Rhyolite groups A-C

On reading through "Chips off the Old Block" by Rob Ixer and Richard Bevins, I was reminded of this statement, in the Conclusions part of the text:

"If the parent orthostat for the rhyolite groups A-C were sampled and it proved to be either SH32d or SH32e then it would demonstrate that widespread and abundant debitage is directly associated with an orthostat, is the partial result of the destruction of that orthostat and has not been introduced into the Stonehenge Landscape for other reasons or by other processes including glacial ones."

A number of things.  I'm still confused by the numbering of these stones.  On the Atkinson photos, 32e (closest to stone 33) looks like a dolerite stump, whereas stones 32c and 32d do indeed look like  rather flaky rhyolites.  Is there a definitive ruling somewhere as to which stone is which?

Second, can somebody please explain what the differences are between the foliated rhyolites in Groups A, B and C?  They are mentioned in several of the key papers, but I am still confused. Presumably they are all foliated rhyolites ......... but if they are different enough to be in different petrographic categories, how can lots of fragments in all 3 groups have come from the same stone?

Third, I don't follow the logic in the argument that if the fragments in the debitage can be related to the destruction of a big stone, that somehow rules out the introduction of debris into the landscape by glacial or other processes.  Surely it is perfectly feasible for debris from a large stone or super-erratic to have been scattered about in the landscape prior to the selection and introduction of a small part of it into a stone hole? At that point it became an orthostat or a standing stone.   You have no way of knowing how big or small that stone might have been prior to its selection and use......  and of course, if it was destroyed later on, there would have been the introduction of even more flakes and debris into the debitage.
  
Update: 

I found this classification in the Craig Rhosyfelin paper:

A. Dark/black, sharp, flinty rhyolite ± joint planes. Rare, pale-coloured, flinty rhyolite is probably weathered dark rhyolite.

B. Rhyolite with a planar fabric. Rare, extreme examples of this group initially were classed as ‘slate/phyllite’.


C. Rhyolite with a pronounced planar and lensoidal fabric ± joint planes.

I'm still confused.  Are these three categories now deemed to be redundant, and have they been rolled into one?  But they sound rather different from one another...... and that being the case, how can they all have come from one stone?

UK's Top 50 Quaternary Sites

Hot off the press!  Published today -- a new booklet from the Quaternary Research Association which is a fantastic teaching resource.  The top 50 Quaternary sites in the UK -- well, actually they got such a response from contributors that there are 80 sites, but the more the merrier......

Feel free to browse happily -- it's amazing what a diversity of Quaternary sites we have in this country.  Probably most of your favourites are in there somewhere.  There is a handy list which you can browse through, with hyperlinks to those sites you want to look at.  Mercifully, the descriptions are short and pretty non-technical.

https://www.qra.org.uk/top-50-quaternary-websites/

Solifluction sediments and colluvium at Rhosyfelin

This photo from 2011 shows the stratified solifluction deposits in which the "proto-orthostat" was embedded when it was discovered.

 

Colluvial and other deposits on the valley floor near the outer tip of the spur. At the base, fluvioglacial and glacial deposits (light grey). Above, dark grey finer-grained sediments, grading upwards into buff / cream coloured colluvium with iron-staining increasing upwards. Above that, an irregular junction with dark brown colluvium and modern soil.

Dr Simon Carr taking samples from the stained layer during a recent visit.

Interbedded with the rockfall debris and overlying the till and fluvioglacial deposits at Rhosyfelin, there is a layer of slope deposits up to 2.5 m thick. It's quite variable and very interesting indeed, and is difficult to interpret both with respect to age and origins.

The material exposed adjacent to the large slab is reminiscent of the “upper head” or stony solifluction layer found above Devensian glacial and fluvioglacial deposits in West Wales coastal sections. Exposures cut in the sediments in 2012 showed that more than 5m from the rock face there is a clear contact between the till and the overlying pseudo-stratified slope deposits. Within the latter there are at least five different but discontinuous layers, with a c 10 cm sandy/silty layer at the base. Above that, there are some layers of fine-grained sediments and others made up predominantly of elongated stones and flakes less than 10 cm in length. In addition to an abundance of sharp-edged local rhyolite fragments there are some large slabs and boulders and also, in the lower layers, rounded and sub-rounded erratics derived from upslope glacial materials. There are many signs of root penetration through this sequence, and the fine-grained layers contain many streaks of peaty organic debris. These materials have moved downslope predominantly from the NW, W and SW. The big flat-topped "proto-orthostat was embedded in this sediment layer when it was discovered. There do not appear to be any ice wedge casts which might suggest the presence of permafrost at the time of accumulation or at a later date, but in lower horizons there are some signs of bedding disturbances possibly attributable to frost-heave processes.

