Stonehenge and the Ice Age
How much do we know about Stonehenge? Less than we think. And what has Stonehenge got to do with the Ice Age? More than we might think. This blog is mostly devoted to the problems of where the Stonehenge bluestones came from, and how they got from their source areas to the monument. Now and then I will muse on related Stonehenge topics which have an Ice Age dimension...
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
Tuesday, 10 November 2026
Sunday afternoon at Rhosygilwen, 15th November
Tuesday, 20 October 2026
Scourse "cancel culture" is facilitated , when it should be condemned. The QRA should pay more attention.........
Another map by the present author, showing the relationship between proposed ice edges for the LGM and local bathymetry. The extension of a lobe onto the coasts of St Mary's and St Agnes would not be an "aberration" (as claimed by Scourse) but a perfectly normal feature of ice flow near the edge of an ice stream. In fact an ice edge running southwards as proposed by Scourse and others is unrealistic -- that would be very much an aberration.
I have been looking at the new Isles of Scilly Field Guide, just published by the Quaternary Research Association. I will review it in more detail later on, but my initial response is one of profound disappointment and anger that the editorial team has somehow allowed this book to be published without adequate oversight. James Scourse is the co-editor and prime contributor, and he has been allowed to promote a "cancel culture" directed specifically at me, by effectively ignoring my contributions to Scilly Islands Quaternary research. This is a pretty appalling abuse of a privileged position, driven by a petty animosity that I find difficult to comprehend.
In fact most of my field observations and conclusions are in line with those published by Scourse -- which makes his animosity even more bizarre.
In 2018 the Quaternary Newsletter published a short paper of mine, entitled Evidence for extensive ice cover on the Isles of Scilly. https://www.researchgate.net/publication/328413421_Evidence_for_extensive_ice_cover_on_the_Isles_of_Scilly
It was properly peer reviewed, revised and published under the supervision of the QN editor and must -- we assume -- have been considered a worthy contribution to the discussion about the Quaternary history of the islands. The article was non-confrontational and perfectly respectful of the work done on the islands across many years by James Scourse. And yet he seems to have considered it to be a personal affront, and he responded with fury in a petulant and indeed arrogant response which the journal published, together with my reply. That was all eight years ago........
https://brian-mountainman.blogspot.com/2019/03/scourse-versus-john-rather-scilly-spat.html
Now, in the new Field Guide, Scourse ignores my work completely apart from three brief citations. Instead, he cites his own response to my article and fails to mention the fact that I disputed every point that he raised. Just a reminder. I argued, on the basis of strong presented evidence, that glacial ice must at some time have covered the whole of the Scilly archipelago; that Late Devensian ice was more extensive than Scourse and others have previously claimed; that the "established" Devensian limit on the northern islands is less certain than claimed, because of a lack of dating controls; and that the Scourse Quaternary lithostratigraphic scheme is more complex than it needs to be. These are important points that deserve careful consideration. But they are ignored by Scourse in this new Field Guide.
Ironically, the QRA, as publishers of this new Field Guide, is now unwittingly participating in the attempt by Scourse to ignore my carefully considered proposals, and sharing in the pretence that the "Quaternary narrative" for the Isles of Scilly is universally accepted and undisputed. In other words, it is participating in the dismissal or "cancellation" of a serious and highly relevant paper published in its own journal. Scourse also displays a complete lack of respect for me as a serious geomorphologist and field worker with a long track record. If nothing else, my paper deserves scrutiny because it is the most recent published contribution to the Scilly Islands Quaternary debate.
Should we laugh, or should we cry?
https://brian-mountainman.blogspot.com/2020/04/the-scilly-nunatak.html
https://brian-mountainman.blogspot.com/2021/11/glacial-wrapping.html
====================
Here is a reminder of the articles that Scourse should not simply have cited but should have scrutinized for the perusal of students and future researchers who study within the island group.
