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

Tuesday 30 April 2024

A Stonehenge prophecy


Thanks to Tony for noticing this one. It was on one of the Wiltshire Facebook pages -- an advert dating from (I guess) around 1950. Quite apart from the pun about a wilting Stonehenge, the advert is strangely prophetic.....

Good adverts home in on things that others do not see -- and in this case the advertising agency working for Shell has recognized the desire of many people (not all!) to worship at the Stonehenge shrine............ Some might see this as blasphemy, but the idea that Stonehenge is a religious iconic structure worthy of respect and even reverence is central to the EH marketing of today!

So the idea that Stonehenge is -- or should be -- a place of worship is humorous at one level but concerning at another. After all, nobody is worshipping a set of beliefs or a holy book or a place of profound thoughts or ideas here, unless maybe we go with the Druids who have commandeered Stonehenge as a key symbolic site and who have attached to it their own theology. This is what Google tells us: For druids, modern-day spiritualists linked to the ancient Celtic religious order, Stonehenge has a centuries-long importance, and they will be there to perform dawn rituals around the solstice in their traditional white robes. It's effectively all about the cycle of life, of death and rebirth.  Of course, it is also about sunrise, and the summer solstice, and about respect for nature, peace and love.........,a%20small%20group%20of%20Druids

So the midsummer and widwinter solstices are celebrated by druids, hippies (oops -- do they still exist?) and tourists in their own peculiar fashion, with a minimum of control by EH. The ceremonies at Midsummer and Midwinter are unashamedly pagan and are of course perfectly harmless -- and those who participate in them are uplifted by the cameraderie and the high spirits, with the assistance of drums, bugles and assorted interesting substances. Other religions are allowed, but keep a low profile.... and we cannot doubt that the events are, for many people, profoundly spiritual and meaningful.

But the Stonehenge religious experience is of course "manufactured" just as the Welsh National Eisteddfod was invented and manufactured by Iolo Morgannwg, who convinced himself, and the world, that he was rediscovering something ancient which had been more or less forgotten. So now the religious life of Stonehenge is a very strange mish-mash of religious beliefs, ceremonial, pseudo-history,  mysticism, spirituality, song and dance, fancy dress and a good deal else.  But be in no doubt -- at the centre of it all is the Great God Mammon.  And as the old Shell advert reminded us long ago, there's money in those old stones.

Monday 29 April 2024

The Ice Age pioneers

Charles Lyell

Louis Agassiz

Andrew Ramsay

Archibald Geikie

James Croll

James Geikie

Carvill Lewis

Thomas Jehu

John Wesley Judd

Henry Hicks

Putting faces to the names.  The standout scientists were Croll, Jehu and Judd, who were decades ahead of their time.

Some of the above were fieldworkers and others were more concerned about theory. Some knew Pembrokeshire, and some did not. But what they have in common is that they were comprehensively ignored by Herbert Thomas when he wrote his famous bluestone paper in 1923 and pronounced that "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."  This of course is a lie -- he knew full well that the geological evidence shows that the ice that crossed Pembrokeshire extended eastwards at least as far as Glamorgan and across to the other side of the Bristol Channel.

Thursday 25 April 2024

The Great Cursus -- the place where the stones were found?

The Cursus in context (courtesy National Trust)

As readers of this blog will know, I'm not a great one for speculations. I spend a lot of my time criticising fantasies and speculations, and people who dress up speculations as the truth.   

But every now and then, a spot of speculation can be fun, and in reading up a bit on the Great Cursus, it seems to me that nobody has ever suggested that it might have been the place where stones were found, or the place from which stones were collected for the building of Stonehenge.  They must have come from somewhere..........

Sounds crazy?  Well, maybe, and my money is still on it being a sort of processional feature, along which people walked for some ceremonial or ritual (ie non-economic or "irrational") purpose currently unknown.  It's a better hypothesis than the Roman race track or the spacecraft landing strip hypotheses........ and I'm not all that convinced by the ideas that the enclosed strip was either sacred or cursed, or that it was deliberately enigmatic, built by people for whom the act of building was all that mattered.  Built for symbolically keeping things in, or keeping them out?  Or was it not an enclosure at all, but a line between a landscape devoted to the living, on one side, and a landscape devoted to the dead, on the other.  Or maybe a line between a ceremonial landscape and a "normal" landscape where people just got on with their lives?  Or maybe it has an "astronomical" origin, aligned as it is towards the horizon sunrise on the equinox? 

I don't like the line idea, because there are two slight embankments, more or less parallel to one another.  If the Neolithic builders had wanted to demarcate a boundary or a frontier, surely they would have been happy with one embankment, maybe made even higher and more prominent?

And the processional idea is also somewhat strange, because the ends of the 3 km routeway are closed off -- so there is no entrance and no exit.  Which way would people have walked?  Westwards or eastwards?  Probably westwards, because near the western end there is a cluster of barrows and other features -- but the round barrows are considerably younger than the Cursus embankment, and so they could not have been involved in any funerary processions heading towards the sunset. On the other hand, the long barrow called Amesbury 42 is close to the eastern end, and so maybe they walked towards that........  and that one has the advantage of being more or less the right age.   

