Wednesday, 18 December 2019

Stonehenge Bluestone Glaciation Pontification


Dr Brian John takes aim on his blog at a mystery man who raises doubts about John's theory that glaciers brought the bluestones to Stonehenge, or at least somewhere near by, by answering some questions put to him. He claims "there is not a shred of hard evidence in support of the idea of long-distance human transport of bluestones from Wales to Stonehenge, either by land or sea." Taking absence of evidence as evidence of absence he declares it must obviously be glaciers then.


https://brian-mountainman.blogspot.com/2019/12/the-stonehenge-bluestones-pontification.html has the full question and answer but briefly, the questions put first, the meat of Dr John's answers for brevity's sake next in italics and my own short thoughts afterwards.

1)Where's all the other bluestones on the Salisbury Plain? Surely a glacier wouldn't have brought only the precise number of them required at Stonehenge...?

Response: this is an absurd point, and I cannot for the life of me understand why people are still making it, after all the advances of recent years. Forget the "immaculate Stonehenge" with 82 bluestones and 82 sarsens. There is no evidence that Stonehenge was ever completed.....It is far more logical to suggest that there never were enough bluestones to finish "the Stonehenge project", and that after playing around with assorted stone settings over many centuries, the builders (maybe the descendants of the originators) just gave up and walked away...... This argues for the use of glacially transported erratics which were systematically collected up and used -- until there were none left in the Stonehenge landscape.

So not a single bluestone left unfound in a till deposit? Really? No little ones that weren't big enough to be erected? No pebbles? That is stretching the bounds of believability.

2. While sampling the various types of stone isn't allowed at the site, the volume of chips found in the wide area would easily correspond with the presumed number of present and missing stones. There's lots of visual evidence that points to stone-bashing throughout the life of the monument. See also the 'Stonehenge Layer'.

Response: The suggestion that the "volume of chips" somehow corresponds with the presumed number of missing stones does not survive a moment's scrutiny. Some mathematics please!...

OK. Roughly to get order of magnitude, 30 two tonne stones missing (above ground). 60 Tonnes of Bluestone. Stonehenge layer covers roughly 120 square meters. Stonehenge layer is the debitage from making trinkets so assume wastage at a quarter the of weight, but if trinkets are made elsewhere, as bluestone debitage found elsewhere might suggest, halve that. So the expected weight would be in the order of 1/8 tonne per square meter - 125kg per square meter (1/8 of 60 tonnes spread over 120 square meters) . The layer is 350mm thick of which a large proportion is bluestone, say equivalent to 50mm of it. Which would be 130kg of bluestone at a 2.6 tonne cubic meter density. Very, very rough maths but as a first pass to get an idea of magnitude not too far off.

3. The vacant stone-pipe at Rhosefellin more than suggests it was removed by humans -- no glacier would select a single example from that face and leave the others intact. Despite what Dr Johns says, the site was a well-used quarry from as far back as the Mesolithic. The petro-chemistry of that pipe matches Bluestone-44, that stone having been sampled before the present rules applied.

Response: Ah -- Rhosyfelin! A lovely spot. Right on my doorstep. Now we are seriously into the realms of fantasy. "The vacant stone pipe" or "monolith extraction point" (as MPP likes to call it) does not exist....

You say, he says. Shall we just say the jury is out on whether the monolith was levered out or fell out? But that doesn't tell us much about how it made the rest of the journey. The question of the quarrying is a different one to the transport and conflating the two is unhelpful.

4. In the 1920s HH Thomas was wrong about a possible source being Carn Meini -- they are now known to include Carn Goedog and probably Bedd Arthur. There is a lot of archaeological evidence surrounding these sources.

...most definitely not Bedd Arthur. The latter is not a rock outcrop but a stone setting including small locally-derived monoliths; nobody has ever claimed that it was a source for Stonehenge monoliths. More care, please.

No comment to the archaeology around Carn Goedog I note.

5. There is a marked difference in size and shape between the outer bluestone ring and the inner horseshoe. This strongly suggests they arrived at different times -- the outer ring almost certainly near-original, with the taller versions being installed after the Trilithons went up, much much later. How likely is it these were collected from deposits of the near-environs in such precise order?

...I strongly disagree that the stones arrived at different times, as a result of two distinct stone-collecting expeditions. There is no evidence to support that contention. There was no "precise order." I agree that the stones have been rearranged many times, and my reading of the evidence is that in the last re-setting the "best" of the bluestone assemblage (including the tallest and most elegant pillars) were selected for the horseshoe, and some of them were carefully worked and embellished.

Sorry, having spent many hours in close communion with them they are an as obvious two different sets of stones as one could wish for. There are no intermediate members of the sets.