Brian John. 2016. The southernmost extent of the Irish Sea Glacier: observations from the Isles of Scilly. Researchgate Working Paper, September 2016, Version: 4
Brian John. 2018. Evidence for extensive ice cover on the Isles of Scilly. Quaternary Newsletter 146, October 2018, pp 3-27.
Brian John. 2019. Reply to Scourse "Comment on Evidence for extensive ice cover on the Isles of Scilly by Brian John. Quaternary Newsletter 147, Feb 2019, pp 7-9.
Bennett, J. A., Cullingford, R. A., Gibbard, P. L., Hughes, P. D., & Murton, J. B. (2024). The Quaternary Geology of Devon. Proceedings of the Ussher Society, 15, 84-130.
Some of the exposures of Devensian till on the Isles of Scilly:
https://brian-mountainman.blogspot.com/2016/04/devensian-till-on-isles-of-scilly.html
Posible glacial deposits on the island of Samson:
https://brian-mountainman.blogspot.com/2024/01/glacial-erratics-on-samson-isles-of.html
The Scilly nunatak:
https://brian-mountainman.blogspot.com/2020/04/the-scilly-nunatak.html
https://brian-mountainman.blogspot.com/2020/04/the-ice-edge-on-scilly-nunatak.html
Glacier ice in the Celtic Sea arena -- the eastern terminus:
https://brian-mountainman.blogspot.com/2020/04/the-devensian-celtic-sea-piedmont-lobe.html
There is no particular logic behind the idea that in the LGM the ice edge lay precisely on the northern fringe of the Isles of Scilly........
Tuesday, 13 October 2026
Peter Kokelaar's latest blog update
Some of the Scottish erratics found in the Gower raised beaches by Peter Kokelaar, with acknowledgement to his latest blog post. The pebbles are identified in the caption to Fig 7.
In his latest blog update Prof Peter Kokelaar concentrates on the Scottish erratics found in Gower exposures of the Ipswichian raised beach and on the debate about the source of the Altar Stone. He also makes a new contribution to the discussion about zircons and the work of Clarke and Kirkland. He does not mince his words, and his vocabulary is refreshingly colourful...........
https://kokelaargower.com/stonehenge/
He is particularly scathing about the human transport hypothesis with regard to the Stonehenge bluestones. He refers to "serious subjectivity" and "media hype", and to the degrading of public trust in so-called experts. He agrees with my point that some of the extreme components or "fantastic claims" in the MPP bluestone narrative are now effectively debunked.
Quote:There is aninteresting discussion on the zircon work in western Scotland and elsewhere, and again it is argued that the work of Clarke and Kirkland is inadequate and unreliable.
"The claim that the cow-tooth findings add to confirmation of the “theory” that cattle were involved in transport of the megaliths is udderly ridiculous. Apart from confusing theory and hypothesis in this media hype, the unjustified claims were disturbing as they came from the Press Office of the British Geological Survey. No sane geologist would support them. Actually, the original scientific report of the cow-tooth findings, in contrast to the hype, was quite reserved, acknowledging limitations to interpretations that should be borne in mind. What is it then, really, that causes decent science to be so compromised in the media? There certainly is cavalier ignorance on the part of media producers, whose driver seems to be promotion of viewing figures or sales… Honesty about the issues might have been more interesting and more stimulating of genuine interest… Some of the media nonsense is arrogant and insulting."
Isles of Scilly back in the frame
Then we come to another problem of lithostratigraphy. Once somebody has studied a region in detail and published what might be deemed to be "definitive" studies of the sedimentary sequence, with "formation" or "member" labels attached, and type localities identified, there is a tendency for those labels to be over-used or applied in a non-critical fashion. I became very much aware of this during my short visit to the Isles of Scilly a couple of years ago, as I looked at innumerable coastal sections on all of the main islands. In a QN article I described and interpreted the deposits as best I could, given the limitations of time and resources:
Right from the start, I had problems in fitting the sequence and the characteristics of the deposits into the stratigraphic sequence devised by James Scourse in 1991 and subscribed to (with minor modifications) by others since then. There were two problems, one relating to the choice of type localities, and the other to the choice of stratigraphic labels.
