How much do we know about Stonehenge? Less than we think. And what has Stonehenge got to do with the Ice Age? More than we might think. This blog is mostly devoted to the problems of where the Stonehenge bluestones came from, and how they got from their source areas to the monument. Now and then I will muse on related Stonehenge topics which have an Ice Age dimension...
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Sunday, 31 March 2024
Roches moutonnees on the north face of Mynydd Preseli
Thursday, 28 March 2024
If it's rounded, it ain't quarried.....
Two nice photos from our walk down on the Parrog in Newport, the other day. These are two big erratic boulders on the shore platform, just a few yards from the coastal footpath. They are both dolerite boulders. One of them is clearly a glacial erratic, resting on the black mudstone shore platform and probably very close to where it was originally dropped by the ice. The other one has clearly been bashed about a bit, with chunks knocked off it, I suspect by the men who were building the coast defences and placing big boulders along the base of the Parrog sea wall.
The bulk of the bluestones at Stonehenge look like the big boulder in the top photo. If they had been quarried, as Ixer, Bevins and Parker Pearson would like us to believe, they would have looked more like the boulder in the bottom photo. This little matter of stone shape and surface characteristics is something tht the MPP team mambers consistently and quite deliberately ignore. That struck me again the other day when I looked again at the famous "Lost Circle" BBC film, in which MPP pretends that the people who supposedly quarried the Waun Mawn and Stonehenge monoliths were looking for gorgeous pillars. Well, if Stonehenge is anything to go by, and if we follow the logic of the archaeologists that the bluestones were carefully selected at their places of origin, we have to conclude that the megalith hunters had a strong preference for small, weathered, rounded glacial erratics.
Wednesday, 27 March 2024
Hooray for Artificial Stupidity!!!
Tuesday, 26 March 2024
The BBC, the Lost Circle and the rise of pseudo-science
The famous "Lost Circle" programme fronted by the "astonished" Alice Roberts was on the telly again last night, in spite of the BBC being warned in 2022 by me -- and probably lots of other people -- that it is filled with pseudo-science. When I sent a formal complaint in last time, the BBC responded that "we've received no information that would lead us to form the view that the film can't be shown again." Well, as others will know, it's not easy to send them information, and they do not go out of their way to look for it either. ........
The documentary has now been shown NINE times on BBC channels alone, and is also permanently available on iPlayer and YouTube -- so it's a nice little earner for all those involved. This is the marketing pitch:
In a world exclusive, Professor Alice Roberts follows a decade-long historical quest to reveal a hidden secret of the famous bluestones of Stonehenge.Using cutting-edge research, a dedicated team of archaeologists led by Prof Mike Parker Pearson have painstakingly compiled the evidence to fill in a 400-year gap in our knowledge of the bluestones – and to show that the original stones of Britain’s most iconic monument had a previous life.
From the grand fantasy of medieval Merlin legends, to the chemical signatures in microscopic rock fragments, no stone is left unturned in the search for new evidence. By combining innovative 3D scanning techniques, traditional field archaeology and novel laboratory analysis, the team have discovered when and where the stones for Stonehenge were quarried and where they first stood.
Alice shows how the team discovered that the stones must have been quarried 400 years before they were first erected at Stonehenge. The team then focuses on trying to find out if the same stones had an earlier life.
Alice joins Mike as they put together the final pieces of the puzzle – not just revealing where the stones came from and how they were moved from Wales to England, but also solving one of the toughest challenges that archaeologists face.
Their revelations will rewrite the history of Stonehenge forever – this is the story of Stonehenge’s lost circle.
Darvill, T. 2022. Mythical rings? Waun Mawn and Stonehenge Stage 1. Antiquity, 4 November 2022, pp 1-15.
Pearce, N.J.G., Bevins, R.E., and Ixer, R.A. 2022. Portable XRF investigation of Stonehenge -- Stone 62 and potential source dolerite outcrops in the Mynydd Preseli, west Wales. Journal of Archaeological Science: Reports 44 (2022a), 103525.
Parker Pearson, M., Pollard, J., Richards, C., Welham, K., Kinnaird, T., Srivastava, A., Casswell, C., Shaw, D., Simmons, E., Stanford, A., Bevins, R., Ixer, R., Ruggles, C., Rylatt, J. & Edinborough, K. 2022. How Waun Mawn stone circle was designed and built, and when the Bluestones arrived at Stonehenge: A response to Darvill. Antiquity, 96 (390), pp 1-8.
John, B.S. 2024. The Stonehenge bluestones did not come from Waun Mawn in West Wales. The Holocene, March 20, 2024 (published online) 13 pp.
Saturday, 23 March 2024
The Bluestone Interview
I have had a number of requests from people who could not make it to my talk the other day for a summary of my main points. I'll get round to doing that before long in a blog post, but in the meantime here is a reminder of the interview I did with broadcaster Wyn Thomas, on local radio five years ago. It's just 12 minutes long, but in the conversation we cover some of the main issues.
