In the midst of all the media celebrations about the solving of the great sarsen stone mystery, I'm quite intrigued by some of the comments from quite senior academics in Twitter conversations with David Nash. There seems to be more or less universal praise for the research, which suggests to me that nobody has actually read the article properly, and that academics have simply been reacting rather lazily to the press coverage and the items broadcast on the BBC, ITV, and Sky.
I am really the only person concerned about the following?
Ref: Nash et al, 2020: https://advances.sciencemag.org/content/6/31/eabc0133
1. No attempt is made to explore the possibility that the Stonehenge sarsens were all picked up from the chalklands of Salisbury Plain. (Instead, for some reason, areas like the North Downs, the East Anglian Heights, and Dorset were treated as higher priorities.)
2. The conclusion that 50 of the 52 Stonehenge sarsens are from one common source is not adequately supported by Figure 2 of the paper, since only some of the 260 data points (5 readings were taken from each stone) are identified, and there are many "outliers" which are simply ignored. I have been unable to access the full data sets and supplementary materials -- I don't know why. (I don't have a problem with most of the Stonehenge sarsens having a shared geochemistry -- that's what one would expect if the stones were picked up locally -- but it would be good to know just how wide the variability is, rather than just being told that 50 of the sarsens have come from a single source.) Here is the link, if anybody else wants to try: http://advances.sciencemag.org/cgi/ content/full/6/30/eabc0133/DC1
3. The "matching" of the Stonehenge sarsens to the sarsens of West Woods is dependent upon the examination of just ONE sarsen from West Woods and just ONE sarsen from Stonehenge. This is completely unsatisfactory, as the authors of the paper must know. And yet they have claimed that "most of the sarsens at Stonehenge have come from West Woods."
4. I'm worried that the plotting of the trace element data for stone 58 and for the 20 sampled sarsen sites does not involve a direct "like for like" comparison. This is because the core samples were done on rock taken from deep within the sarsen stone, while the other measurements were from non-invasive surface readings. I would like to know how this might have affected the information plotted.
5. The plot of trace element ratio data for West Woods is used by the authors of the paper as the "killer fact" that establishes beyond all reasonable doubt that the Stonehenge sarsens came from this site. And yet, when we look at it carefully, its value is very limited indeed.
Note added 7th August 2020: Since this post is still getting lots of hits (590 so far, and counting) and since most readers will not have the stamina to read more than 50 discussion contributions, this is the state of play:
Point 1. This is still a matter of concern
Point 2. Lead author David Nash is adamant that 50 of the Stonehenge sarsens are from a common source, and that the scatter seen on Fig 2 of the paper is down to natural variation within samples. I'm still not convinced. Further research will no doubt reveal the truth.
Point 3. I'm happy to correct this. In fact THREE stones from West Woods were sampled. I was misled by an error in the paper (now acknowledged by David) which referred to "20 field samples" (ie one from each of 20 sampled field locations) when it should have referred to "60 field samples" (ie three sampled boulders in each location). I should have checked this out in the Supplementary Data files, but initially had problems accessing them. Anyway, apologies for that mistake.
Point 4. Again, my mistake. I was misled by some ambiguous wording in the paper to believe that ALL of the sampling was non-invasive. In fact the non-invasive sampling was done just at Stonehenge (the stones are deemed too precious to harm in any way), while the stones from other sites were investigated via rock samples taken to the lab. I should have read the paper more carefully. There was a "like for like" comparison of the stone 58 (Stonehenge) core with the 60 or so samples taken from other locations.
Point 5. David claims that the West Woods trace elements ratio graphic is as close to a perfect match with the data from core 58 as it is possible to get. He also says that a perfect match would only be proposed if ALL of the element ratios overlap on the graphic. To me, it looks as if one of them (Uranium?) doesn't overlap, but that may be down to my fuzzy computer screen....... At any rate, I haven't changed my view that the best we can currently say is that "Of the 20 potential sarsen provenencing sites so far investigated, West Woods provides the best match, and on current evidence it is the most likely source for the bulk of the Stonehenge monoliths." That is very different from saying "We now know where the Stonehenge sarsens came from."
Additional Note 10th August 2020. David is very upset again, and claims that I am misrepresenting him. In point 2 I used inverted commas around the words "scatter" and "natural variation" -- as I often do without any disrespect or cynicism. If the word "cluster" is acceptable, I am not sure why there is a problem with the word "scatter." Anyway, I have now removed the offending inverted commas, and hope that that will make him happy. Time will tell whether the 50 Stonehenge sarsens are from exactly the same source, and whether there are other variables (as yet unidentified) that affect PXRF readings. (In my time, I have seen many wonderful new techniques being used. Initially they are all believed to provide "correct" information -- until, later on, the correction factors kick in, and interpretations and conclusions have to be revised, sometimes very dramatically........) Next, David is upset that I mention "some ambiguous wording" in my point 4. This is getting ridiculous, and I'm getting fed up. Almost all papers contain phraseology that could have been better, and this one by Nash et al is no exception. The last paragraph of the Introduction should have referred to "rock samples taken from a representative range of sarsen boulders" to make it clear that an invasive technique was involved. And OK -- if David tells me that there is an overlap on the graphic for the U element ratio, I'll take his word for it.
It's a bit rich that David bangs on furiously about my "misrepresentations" of his scientific research, but cannot even bring himself to apologise for his own mistake in referring in the paper to 20 field samples of sarsen when the figure should have been 60. Just a typo? Hmmmm...
On everything else we will agree to differ, and if David wants to say anything else he can say it elsewhere.