It's intriguing that the Cursus seems to be unrelated to the landscape in that it drops down across the chalklands into Stonehenge Bottom valley and up again on the other side, so topography does not seem to have determined its location.

So is there anything that might point us towards the Cursus as having something to do with stones -- either bluestones or sarsens?  Or both?  Well, it may or may not be significant that there are abundant records of bluestone "fragments" being found in association with the Cursus -- especially at the western (Fargo Plantation) end. The finds are mostly from field walking collections; there are only two recorded excavations running across the whole width of the Cursus, one in 1917 and the other in 1959. The other excavations have been on the embankments -- mostly concentrating on the search for materials (such as antler picks) that might permit radiocarbon dating.

The researcher who seems to have been most intrigued by the Cursus was Jack Stone in 1949 -- according to some sources  he cut a trench across the Cursus and was so impressed by the concentrations of bluestone fragments near Fargo Plantation and between the Cursus and the site of Stonehenge that he thought there might have been a "bluestone monument" at the former site that was dismantled, modified and then reconstructed in the monument we see today. If bluestones were at one time scattered across the landscape as an erratic trail or train aligned with the direction of ice movement, and then collected and used as building materials, we might expect to find occasional extraction pits or hollows, and maybe patches of degraded till.  No such things are known -- although it has to be said that nobody has ever looked for them.

And if this ever was a "collecting ground" for bluestone erratic boulders, slabs and pillars, the tract of country involved might have acquired sufficient ceremonial or sacred status to justify marking it out with the embankments that we can still -- with difficulty -- see today.

This is just a suggestion, and I am not at all sure how seriously to take it. But remember -- you saw it here first.............

The Cursus, seen from the Fargo Plantation end

Wednesday 24 April 2024

Our ancestors were not as stupid as you might think........

All hail the bluestone route to Stonehenge.  Used in an article demanding greater respect for the intelligence of Neolithic tribesmen -- a nonsense illustration clearly created by artificial intelligence.  Or maybe by artificial stupidity.
How ironic is that?

This is quite wonderful.  Our old friend Tim Daw, over on his blog site, is fighting the corner on behalf of our heroic ancestors, and accusing people like me of a lack of respect for their intelligence.   He reproduces a press release (presumably from EH at Stonehenge, or from Cardiff University) in which Win Scutt accuses sceptics of the human transport thesis of "insulting our Neolithic ancestors" and urging us to have a greater appreciation of their capabilities.

Not for the first time, Tim completely misunderstands the situation. I have the greatest respect for the intelligence of our Neolithic ancestors, and I should have thought this is pretty obvious to anybody who reads this blog as avidly as Tim does. 

After all, they had aspirations to build Stonehenge, and even if they never managed to finish it because they ran out of stones, they did at least try. They moved a lot of rather large monoliths at Stonehenge, Avebury and elsewhere, and used some rather smart building techniques. They shaped some of the stones into rather elegant pillars. They may even have been smart observers of the movement of the sun, the moon and the stars in the sky. But to suggest that they were stupid enough to try and transport 80 big bluestone boulders and slabs all the way from Preseli to Stonehenge, across savage terrain, and then shaped some of them into pillars, thereby reducing their bulk and weight by maybe 50%, is a real insult to their intelligence. I think they did what any smart group of individuals would have done when they saw an opportunity to use relatively abundant stone resources on the rolling chalklands of Salisbury Plain. They decided to build a highly imaginative structure more or less where the stones were found. That was truly exceptional. 

They were smart enough to know all about cost / benefit analysis, and carried on with the work for as long as they had available stones. They had to go further and further afield to find the stones that they needed, but as they did so their costs (in manpower and effort) increased inexorably, and the benefits diminished. At last, when the costs far outweighed the benefits, and with only about 50% of the desired stones in place, they experimented with various stone settings, decided that none of them were exactly what they wanted, and eventually gave up on the whole thing. Just as any other group of intelligent human beings would have done, they went off and did something else which involved less effort and which brought them more pleasure.......... maybe an orgy or two over at Durrington village........

So three cheers for our Neolithic ancestors. May they continue to thrive!!


Here is the press release:

Doubting the overland transportation of the stones is insulting to our Neolithic ancestors.

Professor Keith Ray, a university professor and archaeologist, embarked on an extraordinary journey—a 222-mile trek through the Welsh and English countryside. His mission? To reach the iconic Stonehenge on schedule. But this wasn’t just a leisurely stroll; it was a quest to trace one of the possible routes that Neolithic peoples might have used to transport the massive megaliths from the Preseli Hills in Wales to the Salisbury Plain.

On Sunday, April 21, Professor Keith Ray achieved his goal, arriving at Stonehenge. Along different sections of his walk, he was joined by numerous academics, archaeologists, and other experts who accompanied him to learn about the terrain first hand. The journey took less than a month, and it provided valuable insights into the ancient landscape.