Wyn put this onto YouTube without me knowing anything about it, and I came upon it purely by chance, when checking what was out there on the subject of the bluestones. The sound quality is not very good, since the interview was done over the telephone.
Britain's Pompeii -- what, again?
There's a big push to promote the Must Farm findings as of vast importance for our understanding of Bronze Age Britain. And there is the Pompeii comparison. With some justification, I think, since the finds really are spectacular........
But wait a minute -- haven't we heard this sort of thing before? Why yes -- none other than our old friend MPP used the Pompeii comparison when talking about Rhosyfelin and its supposed quarry. A reminder of ancient history. At the end of the September 2011digging season Mike announced to the world that the "Pompeii of prehistoric stone quarries" had been found, at a location given to him by geologists Richard Bevins and Rob Ixer. He repeated this phrase in his 2012 book, on a section about Rhosyfelin between pages 286 and 291. After the bit about Pompeii, MPP said: "We could hardly believe our luck. This was a smoking gun; the game was up for anyone still trying to argue that the bluestones were not quarries in Preseli during the Neolithic, and then taken to Wiltshire."
Ah, youthful enthusiasm knows no bounds -- and who cares about a spot of hyperbole when you are among friends? Perhaps a little more caution might have been in order, but MPP and his colleagues don't do caution.
Anyway, the Pompeii comparison always was preposterous, since it implies a find that reveals a huge amount of data about the culture, life style, clothing, social order, economy, belief system, etc of a whole community that was wiped out in a catastrophe. I can understand the use of the term with respect to Must Farm, because there a catastrophic fire wiped everything out and brought habitation of the site to
an end. Not on quite the same scale as Pompeii and the volcanic eruption of 79 AD, maybe, but the metaphor is a good one. And as for Rhosyfelin? Well, there never was a quarry there, of course, and what has the site told us about the community that lived in North Pembs during the Neolithic? It has told us that over a long period of time people used to come into the valley of the river Brynberian for a spot of berry picking, hunting and fishing. It's a very pretty location, with a rocky crag, birds singing in the woods, bright sunshine inn the summer and shelter from the wind and rain in the winter. The locals certainly lit camp fires there, so at times they might have stayed overnight. They might have eaten hazel nuts and blackberries. They might have taken some sharp edged bits of rhyolite and used them as cutting or scraping tools. And that's it. The same could be said of multiple sites all over the northern part of Pembrokeshire, which remain unexamined by the archaeologists. So to claim any sort of uniqueness or cultural significance for Rhosyfelin is quite frankly absurd.
Friday, 22 March 2024
Coastal retreat at Abermawr
I have been studying the Quaternary sediment sequence at Abermawr for more than 60 years and have watched with fascination as the coast has retreated inexorably during that time span. When I started coming here the rocky outcrop in the centre of the photograph was not visible at all -- it was buried completely under the storm beach ridge. The ridge is being pushed further and further up the valley, on top of the Holocene sediments in the bog. The peat beds that have been overridden are now exposed intermittently on the seaward flank of the storm beach, and the "submerged forest" is currently covered by the sandy beach. I think that in my lifetime the coast has retreated by about 40m.........
Thursday, 21 March 2024
The Stonehenge bluestones did not come from Waun Mawn in West Wales
At last this article is published, in HOLOCENE journal, having been in the pipeline for around 12 months. Partly my fault, since I have been rather preoccupied with my lovely wife's health issues. Anyway, it is fully refereed and edited, in case you wondered, to the journal's normal high standard.
It's a cause of irritation that it is behind a paywall, but I have placed a PDF version of the accepted manuscript onto Researchgate, here:
So this is my contribution to the learned debate which I trust that MPP and his colleagues will all welcome -- nobody wins when researchers pretend that their output is accepted with universal acclaim......
ABSTRACT
This paper examines the hypothesis that Waun Mawn in West Wales provided the bluestone monoliths that were used at Stonehenge. Some archaeologists believe that the site supports the last remains of a giant stone circle or ‘Proto Stonehenge’ which was dismantled and transported to Salisbury Plain around 5000 years ago. It was claimed, after three excavation seasons at Waun Mawn in 2017, 2018 and 2021, that there is firm evidence of some standing stones which were later removed or broken up, but it has still not been demonstrated that there ever was a small stone circle here, let alone a ‘giant’ one. Furthermore, there have been no control studies in the neighbourhood which might demonstrate that the speculative feature has any unique characteristics. There is nothing at Waun Mawn to link this site in any way to Stonehenge, and this is confirmed by recent cited research. No evidence has been brought forward in support of the claim that ‘this was one of the great religious and political centres of Neolithic Britain’. It is concluded that at Waun Mawn and elsewhere in West Wales there has been substantial ‘interpretative inflation’ driven by the desire to demonstrate a Stonehenge connection.Wednesday, 20 March 2024
Abermawr -- the mystery deepens
McCarroll D, Rijsdijk KF. 2003. Deformation styles as a key for interpreting glacial depositional environments. Journal of Quaternary Science 18: 473–489.