7. Show me evidence of a glacially entrained Welsh Bluestone south of Bristol.
The idea of glacial transport has been thoroughly examined and found to be implausible. It's not the conspiracy of prevailing thought -- it's very well established.

Response: If you don't mind me saying so, that is an arrogant and dismissive statement put out by somebody who does not know the literature. Can Mr X please tell us which experts have found the glacial transport idea to be implausible?....Mr X needs to do some enlightening Christmas reading. On the matter of glacially entrained bluestones south of Bristol, he just needs to buy a copy of my book...


So no answer to the key point: "Show me evidence of a glacially entrained Welsh Bluestone south of Bristol"

So still no evidence of bluestones being brought by glaciers to the English side of the River Severn, and once you accept, which he does, that the builders of Stonehenge could manoeuvre the stones a short distance then it is logical that could have moved them hundreds of miles. It is just a question of time.

I think we have moved on from Atkinson's view that the builders of Stonehenge were “howling barbarians, practically savages,” and acknowledge them as skilled tenacious craftspeople who had no need of a deus ex machina in the shape of glaciers, aliens or Merlin. So until we see a shred of evidence that glaciers brought the bluestones across the water we are entitled to ignore the Glacial transport theory. The question has rightly been put but there are no observations to support the hypothesis of glacial transport nor has the null hypothesis, that they were transported by humans, as many other stones at that period were and as even they were on part of their journey, been put in doubt by any observations.

Conclusion: There is not a shred of hard evidence in support of the idea of long-distance glacial transport of bluestones from Wales to Stonehenge, either by land or sea.

14 comments:

  1. Thanks Pete -- now we are all pontificating. More and more assumptions piling up. We could go on for ever. I have never claimed that there is solid and incontrovertible evidence for glaciation on Salisbury Plain -- although the shapes and characteristics of all those glacial erratics in the outer circle seems pretty good to me.

    Just a few points:
    1. Re "unfound bluestones" -- there may be till somewhere on Salisbury Plain, or it may be so old that it has been destroyed. Again absence of evidence is not evidence of absence. There are certainly smaller bits and pieces of bluestone in the sediments that are too small to have been used as monoliths. Abundant scattered references to finds, as you know. Some serious research needs to be done on the packing stones, for a start.
    2. The weight of bluestone debris? A noble effort, but the Stonehenge Layer is highly variable in thickness and distribution, and the density of stones per cubic metre is also highly variable. If you think that there may be enough in the way of fragments to account for 30 bluestones, remember that Rodney Castleden calculated that there was enough debris to account for 3. Hmmm -- who is closer to the truth, I wonder?
    3. THE monolith? Assumptions again -- and it wasn't me that raised this issue. Just referring to Neil's little list.
    4. Carn Goedog? Come now, Pete. You know I have done a paper on Carn Goedog, which almost everybody has read. In case you missed it:
    https://www.researchgate.net/publication/332739336_Carn_Goedog_and_the_question_of_the_bluestone_megalith_quarry
    421 reads, and counting.
    5. Two different sets? Your humble opinion ....... what would an intermediate stone actually look like?
    7. Glacially entrained Welsh bluestones south of Bristol? In the Somerset glacial deposits there are dolerites, rhyolites, tuffs and limestones -- there has been no definitive geological work,but a number of workers have suggested Pembrokeshire provenances.
    Many other stones have been transported long distances by the builders of megaliths? Really?!!! That's not what Olwen Williams-Thorpe and her colleagues concluded, after the only decent study on the subject.
    No observations support the glacial transport hypothesis? That is just not true - there is abundant evidence to the west of Salisbury Plain- but I would agree with you that there is a big question mark still over the chalk downs.

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  2. Sorry Tim -- I put in "Pete". Late at night, and not paying attention..... goodnight!

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  3. The questions look oddly familiar, almost as if I could have written them myself ...

    In any case, Dr Johns is a lovely man who's taken the time on several occasions to enlighten me concerning certain aspects of how glaciers work. These things are marvelous engines with more than a few surprises.

    Unfortunately, after exhaustive review, I have come to the conclusion that it is unlikely to a high degree of probability that sheets of ice transported the Bluestones to Stonehenge or its near environs.

    And while I concur that absence of evidence isn't evidence of absence, I must hark to the first question, which throws that quote to the wind. No doubt about it -- glaciers leave enormous trains of evidence behind, and there simply isn't any for a considerable distance to the north, east, or west of the Salisbury Plain.

    So how did the 80+ Bluestones get there?
    Well, there's only one plausible explanation.

    Best,
    ND Wiseman

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  6. I do tend to agree that if we want to worry about anything, it is probably the climate crisis we should be concentrating on......

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  12. Some might say there are "glaciation" phenomena closer to home... Like the Comments facility on this so-called 'WEBsite'...

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