THE BOOK
Some of the ideas discussed in this blog are published in my new book called "The Stonehenge Bluestones" -- due for publication on June 1st 2018. After that, it will be available by post and through good bookshops everywhere. Bad bookshops might not have it....
To order, click
HERE

Sunday, 20 May 2018

Seymour thesis on vegetation development in Holocene Preseli


I had not realised that this thesis from Philip Seymour had been digitised.  Anyway, it is a useful resource in that it describes environmental change since the last "cold snap", as recorded in the pollen record.  It's very tightly focussed, and I would have like to see a bit more awareness of the wider context; my sense is that there was a concentration at the time on working out what anthropogenic changes there were -- still a reaction, maybe, to the old ideas of environmental determinism......

Some of the sites examined were in the eastern Preseli area -- referred to by the author as the "Bluestone Area".  One interesting thing is the author's unswerving allegiance to the human transport thesis; he says there is so much evidence of human occupation and activity in the area around Foel Drygarn and Caen Meini that Kellaway's glacial transport thesis becomes "unnecessary" !!  Hmmm.... It was a long time ago, and we'll let that pass.

But a useful document nonetheless......


The environmental history of the preseli region of South-West Wales over the past 12,000 years

Seymour, W. Philip
Date: 1985

Citation:
Seymour, W. P. (1985) 'The environmental history of the preseli region of South-West Wales over the past 12,000 years', Institute of Geography and Earth Sciences, Aberystwyth University

Abstract:
The project involves a detailed palynological investigation into the environmental changes that took place during the Late-Devensian Lateglacial and Flandrian periods in the Preseli district of northern Pembrokeshire, south-west Wales. The approach adopted specifically takes into account the considerable diversity in terms of subenvironments and ecological habitats within the field area, with representative sites on the northern coastal plain, the exposed ridges of the Preseli Hills, sheltered valleys which dissect the uplands, and the flanking plateaux. In this manner and through definition of local pollen assemblages, unrepresentative extrapolations are minimised and an unbiased regional chronology has been produced. Results indicate that the distinctive climatic character of Pembrokeshire was probably manifest throughout the entire period under discussion. Thus, Corylus was locally present during the Late-Devensian Lateglacial Interstadial as it expanded from refugia to the south and west, and its extension very early during the Flandrian is also recognised. Conversely, Betula was relatively subdued during the Lateglacial and Early Flandrian, therefore suggesting that migration across the Cambrian uplands to the east was inhibited, particularly with the prolonged influences of the Loch Lomond (Younger Dryas) stadial on the high ground. The early establishment of mixed oak forest on the coastal plain is also recognised, although with some variation in its distribution within the field area. Apart from iiilocalised occurrences of carr woodland, however, the main Alnus rise did not occur until c. 6800 BP, when it is suggested that the rising sea-level may have been largely instrumental in creating suitable habitats on the littoral lowlands. During the later part of the period in particular, the variable activities of prehistoric populations are evident. Especially notable is the centre of activity during the Late Neolithic - Early Bronze Age near the site associated with the origins of the Stonehenge Bluestones. During the post-Roman period several cycles of increased exploitation and abandonment are recognised and these correlate well with historical evidence.

Saturday, 19 May 2018

Blanket peat on Waun Mawn


Exposure in the side of one of the drainage channels on Waun Mawn, on a gentle south-facing slope.  Here we see about 30 cm of iron-stained / gleyed regolith made of broken meta-mudstone debris with signs of cryoturbation.  Above that there is a thin layer with streaks of organic material, and above that about 10 cm of "blanket peat" containing a network of roots from the present-day turf layer at the surface, which is only 5 cm thick.  This is quite typical of the moorland hereabouts.  There is no sign of Devensian till at this location.


I have been taking another look at the "progress report" written by Prof MPP for the Rust Family Foundation:

http://www.rfamfound1.org/proj23find.html

In the section on Waun Mawn some stress is placed on "the date of peat formation" as a guide to the age of the sockets and the speculations surrounding stone removal.

As far as the biggest recumbent stone in the putative "proto-Stonehenge" circle is concerned, MPP says this: Its former stone socket is lined with many packing stones, and the peat fills of this socket indicate that the stone fell after the onset of peat growth."

On the other hand, "The smaller recumbent stone excavated in 2017 is on the east end of the arc and is just under 1m long (fig.4). The fill of the stone socket contains only brown loam and no peat, indicating that it filled before the growth of peat. Thus this stone came down before peat growth."

Then again:  "Emptied stone sockets with stone packing (but no surviving monolith) were identified beyond both ends of the arc of monoliths. The socket on the west side was a circular pit (0.85 m- diameter and 0.3 m-deep) containing large packing stones set vertically. The emptied socket had filled with brown soil before any peat formation. Deformation of the edge of the pit showed that its former standing stone had been removed towards the north."
"We discovered two empty stone sockets on each end of the arc, suggesting that these stones may well be the remains of a dismantled stone circle (figs.5,6). Megaliths were removed from these sockets before the onset of peat growth on this site, indicating that the stone
circle was dismantled in the distant past."

Tying things up and seeking to demonstrate (even at this very early stage) that there WAS indeed a stone circle here, on the basis of very scanty evidence, MPP concludes:  "It can be assumed that the lack of peat in three of the stone sockets indicates that their standing stones were removed before the growth of blanket bog. This is likely to have started growing around 3,000 years ago, which would indicate that the stones came down in the Neolithic or earlier Bronze Age."

This is all seriously confusing.  MPP suggests that blanket peat formation here did not start until 3,000 years ago, which would place it in the Sub-Atlantic climate phase (pollen zone VIII), well after the elm decline and 3,000 years later that the date normally assumed for blanket peat development in the uplands of Wales.  In most of the texts and in Gallego-Sala et al (2015) it is suggested that in upland Wales blanket peat development probably started early -- maybe as early as 7,000 years ago --  during the Atlantic "climatic optimum" when it was warm and wet.  It's also suggested that around 3,000 years ago, at a time of lower rainfall totals, and an increase in ash and birch cover, blanket peat development might actually have slowed.  After 3,000 years ago, blanket peat initiation occurred only in a smallish number of "less favoured" locations. 

In the Preseli uplands, we can reasonably assume that blanket peat development will have started at the same time as in the other uplands of Wales where there were acid soils and high precipitation rates.

Nothing seems to fit.  So we have a problem........

Could it be that the things being called "stone sockets" are not stone sockets at all, but are simply surface depressions or irregularities that have nothing whatsoever to do with standing stones?

