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....
To order, click HERE
Sunday 29 May 2022
Friday 20 May 2022
One would have thought that a serious exhibition organized by -- among others -- the British Museum would have separated out the facts and the speculations. But no -- speculations are presented as if they are facts over and again. For example:
Mike Pitts on the BM blog site, going on about quarries, overland transport by tribal groups, and a "lost circle" built and then dismantled. The orthodox narrative rules, and higher authority dictates that nobody should deviate from it by a single inch. It's more than a little pathetic, as well as being completely dishonest :
Stonehenge is very unusual in the ancient world for the distances over which its materials were transported to the site, especially those megaliths we know as bluestones. Most of these, made from different types of igneous rock, were quarried in south west Wales – I estimate their journey at 220 miles.
"Chemical analysis suggests that several lived and died in West Wales before their remains were interred within the monument...."
A couple of days ago I went up to Swansea University to give a talk on the bluestones to the local U3A group. A good audience, a lot of interest, and some really intelligent questions and discussion afterwards.
It was a particular pleasure to see in the audience Mike Bristow, my geography teacher when I was a kid in Haverfordwest Grammar School, 1951-59. He's 92 now, and still going strong. He's been living near Swansea for quite a few years. I owe him a huge amount -- it was he who introduced me to geomorphology and gave me my love of the landscape, and who taught me to question everything. Scepticism is different from cynicism -- as I try to demonstrate on this blog. Mike also taught me to trust in my own judgment, so long as it is based on a sound understanding of the nature of the evidence available. Thank you Mike, for all that you gave to me and a whole generation of geography pupils long ago, in those days of innocence.......
Thursday 19 May 2022
Tuesday 17 May 2022
"I have had a quick skim through the paper you attached and my general feeling is that the data are so compromised that I simply wouldn't have used them. Their understanding of XRF is sound, but the issues they have had with low totals and wet vs dry attenuation have forced them to be very selective in which data they accept and which they don't. In principle, it's certainly possible to acquire meaningful data for sandstones (the finer-grained the better), but the detector should be held orthogonal to a very flat dry surface (not laid on a tripod on an irregular wet surface) and the Ba, Sr, Ca etc could well be within clays and feldspars, rather than barytes and calcite. Such XRF is essentially a surface detection technique, so there is also the problem of weathering crusts to consider, not to mention burial within a chalk soil and whatever artefacts have been induced by archaeological processes and modern "witch" ceremonies!"
2. Of course, the authors were 'forced' to use pXRF by English Heritage's stubborn refusal to allow a fresh sample (ideally a 1" core) to be taken from the actual Altar Stone -- from below the present ground surface (so it would be invisible to visitors) and then filled with concrete before reburial. Given the shenanigans that take place on every Summer Solstice at Stonehenge, which have included lighting fires on the Altar Stone, EH's attitude demonstrates a double standard to say the least.
3. Unless you are dealing with pure quartz arenites, the detailed composition of sandstones (at both large and small scales) is vertically and laterally variable. Source rock composition, the nature/energy levels/duration of the transporting mechanism(s) and subsequent diagenetic effects play key roles of course but, at a smaller scale, the interplay of stratification type (a product of bedform) and texture (i.e., grain size and sorting, combined with hydraulic equivalence) can generate significant local differences in sandstone mineralogy. For instance, heavy minerals can be concentrated at the toes of cross-bed foresets and micas (and other 'lights') in the troughs between ripple or dune crests. Even when conducting multiple analyses, if your analysis spot is only 8mm in diameter, such compositional heterogeneity has to be factored into pXRF sandstone data interpretation.
4. Bearing that in mind, I find it remarkable that this article contains NO descriptions of the grain sizes or other macroscopic characteristics of the samples, except (from Thomas, 1923) for the statement that the Altar Stone is a "grey-green micaceous sandstone". That in fact is my description; Thomas (1923) described its colour as "pale sage-green".
5. The conclusion that the Altar Stone and debris fragments are of essentially the same composition (p.6) is based on the values they obtained for "high atomic number elements" -- namely (table 4) Mn, Sr, Zr, Mo, Pb, Th and U, which presumably are in large part a reflection of the samples' heavy mineral assemblage compositions. Do the samples contain heavy mineral laminae? Lacking a macroscopic description of these sandstones we cannot tell figure 5 is of no help in this regard).