Win Scutt, senior properties curator for English Heritage, labeled Keith’s trip an “absolutely astonishing, heroic achievement”. At the seminar about the trip it was emphasized that doubting the overland transportation of the stones was insulting to our Neolithic ancestors and researchers were urged to have appreciation for their capabilities.

Keith Ray’s low-tech research method led to an interesting discovery: a route through the hills and mountains between Wales and England that never required more than a 20-degree climb. Along the way, he was joined by over 20 other academics. Keith observed that the lines of travel often followed ancient paths, demonstrating how the ancients navigated the landscape by going with the land and following the path of least resistance.

Kate Churchill, an archaeologist at Churchill Archaeology in Monmouthshire, walked part of the way with Keith. She found the experience comparable to walking during Neolithic times, allowing her to “stop and look at the landscape and be inspired.”

Professor Keith Ray’s remarkable journey sheds light on the historical connections between Wales and Stonehenge, revealing the ancient pathways that once connected these distant lands.

(Press release via Microsoft CoPilot)


In the Salisbury Journal, we see the following: Win Scutt, senior properties curator (west) for English Heritage, who labelled Keith’s trip an “absolutely astonishing, heroic achievement”,  said it was insulting, in light of all the evidence, for academics to still doubt the stones’ overland transportation.

Er, excuse me, but "in light of all the evidence" ??? ........and what evidence might that be? Does Win know something that the rest of us don't?

Bluestone lithics from the Stonehenge landscape

Lots of sockets and lots of stones -- from the Darvill / Wainwright 2008  dig at Stonehenge.  The packing stones on the left are probably all sarsens, but there is a lot else going on here.

Thanks to Tony for a number of comments recently about the bluestone lithics in the Stonehenge landscape.  There are -- by common consent -- thousands of them, dug up and revealed in Stonehenge digs, in field walking exercises, and in excavations elsewhere in the Stonehenge landscape.  Most of them are ignored or thrown away, and Ixer and Bevins choose not to take them seriously unless they are clearly related to known bluestone orthostats -- so that neatly eliminates anything "inconvenient"............

See Julian Richards, 1990 -- The Stonehenge Environs Project, EH, London

But it isn't that easy. Stone and Richards, in various publications, refer to a "wide distribution" of fragments of dolerite, rhyolite and volcanic ash, and they refer to many rock types that are not represented in the bluestone orthostat assemblage.  They refer to "unknown" rhyolites, ashes, dolerites and quartzites.  Mostly they label the bluestone finds as flakes, fragments, slabs, hammerstones or tools -- demonstrating an unwillingness to contemplate the presence of bluestone boulders, cobbles or pebbles that might have nothing to do with human activity.

And the things that are all too easily referred to as "tools" may indeed not be tools at all, but perfectly natural small bluestone erratics such as we might find in any degraded glacial deposit:

Here is another old photo from a 1902 excavation at Stonehenge, again assumed to show "sarsen stone and flint implements" -- with no apparent awareness that some might simply be glacial erratics......

In the photographic record of the Atkinson and earlier digs at Stonehenge, over and again we see packing stones and small boulders that are simply ignored and thrown onto spoil heaps.  Appalling!  Watch this space.........

Atkinson helping to remove a packing stone
See also:

P 15.  In the centre we found a shaft. Atkinson must have skimmed the edge of it in 1964, but most of it lies within our trench. It is about 1.1m deep and has a very homogenous fill. Right in the top there was a very fine block of bluestone, which Rob Ixer has provisionally identified as a piece of very fine-grained siltstone or sandstone; geologically speaking, this can be paralleled by a piece found in the cursus by J F S Stone some years ago. So we have an interesting circulation of bluestone fragments; this is a substantial piece and all around it is a scattering of flakes and smaller pieces, which have been broken off.

The Antiquaries Journal, 89, 2009, pp 1–19  The Society of Antiquaries of London, 2009 doi:10.1017⁄s000358150900002x. 
First published online 21 April 2009

STONEHENGE EXCAVATIONS 2008 Timothy Darvill, VPSA, and Geoffrey Wainwright, PSA

Tuesday 23 April 2024

The new Holocene article

It's one month since publication, and this is the link to my article in The Holocene journal:

It's flagged up as open access, but as we all know, that does not mean access to all who may wish to read it.  If you can't get at it on the journal web site, it is also here on Researchgate:

This is the final accepted version in the format I submitted -- so it appears slightly different from the version published in the journal.  But it's all there......... and has over 2,600 reads so far, so people are taking it seriously.

If you want a PDF of the article as published, let me know, and I will get a copy off to you. I am allowed by the publishers to distribute copies to friends and fellow researchers for their personal edification!

John, B.S. 2024. The Stonehenge bluestones did not come from Waun Mawn in West Wales. The Holocene, March 20, 2024 (published online) 13 pp.

Sunday 21 April 2024

Hooray for the invisible stone carriers!

Just when you thought it couldn't get any more bonkers, it did............