================

Gallego­-Sala, A. V., Charman, D. J., Harrison, S. P., Li, G. and Prentice, I. C. (2015) Climate­-driven expansion of blanket bogs in Britain during the Holocene. Climate of the Past Discussions, 11 (5). pp. 4811­-4832.
ISSN 1814­9359 
Available at http://centaur.reading.ac.uk/48736/

PS.  The only detailed work on the development of vegetation in the Preseli - North Pembrokeshire area is a thesis by Philip Seymour, completed in 1985.  It can be seen here:
http://cadair.aber.ac.uk/dspace/handle/2160/3307

It's essentially a pollen analysis study based on a variety of upland and lowland suites, recording changes in pollen frequencies in sediment sequences.  It makes the point that the development of blanket peat bogs was never very great in this area, partly because of the lack of extensive plateau surfaces where waterlogging could occur.  So drainage -- mostly on gentle slopes -- was generally sufficient to prevent blanket peat development.  This is borne out by the generally thin peat layers which we find across most of the landscape -- 10 cm is a rather typical thickness.  Did all of the peat start to develop at about the same time?  And was that time associated with the Neolithic / Bronze Age increase in land clearance associated with forest burning and increased grazing activity?  Seymour suggests that this was the case, and that peat development before the Neolithic was not very marked, especially on fairly well-drained slopes.  He takes a rather anthropogenic approach, suggesting that peat and soil development was very much influenced by settlement and land use practices.  But there is a danger of circular reasoning -- was the environment causing man to make certain land-use decisions, or were cultural decisions shaping the environment?  Walker and McCarroll (in the QRA Field Guide for West Wales, 2001) take a more nuanced approach, agreeing that periods of peat development are associated with periods of increased rainfall, leaching, iron pan creation and waterlogging  -- while admitting that there is such a wide range of dates for the "onset of peat development" in West Wales that land use practices and settlement pressure must have some role to play.

It will be interesting to see what turns up when Waun Mawn is examined in greater detail.....





The raised beach platform at Lydstep Point

Looking east

Looking west

This is probably the most spectacular raised beach platform in Pembrokeshire -- it's about 100m long,  and up to 25m wide, and is tucked into the little bay between Lydstep Point and Whitesheet Rock.   It cuts across near-vertical strata, and appears to have nothing to do with any faults or fractures in the Carboniferous Limestone.  It's difficult to photograph because it is so extensive -- but everywhere it has quite a gentle gradient down from a distinct notch cut into the cliff slope, and at its outer edge there is a sharp drop down into the sea.

The most fascinating thing about this platform is that it is incredibly chopped up -- criss-crossed with fissures and chasms and undermined by caves.  It is actually quite difficult to walk across it because of these surface irregularities.  This, to me, indicates very great age --  the chasms, pits and collapsed caves are all signs of marine processes currently destroying something formed a long tome ago, at a time when sea level was rather stable, around 15-20 m above its present level.  I think that this raised beach platform is at a higher level than that of Broad Haven -- which is also cut into a limestone coast.

In spite of a thorough search, I found no traces of a raised beach here (cemented or loose) and no trace of any till.  But there is an area of about 10m x 10m where cemented limestone breccia rests on the platform and has survived subsequent erosion -- storm waves certainly get onto this platform when there is a southerly gale combined with a high tide.


Here the breccia is about 1m thick, and about 2m  thick in a few places -- and it has to be related to the limestone breccia on the neck of the small peninsula just 450m to the west.  The other interesting feature of the platform is the presence of a number of widened fissures and "slit caves" cut into the face of the old cliffline at the bach edge of the platform.  These are perfect locations in which animal remains and maybe other organic materials might be found.  These would be invaluable in working out the chronology of this site.


My instinct is that there might be raised beach cobbles -- and maybe ancient till -- beneath the cemented limestone breccia, waiting to be discovered.  The rock platform itself may even predate the Anglian glacial episode -- but it could of course be a composite feature, freshened up during several interglacial high stillstands of the sea.



Hut circle on Waun Mawn


The hut circle on Waun Mawn -- some stones visible, and others buried in the turf.  Too small to be a stone circle, and too big to be the remains of a cromlech, I suspect......

I went over to Waun Mawn to see if I could find the little hut circle shown on some of the old maps.  I found it all right --- it's very small indeed, less than 5m across, so if it was a hut it must have been very cosy.......

It's located about 200m from the single standing stone to the north of the Gernos Fach track.  Go directly upslope from the standing stone, and you'll see the small grassy mounds and the stones towards the eastern edge of a grassy area surrounded by low gorse bushes.


The single standing stone on Waun Mawr, on the north side of the farm track

Friday, 18 May 2018

Lydstep ancient till site confirmed


National Trust map of Lydstep headland, showing key Pleistocene sites


Further to my earlier note about the suggested ancient till at Lydstep, I have been back there today to check it out -- and it is very impressive indeed.

https://brian-mountainman.blogspot.co.uk/search?q=+Lydstep

https://brian-mountainman.blogspot.co.uk/2014/03/classic-pembrokeshire-pleistocene.html

The first record of an ancient till at this site is from Arthur Leach, in his papers and manuscripts held in Tenby Museum:


I also visited the site and published a brief record of it in 1974.  The key location is a little peninsula that extends southwards from the "heel" of the big peninsula.  Here, by a freak of nature, a vast expanse of cemented limestone breccia has been protected from extensive marine erosion.  An area of at least 30m x 20m supports a most unusual -- and slightly surreal- -- landscape of concreted ridges and hummocks of limestone debris (mostly sharp-edged fragments which are partly frost-shattered and partly natural scree slope accumulations) on an undulating rock platform about 20m above sea-level.  I agree with Leach that this is not a wave-cut platform -- it is too high, and it does not have a wave-cut notch against an old cliffline.  I have struggled a bit to work out where on earth all this shattered scree has come from, and  have come to the view that it cannot all have come from the cliff slope to the north.  I think this is the floor of an old karst dry valley like the one that runs northwards from the western edge of Lydstep Headland today.  The southern side of this valley has, I think, been completely lost to marine erosion.  This is an indication of the great age of the breccia and everything that lies beneath it.


Cemented limestone breccia about 2m thick on the little peninsula at Lydstep, with the karst coast beyond (looking west)


Cemented limestone breccia about 3 m thick, at the foot of the northern valley slope.  There is no till exposure at this location.


Cemented limestone breccia sheet about 2m thick, resting on broken limestone bedrock.  To the left of centre is a chasm that falls straight down to the sea below.  


Looking straight down through another gaping hole in the sheet of limestone breccia.  The breccia now forms the roof of a gigantic cave, and eventually it will all collapse into  the sea........

