What about the Bluestone pXRF studies?

The recent paper on Stonehenge Sarsen Debitage* ends with this conclusion:

"Our key message is that studies attempting to use surficial (pXRF) analysis to provenance any excavated artefact must demonstrate that weathering processes following burial did not significantly alter the primary chemical signature of the material before any meaningful provenance interpretations can be made."... "Any future attempts to provenance excavated dolerite fragments at the monument (likely derived from the in situ dressing of megaliths and/or the removal of flakes in more recent history) must consider differences in the weathering regime experienced by the buried fragments, exposed potential outcrops and standing stones. Due to its mineralogical composition, dolerite is more susceptible to chemical weathering than sarsen. Thus, one should expect differences in weathering to be much more significant between buried dolerite fragments exposed to subsoil weathering, and dolerite outcrops and megaliths exposed to differing intensities and durations of subaerial weathering."

This obviously could be thought to apply to the existing analysis of the bluestone dolerites, and any other non-sarsen stone.

So is there a problem?

Firstly, apart from the Newall boulder (https://www.sarsen.org/2023/07/the-erratic-that-came-in-from-cold.html), all the pXRF analysis has been on exposed Stonehenge stones comparing to exposed Welsh rocks, so they are like for like comparisons. And the Newall boulder was further analysed to show it was part of a broken monolith from Craig Rhos‐y‐Felin** 

Secondly the geochemistry revealed by xPDF is only part of the story. The recent Ixer, Bevins et al papers have also used petrology, understanding the matrix of the rock, to identify sources.

For instance in Bevins, Richard & Ixer, Robert & Webb, Peter & Watson, John. (2012). Provenancing the rhyolitic and dacitic components of the Stonehenge landscape bluestone lithology: New petrographical and geochemical evidence. Journal of Archaeological Science. 39. 1005–1019. 10.1016/j.jas.2011.11.020 the authors showed how Craig Rhos‐y‐Felin rhyolite had been misidentified as microtonalite, the geochemistry was very similar but the petrography different. This holistic approach to identification instills confidence. 

But the big difference is in the nature of the stones. Sarsen is over 99% silica, it is the white Wonderloaf of rocks. The various bluestones are complex rocks with other compounds in great abundance in them. So the presence of a small amount of chemical changes from weathering is important on Sarsen but not for bluestone. As Rob Ixer says; "A smear of marmite on plain buttered toast would be tasted but the same smear on jalapeno-anchovy toast would add nothing."

So the valuable lesson of the problems of using pXRF on Sarsen for sourcing studies doesn't cause worries about the reliability of the recent Bluestone papers, and is unlikely to be a problem in the future. 

David Nash responds:  Interesting thoughts but I wouldn’t be quite so confident about work on dolerite orthostats. These would have had fresh faces when quarried, and then slowly weathered at Stonehenge. The surfaces of comparator outcrops in Wales would have been weathering for much longer. This means that the Preseli outcrops are likely to be more altered by weathering than the comparatively fresh orthostats. Plus the weathering environment in wales will be different to that of Salisbury Plain. PXRF work needs to bear these differences in mind.

* Local and exotic sources of sarsen debitage at Stonehenge revealed by geochemical provenancing,
T. Jake R. Ciborowski, David J. Nash, Timothy Darvill, Ben Chan, Mike Parker Pearson, Rebecca Pullen, Colin Richards, Hugo Anderson-Whymark,
Journal of Archaeological Science: Reports, Volume 53, 2024, 104406, ISSN 2352-409X,
https://doi.org/10.1016/j.jasrep.2024.104406.(https://www.sciencedirect.com/science/article/pii/S2352409X24000348)

**Lithological description and provenancing of a collection of bluestones from excavations at Stonehenge by William Hawley in 1924 with implications for the human versus ice transport debate of the monument's bluestone megaliths: DOI:10.1002/gea.21971
Richard Bevins  Rob Ixer  Nick Pearce  James Scourse  Tim Daw
https://onlinelibrary.wiley.com/share/author/YUUAUVRWBNTZTPSQVBGM?target=10.1002/gea.21971

Possible Stonehenge Debitage Sources

The two "exotic" sources Nash et al identify as possible sources for sarsen at Stonehenge are Stoney Wish near Ditchling Sussex and on the side of the A272 near Bramdean in Hampshire.