Maximum extent and readvance dynamics of the Irish Sea Ice Stream and Irish Sea Glacier since the Last Glacial Maximum
J. D. SCOURSE et al,
Abermawr is located on the north coast of Pembrokeshire (Fig. 1B), where Irish Sea ice has impinged on a north‐draining catchment 4–5 km west of Fishguard. The sequence at Abermawr (McCarroll and Rijsdijk, 2003) shows Irish Sea glacial sediments overlying locally derived breccia and gravels. The glacigenic sequence is deformed and comprises Irish Sea till overlain by offlapping outwash sands and gravels. The offlapping upper flows represent melt‐out, flow tills and paraglacial slope wash redistributing the glacial sediments. The Abermawr coastal exposures in July 2013 showed Irish Sea diamicton, incorporating thin channel fill outwash sands, which were sampled for T4ABMW01 (Fig. 2A). The OSL sample was taken from a ~0.1–0.15‐m‐thick unit composed of horizontally laminated fine to medium sand that appeared to form an ice proximal outwash channel fill (Fig. 2B).
The remarkable persistence of Devensian chronology; and more about Abermawr
Well, this is fun. In the light of my recent posts about Devensian glacial chronology, I was struck by the very familiar look of that old climatic oscillation diagram from 50 years ago -- based on the work of West, Godwin, Epstein, Zagwijn, Peaepe and others in the period 1950 - 1970. Their pioneering recreations of paleoclimates, based on pollen analyses, oxygen isotope studies, molluscan faunas, varves, radiocarbon dating, dendrochronology etc, were surprisingly accurate -- and they have stood the test of time.
I thought it would be quite entertaining to take part of that brilliant Sidestone Press diagram, flip it onto its side, turn it inside out, and then to set it alongside the diagram based on Richard West and others. Bingo -- an extraordinary match, after five decades of increasingly sophisticated research. Now of course we have all the modern deep sea and ice core research, computer modelling, marine isotope stages and so forth -- but we can see that the founding fathers were pretty well spot on, not just with the big or high amplitude oscillations but with the minor ones as well, in the period we refer to as the Early and Middle Devensian.
Just a reminder:
MIS1 -- the Holocene, the last 12,000 years, starting at the end of the Younger Dryas stage.MIS2 -- the Late Devensian or Last Glacial Maximum, lasting from c 31,000 BP to 12,000 BP. The peak in the British Isles was around 26,000 years ago.
MIS3 -- c 70,000 BP to 31,000 BP -- encompassing the Early and Middle Devensian
MIS4 -- around 71,000 BP, the onset of the Devensian / Weichselian / Würm / Wisconsin glacial stage
MIS5 -- subdivided into 5 sub-stages, starting 130,000 BP and ending c 71,000 BP. Eemian / Iswichian Interglacial. Warm peak around 109,000 BP, but considerable oscillations.
This sequence is under constant review, and some versions may be substantially different from the Wikipedia version.
Anyway, it's good to know that here, at least, we have an hypothesis or a hypothetical time-line that has been scrutinized continuously for over 50 years and altered in its details by ongoing research, but which has in its broader outlines survived the test of time. Karl Popper would have been pleased.........
From a previous post:
This is the most comprehensive exposure of Late Pleistocene deposits in West Wales. There are exposures at both ends of the bay. Storms have revealed an Ipswichian raised beach on a rock platform remnant, and above that there is a sequence of periglacial deposits made up of angular bedrock fragments, but incorporating far-travelled erratics. Above that is a clay-rich Irish Sea till of Late Devensian age and containing striated clasts, fragments of carbonized wood and sea shells. The main components of the till are sea-floor deposits, dredged up by glacier ice moving across the old coastline and later laid down by lodgement and shearing. There are also flow-tills, and the glacial deposits are capped by fluvio-glacial materials, an upper head (referred to in the past as “rubble-drift”), sandy loam and modern soil. The deposits represent a complete advance/retreat cycle close to a glacier margin. In the upper head there are fossil ice-wedges and involutions of Late Glacial age. Beneath the storm beach there are peat beds and remnants of the “submerged forest”, and these organic-rich sediments can be examined in the marsh on the landward side of the storm ridge. There is a continuous stratigraphic record here, probably stretching back c 100,000 years.
Rijsdijk, K and McCarroll, D. 2001. Abermawr, in The Quaternary of West Wales Field Guide, QRA, pp 32 - 38.