At the eastern edge of the breccia exposures, there is a spectacular overhang or projection of the breccia sheet, sticking out eastwards by about 2m -- and beneath is is the classic exposure of ancient till.  The grid ref is approx SN 088975.  


The spectacular overhang beneath which the ancient till deposit has been protected.

The till exposure is about 10m long, and the till is about 1 m thick.  It is solidly cemented, like the breccia above it.  It rests directly on an undulating bedrock surface that has the appearance of ice moulding -- but no striations could be seen because of heavy manganese oxide staining. 


Cemented till (here containing mostly broken limestone fragments) resting directly on a stained bedrock surface


Approx 1 m of cemented till exposed beneath the overhang.


Large erratic block and smaller cobbles in a sandy till matrix, beneath the overhang.


Erratics in the cemented till, including ORS, buff sandstones, mudstone and shale fragments, as well as many local limestone fragments.


Here and there above the till is a cemented deposit of sandrock or sandy loam, foxy red in colour and full of interesting holes.  Animal burrows, or root holes, created when the sediment was fresh and soft?

I have a full record of the site, and the Pleistocene sequence seems to be:

4.  Up to 3m of cemented limestone breccia, in places blocky from catastrophic rockfalls, and in places full of smaller (frost-shattered?) fragments.  No clear stratification.

3.  Cemented sandrock containing some till and limestone fragments -- up to 20 cms thick.

2.  Cemented ancient till up to 1 m thick, containing abundant foreign erratics.

1.  Bedrock floor of old valley, apparently smoothed beneath glacial deposits.

There are no raised beach deposits here, and no fluvioglacial deposits either.  The best guess must be that the till dates from the Anglian glaciation, that the brickearth represents a climatic amelioration (interglacial?), and that the thick cap of limestone breccia has accumulated during the whole span of the Devensian glacial episode.  There is no fresh Devensian till here, but it is found a short distance away (about 200m) at the head of the creek leading into the dry valley.

As far as I am aware, this is the most extensive and most accessible ancient till deposit in Wales.






Devensian till at Lydstep



While out on o bookselling trip today I was inspired by the gorgeous summer weather to take a small diversion to Lydstep, where I wanted to check out an old record of mine regarding an ancient till deposit.  More of that in another post.

What I also discovered, on descending to the beach (which you can only do at low tide), was a splendid exposure of fresh till which has to be Devensian.  It's located in the stream gully where one has to scramble down from the grassy floor of the dry valley to the boulder-strewn beach.  The grid reference is SN 087976.

The exposure reveals at least 2m of fresh till, with a sandy and gravelly matrix and a wide assortment of striated, faceted and worn cobbles and smaller stones of many different lithologies -- including ORS, grey and buff sandstones and quartzites, blackish mudstones, shales, flints and quartz pebbles.   There's very little rounded material, suggesting that no raised beach or Pliocene pebble beds have been incorporated here.

The till is exposed almost up to the ground surface, and is capped only by the thin soil layer.  There is a lot of slumping on the exposure, but the till appears to be  underlain by a foxy red clay-rich deposit (at least 1 m thick) that appears to be relatively stone-free.  I could not determine whether this was a basal clay-rich till layer or a locally-derived gash breccia such as we see in many fissures along the limestone coast.

Anyway, this is one of the most coherent and easily accessible fresh till exposures on the South Pembrokeshire coast,  and there can be little doubt about its age, since it is completely uncemented (in an environment dominated by calcium carbonate) and has no scree or slope deposits on top of it.  It has to be Late Devensian in age.

As a matter of interest, this boulder rests on the beach just a few metres away, in a jumble of other large boulders.  It looks to me like gabbro -- similar to the gabbro that outcrops near St David's Head.  But that's just an educated guess......


Heavily abraded boulder of gabbro (?) not far from the till exposure at Lydstep.  It's one of the largest erratics seen thus far along the south Pembrokeshire coast.


As a matter of interest, the other posts describing Devensian till on the South Pembrokeshire coast are here:


https://brian-mountainman.blogspot.co.uk/2011/08/glaciation-of-south-pembrokeshire.html


https://brian-mountainman.blogspot.co.uk/2018/04/the-devensian-ice-limit-in.html

https://brian-mountainman.blogspot.co.uk/2011/08/glaciation-of-caldey.html

Thursday, 17 May 2018

Glaciation of the Bristol - Gloucester region



This is an interesting summary from the Earthwise (BGS) web site.  Found here:


It's bang up-to-date, having been revised in January 2018.  As the authors say:  "Evidence in Somerset and Avon, combined with that from South Wales, for an Anglian glacier moving up the Bristol Channel has been accumulating in the last decade or so."

Show this to anybody who suggests that ice never flows eastwards, or that the Irish Sea Glacier never crossed the Bristol Channel and penetrated far into Somerset.........

There is no assessment here of the likely easternmost limit of the Anglian ice.

----------------------------------------


Glacial deposits, Quaternary, Bristol and Gloucester region


based on Green, G W. 1992. British regional geology: Bristol and Gloucester region (Third edition). (London: HMSO for the British Geological Survey.)

Glacial deposits

The glacial deposits of the region are mostly scattered remnants and provide difficult problems of interpretation. The earliest drift deposits are represented by remaniĆ© patches of erratic pebbles of quartz, ‘Bunter’ quartzite and, less abundant, strongly patinated flint lying on the surface of or within fissures in the Cotswold plateau up to a height of 300 m above OD. On the eastern boundary of the present region and in adjacent areas to the east, there are scattered patches of sandy and clayey drift with similar erratics, which are now known collectively as the ‘Northern Drift’. The general opinion is that the deposits are heavily decalcified and probably include both tills and the fluviatile deposits derived from them. They predate organic Cromerian deposits in the Oxford area and thus provide evidence for pre-Cromerian glaciation (see summary in Bowen et al., 1986)[1].

High-level plateau deposits in the Bath-Bristol area comprise poorly sorted, loamy gravels with abundant Cretaceous flints and cherts and have been correlated with the ‘Northern Drift’.

The Anglian glaciation is better represented in the district. In the Vale of Moreton there is a three-fold sequence. At the base lies the Stretton Sand, a fluviatile, cross-bedded quartz sand, which has yielded a temperate fauna including straight-tusked elephant and red deer. This was formerly dated as Hoxnian in age but now must be considered to be older. The Stretton Sand is similar to the supposedly younger Campden Tunnel Drift (see below), and it has been suggested that the temperate fauna in it is derived from an earlier interglacial deposit. The overlying Paxford Gravel, which comprises local Jurassic limestone material, has yielded mammoth remains and has an irregular erosive contact with the Stretton Sand. At the top, up to several metres of ‘Chalky Boulder Clay’ with derived ‘Bunter’ pebbles may be present. Thin red clay is locally present immediately beneath the till, possibly representing a feather-edge remnant of the glacial lake deposits of Lake Harrison.