To help identify them here they are:

Click pictures to embiggen

For a source of monoliths the geochemistry, the petrography (the internal matrix of the stone) and the form of the natural rocks has to match. West Woods still has large boulders despite years of breaking and removal that are the size of some of Stonehenge's stones. Do these sites match up to this or as the paper suggests are they sources for small hammerstones or similar sized stones?  

There is a question mark over where the Bramdean stones originated as the circle of stones seems to date from about 1845   - https://pastrambles.wordpress.com/2015/02/22/the-bramdean-circle-of-stones/   erected by "Colonel George Greenwood of Brockwood (formerly Brookwood) House, a large property down the lane on the other side of the crossroads...there are two possible explanations of the Colonel’s motivation for building the it in 1845 or thereabouts: “One…is that he wished to see how long it would be before they were regarded as relics of the ancient past – this is commonly said of them today. The alternative is that they were a demonstration of the power of his tree-lifter”. The tree-lifter was the Colonel’s invention for transplanting trees up to 30 feet in height with their ball of earth intact, a feat the apparatus apparently made possible for a single individual to do at a rate of one tree per day. The somewhat aptly-named Colonel Greenwood was very enthusiastic about the importance of trees to the landscape and wrote a book in 1844 called The Tree-lifter, Or a new method of transplanting forest trees,....Colonel Greenwood is said to have excavated local archaeological sites and was a keen geologist referred to as ‘the father of subaerialism’, ascribing the greater inequalities in the earth’s surface to atmospheric influences. ..It was said in his obituary that “had he fallen amongst geologists in early life, instead of amongst ‘thoroughbreds’, he would doubtless have occupied a leading place among men of science”. ... Incidentally, the colonel is buried nearby at All Saints church, Hinton Ampner, his grave stone a recumbent sarsen which stands out pleasingly amongst all the more traditional ones. " 

 

A few thoughts on the 2024 Sarsen Debitage Paper

Local and exotic sources of sarsen debitage at Stonehenge revealed by geochemical provenancing

T. Jake R. Ciborowski, David J. Nash, Timothy Darvill, Ben Chan, Mike Parker Pearson, Rebecca Pullen, Colin Richards, Hugo Anderson-Whymark,

Journal of Archaeological Science: Reports, Volume 53, 2024, 104406, ISSN 2352-409X, https://doi.org/10.1016/j.jasrep.2024.104406. (https://www.sciencedirect.com/science/article/pii/S2352409X24000348)

An exciting addition to Stonehenge Research, identifying the sources of the stones not only satisfies the Stonehenge completist but also provides hints into the society that built it. The paper is very thorough and open and deserves study, even if the technicalities are beyond your ken.  

The authors have been admirably restrained in drawing conclusions about the sources of the debitage but it is worth emphasising the shortcomings they admit to. This is very much a preliminary paper and the tentative sources are just that.

The first problem is that they are using only twenty sample sites to compare with, the sites are detailed in David J. Nash et al. , Origins of the sarsen megaliths at Stonehenge. Sci. Adv.6,eabc0133(2020). DOI:10.1126/sciadv.abc0133  

Click to embiggen

There is much more work to be done in sampling and plotting the variations in Sarsens before there can be confidence that all potential sources or areas are known.

Secondly because of the well explained constraints they were working under the analysis had to be purely geochemical, whilst it isn't quite true that Coal and Diamonds are the same geochemically the principle that identification needs more than just the chemistry is valid.

These points are known and acknowledged by the authors but in the excitement of considering how and why sarsen may have come from across southern Britain to Stonehenge they need to be born in mind.

That long distance transport of stones and maybe even soil, Silbury?,  was a Neolithic practice is well known, but this study points to where new archaeology research may be fruitful.

There is one small inconsequential archaeological error I think I noticed in the paper. The position of excavation STH08 is erroneously plotted. I believe it is nearer the red rectangle I have overlain below.

As I blogged before it is a shame the excavation report* doesn't include a plan so it might be a problem if the plan becomes the record that is referred to in the future.