John, BS 1970. Pembrokeshire, in Lewis, CA (ed) The Glaciations of Wales and Adjoining Regions, pp 229-265
Welcome to Archwilio
At long last the Welsh archaeology data base is up and running, and seeming to work quite well. It's still a bit clunky when you try to zoom in and out on the satellite map, but that will no doubt improve.........Good news for all who have been frustrated in the past by the process of searching through assorted user-unfriendly sites for the info they want. Now everything seems to be in one place.
This is the link:
https://archwilio.org.uk/wp/?fbclid=IwAR2-Jw2sd5JvbYYk63iSBc6aWEP9ekg3Kwx3eVK6uRwSB8LHuej1WmsZ2wQ#intro-widgets
You can search on a parish by parish basis, zoom in and out, and click on specific sites for the database record to come up. You can also click on links to the PDFs of all the key fieldwork reports from past dacades. So congratulations to all concerned.
For example:
This is the link to the great inventory and report from Nikki Cook of funerary and ritual sites in Pembs, published by Cambria Archaeology.
http://www.walesher1974.org/herumd.php?group=DAT&level=3&docid=301360156
I wanted to check Prof MPP's claim that the Waun Mawn area was "one of the great religious and political centres of Neolithic Britain." It is clear that there is no basis for that claim; other parts of Pembrokeshire have greater concentrations of ritual sites, and even allowing for the destruction or dismantling of prehistoric features there is nothing that marks out Waun Mawn - Brynberian - Rhosyfelin - Carn Goedog as special in any way, or that demonstates any cultural links between those named sites.
Tuesday, 19 March 2024
Ancient monument links examined by Richard Bradley
The author starts with a summary of the diffusion and connections as they were developing around 3,000 BC. He says that around that time regional rather than local connections were becoming more important, and adds: "These issues regarding changing patterns of movement and regional connections are particularly relevant to a discussion in this journal of the relationship between Stonehenge in Wessex and a recently investigated monument at Waun Mawn in south-west Wales (Parker Pearson et al. 2021, Parker Pearson 2022; Darvill 2022). The discussion raises some important questions."
In his discussion of Waun Mawn and Stonehenge Prof Bradley does sound somewhat sceptical about the latest MPP theory that what was exported from Waun Mawn to Stonehenge was an IDEA and not necessarily a stone monument! But he accepts without question that bluestone were "brought" from West Wales to Wessex and that there was an arrival date; and he accepts that "there are quarries in south-west Wales where excavation shows that monoliths of similar lithology to the Stonehenge bluestones were extracted during the Neolithic and later periods." He also accepts without question the assertion that all of the sarsens were "obtained from 25 km away near Avebury". One would have liked some more critical scrutiny and a greater awareness that Tim Darvill is not the only one who has questioned some of the key assumptions of the MPP team. The "lost circle" and the "quarries" are hotly disputed in the literature, and there are serious questions about the provenancing of the sarsens. These disputes in the peer-reviwed literature should have been acknowledged.
On the relocation of monuments and stones from one place to another, the examples given (Stenness, Avebury, Newgrange etc) are unconvincing, with too many suggestions and assertions and not enough facts.
In the section on "combining materials from different sources" Prof Bradley far too easily accepts the idea of human beings moving stones about, hither and thither, without even mentioning glacial erratic distributions or even the details of local rock outcrops. He appears to be quite unaware of the work of Stephen Briggs, Olwen Williams-Thorpe and others on erratic transport routes and opportunistic stone collection. Then there is this extraordinary statement concerning the distribution of bluestones in the overall layout of Stonehenge: "Not all of them originated from the same quarry and their organisation within the new monument reflects their natural distributions in the geology of south-west Wales. The setting of Welsh materials can therefore be characterised as a transported landscape....." I do not know of any evidence that supports any of that, and the idea of "a transported landscape" is pure fantasy.
In the section on "copying distinctive monuments outside their usual distributions" the author lists a host of monuments with "similarities" or "similar ground plans" or "links" -- and while I appreciate the attempts to find order and to classify monuments into cultural groups I do have worries that what is going on here is an attempt to find order in chaos. In any two or three monuments you can find SOME common denominators (earth banks, tall stones, stumpy stones, rings, rows, alignments etc) -- and I wonder if all of this tells us more about the minds of the archaeologists than about the minds of the Neolithic tribes of Britain........
On shared elements across vast distances, the author again refers to Waun Mawn and Stonehenge, and he does at least acknowledge the disagreements involving Barclay and Brophy, Madgwick, Parker Pearson and others. But he cannot resist mentioning the idea that "architectural connections between different regions celebrated alliances formed between distant communities". This was pure speculation five years ago, and nothing has changed.
In his conclusion, Prof Bradley reminds us that "connections" existed that had nothing at all to do with Stonehenge. That is of course a point worth making. But then he spoils it all with this statement about the old ruin: "The long-distance movement of building material might have been peculiar to that site....." Oh dear -- for the umpteenth time, the long-distance transport of bluestones from here to there has NEVER been demonstrated through the provision of hard evidence. Speculation is not a substitute for facts.