From the Stonehenge facebook page:

Today, English Heritage Senior Properties Curator, Win Scutt joined part of a 230-mile walk of one possible route for the transport of bluestones from the Preseli Hills to Stonehenge.

The Stonehenge bluestones made an epic journey to get here and how they were transported from Wales during the Neolithic period remains one of the greatest mysteries.

Professor Keith Ray designed the long-distance route and is walking its length on consecutive days, to explore the landscape through the eyes of Neolithic people and visualise how the land may have looked over 5,000 years ago. Those taking part in the experimental walk have reflected on the choices and challenges which the stone-carriers may have faced if they had travelled along the same route.
It’s thought that this is the first time that the journey has been made on foot in modern times.

From the BBC report:

Professor Ray said he wanted to draw attention to these scientific discoveries and it was also important to consider the "whole question of Neolithic journeying and its purposes".

"I would say Neolithic people were very aware of significant communities and that's how they organized it so that they could follow a route linking with particular communities."

Heather Sebire, senior properties curator at English Heritage said: "We've never known exactly how the stones were brought from so many miles away to this ancient landscape 5,000 years ago.

"Professor Ray's endeavours will help keep the discussion around this fresh in the minds of archaeologists and the public.


The Millennium Stone pull in the year 2000.  A shambles, even with abundant manpower, asphalt roads, modern ropes, low friction netting, heavy lift cranes and standby JCBs..........  How much more evidence do you need before you get the message that the whole idea of overland monolith transport was and is ludicrous?

So what about the Millennium Stone fiasco?  To this day, that is the only serious piece of experimental archaeology ever done that took die account of terrain, weather, available technology etc.  Conveniently forgotten by the Stonehenge management......

Well, I hope that Prof Ray enjoyed the walk and feels all the better for having done it.  But the EH staff should be ashamed of themselves, propagating a myth that they know is unsupported by hard evidence and which is seriously challenged by others, including myself.   It's all about marketing, and all about money.   As long as the Stonehenge cash registers keep on jangling, who cares about the truth?  

Friday 19 April 2024

Another computer model


There is a new and rather spectacular computer generated interactive and animated "icemap" showing the expansion and contraction of the BIIS and the SIS during the Late Devensian. It's free for anybody to use, and it has been created by Henry Patton at Tromsø University in Norway.

It's visually very attractive and seems to me to be pretty reliable for the most part. However, there is a major issue with dating, and the peak of the LGM is shown here as around 22,500 yrs BP as compared with around 26,000 yrs BP in the BRITICE reconstruction. Who is correct? This is a very substantial difference, no doubt explained by differences in the calibration of radiocarbon and marine isotope dating........

Also, Henry seems to have been using different databases for different parts of this computer programming exercise. On the ice extent map, the Devensian ice edge is shown hitting Salisbury Plain. That will cause quite a lot of discussion, since the BRITICE reconstruction is far different -- and with most researchers suggesting that the inner part of the Bristol Channel was not affected by glacier ice during the LGM, but that ice extent was greater during earlier glacial episodes.

Also, on the map showing actual LGM ice limits, the line used by Henry is very unreliable, being based on an acceptance of the "ice free corridor" in central and south Pembrokeshire -- which I demonstrated as being unreliable theoretically and in practice, in my 2023 QN article.

But all in all a very worthwhile and attractive teaching aid which will fascinate a new generation of budding glaciologists!

The LGM maximum line as shown on the new model.  The representation of the Bristol Channel as being effectively ice-free does not stand up to scrutiny.

The Lost Circle -- British Open Brass Band Challenge!!

You couldn't make this up. "The Lost Circle" has now been set to music by Belgian composer Jan Van Der Roost as a test piece for the British Open Brass Band competition.

This is hilarious on one sense. But it is also a stark reminder of the manner in which wild speculations and dodgy science can turn fantasies into myths and in turn into something seen by others (such as Belgian brass band composers) as established truth. The commissioning sponsors have clearly all been swept up in the media frenzy about Waun Mawn, and probably just loved that famous TV documentary fronted by Alice Roberts.  One cannot doubt that in good faith our friend Jan the Composer has accepted that the "Lost Circle" at Waun Mawn did actually exist -- before going on to explore musically what the "how and why" might have been.

So are MPP and his merry men feeling guilty about misleading gullible members of the public so comprehensively? I doubt that very much...........


Here is the blurb:

British Open announces 2024 test-piece

'The Lost Circle' by Jan Van Der Roost will pose questioning musical challenges for bands wishing to construct a British Open winning performance at Symphony Hall this year.

The composer explored both why and how the Bluestones of Stonehenge came to their final resting place

A new commission by the critically acclaimed Belgian composer Jan Van Der Roost has been announced as the set-work for the 2024 British Open Championship.

'The Lost Circle' is his fifth major contest composition and has been commissioned through an international consortium of organisations, including the British Open alongside the national bodies of Belgium, The Netherlands, Norway, Switzerland, Germany and Austria.

