagues around 20 years previously. For practical reasons these came from prominent rock outcrops and not from the intervening saddles, cols and lower parts of the landscape. That, of course, introduced sampling bias. This bias has run through into the abundant studies by Rob Ixer, Richard Bevins and others within the last 15 years. They have studied hundreds of thin sections and collected samples from the high crags, always on the assumption that these are the "candidate" locations from which the bluestone monoliths must have come. They have found no perfect matches with Stonehenge samples, and although their provenancing work must by now have become reasonably accurate, they have had to admit, over and again, that some of their samples just do not quite fit their preferred source locations.   As I have suggested many times on this blog, some of the foliated rhyolite material at Stonehenge might have come from Pont Saeson - Rhosyfelin, from one or more outcrops currently unsampled.  Some of the spotted dolerite boulders and debris at Stonehenge might have come from the Carn Goedog sill, which covers c 60,000 sq m, but not necessarily from the tor itself.



Carn Goedog, Carn Alw and Carn Breseb -- lots of samples from the tors, but how many from the intervening landscape?

In their most recent "provenancing paper", Bevins et al (2022) demonstrate all too clearly how biased all of their work has been, regarding the attention paid to the "high crags".  In seeking to discover where the unspotted dolerite boulders and fragments at Waun Mawn might have come from, it is clear that their underlying assumption is that the stones must have been fetched from somewhere else. That's dodgy enough as it is, but then the additional assumption is that they must have been fetched from somewhere prominent. All of their "candidate sites" subjected to detailed analysis are high crags or tors -- for example Cerrigmarchogion, Carn Ddu Fach, Carngoedog, and Carn Fach.  They do not provide matches for Waun Mawn, and so further analyses are undertaken on samples from Cerrig Lladron and Carnau Ysfa -- small crags or tors closer to Waun Mawn.  Cerrig Lladron is found to give the best petrological / geochemical match, and so that is proposed as a probable source for the Waun Mawn monoliths.  They claim that these are the closest rock dolerite outcrops to Waun Mawn, but that is incorrect. There are other outcrops of dolerite on Waun Mawn moor itself, adjacent to the site of the supposed "lost giant circle".   The fact that these outcrops were completely ignored in such a detailed study is extraordinary.

Bevins, R.E., Pearce, N.J.G., Parker Pearson, M., Ixer, R.A. 2022. Identification of the source of dolerites used at the Waun Mawn stone circle in the Mynydd Preseli, west Wales and implications for the proposed link with Stonehenge. Journal of Archaeological Science: Reports 45 (2022) 103556.

https://www.researchgate.net/publication/ 362119860_Identification_of_the_source_of_dolerites_used_at_the_Waun_Mawn_stone_circle_in_ the_Mynydd_Preseli_west_Wales_and_implications_for_the_proposed_link_with_Stonehenge

So this question arises: might the bulk of the Stonehenge bluestones have come from unsampled parts of the known and mapped Preseli intrusions and volcanic rock outcrops?

In answer to that question, we can point out that it is no longer tenable to refer to a small number of preferred bluestone locations in which quarrying activity was concentrated. The geologists themselves have had to admit that the sheer abundance of rock types in the Stonehenge bluestone assemblage points to multiple provenances, and that in itself points to glacial, rather than human, bluestone transport.

This brings us to glacial theory. From what we know about glacial entrainment and the transport of "quarried" or plucked blocks under or within an overriding glacier, is it possible that the Stonehenge bluestones have come exclusively from the high crags? From a number of recently published papers, this scenario looks increasingly unlikely. Back in 1965 my old friend Prof David Sugden argued, in his doctorate thesis, that some of the tors in the Cairngorms appear to have been protected, rather than eroded, by overlying ice. A number of subsequent articles, involving many different researchers, have pointed to the survival of tors on high mountain plateaux in other glaciated regions because the thin ice that covered them was cold based and largely immobile. In contrast, erosion was concentrated on the lower slopes and in the troughs where the ice was thicker, warm-based and fast flowing. This means that it was more "aggressive" in landscape transformation.

This suggestion appears to be supported by some of the new work on the cosmogenic exposure ages of rock surfaces in glaciated areas.  To generalise, samples taken on the surfaces of erratic boulders appear, more often than not, to make sense; but samples taken on summit bedrock slabs are throwing up so many anomalies that it must be inferred that the recorded ages are false because of "age inheritance" over maybe hundreds of thousands of years.  This in turn points to very limited or minimal glacial erosion or actual protection on these high rock surfaces.  I will shortly be doing another post on this.  See my comments on Carningli and Lundy Island:



I have suggested in a number of publications (including my 2018 book called "The Stonehenge Bluestones") that although the high crags of Preseli do show evidence of glacial moulding and abrasion processes, the bulk of erosional activity was concentrated on the up-glacier or northern slope of Preseli, where erosional activity was optimised under streaming or fast-flowing ice where there was melting on the bed. These "erosional hot spots" probably did not coincide with the tors or high crags, but with the intervening areas, valleys (like the Afon Brynberian gorge around Rhosyfelin) or with roche moutonnee features where there were great variations in glacier bed conditions. In Scotland they call these areas "straths" -- but we could call them moorlands (as distinct from the higher plateaux areas).    I will develop this in future posts.

But for now, here is a thought. I THINK THAT ALL OF THE GEOLOGICAL PROVENANCING WORK DONE OVER THE PAST 15 YEARS BY BEVINS, IXER AND THEIR COLLEAGUES MIGHT WELL BE COMPROMISED OR DEVALUED SIMPLY BECAUSE THEY HAVE TAKEN ALL OF THEIR SAMPLES FROM THE WRONG PLACES.