6. Are the authors correct in concluding that the rock fragmentss they analysed came from the Altar Stone? I'm sceptical and, at best, think more substantive evidence is required. However, even if they are right, I believe that any definitive study of the Altar Stone's provenance must be based on samples taken from the Altar Stone itself, not small, proxy specimens. In my opinion, any such provenance study has to begin by thoroughly documenting the Altar Stone's macroscopic characteristics followed by detailed thin section analysis. As I've noted before, thin sections can be a wonderful source of information about a sandstone's original compositional and textural characteristics and its subsequent diagenetic history. The authors here are enamoured with high-tech analytical techniques but are in danger of neglecting the fundamental building blocks of any sandstone provenance work. (NB. Way back in 1973 (!) I noted that the visible portion of the Altar Stone was a fine-grained, muscovite-rich, small-scale trough cross-laminated, grey-green sandstone that appears similar to a number of such sandstones found within the Lower ORS sequence of South Wales. Its largest surface is bedding parallel and stratigraphically, the block appears to be lying right way up.)
7. There is still a discussion about the petrographic description of the Altar Stone given by H.H. Thomas in his classic 1923 paper; was it really based upon a thin section taken from the Altar Stone itself? Not everybody accepts that, but I prefer to give my namesake the benefit of the doubt.
8. Since they found barite in an Altar Stone proxy sample (FN 196) using SEM-EDS (see Bevins et al., 2020; and figure 5 of this new article), the authors seem to have become obsessed with its importance in unravelling the provenance of the Altar Stone. Perhaps they're right, but I'm a bit dubious about that since, with a maximum modal content of 0.8% BaSO4, it is still just a trace mineral. I think other, more obvious characteristics will prove to be of greater value. For their pXRF data presented in table 5, the authors assume all Ba to occur as barite but (as they grudgingly acknowledge in the table caption) it seems far more likely to me that the Ba is actually present within K-feldspars, micas and clay minerals (e.g., illite).
Monday 16 May 2022
Journal of Archaeological Science
Available online 9 May 2022, 105557
De Smedt et al
"Novel insights into prehistoric land use at Stonehenge by combining electromagnetic and invasive methods with a semi-automated interpretation scheme."
Wednesday 11 May 2022
There is some press coverage today of new research by a Belgian / UK team using geophysical methods to identify sub-surface irregularities including some quite deep pits. I'm trying to get hold of a copy of the paper, which is behind a paywall. The authors talk about large pits, smaller pits and "natural features" -- and of course there is some speculation in the media about animal trapping pits in the days before Stonehenge was built.
Philippe De Smedt, Paul Garwood, Henry Chapman, Koen Deforce, Johan De Grave, Daan Hanssens, Dimitri Vandenberghe.
Journal of Archaeological Science
Available online 9 May 2022, 105557
Geophysical survey methods have led to high-resolution mapping of subsurface remnants of ancient landscapes at continually expanding spatial scales. Yet, particularly when applied across entire archaeological landscapes, spanning hundreds of hectares, resultant datasets provide little direct information about inhabitation, environments or change over time.
Focusing on a 2.5 km2 area around Stonehenge, we show how geophysical soil survey, when combined with targeted sampling and excavation, can enable reliable empirically-grounded identification of complex activity traces. Particular focus lies on anthropogenic dug pits, identification and interpretation of which are vital in European earlier prehistoric archaeology due to their close connection with inhabitation and ceremonial practices. By integrating frequency domain electromagnetic and invasive datasets, and using a semi-automated interpretation scheme, we identified previously unknown concentrations of large pits (with diameters >2.4 m) among several thousand smaller pits and natural features across the Stonehenge landscape. Excavations of a subset of identified features demonstrate that, in this area, our investigative methodology is 66% accurate for identifying large anthropogenic pits. Our results have significant implications for understanding Stonehenge and its landscape setting, revealing elusive forms of Mesolithic to later Bronze Age land use that - even within the world's most intensively researched archaeological landscape - have gone unrecognized until now.
These findings underscore both the crucial role of archaeological excavation as an essential basis for reliable interpretation of geophysical data, as well as the perils of inductive visual interpretation of features’ morphologies and their spatial configuration in non-invasive survey data.
Friday 6 May 2022
On the River Clydach, which flows across our land, there are a number of white-water cataracts, and from careful observation I can say that each one coincides with a small dolerite sill. The quieter stretches in the river coincide with the areas of Ordovician shales. This is an obvious relationship -- but the interesting thing is that the dolerite sills are not shown on the BGS definitive map, and neither are a number of rhyolite outcrops in the area. All we see is a single large dyke up to 200m wide. So the "micro geology" of the area is not very well known, except in areas like Tycanol Wood where mapping was done in detail as part of a doctorate project. The same is true of most of North Pembrokeshire, including Mynydd Preseli where extensive moorlands make the defining of geological boundaries very difficult. At one stage I was quite good at geological mapping, but where there are no outcrops at all to work with, one has a problem........