====================
Recent research has considered the relationship between Stonehenge and sites in south-west Wales, raising questions about whether the first monument at Stonehenge copied the form of an earlier stone circle at Waun Mawn and how the relationship between these sites was connected with the transport of bluestones between the different regions. But Stonehenge and Waun Mawn are not the only prehistoric sites in Britain and Ireland that share architectural elements and hint at social connections across vast distances of land and sea. This debate article explains how the questions raised about these Late Neolithic monuments can and should be applied to other monumental complexes to explore this insular phenomenon.
Happy days!
Found this in my box file -- and it brought back happy memories of the glorious Millennium Stone pull in the year 2000. I did my stint on one of the days, and came away from the exercise convinced -- like everybody else, that the whole idea of overland stone transport all the way to Stonehenge was dreamed up by somebody who had no appreciation at all of the nature of the West Wales landscape as it must have been in the Neolithic.......
New Scourse paper on giant erratics is deeply flawed
There is a new and very strange article by James Scourse in the journal JQS. It purports to be on the subject of the giant erratics scattered around the coasts of SW England -- but of course it is really all about the bluestone monoliths of Stonehenge, without actually mentioning them at all.
It's common knowledge that one of the strongest arguments in favour of the glacial transport of the bluestones revolves around the presence of far-travelled giant erratics (and smaller ones) at Saunton, Croyde, Freshwater Gut, Porthleven and elsewhere which are deemed to have been emplaced by glacier ice in one or more pre-Devensian glacial episode. Like many other researchers, I believe that if glacier ice was powerful enough and extensive enough to reach the coast of southern Cornwall and the edge of the Celtic Sea shelf, it was also capable of reaching Salisbury Plain. That belief is strengthened by much of the computer modelling work on the BIIS. The thinking (articulated by Kellaway, Thorpe et al and many others including myself) is that the famous erratics cannot have been emplaced from floating ice because sea-level during sea ice episodes must have been around -100m, far too low to explain the presence of erratics on the present-day coastal platform. No no, says James Scourse in his latest paper, floating ice transport and stone dumping on the platform were perfectly possible, because of isostatic depression of the coastline during the early part of the Devensian. That involves thick ice -- and Scourse argues that there is some evidence for its existence, while admitting that there is work in progress.........
First, the paper details:
J. D. Scourse
Journal of Quaternary Science
First published: 12 March 2024
https://doi.org/10.1002/jqs.3611
The journal classifies the paper as an "invited review" -- and it seems to have been invited by the editor Neil Roberts. It does appear to have been peer reviewed, and it may be based largely on a 2022 lecture given by James Scourse at a QRA Discussion Meeting. Has the paper been a long time in the pipeline? Probably not, since the article incorporates references from 2023. The author cannot therefore claim ignorance of recent publications that might have been relevant to his discussion.
ABSTRACT
The extent, chronology and dynamics of the pre-Marine Isotope Stage (MIS) 2 last British–Irish Ice Sheet (BIIS) are not well known. Although the BRITICE-CHRONO Project has detailed the maximum extent and retreat phases of the last BIIS for the period after 30 ka and into the Last Glacial Maximum (LGM), the Project identified several pre-existing datasets and generated new data that implied glaciation pre-dating the LGM but which post-dated the Last Interglacial (Eemian; MIS5e); these data are reviewed here. There are no dated till units but are other indicators clearly indicative of glaciation: deep-sea ice-rafted detritus flux into the adjacent NE Atlantic, cosmogenic rock-exposure age dating from glaciated surfaces in Wales and the island of Lundy (Bristol Channel), and optically stimulated luminescence (OSL) ages of proximal glacifluvial sequences on the Isle of Lewis (Outer Hebrides) and in the Cheshire Basin. Taken together these indicate BIIS inception during MIS5d, growth into MIS4 and evidence for dynamic retreat–advance phases during MIS3. OSL evidence for high relative sea level indicated by raised beaches in southern Ireland during MIS4 and 3 at a time of lowered glacio-eustatic sea level indicates substantial glacial isostatic loading, explained by the early growth of the BIIS during the last cold stage. High relative sea level during MIS4 and 3 coincident with adjacent calving ice sheet margins provides an explanation for the rafted giant erratics found around the shores of southern Britain and Ireland.
