Another attack on the Altar Stone's "Scottish origin"

As we know from a vast media campaign and from abundant posts on this blog, the idea that the Stonehenge Altar Stone (stone 80) came from "Orcadian" NE Scotland is now taken as an accepted truth.  There have been some differences in interpretation from the Bevins - Ixer - Pearce team and the Clarke and Kirkland team, but their papers make some pretty brash claims which have never been properly interrogated in the specialist literature.  Well, all that is changing, and with a number of geologists now working on the case, I predict that the whole edifice of the "Scottish Altar Stone" will soon come crashing down. 

Key publications:

A Scottish provenance for the Altar Stone of Stonehenge. 2024. Anthony J. I. Clarke, Christopher L. Kirkland, Richard E. Bevins, Nick J. G. Pearce, Stijn Glorie & Rob A. Ixer. Nature 632, 15 Aug 2024, pp 570-587.

https://www.nature.com/articles/s41586-024-07652-1

Was the Stonehenge Altar Stone from Orkney? Investigating the mineralogy and geochemistry of Orcadian Old Red sandstones and Neolithic circle monuments. 2024. Bevins, R., Pearce, N., Hillier, S., Pirrie, D., Ixer, R. A., Andò, S., Barbarano, M., Power, M. R., & Turner, P. (2024). Journal of Archaeological Science: Reports, 58, Article 104738. A
https://doi.org/10.1016/j.jasrep.2024.104738

Clarke, A. J. I., Veness, R. L. J., Kirkland, C. L., Clark, C. D., Gandy, N., Emery, A. et al. (2026) From Highlands to Henge: Refining the Provenance and Transport Pathways of Stonehenge's Altar Stone. Journal of Quaternary Science, 1–8.
https://onlinelibrary.wiley.com/doi/epdf/10.1002/jqs.70080

I have expressed my grave concerns about the methods employed by the two teams (working separately or jointly) and about the reliability of their analytical results, and these concerns are reinforced by new work by Ciborowski and Nash.

https://doi.org/10.1016/j.jasrep.2026.106012

Hidden in the depths of a highly technical analysis of geochemical methods of stone provenancing, there are two short sections (5.5c and 5.5d) which are of direct relevance.

Just a reminder:  I have heavily criticised the sampling procedures used by the above research teams, who have used proxies or surrogate samples both for the Altar Stone and for the ORS rocks of the Ordcadian Basin. The Altar Stone samples come from old museum collections of rock fragments that may or may not have actually come from the Altar Stone, and the ORS bedrock samples were bought from a rock shop in Whitby.  Nobody initially did any fieldwork.  Quite extraordinary.

I have also criticised the use of just as few analysed samples as proxies for the vast area of the Orcadian Basin, most of which is of course unsampled and unknown. I have many other criticisms too, which can be checked out by putting "Altar Stone" or " Clarke" into the blog search box.

Back to the present day.  Ciborowski and Nash (in their latest contribution, just a few days old) express concerns about "ambiguities" in the use of bivariate geochemical plots by Bevins et al.  (That is a coded way of saying that there are strong suspicions of bias.) They are particularly concerned about the aggregation of samples by those who are promoting the Orcadian connection.   They claim that "pooling" or aggregating data from multiple disparate samples across an entire region to create a generalized "average" or "mean" signature is fundamentally unscientific. They show that when researchers use an aggregated average to characterize a target source area, they erase the localized, internal variations of the actual geology.  By smoothing out the data mathematically, you can inadvertently force a statistical match that doesn't exist anywhere  in reality.  The claimed statistical link between A and B  is an artifact of the analytical method, not an expression of a geological match.