In my QN paper I used these Scourse terms sparingly, just where I thought they might help in understanding the stratigraphic sequence -- but I have been heavily criticised by Scourse for occasionally placing the deposits I observed into the "wrong" category in the "accepted lithostratigraphic sequence" !! Hmmm. As far as I am concerned, I have not accepted anybody's sequence, and will not accept any sequence unless it seems to me to be either accurate or useful. In ice wastage environments depositional circumstances -- at exactly the same moment in time -- from place to place can vary enormously, and that needs to be recognized. It is a singularly fruitless exercise to become worked up about the application -- or non-application -- of predetermined labels when the only questions worth asking are these: What happened? And when?
Hence my scepticism about lithostratigraphic labelling. There are bad labels, and bad type localities. If we become obsessed by labels and type localities, we can easily be dragged into a scenario in which we "force" the sediments we find into predetermined boxes -- and in the process lose scientific objectivity. If labels are worth using, they will survive. If some of them are causing more trouble than they are worth, they should be dumped.
Thursday, 8 October 2026
Haverfordwest Gorsedd Circle
The definitive guide to the modern Gorsedd Circles of Wales:
https://sublimewales.wordpress.com/attractions/18th-and-19th-century-stone-circles/gorsedd-circles/
Michael Freeman has done great work on this, and his beautifully illustrated blog is well worth a visit.
See also:
The huge node stone and the steps -- used in the Gorsedd ceremonies. One of the stones looks like a basalt -- it might have come from a local quarry. The other stones have most likely come from the surface litter.
Sunday, 27 September 2026
Reminiscences from hither and thither
When one gets old, one easily slips into nostalgia, and one thinks more about the past than the future. Over a long life I have had a lot of fun, and have maybe made a small difference to the way the world works.......
Tuesday, 22 September 2026
That spectacular article about the Devil's Arrows: six fatal flaws
Clarke, A. C., Leary, J., & Kirkland, C. L. (2026). Deliberate prehistoric sourcing of the Devil's Arrows. Proceedings of the Royal Society A. [rspa.2026.0504].
https://royalsocietypublishing.org/rspa/article/482/2345/20260504/483254/Deliberate-prehistoric-sourcing-of-the-Devil-s
I have now had a chance to go through this paper in more detail, and to discuss it with other experts. So here we go. Let's discuss the technical deficiencies in sampling symmetry, statistical sample density, and logical consistency in provenance attribution. It's a bit complicated.......
There are serious doubts about the empirical validity and logical framework of the recently published paper by Clarke et al. (2026) regarding the provenance of the four Devil's Arrows monoliths [rspa.2026.0504]. While the application of high-resolution U-Pb isotopic testing on accessory minerals is a welcome addition to archaeological science, a critical examination of the raw data structure and methodological parameters reveals significant vulnerabilities that undermine the paper’s primary conclusions and indeed its spectacular title. The article has been widely promoted via the media, and the record must be set straight.
The peer review process used by editor of this prestigious Royal Society journal has apparently failed to pick up on six severe methodological and logical flaws:
1. Severe Asymmetry in Sampling and Provenance Controls
The paper compares an undocumented, crushed bulk rock sample from a single, prominent modern tourist location (Brimham Rocks SSSI) (Fig. 1) against non-destructive, surface-adhesive "sticky tape" scrapings taken from the heavily weathered faces of three monoliths and the fresher face of another [rspa.2026.0504] (Fig. 2). The authors fail to present any spatial control sampling across the lateral extent of the target stratigraphic layer. We have no idea where the sample came from within the 30m thick sedimentary sequence, or within the SSI which has a surface area of 1.84 sq km. We are not told whether the rock sample represents the upper or lower boundaries of the sequence, or how the mineral concentrations shift vertically through the 30-metre thickness or laterally across the site. This is an absolute failure of scientific protocol. It means the experiment is completely unreproducible.The Kinderscoutian Brimham Grit is a continuous, sprawling sedimentary formation which occurs across c 140 square kilometres of the North Yorkshire Pennines. Because detrital mineral suites reflect continental river systems, the mineral "barcode" match to this formation must apply to the entire regional sheet, not to a singular geographic coordinate (Morton et al., 2005).