The paper concentrates on the question of whether there was a substantial BIIS prior to 31,000 yrs BP, ie during the Early and Middle Devensian. Scourse summarises much research dats from the North Atlantic on ice rafted debris in deep sea sediment cores -- and he suggests that the evidence shows the presence of a BIIS of limited extent after 70,000 yrs BP. This is consistent with evidence showing Laurentide and Fennoscandian ice sheet existence, waxing and waning, around the same time. There does seem to be substantial evidence for a quite expansive glaciation in MIS4, including the coalescence of the Fennoscandian and British and Irish Ice Sheet (BIIS). This enlarged ice sheet is called by some the European Ice Sheet or EIS. So far so good -- no problem with any of that, apart from the positioning of the MIS4 (around 60,000 yrs BP) ice edge to the south of Pembrokeshire by Batchelor et al, 2019. That is clearly incorrect, and goes against all the field evidence accumulated over the past 50 years. Just another example of a model that could have done with some more ground truthing!
Scourse gets into much trickier territory when he discusses the evidence from Lundy Island, including the claim made by Rolfe et al (on the basis of cosmogenic dating) that the island was affected by Early Devensian glacier ice but not LGM glacier ice. Scourse makes it clear that the cosmogenic exposure ages presented by Rolfe et al are hotly contested. He also refers to cosmogenic dating information from the high peaks of North Wales and OSL data from NW Scotland, the North Sea Basin and the Cheshire Basin, again suggesting BIIS growth in MIS3. But again there is contrary evidence, and it appears that the dating of rock surfaces and glacially derived sediments within the glaciated parts of the British Isles is currently in state of flux.........
Then the author gets into raised beaches (which or of course in some places not raised very much at all). He refers to the Courtmacsherry raised beach in southern Ireland, and the attempts at dating using the OSL method.
Quote:
"A total of 22 OSL ages from the Courtmacsherry Raised Beach therefore indicate deposition during the last glacial stage prior to MIS 2. Both Ó Cofaigh et al. (2012) and Gallagher et al. (2015) conclude that to generate relative sea level (RSL) at an elevation close to modern mean sea level at this time implies significant glacio-isostatic depression and hence ice loading. Ó Cofaigh et al. (2012) highlight the presence of erratics within the raised beach sequences, as previously reported by Wright and Muff (1904), and the lack of any diagnostic palaeoecological content that would enable a palaeoclimatic assessment."
On the other hand Scourse notes that all of the dates obtained from raised beach exposures around the Bristol Channel suggest that the deposits are of Last Interglacial (Ipswichian) age, as suggested by the great majority of field workers on these coastlines.
So there is a dilemma. Are the dating exercises on the Courtmacsherry raised beach all incorrect, or could there really have been a unique set of circumstances there, related to proximity to a large ice mass that caused isostatic depression equivalent to eustatic sea-level lowering in MIS3?
With regard to the Courtacsherry "anomaly", Scourse argues for a eustatic lowering of c 80 m during MIS4, and states that in order for raised beach formation to have operated at that time there must also have been c 80m of isostatic depression caused by a "proximal ice sheet", which did not progress across the coastline. To achieve that, there must have been an ice thickness of c 400m. What is the evidence for that? Scourse admits that the evidence in the field does not support the idea -- and information from all over the British Isles suggests that although there may have been a substantial ice sheet during MIS4, it was much less extensive than that of the LGM or MIS2. In order to explain a substantial crustal depression of c 80m, Scourse has to resort to some rather intriguing speculations involving an ice mass with a very steep gradient and with an accumulation centre further to the west than that of the LGM. He even strays into the field of glaciology, suggesting a cold-based ice sheet with limited basal sliding in MIS4 as distinct from a warm-based ice sheet with rapid sliding and a low surface gradient in MIS2. I can agree with that, and have played about with similar ideas myself! But I cannot agree that there is any evidence that might support an 80m isostatic depression around the coasts of the Bristol Channel which might have facilitated raised beach formation at approx the same level as the raised beaches as we see them today.
But then the author argues for millenium-scale or rapid oscillations in the MIS4 ice sheet, as distinct from the longer-term and slower oscillations of the LGM ice sheet. That is is conflict with most of the conclusions coming out of the BRITICE-CHRONO research -- namely that there was a sort of surging behaviour with catastrophic melting during the final dissolution of the ice sheet.
Winding up, Scourse mentions the past debate about the giant erratics on the coasts of Devon and Cornwall, and says: "It has been assumed that the timing of ice rafting involved was during the Anglian glaciation (MIS12) or earlier (Kidson et al., 1977; Bone, 2022) but, given the evidence reviewed here, it is likely that at least some were emplaced during MIS4–3."
As for the relevance of all this for the "giant erratic" debate, the following points come to mind:
1. Scourse fails to mention that the erratics on the coasts of Devon and Cornwall are not all at or near present sea-level. Some of them are more than 60m above sea level, and I have mentioned them many times on this blog. The Ramson Cliff erratic is at c 80m asl, and the Shebbear erratic lies at c 150m asl. There is no way that these erratics can be explained away by reference to cold-climate isostatic depression and ice rafting, and Scourse should have admitted this. Glacial transport and dumping in a past extensive glaciation is the only explanation that makes any sense.