*(The Antiquaries Journal, 89,2009,pp1–19r The Society of Antiquaries of London, 2009 doi:10.1017⁄s000358150900002x. First published online 21 April 2009)   

Local and exotic sources of sarsen debitage at Stonehenge revealed by geochemical provenancing,

David Nash et al have released a new paper on the Sarsen Sources of Stonehenge:

T. Jake R. Ciborowski, David J. Nash, Timothy Darvill, Ben Chan, Mike Parker Pearson, Rebecca Pullen, Colin Richards, Hugo Anderson-Whymark,

Local and exotic sources of sarsen debitage at Stonehenge revealed by geochemical provenancing,

Journal of Archaeological Science: Reports,  Volume 53, 2024, 104406, ISSN 2352-409X,

https://doi.org/10.1016/j.jasrep.2024.104406.

(https://www.sciencedirect.com/science/article/pii/S2352409X24000348)

Abstract: The application of novel geochemical provenancing techniques has changed our understanding of the construction of Stonehenge, by identifying West Woods on the Marlborough Downs as the likely source area for the majority of the extant sarsen megaliths at the monument. In this study, we apply the same techniques to saccharoid sarsen fragments from three excavations within and outwith the main Sarsen Circle to expand our understanding of the provenance of sarsen debitage present at the monument. Through pXRF analysis, we demonstrate that the surface geochemistry of 1,028 excavated sarsen fragments is significantly affected by subsurface weathering following burial in a way that cannot be overcome by simple cleaning. However, we show that this effect is surficial and does not have a volumetrically significant impact, thus permitting the subsequent use of whole-rock analytical methods. Comparison of ICP-AES and ICP-MS trace element data from 54 representative sarsen fragments with equivalent data from Stone 58 at Stonehenge demonstrates that none are debitage produced during the dressing of this megalith or its 49 chemical equivalents at the monument. Further inspection of the ICP-MS data reveals that 22 of these fragments fall into three distinct geochemical ‘families’. None of these families overlap with the geochemical signature of Stone 58 and its chemical equivalents, implying that sarsen imported from at least a further three locations (in addition to West Woods) is present at Stonehenge. Comparison of immobile trace element signatures from the 54 excavated sarsen fragments against equivalent data for 20 sarsen outcrop areas across southern Britain shows that 15 of the fragments can be linked to specific localities. Eleven of these were likely sourced from Monkton Down, Totterdown Wood and West Woods on the Marlborough Downs (25–33 km north of Stonehenge). Three fragments likely came from Bramdean, Hampshire (51 km southeast of Stonehenge), and one from Stoney Wish, East Sussex (123 km to the southeast). Technological analysis and refitting shows that one of the fragments sourced from Monkton Down was part of a 25.7 cm × 17.9 cm flake removed from the outer surface of a large sarsen boulder, most probably during on-site dressing. This adds a second likely source area for the sarsen megaliths at Stonehenge in addition to West Woods. At this stage, we can only speculate on why sarsen from such diverse sources is present at Stonehenge. We do not know whether the fragments analysed by ICP-MS were removed from (i) the outer surface of Stones 26 or 160 (which are chemically distinct to the other extant sarsen megaliths), (ii) one of the c.28 sarsen megaliths and lintels from the c.60 erected during Stage 2 of the construction of Stonehenge that may now be missing from the monument, or (iii) one of the dismantled and destroyed sarsen megaliths associated with Stage 1 of the monument. With the exception of the fragment sourced from Monkton Down, it is also possible that the analysed fragments were (iv) pieces of saccharoid sarsen hammerstones or their pre-forms, or (v) small blocks brought on-site for ceremonial or non-ceremonial purposes.

Keywords: Stonehenge; Sarsen; Silcrete; Geochemical provenancing; pXRF; ICP-AES; ICP-MS

David kindly explained the findings on X (née twitter) 

https://threadreaderapp.com/thread/1750941470075371525.html

First, we analysed 1,028 sarsen fragments from 3 trenches dug at Stonehenge in 2008 using pXRF to see if there were differences within and between the trenches. In short, there weren't, due to subsoil weathering effects. Morale: don't bother using pXRF for this sort of thing.

