Map showing the extent of superficial deposits in Great Britain (BGS).
One of the most perceptive comments comes from Prof David Evans from my old Geography Dept (in Durham University). David points out that the lead isoscape map (or any other isoscape map, for that matter) cannot be deemed to be at all accurate unless it is based on the analyses of samples taken from superficial deposits such as till or glaciofluvial sands and gravels. As far as we can see, the samples used in the creation of the "lead isoscape map" have been taken exclusively or largely from lead ores found in quarries, mines or surface spoil, or from bedrock outcrops. The texts of the key papers hardly mention superficial deposits at all, and the underlying source for the map is the solid geology map of Great Britain. Hence we have mentions of assorted geological provinces that coincide with Mesozoic, Upper Palaeozoic and Lower Palaeozoic domains......
This is a very strange state of affairs, since on the other side of the North Sea related studies are concerned not with solid geology and rock outcrops but with the distribution of superficial deposits. If you are trying to trace where grazing animals might have spent part of their lives, you have to accept that the prime isotopic signature features will have come not from bedrock but from the nature and thickness of the superficial deposits on the grazing route.
In a study of the grazing animals associated with the Viking settlement of Birka in Sweden, the researchers used a regional map of superficial deposits in seeking to find signature matches and animal provenances. They discovered that some animals had travelled from grazing areas c 180 km away.
Walking commodities: A multi-isotopic approach (δ13C, δ15N, δ34S, 14C and 87/86Sr) to trace the animal economy of the Viking Age town of Birka
Nicoline Schjerven et al
https://www.sciencedirect.com/science/article/pii/S2352409X24001718?via%3Dihub
Journal of Archaeological Science: Reports
Volume 56, June 2024, 104543
ln a study of strontium and other isotope signatures in the Netherlands, the authors ignored the bedrock geology map and concentrated entirely on the isotope signatures of the main groups of superficial deposits including glacial till. They stated that because much of the Netherlands is composed of relatively young glacial and river deposits, the strontium isotope ratios are determined primarily by surface sediments, not the underlying ancient bedrock.
It is strange that the British paper by Evans et al makes no mention of superficial deposits, since the lead author (Prof Jane Evans) was a co-author of several of the key papers relating to other countries that have been heavily glaciated.........
At this point it needs to be pointed out that for lead isotope studies it can be accepted that grazing animals will consume (deliberately or accidentally) small quantities of soil, mud and dust that are derived largely from underlying sediments. By and large, these materials will not have come from bedrock which may be buried beneath sediments many metres thick. It would be disingenuous to pretend that "ingested mineral materials" should be discounted because they might be contaminated as a result of industrialisation over the past few centuries. If they are good enough to be used in studies in Sweden, the Netherlands and elsewhere, they are good enough for the British Isles.
So the map that should. have been used as the base map for the lead isoscape studies is th one above, showing generlised ice movement directions and the distribution of glacial sediments. Both till and glaciofluvial sediments are made of rock debris derived from areas overridden by glacier ice. By looking at the established maps of iceflow it is possible to draw conclusions on what "inherited signatures" there might be. Thus the glacial tills around the Bristol Channel should carry an inherited isotopic signature from Lower Palaeozoic rocks situated upstream. The tills of the English West Midlands will contain inherited isotopic signatures from the Welsh uplands and from the Pennines, and perhaps from even further afield. The tills of the Oxford region were generated by "Northern ice" and will contain inherited signatures from the Pennines. The tills of the East Midlands will contain inherited signatures from NE England and maybe even further afield.
To summarise, the geological maps of superficial deposits show that the published contour lines between adjacent "isoscape" regions have almost everywhere been drawn in the wrong positions. Broadly, ice movement directions show that bedrock-derived debris has been moved southwards, leading to "inherited signatures" some distance from the bedrock lead sources. The bio-availability of isotopes is therefore misrepresented in maps such as this:
It follows that there may be many more potential source areas for the "Stonehenge cattle tooth" than those considered by the authors of the published article. The suggestion that the cow that owned the tooth came from SW Wales is completely unsupported by hard evidence. It is much more likely that it came from the Cotswolds or the Thames Valley.
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See also
https://pmc.ncbi.nlm.nih.gov/articles/PMC12173513/
Strontium isoscapes for provenance, mobility and migration: the way forwardMaximilian J Spies et al
R Soc Open Sci. 2025 Jun 18;12(6):250283
Proceedings of the Geologists' Association, Volume 126, Issues 4–5, October 2015, Pages 608-632
Steve Booth, Jon Merritt, James Rose
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