Quote: When the U-Pb zircon signatures of the individual ‘Altar Stone’ samples are compared to those of the individual ‘Orcadian Basin’ samples, any meaningful similarity between the two groups disappears. Indeed, the more valid conclusion that may be drawn from the U-Pb zircon data in Clarke et al. (2024) is that, even with five comparator analyses, none of the individual ‘Altar Stone’ samples look anything like the Orcadian Basin in terms of U-Pb zircon geochronology. This observation alone suggests that the Altar Stone is not from northeast Scotland.

https://www.sciencedirect.com/science/article/pii/S2352409X26004475?via%3Dihub

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Looking in on this spat from the outside, this seems to me like a pretty fundamental attack on the analytical methods employed by those who are promoting the "Scottish Altar Stone" hypothesis.  And various little birds have told me that there is more to come......

Stone 62 -- a nice academic spat about methodology

Unspotted dolerite stone 62 at Stonehenge (courtesy Simon Banton)

I came across this on the University of South Wales web site:

https://pure.southwales.ac.uk/ws/portalfiles/portal/39397422/1-s2.0-S2352409X26003093-main.pdf

https://doi.org/10.1016/j.jasrep.2026.105874

On following it up, I find that there are three papers and a rather intense and detailed academic spat -- all centred on the methodology for the spot provenancing of dolerites on Mynydd Preseli.  It makes a nice change to find an academic dispute that I am not actually involved in! Anyway, in the right corner, Pearce, Bevins, Ixer and Pirrie, and in the left corner Ciborowski and Nash. These two teams have argued rather violently once before, on the matter of the sarsens of West Woods and Stonehenge, but for now we will leave that to one side.

Here are the other two references:

https://doi.org/10.1016/j.jasrep.2025.105513 (the original article by C&N)

https://doi.org/10.1016/j.jasrep.2026.106012 (the C&N response to the Pierce et al response)

To summarise:

The dispute is very technical, but in essence it is about visual bivariate plots versus mathematical precision and standardization.  The clash exposes a fundamental rift in how these two teams of specialists believe archaeological stone sourcing should be conducted.

Pearce, Bevins, & Ixer have for many years had visual bivariate grouping graphs right at the centre of their provenancing work.  For example, in 2022 they used portable pXRF to analyze Stonehenge Stone 62. They plotted elemental data (like Zirconium, Titanium, Barium, and Rubidium) on a series of visual bivariate graphs.  They concluded that because the data points from Stone 62 visually overlapped with the "field" of a specific small Preseli outcrop called Garn Ddu Fach, it was the definitive source.
This conclusion was inevitably tied into the attempts by Parker Pearson and others to link Stonehenge to nearby ancient sites like Waun Mawn.

 Nash and Ciborowski stepped in to challenge this subjective (and perhaps biased) visual approach. They explicitly argued that relying on a few chosen elements in a bivariate space introduces possible error. They argued that you cannot just pick two elements at a time, draw a loop around a cluster on a graph, and call it an objective match. To remove human selection bias, they developed a highly standardized mathematical method (using geometric mean multi-element ratios).

 In a defense of their methodology, Pearce et al fired back, explicitly stating that “the simple graphical approach using bivariate plots produces the clearest assignment of artefacts to sources.” They argued that  complex mathematical equations actually overcomplicate the data and create false anomalies, whereas a clean X-Y plot provides the most practical "fingerprint". They even pointed out data-formatting flaws in Nash's critique, arguing that Nash's team used rounded data numbers that distorted the true placement on the graphs.

In their latest contribution Nash and Ciborowsky push back, repeat their concerns about the subjectivity involved in selected and possibly cherry-picked bivariate graphs, and argue for an acceptance of a standard mathematical procedure based on ratios of multiple elements against a single immobile element (Zr).

We have probably not heard the last of this............

I'm not going to take sides here, but I am going to say that I have expressed many concerns in the past about the possibility for corruption to creep into bivariate graphs when they are used for "definitive" spot provenancing.  The corruption might be very suble.  Ah, the lure of banner headlines in the media is never very far away.