At the northern end of the Cotswolds, in the gap between Ebrington Hill and Dovers Hill, the Campden Tunnel Drift consists of well-bedded sand and gravel with ‘Bunter’ pebbles and Welsh igneous rocks, and two beds of red clay with boulders, probably a till. The deposits occupy a glacial overflow channel, up to 23 m deep, caused by the ponding of the Avon and Severn valleys by the Welsh glacier farther downstream.

Evidence in Somerset and Avon, combined with that from South Wales, for an Anglian glacier moving up the Bristol Channel has been accumulating in the last decade or so. The construction of the M5 motorway through the Court Hill Col on the Clevedon–Failand ridge led to the discovery in the bottom of the col of a buried channel, 25 m deep and filled with glacial outwash deposits and till. Drilling has since proved similar drift-filled channels in the Swiss and Tickenham valleys crossing the same ridge. South of the ridge, and rising from beneath the Flandrian alluvium of Kenn Moor, marine, brackish and freshwater interglacial sand and silt overlying red stony and gravelly till and poorly sorted cobbly outwash material were disclosed in drainage trenches and other works. AAR results indicate that whilst the bulk of the interglacial deposits are Ipswichian in age, samples of Corbicula fluminalis from fluvial deposits directly overlying the glacial deposits give a much earlier date and suggest that the latter are Anglian in age (Andrews et al., 1984[2]). Similar local occurrences of possible till have been reported beneath the Burtle Beds of the Somerset levels. In the light of these and other discoveries, the glacial overflow hypothesis of Harmer (1907)[3] for the cutting of the Bristol Avon and Trym gorges has been revived to explain why these rivers cut through hard rock barriers in apparent preference to easier ways through adjacent soft rocks.


References


Bowen, D Q, Rose, J, McCabe, A M, and Sutherland, D G. 1986. Correlation of Quaternary Glaciations in England, Ireland, Scotland and Wales. Quaternary Science Reviews, Vol. 5, 299–340.
Andrews, J T, Gilbertson, D D, and Hawkins, A B. 1984. The Pleistocene succession of the Severn Estuary: a revised model based upon amino acid racemization studies. Journal of the Geological Society of London, Vol. 141, 967–974.
Harmer, F W. 1907. On the origin of certain canon-like valleys associated with lake-like areas of depression. Quarterly Journal of the Geological Society of London, Vol. 63, 470–514.

This page was last modified on 30 January 2018

Biological processes at Rhosyfelin


I'm increasingly convinced that biological processes are -- and have been for a long time -- of great importance in the evolution of the landforms at Rhosyfelin.

If one looks back at the Devensian, and at the history of other crags and rock faces (for example, on the coast) one sees the effects of frost shattering over a period of around 70,000 years -- during which there must have been continuous or discontinuous permafrost and an ongoing process of rock breakage at the surface.  Many fracture patterns must have been exploited, with fractures opened or widened by freeze-thaw processes.  Then, in the intervals when scrub or woodland vegetation was able to take hold, the expansion of root systems must have continued the work, forcing fractures to widen even further, until failures occurred, accompanied by large and small rock fragments crashing down and accumulating on the flank of the crag.  This is what we see in all the photos -- interpreted as quarrying waste by the archaeologists and as natural rockfall or slope accumulations by geomorphologists.  

The process continues to this day -- maybe at a faster rate now than in the past, given the nature of the present climate and the occupation of the upper part of the crag by  gorse, hazel, willow and other bushes and small trees.  Root expansion does part of the work, the the rocking of trees and shrubs in the wind is another very active process.  I'm planning more work on this -- watch this space.........

Ramsey Island


This is a fabulous false-colour laser image of Ramsey Island, showing  what incredible detail can now be picked up on the land surface with modern technology.    This was created as part of a survey of archaeological features, but topographical features are also fascinating -- the two hill masses are heavily ice-moulded, and during the Devensian (and earlier glaciations) the island took the brunt of the weight of the Irish Sea Glacier as it came in from the NW.

We have already wondered, on this blog, about the link between the giant erratics at Broad Haven and the island of Ramsey, and we have strong suspicions that at least some of the material on Flat Holm has come from here too.

The northern hill mass is made of microtonalite, and the southern one has a varied geology, with rhyolitic pyroclastic rocks, some sandstones and conglomerates, and in the south, other rhyolites in a complex relationship with Ordovician sedimentary rocks.




Wednesday, 16 May 2018

The old and the new at Stonehenge


Somebody posted this on another Stonehenge blog site, showing what good company I keep in the Stonehenge Visitor Centre.  A batch of the new book is winging its way to Stonehenge as I speak -- so I suppose that for a little while (until old stocks are sold out) the visitors will be able to buy the cheaper old book alongside the more expensive and more up-to-date new one.   You get what you pay for in this world.........

By the way, all credit to EH for selling my books, which might be considered by some to be subversive if not downright disruptive!  Maybe the archaeologists do not speak to the shop staff, who may be rather more concerned with running their operation at a profit than with toeing the party line on interpretations.

Anonymous posts will be treated as spam

Please note:  I still get up to 20 anonymous posts every day, most of which are nonsense posts which are correctly identified  as spam, sent by people to random Blogger sites when they have nothing better to do.  Every now and then, I notice in the trash can that there is something that is relevant to a discussion -- but it will still get filtered out and treated as spam because of the preference settings on the site.  Normally I do not even get to see these messages -- they are dumped straight away.  So if you have anything to say, please use your correct identity when you submit a comment, or at the very least, use a pseudonym which can act as your "handle".  That way, your voice might be heard......

Did "Antiquity" authors conclusively falsify their own quarrying hypothesis?

"Tis but a scratch....."


As readers of this blog will know, when Mike Parker Pearson and thirteen of his colleagues published their glossy and detailed paper on Rhosyfelin in December 2015, claiming they they had found a wondrous Neolithic bluestone quarry, the media loved it. The media also loved the fact that at almost the same time Dyfed Elis-Gruffydd, John Downes and I published two peer-reviewed papers which showed that there was no quarry at Rhosyfelin, and that all of the so-called engineering features were entirely natural.