2. Violation of Minimal Grain-Count Statistical Thresholds
To achieve an acceptable 95% to 99% confidence level that minor mineral age populations have not been missed, established sedimentological protocols dictate an absolute minimum of 60 to 117 individual grain analyses per discrete sample (Vermeesch, 2004). While the authors aggregate a total pool of 236 dated zircon grains from the monuments across Figure 3, their comparative breakdowns in Figure 4 expose a fatal lack of data density. The authors split the monument data into two age-segregated sub-panels: a 90-grain subset mapping the deep-time spectrum (500–3500 Ma) and a 146-grain subset mapping the younger spectrum (300–600 Ma) [rspa.2026.0504]. In doing so, they reveal that their primary geographical point-control—the comparison baseline sample for Brimham Rocks—relies on an astonishingly small pool of just 29 grains [rspa.2026.0504]. Attempting to verify an exclusive geographic match to a massive regional sedimentary unit using a sample that fails to reach even half of the industry-accepted minimum threshold is unacceptable.
3. Artificial Variance Dilution via "Phantom" Data Aggregation
Rather than executing a robust point-to-point comparison (individual monolith vs. specific outcrop candidates), the authors combine their low-yield, heterogeneous grain counts into a single, pooled composite "blob” to smooth away internal variance. Furthermore, the Multi-Dimensional Scaling (MDS) diagrams are heavily packed with distal, irrelevant regional "noise" datasets (e.g., Precambrian basement terranes and distinct Triassic strata) [rspa.2026.0504]. This mathematical dilution dramatically compresses the relative variance of the graph, artificially forcing the visually distinct raw histograms of the Arrows and Brimham Rocks into an unrepresentative, close cluster.
4. The Dismissal of the Glacial Transport Option
A fatal flaw of the paper’s internal logic lies in its selective deployment of Late Devensian (LGM) ice-flow models. In the results section, the authors explicitly acknowledge that a literature search yields a lose match between the Devils Arrows samples and the Langsettian sandstones of the Pennine Basin Lower Coal Measures (PLCM) at Binchester Crags [rspa.2026.0504]. They choose to ignore the fact that reconstructed complex ice flow directions (Thorpe and Williams-Thorpe, 1991; Clark et al., 2022) point to a strong possibility of glacial erratic transport from the southern part of County Durham to the Boroughbridge area during several glaciations (Livingstone et al, 2012) (Fig. 3). The Park Farm borehole record, from a site near Boroughbridge, reveals the Vale of York Formation, a glacial diamicton laid down during the Dimlington Stadial and carrying abundant Carboniferous sandstone erratics from the north. But Clarke and his colleagues then use the ice-flow direction map to demonstrate the “impossibility" of glacial erratic transport between Brimham Rocks and the Devils Arrows site, and invoke speculative human transport instead. This demonstrates a powerful and unacceptable bias in their analysis. What is good for the gander must be good for the goose: a model cannot dismiss a statistically superior northern match based on ice direction constraints while simultaneously throwing out those exact same glaciological constraints to protect a highly speculative “human transport" alternative.
5. The Lack of Evidence for the Human Transport Option
Having discarded the ice-flow model, they invent a highly speculative 11-mile human transport route to explain the presence of the Devil’s Arrows monoliths. They present no evidence in support of the human transport hypothesis but instead cite unproven claims of long distance stone transport from Ireland and Scotland — partly based on citations of their own hotly disputed work on the Stonehenge Altar Stone.