2. Scourse fails to mention that the erratics are in places embedded in apparently interglacial raised beaches and associated sandrock and slope breccia deposits. It is clear that they have nothing whatsoever to do with the Devensian climate oscillations; they pre-date the Ipswichian Interglacial.
3. Scourse fails to mention that the Quaternary stratigraphic evidence from all around the coasts of West Wales suggests that prior to the LGM glacial episode there was a long period of slope breccia deposition, with no sign at all of the proximity of glacier ice. There are signs of periglacial / permafrost conditions at times (including churned deposits and fossil ice wedges), but if there was a MIS4 ice edge anywhere, it was not to the south of the Pembrokeshire peninsula. It might have been somewhere to the north, in Cardigan Bay.
Climatic oscillations, stages and Pleistocene stratigraphy of West Wales. This was the situation in 1973, and in spite of some changes in terminology it remains reliable, after 50 years......
5. That being the case, I can see no case at all for ice loading in the Bristol Channel on a scale that might have depressed the crust by 80m or more. Having worked in this field many years ago in Greenland and the Antarctic, I am a firm believer in rather sensitive isostatic adjustments to changes in ice loading, and if anything I would expect that during the MIS4 "glacial phase" there would not have been isostatic depression in the Bristol Channel but isostatic UPLIFT as a result of the forebulge effect.
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The debate will continue, but one just wishes that Scourse had done some more extensive reading of the literature. Suggested bedtime reading:
John, B.S. 1965. A Possible Main Wurm Glaciation in West Pembrokeshire, July 1965, Nature 207(4997):622-623
John, B.S. 1970. Pembrokeshire. In Lewis, C.A. (ed.) The Glaciations of Wales and Adjoining Regions. Longman, London, pp 229-265.
John, B.S.: The Stonehenge Bluestones, Greencroft Books, 256 pp, 2018.
John, B.S.: Evidence for extensive ice cover on the Isles of Scilly, Quaternary Newsletter 146, October 2018, 3-27.
John, B.S.: Was there a Late Devensian ice-free corridor in Pembrokeshire? Quaternary Newsletter 158, 2023, 5-16.
John, B.S., Elis-Gruffydd, D. and Downes, J.: Observations on the supposed “Neolithic Bluestone Quarry” at Craig Rhosyfelin, Pembrokeshire. Archaeology in Wales 54, 2015, 139-148.
John, B.S., Elis-Gruffydd, D. and Downes, J.: Quaternary Events at Craig Rhosyfelin, Pembrokeshire. Quaternary Newsletter, October 2015 (No 137), 16-32.
Monday, 18 March 2024
Bluestone "biface" stones at Stonehenge?
By Steve Thompson and Andrew B. Powell
Published by Wessex Archaeology, 2018
Quote:
The use of sarsen as a material to construct stone circles such as Stonehenge and Avebury may suggest this material had some importance to the occupants of Neolithic Durrington, however it is suggested that the stone was discarded after being unable to be worked further. It is also broadly contemporary with the sarsen phase of Stonehenge, however it is possible sarsen was more commonplace than it is today as a number of solitary standing stones are known locally.
A piece of worked ‘bluestone’ known as a biface was found in a later ditch close to the intersection of the two posthole alignments. This object is similar to ones found at Stonehenge and is almost certainly of Neolithic date. However, whilst it is likely to have been brought to the site at this time, it could equally be a Romano-British curio or trophy. ‘Bluestone’ is a key material of non-local rocks, many of which were brought from Wales, and most famous for its use at Stonehenge and the ritual activity taking place there."
Sunday, 17 March 2024
Marginal channels near Carn Goedog
I have been meaning to survey these channels properly, but have never got round to it. The gradients and micro-morphology could be important. One of those things still on the list.........
Elephant Foot Glacier
Periglacial Carningli
Friday, 15 March 2024
Post Processualism and ArchaeoMythology
That's all very well for those of you who are communicating with colleagues or students who are just as relaxed as you are. But your problems start when you start communicating with others -- especially those who see themselves as scientists working in fields where research and publication procedures are clearly defined and adhered to. And here's the rub. You want to publish in a scientific journal because that will make you look more respectable in academic circles, but that's where you come up against the buffers, because your modus operandi is to tell people what they are looking at and then to give them some information in support of your conclusion. Your work is dominated by speculations, assumptions and assertions which your colleagues allow you to get away with. But now you dress your information up to be as "scientific" as possible in tables, graphs, diagrams, technical data sheets and so forth -- but it's all a con, and you know it. You are using technology because it suits you, but you are not a scientist, because you cannot, or will not, conform to the scientific publishing convention of problem statement, evidence presentation, interpretation and deduction, discussion and conclusion.