Second, we analysed 54 sarsen fragments from the 3 trenches using ICP-MS. This is where it gets interesting. Comparison of the geochemistry of fragments against data for 20 sarsen outcrop areas across southern Britain shows that 15 fragments can be linked to specific areas.

Eleven sarsen fragments were likely sourced from Monkton Down, Totterdown Wood and West Woods on the Marlborough Downs (25–33 km N of Stonehenge). Three fragments likely came from Bramdean, Hampshire (51 km SE of Stonehenge), and one from Stoney Wish, East Sussex (123 km SE).

You might be thinking "Wow, Neolithic people dragged sarsen boulders all the way from Hampshire, East Sussex and other sites on the Marlborough Downs to build Stonehenge, not just from West Woods!" Not quite. Calm down, calm down.

We cannot tell if the fragments are from extant megaliths, or from stones from earlier phases of Stonehenge, or stones that have been removed. It is also possible the fragments were from saccharoidal sarsen hammerstones, or stone brought to Stonehenge for some other reason.

There is one exception - a sarsen fragment sourced from Monkton Down that we know (thanks to expert refitting by Ben Chan) was part of a 25.7 × 17.9 cm flake removed from the outer surface of a large sarsen boulder, most probably during on-site dressing.

We're pretty sure this boulder isn't on site today, unless it is stone 26 or 160, which have a different chemistry to the other extant sarsens. However, it adds a second likely source for the Stonehenge megaliths in addition to West Woods. I'll leave it there. Happy reading!

How to set out the Stonehenge Sarsens - a workbook by Tim Daw

A practical guide to setting out a replica of the sarsen stones of Stonehenge, suitable for school, college or research purposes. By providing a method insights into the building of Stonehenge and the skills of the neolithic builders are gained.

DOI: 10.13140/RG.2.2.10572.59520

https://www.academia.edu/113831164/How_to_set_out_the_Stonehenge_Sarsens_a_workbook_by_Tim_Daw

One Drive Link

The best way to understand a concept is to have to explain it and teach it so this workbook has helped me, I hope it helps others. Any problems getting a copy from the links above give me a shout.

Sexagesimal Stonehenge and the Bush Barrow Lozenge

Sexagesimal Stonehenge – The Geometry of the Stonehenge Sarsen Trilithons.

Tim Daw*

 

Sexagesimal Stonehenge and the Bush Barrow Lozenge - Tim Daw

      Stonehenge is a mystery that attracts explanations which range from the banal to the fantastic. To claim a new theory is original, interesting, and credible is to set a high hurdle. This brief note presents what is believed to be a new geometric design that is simple, elegant, and intriguing.

      The positions of the five sarsen trilithons of the inner horseshoe at Stonehenge can be explained by a simple plan of chords based on the sixty points of the outer sarsen circle. This layout provides an accurate geometry for aligning to all the solstitial sunrises and sunsets.

      The same geometry is exhibited by the Bush Barrow Lozenge.

 

Fantasy Quarry?

 

A paper has been uploaded to Researchgate claiming: Carn Goedog on Mynydd Preseli was not the site of a bluestone megalith quarry

"This paper examines the hypothesis that Carn Goedog, a prominent tor on the north 5lank of Mynydd Preseli in Pembrokeshire, Wales, was the site of a Neolithic quarry from which Stonehenge bluestones were extracted on a large scale. The dolerite sills in the area are geochemically heterogenous, with multiple outcrops. Claims of !precise provenancing" of Stonehenge spotted dolerite fragments to Carn Goedog are questionable.. Geomorphological studies on the tor reveal that pillars suitable for use as monoliths are restricted to a few small areas, difficult to access. Frost-shattered blocks dominate. Many have sub-rounded edges, suggesting long-term weathering and redistribution by glacier ice. Moulded and smoothed surfaces indicate that the influence of overriding ice has been considerable. At Stonehenge, most of the bluestones are abraded boulders which look like glacial erratics. Examinations of the supposed !Neolithic quarry" site reveal that all of the "engineering features" are natural. Stone artefacts owe nothing to quarrying activities, but point to a history of intermittent occupation. Soft shale "wedges" supposedly used for extracting pillars from the rock face are natural and ubiquitous. Radiocarbon dating effectively falsifies the quarrying hypothesis. There was no Neolithic quarry at Carn Goedog, and if blocks of spotted dolerite were extracted and transported away from the vicinity of the tor, the agency was glacier ice." (sic)

That is probably all you need to read, no evidence that bluestones were transported by glaciers, presumably to Salisbury Plain, is offered.