I'm rather intrigued by the fact that since the publication of the new Altar Stone paper on 22 March, there has not been the slightest mention of it in the media. This means that no press release was issued, and this in turn means that the authors do not particularly want any press scrutiny. Perhaps we should not be too surprised, because researchers do not like admitting that their earlier research proposals and conclusions have been wrong. (They should be delighted about it, since that is how science works...... but that's another matter.) Anyway, having encouraged MPP to go on at great length, in a number of publications, about the "A40 Altar Stone haulage route" they are now quietly having to back off on that one, and admit that they really have no idea where the Altar Stone might have come from. (See press item below, from 2020)
This is another huge setback for Parker Pearson, who has always been far too quick to create elaborate narratives based on no evidence whatsoever..........
This is not turning out to be a good year for MPP. First, he had to admit that the evidence from three years of digging at Waun Mawn had not provided any satisfactory evidence that there ever was a partial dismantled "lost stone circle" there, let alone a complete one. Now he has to admit that the proposed bluestone haulage route via Brecon and Abergavenny also has to go onto the bonfire of the vanities. Whatever next? I keep on telling him and his cronies that there are no bluestone quarries either, but sadly, at the moment, they are not inclined to accept my impartial advice, sincerely offered. Give them time. They will get there in the end, having bamboozled the media and the general public for far too long with their pseudo-science and their fantastical narratives.
I have expressed scepticism about some of the Altar Stone work in the past:
and indeed, Bevins and Ixer and their colleagues have themselves expressed (some years ago) the view that the presence of barite cement in "Altar Stone samples" might mean that those samples did not come from Wales at all.
Geologist Richard Thomas has also expressed his concerns about the "matching" of sandstone fragments at Stonehenge with the Altar Stone and the assumption that they all came from a common source in Wales. It will be interesting to see what he makes of the new data. Previously, the geologists have discussed garnets in sandstone samples as being key to the provenancing work -- and now barite is clearly in the frame.
==============In 2020, a big press release. This time, silence.......
Stonehenge's huge blocks DID arrive over land as archaeologists debunk theory the Neolithic slabs were rafted from Wales to Salisbury Plain
• Archaeologists may have debunked a theory on how the slabs were transported
• Using chemical analysis they found the stones came from near Abergavenny
• This means it is unlikely that the stones were taken on rafts on the Bristol Avon
By DAILY MAIL REPORTER
PUBLISHED: 23:29, 1 July 2020 | UPDATED: 23:29, 1 July 2020
It is one of the mysteries of the Neolithic Age – how Stonehenge was created.
Now archaeologists may have debunked the theory that giant slabs of stone were rafted from Wales to Salisbury Plain.
Using chemical analysis, they have matched the six-ton sandstone ‘altar stone’ from Stonehenge to rocks near Abergavenny, just a few miles from the English border.
This finding leads them to believe the boulder was carried across land, in a route roughly following the A40 trunk road that connects Wales with London today.
This could debunk the theory that Stonehenge’s bluestones were taken south to Milford Haven and put on rafts or slung between boats, paddled up the Bristol Channel and along the Bristol Avon to Salisbury Plain.
Dr Rob Ixer, from University College London, who co-authored the study published in the Journal of Archaeological Science, said: ‘This totally destroys the raft theory, it blows it out of the water.
‘This is our second re-examination of the bluestones, but it is our first major finding.’
A friend attended a talk by Richard Bevins the other day, at which he highlighted this latest piece of research on the Altar Stone:
"Linking derived debitage to the Stonehenge Altar Stone using portable X-ray fluorescence analysis."