It will receive its world premiere at the 170th British Open Championship at Symphony Hall, Birmingham on Saturday 7th September.

The work sees the composer return in inspiration to Stonehenge — the ancient site on Salisbury Plain in the UK that has held fascination to humans for millennia. It is, as the composer says, "a monument that has been the subject of questions, guesswork, doubts and speculations from time immemorial."

However, although 'The Lost Circle' is linked thematically in musical inspiration, it is not an "explicit successor" to his earlier 'Stonehenge' composition written in 1992.

Instead, as Jan Van Der Roost writes in his foreword to the 16-minute score, it is a work rich in thematic symbolism. It questions both how and why the inner circle of megalithic Bluestones were brought by ancient people on a 240-kilometre journey from deep in the Preseli hills in West Wales to their final resting place.

Speaking exclusively to 4BR he said: "I am honoured to write 'The Lost Circle' for the British Open and the national associations of Belgium, The Netherlands, Norway, Switzerland, Germany and Austria where it will subsequently be performed at their National Championships.

It follows 'Excalibur', 'Stonehenge', 'Albion' and 'From Ancient Times' in being used at major events, and I will be delighted to hear it performed at the magnificent Symphony Hall in Birmingham for its world premiere."

He added: "It is definitely a challenging and demanding work, but one I hope will be enjoyed by the conductors, performers and audiences alike in the months to come in the UK and Europe."

In making the initial contest announcement, British Open Championship Artistic Advisor, Dr Robert Childs told 4BR: "Jan Van der Roost is rightly regarded as one of the foremost composers writing for the brass band medium.

'The Lost Circle' is a magnificent work — and one which I am sure alongside our colleagues throughout Europe will provide a wonderful musical test for competing bands, and a thoroughly rewarding musical experience for listeners."

British Open Contest organisers Martin and Karyn Mortimer added: "It will be the first time Jan Van Der Roost has written a work to be used at the British Open Championship. We are thrilled to be able to provide the stage for its world premiere. Our thanks got to him and to our consortium friends for making this wonderful piece possible."

Tuesday 16 April 2024

Feedback mechanisms and ice sheet behaviour

Two glacial episodes in Scandinavia -- but why was one more extensive than the other?

This is a very interesting paper on the behaviour of the Scandinavian Ice Sheet. For some time I have been interested in the manner in which feedback mechanisms operate within and on the edges of large ice masses. As readers of this blog will know, I have pondered occasionally on the role played by large troughs (such as Sognefjord in Norway and Nordvestfjord in East Greenland) in the efficient evacuation of ice and the dynamics of the ice mass. Assuming that in each successive glacial cycle these troughs are widened and especially deepened, we can also assume that the efficiency of ice transfer is improved -- but does that mean that ice sheets will get bigger and bigger in each successive glaciation? Not necessarily -- there might be ice edge advances at the trough outlets, but maybe ice edge retreat elsewhere because of ice capture in the trough catchments. In other words, there might be increased ice edge crenellation. This could all get very confusing -- and to their credit Henry Patten and others have already been thinking along these lines with respect to the BIIS.

The authors of the new Scandinavian paper concentrate on the role of gradual sediment filling of the low points in the landscape and the "capturing" of ice flow by spectacular features like the Norwegian Trough. With respect to the BIIS and the Celtic Sea arena, the BRITICE team have already been speculating on whether the Late Devensian Glaciation was the most extensive of all the Quaternary glaciations, partly because of the vast thickness of sea floor sediments across which the ice was flowing -- increased bed lubrication, sediment deformation, accelerated flow rates and a lower surface gradient are all interconnected.  Surging behaviour also comes to mind.  But what are the side effects of the "purges" that seem to have occurred in the Celtic Sea area?  Does a more extensive LGM mean that the glaciation was also more intensive?  Not necessarily.

Interesting questions so far, and not many answers......

Gustav Jungdal-Olesen, Jane Lund Andersen, Andreas Born, and Vivi Kathrine Pedersen, 2024.
The influence of glacial landscape evolution on Scandinavian ice-sheet dynamics and dimensions
The Cryosphere, 18, 1517–1532, 2024

The Scandinavian topography and bathymetry have been shaped by ice through numerous glacial cycles in the Quaternary. In this study, we investigate how the changing morphology has influenced the Scandinavian ice sheet (SIS) in return. We use a higher-order ice-sheet model to simulate the SIS through a glacial period on three different topographies, representing different stages of glacial landscape evolution in the Quaternary. By forcing the three experiments with the same climate conditions, we isolate the effects of a changing landscape morphology on the evolution and dynamics of the ice sheet. We find that early Quaternary glaciations in Scandinavia were limited in extent and volume by the pre-glacial bathymetry until glacial deposits filled depressions in the North Sea and built out the Norwegian shelf. From middle–late Quaternary (   0:5 Ma) the bathymetry was sufficiently filled to allow for a faster southward expansion of the ice sheet causing a relative increase in ice-sheet volume and extent. Furthermore, we show that the formation of The Norwegian Channel during recent glacial periods restricted southward ice-sheet expansion, only allowing for the ice sheet to advance into the southern North Sea close to glacial maxima. Finally, our experiments indicate that different stretches of The Norwegian Channel may have formed in distinct stages during glacial periods since 0:5 Ma. These results highlight the importance of accounting for changes in landscape morphology through time when inferring ice-sheet history from ice-volume proxies and when interpreting climate variability from past ice-sheet extents.