1. Parker Pearson, M. et al. 2015. Craig Rhos-y-felin: a Welsh bluestone megalith quarry for Stonehenge. Antiquity 89: 1331–52.
https://doi.org/10.15184/aqy.2015.177
2. Parker Pearson, M. et al. 2019. Megalith quarries for Stonehenge's bluestones. Antiquity 93: 45–62.
https://doi.org/10.15184/aqy.2018.111
3. Pearson, M. et al. 2021. The original Stonehenge? A dismantled stone circle in the Preseli Hills of west Wales. Antiquity, 95(379), 85-103.
https://doi.org/10.15184/aqy.2020.239
To assume that the tribes of West Wales had the technical skills, the mental maps, the motivation, the manpower and raw material resources, and the leadership to make 80 or so monolith transporting expeditions by sea or overland is to enter a quagmire with no escape. And this is what MPP and his team will be forced to confront as they see their narrative collapsing, bit by bit, around their ears. When Stephen Briggs argued for opportunistic, rather that deterministic, stone gathering in the Neolithic, he was basing his argument on rather solid evidence; and as I have argued many times before, the great mass of the population at the time were not driven by rituals, belief systems, political aspirations or economic ambition but by things that were much simpler -- the need for warmth, clothing, food, safety and comradeship within secure family groups. It was all very utilitarian. The locals inhabiting the slopes of Mynydd Preseli would have had much in common with Dennis the Peasant. They would have had no knowledge at all of Stonehenge, which was at that time in any case just a circular earthwork no more significant than hundreds of others. They would have had no reason to cart lots of stones from here to there, involving a stupendous logistical challenge. They would in any case not have known how to get there................
If Mike and his colleagues want to continue to elaborate their wondrous narrative, let them do it in the pages of this new journal which somebody will surely wish to create -- and in its pages they can entertain each other with fantastical narratives and jolly romps for many years to come, while leaving the rest of us in peace.
Thursday, 14 March 2024
In praise of Popper
This was one of the themes of by talk in Fishguard last night -- I urged people not to blindly "follow the science" (as we were exhorted to do during the dark days of the Pandemic) but to knowledgeably challenge the science presented in learned papers and especially to take everything presented in banner headlines in the media with a large dose of salt.
My main theme, of course, was that we should all recognise mythology for what it is, especially when it is dressed up as science. But more of that anon......
Wednesday, 13 March 2024
Stephen Briggs and others on erratics and prehistoric tool making
I should have thought it was a no-brainer that erratics would have been used as raw materials for tool making back in the Neolithic -- but apparently there has been quite a lot of fuss about this in "lithic" circles. This paper by Stephen Briggs lays out some of the arguments from both sides, and highlights some of the rather nasty animosities too:
As an extension of the idea that Neolithic tool makers had a "deterministic" strategy, it helps if you can demonstrate that their tribal society was capable of creating a landscape full of ritual features which marked it out as being more "advanced" or sophisticated than neighbouring landscapes. This is what lies behind MPP's insistence that the Mynydd Preseli area was one of the great cultural centres of western Britain.......... But it's a circular argument. Because there were quarries and lost circles and so forth, that shows the local tribal society was quite advanced compared with others. And because society was quite advanced, it should come as no surprise that there were sacred places, quarries and stone circles. In my view it's all nonsense. The density of ritual or sacred features in the landscape here is interesting, of course, but no greater than anywhere else in SW Wales, as pointed out by Figgis and many other archaeologists.
Olwen Williams-Thorpe, Don Aldiss, Ian J. Rigby, Richard S. Thorpe
First published: 22 February 1999
Abstract
Sixteen basic and intermediate composition igneous glacial erratics from Anglian (pre-423,000 years) deposits in Hertfordshire and Buckinghamshire, southern Britain, were selected for chemical and petrographic analysis in order to determine their original source outcrops. Major and trace element compositions suggest that seven samples (plus two uncertain) originated in the Lower Carboniferous volcanics of the Scottish Midland Valley (SMV), four came from the Upper Carboniferous quartz dolerite association which crops out in Scotland, northern England (Whin Sill) and extends to Norway, and one came from the northern England Cleveland Dyke. One sample of altered dolerite is ambiguous but has some similarity to the Old Red Sandstone (Devonian) age lavas of the SMV, and one meta-basalt sample may be from southwest Scotland or Scandinavia. These results identify specific outcrops which provided glacial erratics within currently accepted ice trails in the United Kingdom, and provide the first supporting evidence based on geochemistry, rather than petrography, for these ice movements. The distribution and provenance of glacial erratics are of importance in archaeological studies, because erratics provided a potential source of raw material for stone implement production. There is a marked geographical correlation between the distribution of prehistoric stone implements of quartz dolerite in the United Kingdom, and directions of ice movements from quartz dolerite outcrops within Britain. This correlation lends support to the hypothesis that prehistoric man made extensive use of glacial erratics for implement manufacture, as an alternative to quarrying at outcrops and subsequent long-distance trade.