Sexagesimal Stonehenge – The Geometry of the Stonehenge Sarsen Trilithons.

(Updated draft)

Tim Daw*

 

Sexagesimal Stonehenge and the Bush Barrow Lozenge - Tim Daw

      Stonehenge is a mystery that attracts explanations which range from the banal to the fantastic. To claim a new theory is original, interesting, and credible is to set a high hurdle. This brief note presents what is believed to be a new geometric design that is simple, elegant, and intriguing.

      The positions of the five sarsen trilithons of the inner horseshoe at Stonehenge can be explained by a simple plan of chords based on the sixty points of the outer sarsen circle. This layout provides an accurate geometry for aligning to all the solstitial sunrises and sunsets.

      The same geometry is exhibited by the Bush Barrow Lozenge.

 

The All Cannings Plough

The Museum of English Rural Life, Reading has a plough from All Cannings in its collection. It was used on what was my farm many years ago. It has a wooden mouldboard, probably made of elm. By coincidence a photo of the plough is part of the Salisbury Museum collection.

Wooden mouldboards were favoured by the ploughmen,  Albert and his son George Tilley,  when the clay was wet and heavy, they claimed it didn't stick as much.

A story I was told was that when a new mouldboard was sent up from the Hiscocks in the village Albert was affronted that the the "boy" was sent up to fit it. He claimed it didn't draw true so old man Hiscock was summoned to put it right. As he left the workshop he picked up a handful of shavings. After the visit Albert boasted how he knew it needed fettling, so young Hiscock asked his dad what he did. "Just scattered the shavings around".

https://collections.salisburymuseum.org.uk/object/SBYWM:2011R.14.222

https://www.reading.ac.uk/adlib/Details/collect/2569

Champion ploughman Nelson Tamblin demonstrates his skills at the World Ploughing Championships in Shillingford, Oxfordshire, in 1956, using a plough drawn from The MERL collection (MERL 60/1475).

https://merl.reading.ac.uk/blog/2024/01/ploughs-and-ploughing-some-reflections-from-the-headland/

The Marshes of the Pewsey Vale

The route the sarsens, and maybe the bluestones, were brought across the Pewsey Vale to Salisbury Plain was, in my opinion, largely governed by the necessity of staying on the firmer dryer land.

The present damp weather provides a snapshot of the land still liable to flooding despite the many drainage and canalisations of rivers. These are the remnants of the large marshy areas that filled the vale.

My suggested route from West Woods to the top of Redhorn Hill via Marden looks the best.

Source https://check-for-flooding.service.gov.uk/

The Limeslade Bay Erratic discovery

Upon a shore where waves in tempest churn,

A hulking mass of stone, unyielding, lay,

Its surface rough, by ocean's wrath in turn

Made stark and bare, where storms hold their sway.

Within its heart, a tumult seemed to bide,

A hollow drum where roars and rumbles deep

Did echo forth, as though history's tide

Had found a voice within its stony sleep.

And yet, for all the sound and fury pent

Within its depths, no meaning could be found,

No whispered lore, no message heaven-sent,

Just empty noise upon the wind-whipped ground.

So lies the stone, a monument to strife,

A hollow shell where echoes mock at life.

https://www.pembroke-today.co.uk/news/giant-glacial-erratic-hailed-as-missing-piece-of-bluestone-puzzle-505195

A giant bluestone erratic just discovered near Mumbles, on the south Gower coast, has been hailed as one of the most important glacial discoveries of the last century since it proves beyond doubt that the Irish Sea Glacier was capable of carrying large monoliths of dolerite rock from Pembrokeshire up the Bristol Channel towards Stonehenge.

Two years today after this wonderful discovery of a large erratic deposited on a rocky coast by an ice floe we still haven't been allowed sight of the analysis which may reveal where it was plucked from to be dropped in Limeslade Bay. We continue to await with interest.