Monday 15 April 2024

The extraordinary Mr Croll -- the world's first glaciologist


James Croll, looking somewhat unhappy.  He didn't like fieldwork very much -- maybe he had just got wet out on the Scottish moors........

James Croll (1821-1890) was an extraordinary man with very little formal education who became a janitor at the museum of the Andersonian University in Glasgow in 1859 and who taught himself (because of his insatiable appetite for learning and his open access to the university library) physics, astronomy and geology.  He corresponded with Charles Lyell and disagreed with him about the origins of what were then called "drift" deposits, but he was greatly encouraged in his researches by Sir Archibald Geikie, and then obtained a position in the office of the Geological Survey of Scotland.

He is revered in Scotland as one of the country's great scientists and as one of the most original of thinkers, and he stood out from the other "glacialists" of the time, who were mostly geologists who happened to be interested ion the Ice Age. I think we should give him the accolade of being the first genuine glaciologist, because of the manner in which he combined the principles of physics, astronomy, climatology and geology in order to understand how glaciers work and how Ice Ages come and go through geological time. 

He saw the Earth as a single system within which events in one sphere (for example, changes in ocean circulation) had repercussions of knock-on effects in all other spheres. He built on the early work of Agassiz in 1840 to argue strongly against Lyell's "great flood" and for extensive landscape modification by expanded land ice. He developed an astronomical theory of oscillatory climate change 60 years before Milankovitch published a very similar theory. He developed a coherent theory of ice sheet growth and shrinkage, and (without any field measurements to work on) developed the idea of an equilibrium profile. He referred quite clearly to feedback mechanisms in glacier behaviour, and wrote about albedo effects. He considered the effects of ice sheet growth and shrinkage on global sea-level, and proposed considerable eustatic drops of sea-level coinciding with glacial maxima during the Ice age. He even started to explore the idea of isostatic loading and unloading, arising from his observations on Scottish raised beaches. He used bore hole records and used field observations on glacial stratigraphy to illustrate his ideas on glacier oscillations and glacial and interglacial episodes. Most extraordinary of all, he created a "model" of the Antarctic Ice Sheet even though, at that time, nobody had set foot on the Antarctic continent, let alone done any measurements on ice thickness, surface gradients and extent. His "model" incorporated innumerable parameters, most of which are still used in computer-based models today. What might he have achieved had there been computers in his day? Then, from his predictions on the nature of the Antarctic Ice Sheet, he had the temerity to use his "model" to suggest what the Great British Ice Sheet might have looked like at the time of maximum glaciation.......... his map was almost a century ahead of its time, and is reminiscent of the maps still in use around 1960, when I was a student.

He was, of course, in 1879  too radical and too far ahead of everybody else to have escaped unscathed -- and towards the end of his life there was a backlash from the more conservative members of the scientific establishment.  In spite of the fact that he was supported and encouraged by the Geikie brothers, and in spite of his copious and creative correspondence with all the great scientists of his day, he never was a full member of the science elite in Britain, and he was known in some quarters as a "controversialist".  The main criticism directed towards him was that his ideas were unsupported by hard evidence and that he strayed too far into the realm of theory  or speculation.  That was all very sad, because one by one his ideas have been accepted and moved into the mainstream -- and field evidence has supported most of his inspired speculations.  Yes, he made mistakes, but that is what happens on the frontiers of science, and the word "extraordinary" is one that will continue to be used for James Croll by those who examine the origins of the science of glaciology.

‘The most remarkable man’: James Croll, Quaternary scientist
Kevin J. Edwards
Jnl of Quaternary Science
First published: 04 April 2022

This is the abstract from Kevin Edwards's paper about this "most remarkable man":


The year 2021 marked the bicentenary of the birth of James Croll (1821–1890), the self-educated son of a crofter-stonemason, whose life was characterised by a dizzying range of occupations and homes, poor health and financial concerns, and yet he became a pioneer of orbital dynamics and ice age climate change with an impressive record of publication. Drawing upon archival information and recently published observations, this paper explores selected aspects of Croll's biography, his scientific connections and controversies, and that area of his life relevant to Quaternary science. He was a 19th century polymath whose multifaceted contributions have been a catalyst for subsequent systems-based climate science on the grand scale, including the foundations for the seminal work of Milutin Milankovitch on the rhythms of Quaternary environmental change.

See also:

Rose J. 2021. Lyell, the Geikies and Croll's observations on terrestrial glacial sediments and landforms. Earth and Environmental Science Transactions of the Royal Society of Edinburgh 112: 261–274.