In the two and a half years since then, the six senior authors of the Antiquity paper have published abundantly in magazines which do not have peer-review processes, repeating their contention that they have found quarries at Rhosyfelin and Carn Goedog, and steadfastly refusing to acknowledge the existence of the two papers arguing the "natural processes and natural landforms" case.  That dogged and persistent refusal to acknowledge the fact of a debate or a dispute is, as I have said many times, discourteous and also unscientific.  Six senior academics, all in a state of denial.......  and what on earth can they hope to gain from it?  Do they really think that their reputations will be enhanced by completely ignoring the field findings and the interpretations of scientists who have different skill sets from their own?

In post after post, I have dissected the evidence presented in the "Antiquity" paper, for example here:

https://brian-mountainman.blogspot.co.uk/2015/12/the-antiquity-paper-critical-assessment.html

https://brian-mountainman.blogspot.co.uk/2017/10/parker-pearson-et-al-under-scrutiny.html

https://brian-mountainman.blogspot.co.uk/2016/01/geologists-and-neolithic-quarries.html

https://brian-mountainman.blogspot.co.uk/2016/09/clutching-at-hazel-nuts.html

 I have also expressed the view that the paper was so badly organized and so poor in quality that it should never have been published.  Further, I've expressed the view that the abundant radiocarbon dates from the site, from organic materials scattered through the sequence of deposits, did nothing at all to enhance the quarrying hypothesis.  On the contrary, all that was shown by the dates was that there had been a long history of intermittent occupation of the site, probably by hunting parties using the wooded valley for shelter.

It was a strange experience at the end of the "Antiquity" paper, to see the authors seeking to show that their hypothesis had been supported or enhanced by this erratic  scatter of radiocarbon dates, when it was perfectly clear to all readers that it had actually been fatally damaged.    "No problem", said the quarrymen.  "All this shows is that quarrying went on here over a very long period of time, and that monoliths must have been taken away far earlier that we thought, and built into a proto-Stonehenge setting somewhere nearby before being dismantled and taken off to Stonehenge in those bluestone transport expeditions."    The evidence has become more and more elusive, and the narrative more and more complex -- and still hardly anybody in the archaeological community is prepared to say "What a load of cobblers......"

It reminded me at the time of that wonderful Monty Python episode in which the Black Knight keeps on shouting defiance, and insisting that he will be victorious, while his limbs are systematically chopped off, one after another.......

Anyway, it's interesting that Prof Danny McCarroll has now entered the fray (in his review of my new book) by referring to the quarrying hypothesis as "just plain silly".  He also says of the radiocarbon dates: "Those dates have now been published in the journal Antiquity and in fact they lend absolutely no support whatsoever to the quarrying hypothesis; a fair appraisal would be that they actually falsify it conclusively. Unfortunately that is not the interpretation of the authors of what is, sadly, one of the worst papers I have ever read."

The fact that a senior academic with no axe to grind now talks of the quarrying hypothesis being not just fatally damaged but conclusively falsified should give a wake-up call to the six senior authors of that "Antiquity" paper.  When you are in a deep hole, for God's sake stop digging........

It's time for all six of them to admit, on the record: "OK -- we hold our hands up.  We got it wrong.  Back to the drawing board."

I bet there are very few people who have read that paper carefully, giving it the scrutiny it deserves.  The link is below.  Please read it -- you will, I am sure, be appalled.

========================

Mike Parker Pearson, Richard Bevins, Rob Ixer, Joshua Pollard, Colin Richards, Kate Welham, Ben Chan, Kevan Edinborough, Derek Hamilton, Richard Macphail, Duncan Schlee, Jean-Luc Schwenninger, Ellen Simmons and Martin Smith (2015). Craig Rhos-y-felin: a Welsh bluestone megalith quarry for Stonehenge. Antiquity, 89 (348) (Dec 2015), pp 1331-1352.

https://www.researchgate.net/publication/285593380_Craig_Rhos-y-felin_A_Welsh_bluestone_megalith_quarry_for_Stonehenge

Here you will find the "alternative interpretation":

Brian John, Dyfed Elis-Gruffydd and John Downes (2015). "Quaternary Events at Craig Rhosyfelin, Pembrokeshire." Quaternary Newsletter, October 2015 (No 137), pp 16-32.

https://www.researchgate.net/publication/283643851_QUATERNARY_EVENTS_AT_CRAIG_RHOSYFELIN_PEMBROKESHIRE

Brian John, Dyfed Elis-Gruffydd and John Downes. 2015. OBSERVATIONS ON THE SUPPOSED “NEOLITHIC BLUESTONE QUARRY” AT CRAIG RHOSYFELIN, PEMBROKESHIRE". Archaeology in Wales 54, pp 139-148. (Publication 14th December 2015) 

Book launch: everybody welcome



Free talk, book launch and signing session on Friday of next week.  Come along and enjoy a good argument!

In the old days, glaciers really WERE clever......



Have I unleashed a whirlwind here?  Who knows what glaciers will be blamed for next?  I thought I knew their abilities fairly well, but maybe in the good old days, long long ago, they were capable of far more than us poor mortals can appreciate.

Von Daniken, give me the money and I will give you a story that will satisfy all those avid fans of yours.......

Tuesday, 15 May 2018

Another book review



Here is another prepublication book review from one of my readers -- Prof Danny McCarroll.  In this case, he is happy for me to use his name and to use the review as I like.  So here it is, exactly as he sent it:

REVIEW
‘The Stonehenge Bluestones’

I generally steer well clear of long-standing and at times acrimonious debates that lie beyond my own very narrow specialism. The great Stonehenge bluestone debate is a case in point and I have always kept an open mind on the question of their transport from Pembrokeshire to Wiltshire, either as glacial erratics in some early glaciation or by human transport in the Neolithic. The central problem, until recently, was that the strength of opinions far out-weighted that of the evidence on either side. In recent years, however, despite the continued refusal of English Nature to allow the stones to be properly sampled, there has been a flurry of activity and some light is at last being shed. The evidence, new and old, is reviewed by Brian John in ‘The Stonehenge Bluestones’,  published by Greencroft Books.

I always assumed that the Stonehenge ‘bluestones’ were all nearly identical igneous rocks derived from a very small area of the Preseli Hills in North Pembrokeshire. Recent detailed petrological examination of the samples that are available, however, suggests that, on the contrary, the rock types are very varied and must have come from many different locations. Since some of the igneous textures are quite distinctive, the likely source of some small bits of stone have been traced to specific locations, some of which have been archaeologically investigated to look for evidence of Neolithic quarrying activity. I had the pleasure to visit one of those sites, at Rhosyfelin, while the material was still exposed and was singularly unimpressed with the supposed evidence for quarrying activity; it all looked completely natural to me. At the time I thought that maybe I was just missing some subtle evidence that the trained eye of the archaeologist could discern, and that the many radiocarbon dates produced for the site would doubtless be used to critically test the quarrying hypothesis. Those dates have now been published in the journal Antiquity and in fact they lend absolutely no support whatsoever to the quarrying hypothesis; a fair appraisal would be that they actually falsify it conclusively. Unfortunately that is not the interpretation of the authors of what is, sadly, one of the worst papers I have ever read.