But I am going to gently chide both teams involved in this dispute.  They argue about Stone 62 and about Carn Goedog, Carn Ddafad-las and Garn Ddu Fach -- and other upstanding tors -- as if they are the only locations that matter:  prominent features in the landscape which must have been (they assume) the focal points in the Neolithic landscape.  But it has never been demonstrated that upstanding tors have provided more monoliths for Stonehenge or anywhere else, in preference to less prominent intervening areas.  They have not, it appears, ever thought seriously about glacial entrainment mechanisms, and persist with the ancient belief that wherever the stones came from, they must have been fetched by Neolithic stone collectors from prominent sacred places.  Big mistake.

Second, both teams have neglected to  address the issue of sampling bias. Even though Richard Bevins and others may have taken hundreds of samples from the tors and other igneous outcrops on Mynydd Preseli, there are vast expanses of igneous terrain that have never been sampled at all.  The geochemical and petrologocal analyses that have been completed -- and reported in the literature -- may represent the places that happen to have been sampled, but they cannot be taken as truly representative of the igneous masses concerned.  We do not know everything about everywhere.  As I have said repeatedly with reference to Rhosyfelin and the claim by Ixer and Bevins that they have done accurate provenancing of Stonehenge fragments to "within a few square metres" they have no idea where their sampled rock layers may crop out elsewhere, because their sampling point density is nowhere near adequate.  The same is true of the sampling of dolerite on assorted tors in the uplands.

All of the authors involved in this current spat are explicitly claiming they understand the full range of variation of an entire geological formation based on chipping away at a small handful of prominent upland rocks. They treat the landscape as if it contains only a set number of possible "addresses," completely ignoring the millions of tons of un-sampled surface dolerite and low-lying, heather-hidden outcrops such as those of Waun Mawn.

Third, on a related matter, the huge geochemical and petrological variation that occurs within the Preseli sills has not been adequately recognized or factored in to the analytical work.  I pointed this out in my published paper on Carn Goedog:

 https://www.researchgate.net/publication/390565216_Carn_Goedog_on_Mynydd_Preseli_was_not_the_site_of_a_Bluestone_Megalith_Quarry 

... and have said the same thing repeatedly on my blog.  A spot sample from a particular location on Carn Goedog may tell us a lot about that precise sampling point, but it tells us just a part of the story relating to anywhere else. In the exchange of aggressive articles by out two teams as noted above, we find this classic statement from Pearce et al:

"The calculation approach fails to take into account even the most basic petrographic observations, which in the case of Stone 62 at Stonehenge shows that it is a non-spotted dolerite, hence cannot be sourced from a spotted dolerite source such as Carn Goedog." 

Pearce et al do not seem to know that the Carn Goedog tor contains both spotted and unspotted dolerite.  It seems to me that a little fieldwork might come in handy, now and then.

So Carn Goedog is by definition a spotted dolerite tor?  Think again, chaps, and 

preferably do some fieldwork........

Finally, this is a pretty damning admission in Ciborowski et al 2026: ".... incompatible element variation (at least as elucidated by pXRF) within individual bluestone monoliths may be similar in scale to the petrological variation between individual Preseli dolerite outcrops."  And yet they persist in arguing about individual Stonehenge monoliths like stone 62, and about individual tors as places where reliable and representative spot provenancing can be done!!

This is not the first time that attention has been drawn to the variations that exist within individual glacial erratics or Stonehenge monoliths.  The same argument is currently going on with regard to the physical and chemical characteristics of the Altar Stone...........

If we have a wide range of geochemical and petrological characteristics within individual tors of sills on Preseli, and a similar wide range even within individual monoliths like stone 62, accurate spot provenancing becomes virtually impossible.  So why do assorted highly qualified scientists continue to pretend that it is not only possible but desirable?

They do say that Stonehenge makes people slightly mad.   If that is so,  those (including me!) who spend their time agonising over Bluestone 62 (or any other) are probably completely bonkers!

As far as I am concerned, if it can be shown that Stone 62 (or any other) possibly comes from somewhere on Mynydd Preseli, that is quite enough to be going on with.