I'm not joking. I say this in all seriousess. Watch this space.













Tuesday 2 April 2024

The Lost Circle Fog and the gullibility of the media

 


I have been doing an interesting exercise -- checking back on the gullibility of the media and the coverage of the "Lost Circle" story in February 2021.  You will recall that there was a very carefully orchestrated publicity campaign at the time, with the first transmission of the "Lost Circle" TV documentary timed to coincide with the publication of the original Antiquity article. The amount of work that went into this cannot be overstated -- the documentary maker, the broadcaster, the authors of the journal article, the publishers of "Antiquity", the UCL press office and many others must have been in the loop.   All were intent upon maximum publicity and maximum impact -- and who cares anyway about the reliability of what is being promoted as one of the stories of the century?


No wonder, with all that high-powered pressure, that the media fell for it hook, line and sinker. At the head of this post are just a few of the headlines in just a few of the media outlets. There were scores of others in similar vein. The reports were filled with incredulity, certainty and admiration for the exploits and persistence of the research team. Hardly any of the journalists who covered the story expressed any reservations or used the words "possible" or "may".  Most of them simply regurgitated the contents of the UCL press release -- or similar press releases from the press offices of other institutions linked to the research team of about a dozen authors. 

As we knew at the time -- around 3 years ago -- a lot of the contents of the TV documentary and the Antiquity article were poorly researched and deeply misleading. The programme should never have been made and broadcast, and the article should never have been published. I said all that at the time, and I say it again now, following the recent retraction of many of the things that were claimed by the authors themselves. The "complete circle" has gone; the monolith imprint has gone; the geological link with the so-called "quarries" has gone; the monolith export to Stonehenge has gone; and it's now accepted that Waun Mawn had nothing whatsoever to do with Stonehenge.

It's all a bit of a fog, with some reliable information out there somewhere, but almost impossible to discern.......

There are many lessons to be learned -- but will they be learned? I have my doubts. For start, archaeologists (and geologists) should not be so obsessed with IMPACT that they rush into print and present half-baked ideas as realities and inadequate field observations as hard evidence. University press offices should be much more careful about the choice of papers given high-level PR treatment.  Journal editors should be much more careful about their choice of peer reviewers and about their publication decisions.  And the media should be much more circumspect when assessing the press releases coming from certain press offices and when deciding what coverage to give to "spectacular" stories.

Will any those involved in this fiasco regret their errors of judgement, or admit that they have been conned, or apologise to their customers or to those who have grant-aided them?  I doubt it very much.........

And will the media cover the publication of my new paper in The Holocene journal, published after very tight peer review and claiming that Waun Mawn had nothing whatsoever to do with Stonehenge?  I doubt that very much too -- because to cover the story would be to admit to their own gullibility and lack of scrutiny when they published all that tosh about the "Lost Circle" just three years ago.







Sunday 31 March 2024

Roches moutonnees on the north face of Mynydd Preseli


 



The roches moutonnee forms on the north face of Preseli -- photo courtesy Preseli 360

I have written often in the past about the roches moutonnee features on the north face of Preseli, but I have never before seen a photo that captures the forms so well.  Here we can see Frenni Fawr, Foel Drygarn, Carn Breseb and Carn Goedog and their distinctly asymmetric forms -- gentle north-facing up-glacier slopes and steeper plucked faces on their south-facing or down-glacier sides.  When ice has moved across this landscape from left (north) to right (south) abrasion has been concentrated on the northern flanks and plucking or quarrying concentrated on the southern flanks. "Quarrying", by the way, is a specialist term often used in glacial geomorphology, with no suggestion at all of human involvement in the process.

As I have often said before, the extraction of blocks was much more likely on this side of the Preseli ridge than it would have been on the southern flanks.  It's all to do with the laws of physics........


Thursday 28 March 2024

If it's rounded, it ain't quarried.....






Two nice photos from our walk down on the Parrog in Newport, the other day. These are two big erratic boulders on the shore platform, just a few yards from the coastal footpath. They are both dolerite boulders. One of them is clearly a glacial erratic, resting on the black mudstone shore platform and probably very close to where it was originally dropped by the ice. The other one has clearly been bashed about a bit, with chunks knocked off it, I suspect by the men who were building the coast defences and placing big boulders along the base of the Parrog sea wall.

The bulk of the bluestones at Stonehenge look like the big boulder in the top photo. If they had been quarried, as Ixer, Bevins and Parker Pearson would like us to believe, they would have looked more like the boulder in the bottom photo. This little matter of stone shape and surface characteristics is something tht the MPP team mambers consistently and quite deliberately ignore. That struck me again the other day when I looked again at the famous "Lost Circle" BBC film, in which MPP pretends that the people who supposedly quarried the Waun Mawn and Stonehenge monoliths were looking for gorgeous pillars.  Well, if Stonehenge is anything to go by, and if we follow the logic of the archaeologists that the bluestones were carefully selected at their places of origin, we have to conclude that the megalith hunters had a strong preference for small, weathered, rounded glacial erratics.

Wednesday 27 March 2024

Hooray for Artificial Stupidity!!!

 




Thanks to Mary for drawing this to my attention.  I just had to share it -- not sure where it came from originally.  But somebody obviously asked one one of these AI sites for a portrayal of how the bluestones were transported from Rhosyfelin to Stonehenge.  Mynydd Preseli and the Afon Brynberian valley in all their pristine majesty, and our heroic ancestors hard at work.  Absolutely wonderful.

So now you know...........