6. Inadequate Zircon Age Analyses
Independent analysis of the zircon age data by a specialist geologist suggests the foillowing: (1) the zircon age pattern for stone 1 looks different from stones 2 and 3 — there is a larger group of Archaean zircons and a difference in the structure in the mid-Proterozoic age range — all suggesting at least two different sources for the monoliths; (2) given that problem, it is not appropriate to merge all the data into a single “representative” sample; (3) there is a good match between the Brimham Rocks sample and the samples from stones 2 and 3, but the Early Palaeozoic group appears bimodal, unlike any of the monoliths; (4) the Plumpton Rock ages do look different; (5) the dismissal of the underlying Sherwood Sandstone Group is premature, based on a marked contrast with the Triassic, but the papers quoted by Clarke et al use samples in the Wessex Basin, over 150 miles away; (6) the most important point to emerge from this new analysis is that a number of other published data sets do not look very different from Brimham Rocks. For example, a Marsdenian sample looks very similar to Stone 1, and Yeadonian, Rough Rock N and S samples are not dramatically different to Stones 2 and 3. It must also be borne in mind that there are extensive outcrops of Millstone Grit that have never been analysed by zircon specialists. In summary, the conclusions of Clarke et al are highly questionable in terms of the zircon data.
Conclusion
Ultimately, the central thesis of this paper rests on a suspect, shifting statistical strategy. The authors choose to aggregate data when they need to mask individual sample failures, throwing low-yield, weathered monument surface grains into a collective "phantom blob" to fake a robust, unified monument profile [rspa.2026.0504]. Conversely, they choose to split data when they need to disguise a visual mismatch, slicing the continuous age spectrum into separate sub-panels to hide an unviable control sample size [rspa.2026.0504]. This dynamic manipulation allows the authors to bend a chaotic geological footprint to fit a pre-packaged public relations narrative. By substituting tactical statistical smoothing for rigorous field controls and geomorphological fieldwork, they have published a localized point-source attribution that completely collapses under basic sedimentological review.
Thus Clarke et al. have confirmed that the Devil's Arrows have probably come from a Carboniferous deltaic sandstone sheet [rspa.2026.0504], as previously suspected. However, the data presented is statistically incapable of pinpointing a precise geographic source or ruling out local glacial transport from the extensive northwestern outcroppings of that same layer or from the PLCM formation that provides a better match.
It is vital that published conclusions remain strictly bound to their empirical evidence. The authors of this deeply flawed paper must provide a formal clarification, displaying their raw, unaggregated individual monolith histograms side-by-side against a true, non-diluted matrix of Pennine Basin gritstone candidates. Only when they sample for like-for-like similarities and differences across a large range of localities can they expect their work to be taken seriously.
If the authors cannot provide the data requested, I consider that the paper should be retracted.
References
Clark, C. D., et al, BRITICE-CHRONO Consortium. (2022). Growth and retreat of the last British–Irish Ice Sheet, 31 000 to 15 000 years ago: The BRITICE‐CHRONO reconstruction. Boreas, 51(4), 699–758.
Clarke, A., Leary, J., & Kirkland, C. (2026). Deliberate prehistoric sourcing of the Devil's Arrows, Britain's tallest stone row. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 482(2345), 20260504. [rspa.2026.0504].
Livingstone, S.J., Evans, D.J.A., Cofaigh, C.O. et al. (2012) Glaciodynamics of the central sector of the last British-Irish Ice Sheet in Northern England. Earth Science Reviews, 111 (1-2). 25 - 55. ISSN: 0012-8252
Morton, A., Hallsworth, C., & Moscariello, A. (2005). Stratigraphic evolution of Carboniferous sandstones in the Pennine Basin: Heavy mineral provenance constraints. Proceedings of the Yorkshire Geological Society, 55(3), 163–185.
Thorpe, R.S., Williams-Thorpe, O..(1991) The myth of long-distance megalith transport. Antiquity 65, 64–73.(doi:10.1017/S0003598X00079308)
Vermeesch, P. (2004). How many grains are needed for a detrital zircon age spectrum? Earth and Planetary Science Letters, 224(3-4), 441–451.
Williams-Thorpe, O., Potts, P. J., & Thorpe, R. S. (1999). The provenance of archaeological gritstone monoliths in northern England: A geochemical approach. Journal of Archaeological Science, 26(2), 145–161.