Herbert Thomas and the German erratics

I have been doing more research on the origins of the human transport hypothesis (I won't call it a theory today, since it is not supported by enough evidence) and have discovered a delicious irony.  

The inventor of the human transport idea was of course geologist Herbert Thomas, around 1918-1921 -- formulating his ideas in the years after the end of the Great War.  Anyway, in 1921—just three years after the armistice -- Thomas wrote his famous paper tracing the bluestones to the Preseli Hills. At that moment in history, British archaeology was deeply entangled with national identity. The devastating loss of life in the Great War left a fractured national psyche that desperately needed a narrative of ancient British exceptionalism, organization, and cultural supremacy to counter the dominant German archaeological schools of the era and the exciting Neolithic discoveries made in Germany.

To restore national pride, British academic institutions desperately sought narratives of ancient domestic superiority.  Emphasizing that British Neolithic tribes possessed great enough intelligence, social cohesion, and engineering genius to manually haul multi-tonne monoliths across hundreds of miles of wilderness served as a powerful cultural balm. It explicitly positioned ancient British society as far more "civilized" and sophisticated than its continental German contemporaries.  I have dealt with this issue before on this blog, with thanks to Stephen Briggs and David Keys of the Independent newspaper:

In don't for  moment believe that Thomas was an independent and objective scientist simply reporting on his findings and drawing sensible conclusions from his evidence.  He knew exactly what he was doing.

https://brian-mountainman.blogspot.com/2013/04/new-bevins-ixer-paper-on-certain.html

https://brian-mountainman.blogspot.com/2013/03/is-bluestone-myth-based-on-scientific.html

https://brian-mountainman.blogspot.com/search?q=+Thomas+ice+edge

https://brian-mountainman.blogspot.com/2024/04/hh-thomas-knowingly-misrepresented.html

This is what I have said earler about Thomas's deliberate distortion /manipulation of the evidence of glaciation:

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.

Ixer and Bevins have also questioned his competence as a field geologist and petrologist..........
http://www.sciencedirect.com/science/article/pii/S0305440313001076

https://doi.org/10.15184/aqy.2018.10

Anyway, leaving aside Thomas's professionalism and his integrity, he has had pretty much a free ride from the academic community, since most archaeologists and even most geologists seem to have accepted the reliability of what he had to say.  The narrative that he outlined was warmly accepted and then eagerly developed by the likes of Atkinson, Wainwright and Parker Pearson -- and even initially by other geologists.

Now, more than a hundred years later, we come full circle.  We now know that Salisbury Plain behaves identically to  continental equivalents over deep time, where older glacial tills on Cretaceous chalk undergo geomorphological erasure through chemical weathering and periglacial activity. This absence of coherent till reflects the defining characteristics of parts of the North European Old Drift Landscape (Altmoränenlandschaft) created in the Anglian glaciation but unaffected by later ice incursions.

Nobbin megalithic tomb, North Germany

Hünenbett on Riesenberg, near Nobbin, North Germany

 

A century later, standard European geomorphology reveals that German and Danish contemporaneous tribes were simply harvesting natural, large glacial lag erratics left on chalk downlands subject to quite rapid surface lowering.  They had no need to go hunting for rock outcrops or to open monolith quarries.  They used erratic boulders more or less where found, to create structures thet were sometimes quite complex.  By defending the human transport model as an immutable truth, modern orthodoxy is not defending robust field data; it is inadvertently protecting a piece of post-WWI anti-German political propaganda from 1921.

It will be a beautifiul irony if a deepeer understanding of megalithic structures made of glacial erratics on a chalk bedrock base in Northern Germany demonstrates once and for all that the Stonehenge "human transport" scenario is altogether unnecessary, and that the promotion of a wildly fanciful bluestone narrative by HH Thomas and his successors has been a complete waste of time.

