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To address the point re: the provenance of the samples in more detail:
Doubts over the authenticity of the two samples of Altar Stone described in the Nature paper and the disingenuous suggestion that English Heritage might have allowed direct sampling were they asked (John has known for over 10 years that EH will allow no direct sampling of any stone from Stonehenge although it has been asked on quite a few occasions) are groundless. An earlier posting on Megalithic Portal recounts the almost 20 year search for Altar Stone samples and efforts to authenticate them. Indeed the number of different rock types to be found at Stonehenge is so few that separating Altar Stone debitage/samples from Lower Palaeozoic Sandstone and from sarsen macroscopically (confirmed by microscopy and geochemistry) is now routine. Within the Stonehenge Landscape the fine-grained micaceous Altar Stone sandstone is immediately recognisable.
The 19th cent label on the larger Stonehenge sample together with the gap at the base of the Altar Stone, as seen in the 1950 excavation photos, from whence the sample was collected is proof enough. The matching geochemistry between the sample and in situ results taken directly from the Altar Stone (English Heritage did allow direct pXRF measurements to be taken, under very very strict condition) also was a deciding factor in authentication the sample. This is given in great, great, great detail in at least three papers prior to the nature paper. Denying the authenticity belies the facts and smacks of desperation.
Using shop-bought Devonian fish as samples to represent the Orcadian Basin is not a ‘good look; although the samples are from two, well- known –indeed world famous- collecting sites (many have argued over-collecting sites). There can be no doubt but they are Orcadian samples. But the criticism that there are too few Orcadian samples is valid and first made by the referees and initially addressed in the paper. It is being further more systematically addressed with in situ data collecting, (expect news soon).
BUT it misses the point, the Altar Stone has been proved to have come from north of the Iapetus Suture –that is the hub of the nature paper that is the breath-taking discovery. That is to be celebrated rather than flat-worlder, climate-denying sounding sour comments. They are not a substitute for scientific debate.
Where north of the Iapetus Suture, the Orcadian Basin looks our best bet, is the new gold rush.
R.A.Ixer
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