Sugden DE. 2014. James Croll (1821–1890): ice, ice ages and the Antarctic connection. Antarctic Science 26: 604–613.

Croll, J. 1879. On the thickness of the Antarctic ice, and its relations to that of the glacial epoch. Quarterly Journal of Science, January, 34 pp.

This is James Croll's map (1879), incorporating many components since proved to be correct. Compare with the more modern maps below. Croll was sure that the Scandinavian and British - Irish ice sheets were connected in the North Sea. Flowlines across Northern Scotland were largely correct. The Irish Sea ice stream is shown quite clearly. The ice edge is correctly located on the Celtic Shelf edge. However, Croll assumed that glaciers had a constant surface gradient from centre to periphery; the glacial equilibrium profile had not yet been discovered. So he greatly overestimated ice thickness in the centre of the accumulation area. Consequently, his image showing thick glacier ice flowing across southern England was somewhat overenthusiastic!! He has ice flowing down the Bristol Channel from east to west -- precisely the opposite of the ice flow pattern as understood today.

The most recent ice flow maps, mostly computer generated, are more correct that Croll's map -- but they are still faulty in some areas because of modelling mistakes and inadequate ground truthing.


Also found on the web:
Achievements and Key Points

James Croll:

Was the foremost advocate in the 1800s of the idea that climate change is caused by the changing relationship between the earth and the sun.
Devised they theory that climate is controlled by solar insolation – the amount of energy reaching the earth from the sun.
Linked our planet’s ice ages to solar insolation variations caused by: Earth’s elliptical orbit around the sun (100,000-year cycle); precession of the equinoxes (23,000-year cycle); and axial tilt (41,000-year cycle).
Noted how the elliptical shape of Earth’s orbit around the sun varies with time – sometimes the ellipse is more eccentric (elongated).
Said ice ages happen when there is a combination of events: the earth’s elliptical orbit around the sun is at its most eccentric and mid-winter takes place when the earth’s orbit is at its farthest point from the sun. These conditions of reduced sunlight result in lower temperatures, leading to a build-up of ice and snow in the oceans and on the ground.
Said the build-up of ice redirects the trade winds and hence ocean currents. Warm currents like the Gulf Stream no longer bring heat from the tropics to the colder regions, enhancing the orbital cooling effect, leading to ice ages.
Advanced the theory of ice-albedo feedback. This says that if ice begins accumulating at a pole because of a decrease in winter sunlight, then the extra ice will reflect more of the sun’s heat back into space, leading to further cooling.
He (incorrectly) said ice ages alternate between the northern and southern hemispheres – the north and south taking it in turns to have moderate climates and ice climates in a cycle lasting 22,000 years in each hemisphere, with each ice age lasting about 10,000 years.
Although today we know Croll did not get all the details correct, his work provided a mechanism that explained the ice ages. It provided a basis for Milutin Milanković to go further the following century and generate the concept of Milankovitch cycles.


This is an interesting programme from 2010, in which Iain Stewart talks at some length about the life and times of James Croll -- starting about 30 mins into the programme.

Saturday 13 April 2024

Bluestone transport: Edgar Barclay was the originator of the human transport hypothesis -- not HH Thomas

Two of Barclay's Stonehenge paintings

Thanks to Tim Daw for flagging up this little volume a few years ago. I have been looking at it again,  and while a lot of the contents of the book are naive and fanciful, it contains many astute observations and deductions. Barclay clearly had no contact with the "glacialists" of his day, and he makes no mention in his book of the possibility of glacial stone transport.  He was certainly not the first writer to refer to the "prodigious effort" involved in assembling the Stonehenge monoliths and the building of the monument, but (and here I stand to be corrected) he seems to have been the first person to propose the long-distance transport of the bluestones from their places of origin across the sea and overland. (We can safely ignore Merlin the Wizard and Geoffrey of Monmouth for the time being.....)

He was advised (somewhat prematurely) by the geologists of the day that the bluestones cannot have come from any British rock outcrops, and so he speculated that they might have come from Brittany, and that they were transported across the Channel by our ancient ancestors. He also suggests in his text that the bluestones must have been deemed as special or valuable -- in order to justify the "prodigious effort" involved in moving them. Barclay was also aware the the chippings and bluestone fragments scattered about across the Stonehenge landscape, and of a link with the abundant round barrows on the chalk downs.

I think the key passages in the text below justifies us in giving the credit -- or the blame --to Barclay for the invention of the human transport hypothesis in 1895.  What HHT did 28 years later was to correct the source area to West Wales and to add the petrological detail which permitted him to claim (again somewhat prematurely) that he knew pretty well exactly where the bluestones had come from. In 1858 Ramsey had suggested that Wales was the source for the bluestones.   It's worth remembering that neither Barclay nor Thomas believed that the bluestones had been quarried.  Both of them realised that the bluestones were simply weathered boulders collected up from what had been a scatter across the landscape.