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See also:

https://brian-mountainman.blogspot.com/2026/08/the-special-status-of-unhewn-rocks-and.html

on the perceived value or significance of glacial erratics.

The quiet abandonment of the great Neolithic exodus

Daisy Eleanor Spencer, Karen Molloy, Mike Parker Pearson, Ralph Fyfe & Aaron Potito (19 Oct 2025): Prehistoric Landscape Change Around the Sources of Stonehenge’s Bluestones in Preseli, Wales, Environmental Archaeology, DOI:10.1080/14614103.2025.2574741
https://doi.org/10.1080/14614103.2025.2574741

Since our old friend MPP scatters hypotheses just as others might scatter confetti, it's difficult to know what he actually thinks about anything. But I have been reflecting on the fact that the paper by Daisy Spencer et al (including MPP) has received no media attention whatsoever -- so we can assume that there was not even a press release from UCL........ I wonder why?

I wrote to Daisy Spencer about the article and its weird obsession with Stonehenge, but have received no reply. I wonder why?

In the present circumstances it's difficult to know whether we are supposed to accept that there was a mass stone-carrying exodus from Pembrokeshire around 5,000 years ago. Maybe yes, maybe no. Maybe we are supposed to think there was a mass exodus, which does not show up in the environmental change records because a few human beings were left behind, tasked with obliterating all traces of quarrying and stone transport, and carrying on as before? Or maybe the stone-carrying expeditions were conducted by an elite and mysterious group that was in possession of secret knowledge of igneous petrology and stratigraphy?

I haven't given much coverage to this idea, mainly because it is so proposterous. But we can see some of MPP's thinking on a corporate, elite management or specialized lineage-driven transport model in his chapter in the edited volume "Trade Before Civilization: New Perspectives on Long-Distance Trade and Social Complexity" (Cambridge University Press, 2022), and in his highly selective arguments in "The Power of Ritual in Prehistory: Secret Societies and Origins of Social Complexity."

With nowhere else to go, MPP is now forced to drift back toward a variation of the old "elite coercion" or "religious pilgrimage" theories, where a specialized group of elite prehistoric managers (who were of course in possession of esoteric or secret knowledge) somehow convinced a simple and settled West Wales population to let them strip their landscape of their sacred monuments and drag them 140 miles away over land, leaving the local farmers behind to tend the fields.

We will hear more about this as more and more pieces of the edifice collapse. But isn't it rather entertaining that MPP is now homing in on druids and Neolithic bards, having spent much of his academic life assuring us all that Stonehenge has nothing whatsoever to do with the druids? All this just at a time when we are having fun with the Welsh National Eisteddfod, the Gorsedd of Bards, and a Gorsedd Circle made of glass fibre imitation stones? And not so long ago, at the time of the summer solstice, the druids all had a whale of a time prancing around at the old stone ruin on Salisbuiry Plain. Iolo Morgannwg must be chortling away as he looks down from his place in heaven.

More on this shortly..........

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

My recent post on the paper by Spencer et al:

https://brian-mountainman.blogspot.com/2026/07/the-preseli-landscape-change-paper.html

A reminder of what I said in 2019:

https://brian-mountainman.blogspot.com/2019/04/was-there-neolithic-mass-exodus-from.html

So what evidence might there be for a large-scale cultural upheaval in West Wales roughly in the period 5,500- 4,500 BP -- the crucial thousand years in the Stonehenge story? So far as I can see, none at all. True, there are signs of a decline in the construction and use of megalithic tombs (cromlechs or dolmens) for collective burials, and signs of an increase in the setting up of standing stones, either singly or in "settings". And Pembrokeshire does not seem to have been affected by the trend of building large and impressive passage graves like Bryn Celli Ddu on Anglesey and Newgrange in Ireland; but in considering this difference Darvill and Wainwright, in their big 2016 chapter in "Pembrokeshire County History", say that Pembrokeshire was by no means isolated, but simply part of a quite different network of connected politics in which an emphasis as placed on individual graves sometimes covered with round cairns of stone. In their chapter it is difficult to extract hard facts from a context in which Stonehenge always lurks in the background, with circular reasoning much in evidence -- but suffice to say that there is no suggestion, anywhere, of a major hiatus that must have accompanied a "folk exodus" of people carrying stones or petrified ancestors to Stonehenge.