The other big advance of recent years, which is not really covered in this book, relates to the extent not of some early glaciation, where most of the evidence has gone, but of the very last major glaciation, the deposits of which dominate huge areas of Britain and Ireland and that have been well studied for decades. A few years ago I would have confidently stated that we knew the limits of the last (Devensian) glaciation. However, ‘Britice-Chrono’, a large interdisciplinary project funded by the Natural Environment Research Council under the leadership of Chris Clark at Sheffield has changed that view completely. The ‘established’ limits of the last glaciation were based on geomorphological evidence, like the distribution of erratics, but in this project a wider range of more expensive methods were brought to bear, including detailed off-shore survey, satellite and other remotely-sensed imagery and a whole raft of the most up-to-date dating techniques. It turns out that our ‘established view’ of the extent (and thickness) of Devensian ice was not just wrong but wildly inaccurate. The ice was much more extensive than we thought; in many areas where we mapped it as terminating on land it actually reached right out to the shelf edge.

No one is suggesting that the Stonehenge bluestones were carried to anywhere near Wiltshire in the last glaciation. If glacier ice was responsible it would have been in a much earlier glaciation and subsequent glaciations will have removed the evidence further north and west. The evidence for glaciation so far south and east has not really improved, perhaps the strongest being the presence of ‘bluestones’ in archaeological structures that certainly predate Stonehenge. Given the lessons of the Devensian glaciation, however, I am certainly not willing to state categorically that glacial transport of erratics from Pembrokeshire to somewhere near Stonehenge is impossible.

Having read, and enjoyed, ‘The Stonehenge Bluestones’ I have to admit that I still have an open mind. It seems to me that the evidence for glacier ice carrying big stones from northern Pembrokeshire to somewhere near Wiltshire is rather scant. However, the evidence for those stones having been carried by Neolithic people seems to be completely absent, and the supposed evidence for them being quarried at Rhosyfelin is, in my view, just plain silly. I am not tempted to enter the debate in earnest, I do not know enough about the Neolithic or pre-Devensian glaciations, but if I was forced to bet a pint of good pembrokeshire beer, preferably from the Bluestone Brewery at Cilgwyn, I think I would put it on the glacier transport hypothesis.

Professor Danny McCarroll
----------------------------------------------------

Note:  I thought I was forthright enough in my appraisals of the quarrying "evidence" and in giving my opinion of that infamous "Antiquity" paper.  But Danny refers to the quarrying evidence as "just plain silly" and to the paper as "one of the worst papers I have ever read."  I would go with that. He also says that the radiocarbon and other dating evidence at Rhosyfelin falsify the quarrying hypothesis conclusively.  I would go with that too.

I also agree with him that there is no "smoking gun" as far as the field evidence is concerned.  We have two competing theories.    Theory One (the glacial transport theory) is a reasonable one, supported by some evidence; so it deserves consideration and further testing.  Theory Two (the human transport theory) is unreasonable in that it is unsupported by evidence and is simply underpinned by the supposition that Theory One is impossible;  it should therefore be rejected out of hand.  Think Occam's Razor and Hitchens's Razor.......


It's in the Daily Mail. so it must be true......



I wonder if any archaeologists read the Daily Mail?  They clearly don't read Archaeology in Wales or Quaternary Newsletter,  but this might be a bit more accessible.......

http://www.dailymail.co.uk/sciencetech/article-5728911/The-gigantic-stones-Stonehenge-moved-GLACIERS-new-theory-claims.html#reader-comments

By the way, how's your Spanish?

https://www.elconfidencial.com/alma-corazon-vida/2018-05-15/stonehenge-teoria-nueva-el-mayor-secreto_1563671/

https://uk.news.yahoo.com/mystery-moved-huge-bluestones-stonehenge-solved-134532440.html

http://www.foxnews.com/science/2018/05/14/stonehenge-secret-revealed-scientist-suggests-new-theory-about-ancient-site.html

Monday, 14 May 2018

Meanwhile, down under.......



Much to my surprise, they seem rather interested in the new book down under -- here is a piece which I have just come across.  They get some of the facts almost right,  but they are rather a long way away, so we'll forgive them for assorted inaccuracies.......

http://www.news.com.au/technology/science/archaeology/enigma-of-the-bluestones-where-did-stonehenge-builders-get-them-from/news-story/2019eca8c26304edf5f6bf40d5c68624

PS.  Another report:

http://www.countyecho.co.uk/article.cfm?id=116958&headline=Book%20focuses%20on%20Stonehenge%20bluestones&sectionIs=news&searchyear=2018

Sunday, 13 May 2018

Rhosyfelin -- the scrutiny continues




There's much fieldwork still to be done at Rhosyfelin, in spite of the fact that the archaeology dig site has been filled in and is no longer accessible.  Here are some pics from a recent visit, taken by my talented grandson Finley.....





A long house on Waun Mawn?



The single standing stone near the farm trackway.  Is there a nearby longhouse?

Dave M has been referring in recent messages to the time when he hoofed around on Waun Mawn in 1981, and recorded the presence of what he thought was a long house there.  The details are a bit sketchy, and the only record I have been able to find is in the Dyfed Archaeology Report which summarises work in the Tafarn y Bwlch - Waun Mawn area.    This is a screenshot of the relevant entry:


From the grid reference, it appears that the location is not far from the single standing stone which stands near the Gernos Fach track.  I'll see if I can check it out........




Please don't ask.......



Dear fellow bloggers

Much as I would like to give free copies of my new book to all you excellent people who follow and contribute -- or to just some of you, who might think of yourselves as the deserving poor -- I fear that commercial realities get in the way of charitable instincts.

Complimentary review copies have already gone out to magazines and newspapers, and I have already gone over my quota.  (Most of those copies will of course not result in reviews, but that's the way of the world.)

My new book is published by a small publisher (Greencroft Books -- namely me) at full commercial risk.  That's quite a rare situation in Wales, where maybe 90% of books published nowadays are published with grant aid -- in the form of publishing grants, writers' bursaries, design grants, editing grants etc.  In other words, publishing operations are underwritten by the taxpayer, and it is almost impossible for a "mainstream" Welsh publisher to make a loss on a book, no matter how few copies are sold.  As for me, within the next few days I have an extremely large printing bill to pay, and sales revenue is my only source of income.  With the large retailers and the distributors now asking for vast discounts (60%  is becoming the norm even for small quantities) publishing is now a very hazardous business, especially for small publishers.