Richard E. Bevins, Nick J.G. Pearce, Rob A. Ixer, Stephen Hillier, Duncan Pirrie and Peter Turner
Mineralogical Magazine (2022), 1–13
Published online by Cambridge University Press: 22 March 2022
The Altar Stone at Stonehenge in Wiltshire, UK, is enigmatic in that it differs markedly from the other bluestones. It is a grey–green, micaceous sandstone and has been considered to be derived from the Old Red Sandstone sequences of South Wales. Previous studies, however, have been based on presumed derived fragments (debitage) that have been identified visually as coming from the Altar Stone. Portable X-ray fluorescence (pXRF) analyses were conducted on these fragments (ex situ) as well as on the Altar Stone (in situ). Light elements (Z<37) in the Altar Stone analyses, performed after a night of heavy rain, were affected by surface and pore water that attenuate low energy X-rays, however the dry analyses of debitage fragments produced data for a full suite of elements. High Z elements, including Zr, Nb, Sr, Pb, Th and U, all occupy the same compositional space in the Altar Stone and debitage fragments, and are statistically indistinguishable, indicating the fragments are derived from the Altar Stone. Barium compares very closely between the debitage and Altar Stone, with differences being related to variable baryte distribution in the Altar Stone, limited accessibility of its surface for analysis, and probably to surface weathering.
A notable feature of the Altar Stone sandstone is the presence of baryte (up to 0.8 modal%), manifest as relatively high Ba in both the debitage and the Altar Stone. These high Ba contents are in marked contrast with those in a small set of Old Red Sandstone field samples, analysed alongside the Altar Stone and debitage fragments, raising the possibility that the Altar Stone may not have been sourced from the Old Red Sandstone sequences of Wales. This high Ba ‘fingerprint’, related to the presence of baryte, may provide a rapid test using pXRF in the search for the source of the Stonehenge Altar Stone.
Having matched the derived fragments to the Altar Stone we are now in a position to interpret with confidence the data obtained to date on the derived fragments in the search for the source of the Altar Stone. The pXRF results showed the Altar Stone to have high Ba contents which is in agreement with the high modal % baryte identified previously using automated SEM-EDS analysis. This rather unusual mineralogy will be a key element in our search for the origin of the Altar Stone.
We have known about this research for some time -- and indeed it has been obvious for years that pXRF analyses had to be done on the Altar Stone exposed surfaces. So it's good to see the research published at last. Thankfully, this is a straight geology paper unsullied by any archaeological speculation about stone transport mechanisms or haulage routes.
Thursday 5 May 2022
Well, MPP has of course admitted that there probably never was a "lost stone circle" at Waun Mawn, even though there may have been an intention to build one. So that's all right then...........
The tragedy is that so many people still believe the nonsense trotted out in that appalling Alice Roberts TV show. Nice story -- who needs evidence anyway?
Wednesday 4 May 2022
When I was a college student, my tutor Paul Padget (a self-effacing man with a brilliant mind) said to me one day: "If you become a teacher, remember that your function is to ensure that your students become more knowledgeable, and wiser, than you are yourself."
I rather liked that....... and once a teacher, always a teacher.........
I have always tried to hold fast to that ambition -- and that's what drives me to put hard info, critical scrutiny and developing hypotheses onto this blog..........
Tuesday 3 May 2022
On going through my notes from a few years ago, I discovered a reference to a "wonderful exposure" of clay-rich Irish Sea till immediately to the right of cutting B as shown on the above diagram. Most of the till exposed at West Angle is reddish in colour and has a sandy and even gravelly matrix, but in the chance discovery of this exposure in the gully that runs down to the beach, I saw "classic" Irish Sea till with a high clay content, reminiscent of the tills at Druidston and Abermawr. There were many fragments of ORS incorporated, including striated pebbles, and there were also lignite and shell fragments as at Abermawr. Unfortunately I had no time to collect samples.
This reinforces the view that this till is of Late Devensian age. It's the southernmost exposure of the Irish Sea till on mainland Pembrokeshire, but there are other exposures further south, on the foreshore at Amroth and Freshwater West.
The discontinuous exposures of glacial and other deposits at the head of Porthmelgan bay. They are difficult to interpret because of slumping.
I have just received this from the latest edition of the Gower Society Newsletter. There is considerable interest among members in Phil's discovery.
We are a bit frustrated because the samples from the erratic are still in the queue waiting to be analysed -- the lab has a lot of work in hand at the moment. Eventually all will be revealed. Actually, I am sublimely unconcerned about the provenance of the erratic -- I don't really care where it has come from. The most important things are already established -- namely that large erratic blocks were transported up the Bristol Channel during at least one glacial episode, and that the Irish Sea Ice stream was powerful enough to impinge upon the Gower coast in spite of the conflicting pressure from Welsh ice which flowed down the valleys of the Neath, Tawe etc from the western Coalfield and the Black Mountains. If the Irish Sea ice stream was capable of doing that, it was certainly also capable of reaching Somerset and even Wiltshire.