In contrast, there are many signs of continuity, with the adoption and abandonment of different traditions of building things and burying the dead. One tradition that appears to have been neither adopted, used or abandoned is the tradition of erecting large standing stone circles -- which maybe explains why MPP and his merry band have been hunting fruitlessly for "Proto-Stonehenge" for the last eight or nine years. Another tradition that never was developed, used, or abandoned, was the tradition of quarrying large monoliths from the living rock in designated quarries. And yet another assumed tradition for which we have no evidence at all was the tradition of transporting large monoliths across country for great distances.

So, as far as I can see, there is no evidence to support the hypothesis of a major exodus or series of expeditions eastwards from Pembrokeshire towards Stonehenge for the purpose of political unification or for any other reason. On the contrary, the evidence suggests a fairly small and relatively isolated community developing some local trends, copying or adapting others, and maintaining trading links with other communities in all compass directions. The idea that there was a sort of Neolithic "El Dorado" or Holy Land in West Wales is entirely fanciful; megalithic remains are no more spectacular or abundant here than they are everywhere else. If there was a threat from the east at any stage, involving immigrants from the near continent, it would have been strange indeed for local people to have moved TOWARDS the source of the threat, carrying with them assorted symbols of their cultural identity in the form of more than 80 very large stones.

A famous quotation.....

 

Came across this on Hugh's Facebook page. For which many thanks.  Couldn't resist using it.  Quote from a famous archaeologist who shall be nameless....... 

Julian Richards on the Bluestones

 

Julian Richards's hilarious stunt in one of his latest videos on Stonehenge.  This, I fear, is the sort of Stonehenge pseudo-science that we have to deal with nowadays. Should we laugh or should we cry?

In his commentary, Richards says:  "Did the glacier just conveniently deposit about 80 stones of just the right size here on Salisbury Plain, and nothing else?  Where are all the other stones?  Where's the evidence?"

That's the classic straw man tactic.  Invent an assumption that you would like other people to have held, and then rubbish it.  As far as I know, nobody has ever claimed that "80 stones of just the right size" were dumped on Salisbury Plain.  And where does the figure of 80 come from?  Answer -- inside Richards's head. He does not know that the Stonehenge bluestone or sarsen stone settings were ever completed.  We know about 43 bluestones, and maybe that's all there ever were.  And the most parsimonious explanation for the apparent abundance of stone sockets is to say that there never were enough stones, and that the builders used them in one experimental setting after another before finally giving up on the project. 

As for the silly blank pages stunt, he jokingly refers to "a complete guide to all the glacial erratic stones such as Welsh bluestones known on Salisbury Plain to have been naturally deposited."  So who decides what is naturally deposited, and what is not?  If I tell him that bluestone 32 was naturally deposited before being used in a stone setting, how is he planning to prove me wrong?

This is not good science.  But are we surprised?

Landscape and sediment modification on Salisbury Plain

Sarsen litter on Fyfield Down. Here today, but yesterday somewhere else......

Some of the Stonehenge bluestone erratic boulders.  Here today, yesterday somewhere else, higher up.   Courtesy Simon Banton.