I'm not complaining.  In fact, I quite enjoy living life on a knife's edge.  But this is a high-risk business.

The truth of the matter is that I need to sell as many books as possible at full cover price, to offset the very marginal profits coming from trade sales.   So please buy the book from  me, and not from Amazon or WHS!  The button is on the right,  and endless pleasure is just a click or two away........

I'll guarantee to get your copy to you in the week of publication (not earlier than that, since I must not upset the book trade).

So please don't ask for a free copy.  You will be disappointed.

Brian


Thursday, 10 May 2018

Foel Drygarn


I found this fabulous image of Foel Drygarn on the Internet Archaeology site -- I think it is a Cadw image originally.  It shows up extraordinary detail because of the very low winter sun and the sprinkling of snow.   We can see clearly the pitted area of hut circles, the Bronze Age cairns, and the Iron Age fortified embankments.  A classic example of a site that has had intermittent occupation over a very long timespan, and multiple uses as well.

Professional etiquette



I was interested to see this in one of the pre-publication reader reviews commissioned for the new book:

In his 8 pages of references, John creditably cites the publications of the proponents of the human transport hypothesis and opponents of the glacial transport hypothesis. This is a courtesy which has not been returned in recent papers by his opponents.

That does make me rather sad, since for all sorts of reasons it is good academic practice (and sound science) to acknowledge disputes where they exist, to cite the names and the opinions of those with whom you might disagree, and to address the issues raised with respect to your own ideas which have been challenged.  Where I come from, this is a matter of scientific integrity and respect for other specialists.

I may state my views bluntly and defend them stoutly, but I have never knowingly ignored anything thrown in my direction.  This whole blog is, I hope, a testament to my willingness to engage.  And with 1.3 million hits on the site so far, I take that as an indication of the approval of rather a lot of other people..... 

While I am about it, a word of praise for Rob Ixer in his many incarnations.  He and I may disagree on many things including quarries and human transport, but he is at least prepared to stick his neck above the parapet and to argue robustly.  He and I do sometimes use intemperate language on this blog, but we soon get over it, and in the course of our conversations I hope that we do spread a little light on controversial issues! 

When other academics simply ignore opposing views and slip into a state of denial (as MPP and his colleagues have done in their latest paper), they are either suffering from delusions of grandeur or acknowledging that their own ideas are incapable of withstanding scrutiny.    Should we laugh, or cry?


Wednesday, 9 May 2018

Quote for the day



From page 169 of the new book:

"It is never a good idea for a scientist to get into bed with an archaeologist unless he or she is in charge of what happens next."

New book -- special offer for bloggers



Dave has reminded me that it is not always easy to order new books like mine through the big book chains (like WHS and Waterstones) or even through small booksellers, at least in the early days of a title's life.  The reasons for this are mostly technical; my primary distributor is the Welsh Books Council in Aberystwyth, and small retailers and the retail chains have to set up a supply chain through WBC, which might involve haggling over terms including minimum quantities and discount rates.  That can all take time, which is frustrating both for customers and for me.  I want the stock to move -- fast!!

Amazon also has the book available on its site, and is taking pre-publication orders, but I have a love-hate relationship with them, since I have to use them for promotional reasons but get screwed so much on their massive discounts and delivery expectations that it is impossible to make a profit when selling through them.

So I have done some research, and have discovered that it's possible to set up a mail order system directly from the header page of this blog.  You should see a button on the right that will take you directly to my Paypal shopping site.  When an order goes in to Paypal I am normally notified immediately.   For £17 (P+P included) you can get a signed copy of the book and guaranteed delivery in time for publication day, June 1st 2018.  What could be more exciting?

I hope this will work OK.  In case of problems, please let me know.

Book blurb:

A radical new assessment of the myths and the facts surrounding the Stonehenge bluestones. Written in an an accessible style and aimed at the non-specialist reader, the book is lavishly illustrated with over one hundred photos, maps and diagrams. Author Brian John presents the results of exciting new research which suggests that the bluestones are a collection of glacial erratics transported from West Wales towards Salisbury Plain about half a million years ago by the vast and powerful Irish Sea Glacier. He hopes that his findings will increase public knowledge of the events of the Ice Age, and enhance our sense of wonder concerning the powerful forces at play in the natural world. Following a forensic examination of the evidence on the ground in Pembrokeshire and the Stonehenge neighbourhood, the author concludes that theories about so-called Neolithic bluestone quarries in West Wales do not stand up under scrutiny. The bluestones at Stonehenge are now known (from recent geological research) to have come from around 30 different localities. There are no solid grounds for supporting the theory that 80 or more bluestones were carried from West Wales to Stonehenge by Neolithic tribal groups. There is no evidence that the bluestones (including the famous spotted dolerites) were revered or considered special in any way. Furthermore, it now appears most likely that Stonehenge was never finished. It was built where the stones were, and when the builders ran out of sarsen stones and bluestones they simply abandoned their project. Whatever else it may be, Stonehenge has always been, and continues to be, a myth-making factory.  The author argues that archaeologists must take much of the blame for this, since they have been more concerned with the telling of elaborate stories (under great pressure from the media) than with careful evidence collection and sound science. This book should be compulsory reading for all those who think they know what Stonehenge is all about.



Here is an early review, from one of the members of my pre-publication readers panel who has a very distinguished academic record.    It's edited to put on one side some very detailed material on glacial processes, which I promise not to ignore.  I will come back to those points in due course with a separate post.


Geomorphologist Brian John has provided a comprehensive review of the origin and transport of the famous bluestones of Stonehenge. These are blocks (also many chips) of various types of rock, mainly igneous, with varied shapes. One thing that is agreed is that they are not found in bedrock anywhere near Stonehenge. Thus how they came to be there about 4,500 years ago is an interesting question, and one that has produced much controversy between rival hypotheses.

Almost all archaeologists believe that the bluestones were quarried on Mynydd Preseli in north Pembrokeshire and humanly transported to Wiltshire by land, estuary, sea, estuary and land again; or wholly by land. This is used as evidence that Late Neolithic people achieved a remarkable technological proficiency, and had considerable geographical knowledge and strong trade and cultural links between Wiltshire and Pembrokeshire. Brian John is at pains to demonstrate that this is wishful thinking, producing a series of myths supported by unscientific investigations that assume the truth of ruling hypotheses rather than weighing evidence dispassionately and testing alternative hypotheses.

