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Thursday 1 February 2024

The Stonehenge sarsens were from multiple sources -- are we surprised?

Source:  Ciborowski et al, 2024

Thanks to Peter for bringing this new paper to my attention.

Well well -- the sarsen story at Stonehenge gets more and more interesting.  As readers of this blog will recall, we had a bit of a spat with David Nash about the reliability of the evidence pointing to West Woods as the prime source of Stonehenge sarsen monoliths.  Shall we say that on the evidence as it was presented (in 2020), I was not entirely convinced.........

Then along came our old friends Ixer and Bevins in 2021 to make the point that too much certainty in pXRF work is not a good idea, and that results can be heavily influenced by the frequency and locations 
of sampling in the field.  There are other variables that might also skew results, as all who use the technique readily admit.  I & B suggested that the Stonehenge sarsens (and in particular the smaller pieces used as packing stones, hammer stones etc) might well have come from multiple sources.  That sounded perfectly reasonable to me, and their argument was convincing.

Now this latter point is reinforced by a new study from Jake Ciborowski and David Nash, with inputs from some of the key Stonehenge players including Tim Darvill and Mike Parker Pearson, presumably related to the use of data from their Stonehenge digs.

So what does the new paper say? It's long and very complex, and (not surprisingly) there is no move away from the view that almost all of the sarsen monoliths to be found at Stonehenge were carried by Neolithic tribesmen from West Woods. The authors continue to maintain that the pXRF evidence presented cannot be interpreted any other way. 

 In this paper they move on to the "sarsen debitage" and having examined over 1,000 fragments using pXRF methods they decide that "none are debitage produced during the dressing of stone 58 or its 49 chemical equivalents at the monument".  They spend a lot of time in the paper testing for variations in the examined fragments, due to surface weathering and other factors, but conclude that the results are reliable and representative.  They suggest that the samples fall into three "families" with similar geochemical characteristics.  This is where it gets interesting.  They take 54 excavated sarsen fragments and compare them with the data from 20 different sarsen areas in southern Britain, and suggest that only 15 have matches in specific localities -- 11 from the Marlborough Downs, 3 from Bramdean in Hampshire, and 1 from Stoney Wish in East Sussex.  This means that no matches were found for 39 of the fragments, and it means that extremely ambitious (and maybe irresponsible) assumptions are made about the other fragments and their sources on the basis of extremely thin evidence.  For example, what evidence is there that the "geochemical signature" assumed for Stoney Wish is not also found in many other sites much closer to Stonehenge, which do not happen to have been analysed?  That signature may also exist, undiscovered, at sites that HAVE been examined and sampled.  The authors admit that they have a credibility problem when they say, later in their analysis: "......the West Woods outcrop has a compositional range that extends beyond the three samples used to first characterise it".   Hmmmmm.   Let's just say that I am deeply sceptical about anything of significance having been found here........I need MUCH more evidence before I can take any of this seriously.

Quote, concerning the one fragment supposed to have come from 123 km away, in the deep south:  
The presence of sarsen fragments with a geochemical signature exotic to the Marlborough Downs is, however, intriguing. Bramdean lies 51 km southeast of Stonehenge, while Stoney Wish is even further to the southeast at 123 km distant. Given the known extent and direction of movement of Quaternary ice sheets (sic), it is impossible that exotic sarsen material was brought to Salisbury Plain from Hampshire and Sussex via glacial transport (e.g. Lee et al., 2011; White et al., 2017; Scourse et al., 2018; Clark et al., 2022). Instead, the only viable explanation is that it was transported there by humans.   

That is a very big point to make, on the basis of one small and rather dubious fragment of sarsen stone.....

There are some other interesting points in the discussion arising from the analyses of the 4 "rogue"samples.  The authors discuss the use of materials from multiple sources in other megalithic monuments across the British Isles, referring to monoliths, hammer stones and packing stones,  and fragments found in the debitage.  But so obsessed are they with their hypothesis of human transport that not once do they refer to glacial erratics or glaciation.  They prefer rather convoluted explanations of material re-use, recycling and redistribution, with speculative motives added for good measure. They cite the work of Thorpe et al in 1991, but cannot bring themselves even to mention their central point -- namely that the use of materials from multiple sources in a monument is in itself a powerful pointer to the involvement of glacier ice.

I am amazed that this defect was not picked up by the referees or the editor of this paper.........

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 53 (2024) 104406


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.

One last point -- it's rather interesting that the authors of this article (including Tim Darvill and Mike Parker Pearson) are quite happy to see sarsen debitage fragments from Stonehenge analysed with due respect for their relevance.  In contrast, Bevins and Ixer insist, in defiance of logic, that only the Bluestone bluestone monoliths are worthy of serious treatment, and that all "inconvenient" fragments from a multitude of sources in the debitage should be ignored as adventitious.   Unless, that is, the bits in the debitage might have come from one or another of the monoliths, in which case they are given the full treatment.  Funny old world......


Jon Morris said...

"namely that the use of materials from multiple sources in a monument is in itself a powerful pointer to the involvement of glacier ice"

The multiple sources argument does not apply if the locations of the source materials are relevant to the concept/design of the structure (as opposed to construction materials being sourced based only on a specification). As they don't know what the materials sourcing criteria was, they can't make that point: it would be based on a step of faith in an underlying assumption.

BRIAN JOHN said...

yes, it has always been an article of faith that the bluestones were special or sacred -- and maybe even had magical healing powers. Mike PP has also played with the idea that the stones were embued with the spirits of the ancestors, and that they were the most special things that the tribes of West Wales possessed, to be carried with due reverence and presented as tributes to the powerful or dominant tribes that happened to be resident on Salisbury Plain. You have to be rather keen on fantasies to get swept up by this sort of stuff....... especially if you bear in mind that there are 46 (or maybe 30 or 24? who cares anyway?) different stones from different places. Were some monoliths more sacred than others? Were bigger stones more special than little ones? It all falls down, of course, when you have to accept that spotted dolerite and foliated rhyolite (for example) were not treated with any more reverence than the rest of the stones used in megalithic settings in west Wales. All the time, the builders just seem to have used whatever was lying around at the time....