Edgar Barclay (1842-1913)

The artist Edgar Barclay was born in 1842 and studied art in Italy and Germany. For several years as a working artist he divided his time between London and Italy, but he returned to England in the 1880s and began painting rural scenes of Wessex, especially of Stonehenge. He exhibited extensively and was known for his skill in handling light and big skies. He was also an accomplished historian, writing and speaking particularly on Stonehenge. He addressed the British Archaeological Association in 1893. He clearly had good contacts, and wrote "Stonehenge and Its Earth-Works” in 1895. He suggested -- because of the weathering crusts on many of the bluestones -- that they were simply collected as boulders rather than being quarried.


p 6
The inner circle and inner horse-shoe are composed of the foreign  "Blue-stones",  igneous rocks. The locality from which they were originally taken remains undetermined ; experts, after microscopic examination, have affirmed that in "no part of Great Britain is there any stone to be found of the same description." Of these some differ markedly in their nature from others.

p 77
The most arduous operation in connection with the erection of Stonehenge was the transportation of the Blue-stones ; we should, therefore, be forced to believe that although the builders lacked the energy to complete a gap in the Sarsen circle, they nevertheless had the opportunity and energy to fetch and set up the Bluestones. This is a contradiction ; we therefore conclude that stones are missing because the building has suffered from spoliation. Fortunately, ancient records which make mention of Stonehenge inform us how this probably came to pass.

pp 124-126
In conclusion, we take a retrospective glance at the results of our inquiry. To begin, there is the striking fact that Stonehenge consists of stones foreign to the neighbourhood, and belonging to geological formations widely apart ; proof that its construction was a far greater undertaking than the present appearance of the ruin would lead any one to suspect, and of the power of the founders to organize labour on a very considerable scale.

This is specially shown by the case of the Blue-stones, which, according to the judgment of experts, are foreign to this country, and which, so it has been concluded, from the weathered surfaces of some of their chippings, were, like the larger Sarsens, never quarried, but derived from boulders left on the surface, or, more probably, were brought from some sea-washed shore.

The labour of carrying these stones up from the coast was no mean one, and that they should have been transported across the sea is not merely a conspicuous proof of the resources of the founders, but indicates either that those who controlled the work were themselves moved by a strong sentimental motive, or that they played upon a strong sentimental feeling animating others, otherwise so laborious and unusual a course, and one so uncalled for by any utilitarian purpose, would never have been pursued.

The dictum of petrologists, that the Blue-stones are of foreign origin, is in harmony with the tradition that the stones have been transported hither by sea. The geological formation of Brittany points to that country as their probable source, a probability greatly strengthened by historical considerations. Geoffrey of Monmouth, when giving an account of additions effected by King Aurelius to the monastery at Amesbury, followed a tradition which stated that a stone circle was taken down and utilized for that purpose. We have no reason to believe that Geoffrey had knowledge of Stonehenge, situated a mile distant west of the monastery ; and mystified by another tradition which stated that the stones had been shipped, it appears that he in consequence concluded that the stone circle in question must have been situated in Ireland ; thus he kept to the right direction for their source, whilst considerably exceeding the real distance. It is incredible that Aurelius should have brought his building material from that country; he had not the power, supposing he had the crazy desire to do so ; he had no fleet, and the sea was commanded by piratical Saxons, his deadly enemies. In the introduction of the Irish incident we, therefore, recognize Geoffrey's embellishments ; we here see the old familiar artifice of making an incredible story appear veracious, by the introduction of circumstantial details, thus in the thick of the Irish embroglio he makes his characters orate in the time-honoured classical and biblical manner.

The Altar-stone belongs to a different geological formation to either the Wiltshire Sarsens or the foreign stones, and affords another proof of lavish expenditure of labour ; whilst the shaping of the rocks, and the manner in which the superimposed blocks are securely locked in their places by means of tenon and mortise, evidences the attainment of considerable skill.

Moreover, it is a striking fact that these rocks, collected with prodigal labour from sources so widely apart, should have been set up on a bare and desolate down, the surrounding land for the space of several miles being more thickly studded with barrows than any other district in this country, which produces a strong impression, the correctness of which is fully confirmed by closer scrutiny, that the ruin and the gravemounds are in some way connected. We noted the critical positions of the outlying stones, and that mysterious alignments proceed from the ruin and traverse the barrow-studded plain.

The design has manifestly not been dictated by utilitarian necessities, or by aesthetic sentiment, it shows the temple to have been dedicated to Sun-worship, the stones being so disposed as to form religious symbols ; the meaning of that symbolism we have endeavoured to explain, and in doing so we have followed ideas once current in Gaul.

The unity of the design was proved by the relative proportions of the parts, and that the different parts were raised at the same epoch is further attested, first, by the finding together of pieces of the different sorts of stone used in the construction within a gravemound, and, secondly, by chippings of all the rocks having been found in the concreted substance around the bases of the Bluestones. When thus proving the unity of the design, we proved also that the temple is not of prehistoric antiquity, for we have no reason to believe that the ancient Britons were capable of adjusting their buildings with a knowledge of geometry.

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. 


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........!!