I have visited this topic on many previous occasions in this blog,  for example here: 

https://brian-mountainman.blogspot.com/2022/02/southern-england-where-is-glacial-limit.html

https://brian-mountainman.blogspot.com/2016/12/sarsens-and-solution-hollow-dilemma.html

https://brian-mountainman.blogspot.com/2016/08/extraction-pits-solution-hollows-post.html

https://brian-mountainman.blogspot.com/2022/02/salisbury-plain-no-traces-of-ice-action.html

My conviction that Salisbury Plain was glaciated a very long time ago is stronger than ever, and I have argued consistently that there may well have been a patchy cover of till (derived from the west) which has been destroyed and redistributed over the course of 45,000 years or more of continuous denudation.  Oh no, say the usual suspects, if there had been a glaciation you would expect to find a scatter or a trail of erratics across the chalk downland, patches of till and fluvioglacial deposits, and maybe even a terminal moraine or two..........  These people are slow on the uptake, and refuse to accept that there are indeed abundant erratics scattered across Salisbury Plain on the surface and in assorted sediiments, and that the bluestone monolith assemblage (including the Boles Barrow bluestone) is as fine a collection of glacial erratics as you are ever likely to see.

I have also explained in a recent post that the chalklands of Salisbury Plain provide an extremely aggressive geochemical environment in which glacial and other deposits are very readily destroyed:

https://brian-mountainman.blogspot.com/2026/08/salisbury-plain-serene-landscape-but.html

Murton and his colleagues have also made a persuasive case for the destructive operation of periglacial processes, especially when the chalk lands have been "solidified" by the presence of permafrost:

https://brian-mountainman.blogspot.com/2023/01/periglacial-britain.html

https://www.lyellcollection.org/doi/10.1144/EGSP28.5

During the Quaternary, these periglacial processes have perhaps been in operation for 25% of the time, with each glacial episode ushered in by a prolonged periglacial phase and each interglacial ushered in by a phase of rapid ice wastage and rapid warming.   The temperature graph shows a sort of "saw tooth" pattern.  

However, these geomorphological considerations are brought into even sharper focus when we consider the landscape history of Salisbury Plain. In brief, the Plain is not where it used to be (on the altitude chart) when it was last affected by glacier ice, so all of the deposits that were on the chalk surface must long since have disappeared.  Their calcareous components will have been dissolved away, and their quartz-rich components will have been disaggregated and redistributed.  Only in the most freakish or  favourable of circumstances can small fragments of these original sediments have survived in situ. (I use that phraseology because I don't like the word "impossible"..........)

So to what extent has the land surface been lowered during the last 450,000 years or so?  There are several basic calculations in the literature.  These can be tested one against another.

1.  In the assessments of chalk dissolution and land surface altitude reduction since the formation of the Paleogene silcrete duricrust that gave rise to the sarsen stone scatter, the figure of 30 - 100 m appears in the literature, dending on local circumstances.  Tectonic and regional climate changes have varied from place to place, but let's take a conservative figure to 50m of land surface lowering.  Initially the rate of surface lowering was around 2.5 mm per millennium.  Because of regional uplift and climate changes, the rate of lowering increased tom around 10mm per millennium from the beginning of the pliocene, accelerating again to 19.2mm per millennium during the Quaternary -- associated with violent swings in climate and  glacial / interglacial oscillations.  Since the onset of the Anglian glaciatiuon, surface lowering of between 7 and 14m has been suggested, with a widely accepted average calculation of 8.6m.

2.  Modern geomorphological studies suggest that in the UK, under current temperature and rainfall conditions, surface lowering on the chalk is around 15-30 mm per millennium.

3.  The Norber Erratics in northern England, left stranded on a limestone pavement at the end of the LGM, now stand on pedestals c 30 cm high.  That indicates baseline surface lowering at 20 - 25 mm per millennium. 

4.  Surface lowering in the Driftless Area (USA) has been measured at 10-15 mm per millennium, on much more resistant bedrock of Palaeozoic sandstones and dolomite.  The Quaternary rate of surface lowering on the chalk plateau of Normandy is estimated at around 20mm per millennium.

There is a very satisfying equivalence in all these figures.  The land surface of Salisbury Plain has been lowered by 8-10m over the last half million years.  The landscape as it was at the time of the Anglian Glaciation (or the Wolstonian, for that matter) is simply not there any more.  End of story.