More recently, those convinced that Neolithic people went to Pembrokeshire to source their ‘holy’ stones have excavated sites that they interpret as Neolithic quarries. John has many decades of field experience in north Pembrokeshire, and probably knows the region better than anyone else. He is also an experienced glacial geomorphologist and Quaternary sedimentologist who can be trusted to identify features of glacial or periglacial origin. His extended fieldwork in the supposed sites, and his knowledge of many similar sites, leads him to conclude that all the ‘quarry’ features are of natural origin: Ellis-Grufydd and Downes support him, in joint publications.

Having been on the offensive in demonstrating the mythology of much archaeological interpretation, John goes on to defend the alternative hypothesis that an ice sheet (or sheets) carried the bluestones almost all the way to Stonehenge. This has been discarded by archaeologists even though it is known that Irish Sea ice spread up the Bristol Channel, reaching as far as Bath – not in the last glaciation, but nearly half a million years ago. There being no terminal moraine, these old ice limits in Avon, Wiltshire and Oxfordshire are quite vague.

The bluestones have the appearance of glacial erratics, lacking the sharp edges and fresh fractures of quarried blocks. They come from numerous different locations, and include Palaeozoic sandstones as well as rhyolites and dolerites. Fragments (e.g. from the ‘Stonehenge layer’) are even more varied. The whole assemblage, then, suggests the mixing of rocks picked up in various places, which is typical for glaciers; not any focus on specially revered, holy rocks. The glacial hypothesis is not proven, but it seems much less improbable than people carrying many large stones from Pembrokeshire to Wiltshire.

The book is very well illustrated, with many colour photographs, ten maps and four satellite images. All are very relevant and informative. Nevertheless the reader not intimately acquainted with Pembrokeshire and Wiltshire will feel the need for detailed Ordnance Survey maps, as many place names in the text will not be found on any of the maps. The glacial sites listed on pages 196-203 are scattered over a wide area and it would be useful to know not only their locations, but especially their altitudes.

In his 8 pages of references, John creditably cites the publications of the proponents of the human transport hypothesis and opponents of the glacial transport hypothesis. This is a courtesy which has not been returned in recent papers by his opponents.

It is really surprising that such improbable myths as long-distance human transport of heavy blocks of rock should be not only entertained, but also unquestioningly accepted by so many investigators. After the election/referendum results of 2016, we should not be surprised at the credulity even of educated people. Of course archaeologists have to use a lot of imagination in any interpretation of ancient materials, especially from a pre-literate age. But the general lesson here is that it is very dangerous to go out to prove a single attractive hypothesis.







Moel Ty Uchaf, North Wales (amended)


This is a gorgeous "bouldery" stone circle too -- called Moel Ty Uchaf, near Llandrillo in Denbighshire.  This one is thought to be Bronze Age, but it is rather mysterious.  There is a raised platform in the middle, and there are many other stone settings and mounds in the area, indicating considerable Bronze Age (and Neolithic?) activity.

Here is one of my Powerpoint Presentation slides, showing what an extraordinary similarity there is between the Moel Ty Uchaf stones and the bluestones at Stonehenge.



The builders of both monuments were perfectly happy to use whatever stones were to hand -- and in those circumstances, why would they have bothered to go quarrying for elongated pillars?

The Stonehenge Bluestones -- contents list


Above is the poster for the book -- currently being distributed, and on schedule for publication day, 1st June 2018......

Contents as listed below:

Contents


1. The Enigma of the Foreign Stones 7

Sarsens and bluestones 9

The Pembrokeshire connection 12

The Preseli tors 15

Notes 19


2. Stonehenge and the Bluestones 21

The holes and the stones 21

Earthworks and pits 22

The stone settings 26

Reconstructions 31

Many pits, but how many stones? 37

The origins of the sarsens 41

The origins of the bluestones 44

The Stonehenge Layer 46


3. The Bluestone Transport Myth 49

Once upon a time..... 50

Testing the myth 60

The Millennium Stone fiasco 66


4. The Fable of Merlin the Wizard 75

Concerning the prophecies of Merlin 75

The back story 80

Politics and marketing 82

Proto-Stonehenge 84


5. Spreading the Myth 87

Variations on a theme 87

Dating the bluestone expeditions 92

Other dating methods 97

The starry sky 98

The Boscombe Bowmen 100

Barbecued beefburgers 101

The Neolithic argonauts 103

The Enchanted Land 108

The healing springs 112

The 2008 Stonehenge dig 116

Neolithic diplomacy 118

The stones of the ancestors 119

Orthodoxies and Dissidents 121


6. The Bluestone Quarrying Myth 125

The Carn Meini “quarry” 125

The Rhosyfelin “quarry” 131

The Carn Goedog “quarry” 143

The making of the myth 150


7. The Science of the Stones 157

The geological evidence 157

Modern research 161

Packing stones and mauls 169

Axe-heads and battle axes 170

The Altar Stone 172

Those other sandstones 175

The Berwick St James mystery 176

The volcanic ashes 177

Other inconvenient stones 178

The clay-with-flints puzzle 181

The “periglacial stripes” 182

The bluestone assemblage 183


8. The Work of Ice 185

The wider context 185

Glacial features of eastern Preseli 187

Glacial traces in the South-West 195

Reconstructing the glacier 204

Glacier modelling 206

Ice movement and entrainment 208

Erratic transport 211

The bluestone erratics train 214

Erratics, magic and mythology 217

A Matter of Convenience 220


9. The Balance of Probabilities 221

On human quarrying and transport 221

On glacial entrainment and transport 230

Keeping it simple 238


10. Conclusions


References


Tuesday, 8 May 2018

Geochemical fingerprinting of the Stonehenge sarsens


At last, there is a chance that the origins of the Stonehenge sarsens might be sorted out.  The researchers are due to finish this project in about one year's time.  But it appears that they have already decided -- in line with what David Field has been saying -- that the sarsens have NOT all come from the Marlborough Downs.......


https://www.brighton.ac.uk/research-and-enterprise/groups/past-human-and-environment-dynamics/geochemical-fingerprinting-the-sarsen-stones-at-stonehenge.aspx


Quote:
The sources of the stone used to construct Stonehenge have been debated by archaeologists and geologists for over a century. The smaller Bluestones, derived from west Wales, have attracted most attention. In comparison, virtually no work has been done on the sources of the larger sarsen stones (silcretes) used to construct the central Trilithon Horseshoe, outer Circle and peripheral settings. Conventional wisdom suggests that, given their size, the sarsens were all sourced from the Marlborough Downs. However, petrological, mineralogical and laser-scanning analyses indicate considerable variability among the Stonehenge sarsens, making this assumption questionable.