Further downslope, where the surface gradient decreases, the stones in this layer become less abundant, and it is predominantly made up of colluvial gravels, sands, silts and clays. Resting directly on the fluvioglacial deposits on the edge of the Afon Brynberian floodplain, there are at least three bands which are difficult to correlate precisely with the layers at the upslope end of the dig site. That having been said, there do not appear to be any discontinuities or unconformities that might show a long break in sedimentation.

At the base (close to the valley floor water table) there is a blue-grey layer at least 30 cm thick. It is clay-rich but incorporates bands of gravels which appear in places to have been deformed either by loading or frost-heave processes.

Above that is a layer up to 80 cm thick made up of sands, silts and clays but with some gravel and stone inclusions. There is no sharp junction between this and the underlying grey-blue sediment; texturally the two bands appear to be related. In this deposit there are occasional fragments of charcoal, suggestive of either natural / accidental burning of woodland or scrub in the vicinity, or else human occupation. This layer is buff- or cream-coloured at its base, but passing upwards iron-staining becomes more and more prominent, until the sediment has a distinct foxy-red colour similar to that on the till surface elsewhere on the site. It is noteworthy that the iron-enriched band transgresses the junctions between stratigraphic layers, suggesting that it is a pedogenic feature related more to water table oscillations than to age. (Iron "pans" are common in podzol soil horizons across north Pembrokeshire.)

Finally there is a grey-brown surface layer made of accumulated fine-grained slope materials, passing upwards into modern soil. There is a high content of organic matter, and more fragments of charcoal. This layer is up to 80 cm thick on the lower part of the site.

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This layer with many internal variations has to be post-glacial because it sits directly on till and fluvio-glacial gravels. But how old is it? Does it represent the whole period between c 18,000 years ago (when the last of the ice may be assumed to have melted away) and the present day? Or could there be a lot of sediments missing, and could it be of much more recent date?

Radiocarbon dates from some of the charcoal inclusions might help with the dating process: but one technique that might be particularly useful is OSL dating (optical thermoluminescence dating) which is best used on sediments that at the time of formation were exposed to daylight. The solifluction deposits might not be very suitable for sampling, but the colluvial deposits might be;   advice is needed on this.

Somebody's reading all this stuff........

I switched on the computer earlier on and found that there was a nice round figure on the counter.  Almost as exciting as watching the mileometer on a car gradually passing the 100,000 mile mark........

So a pure fluke.  But it's always good to know that there are a few readers out there.  What also interests me is that so few actually contribute to our discussions.  Maybe they look at the comments pages, and get put off by all that metaphysical / folk music stuff........  no matter, I rather like all you strange, crusty, eccentric, and expert contributors who make up our little community!  Obviously, or I would have gone off and done something else long ago.  So thank you all for what you bring to our common pursuit of the truth.

Show, don't tell.........

One of the great guiding principles of science is "Show, don't tell........"  That was something drummed into me when I started on my doctorate research, all those years ago, and the principle won't have changed in the years that have passed.

Everybody who has been required to submit a doctorate thesis will have been instructed by his / her supervisor to conduct research in a meticulous fashion, with good recording, and to them write a thesis more or less as follows:  Background to the problem >> statement of the problem itself >> working hypothesis to be tested >> presentation of evidence from the lab or from the field >> synthesis and summary of major results >> relevance to the problem being tested >> conclusions re confirmation or rejection of the working hypothesis.  At the end of it all, you only get your PhD or D Phil if you have moved forward the sum total of human knowledge in a meaningful way and have demonstrated a capacity for clear and independent thought.

Peer-reviewed scientific papers should of course follow the same route.  That is not to say that all peer-reviewed papers are honest and truthful -- you just have to look at "Retraction Watch" to see how much scientific fraud and corruption there is out there, especially in those areas where huge commercial interests are involved -- such as pharmaceuticals or agrichemicals.  But powerful media interests can also lead to results being skewed, and to research being slanted towards the establishment of the spectacular or the newsworthy rather than towards the truth.  So we need to be concerned about the recent news that the National Geographic Magazine is being taken over by James Murdoch and Fox.

https://www.washingtonpost.com/lifestyle/style/national-geographic-magazine-shifts-to-for-profit-status-with-fox-partnership/2015/09/09/7c9f034e-56f0-11e5-8bb1-b488d231bba2_story.html

That's seriously scary, given what the new owners have done in the past to pretend that climate change is a myth, and given Fox's role in that infamous trial a few years ago which established the principle in American law that media organizations are not obliged to tell the truth.  The truth, according to the judge in that case, is whatever you deem it to be...........  just think for a moment what the implications of that statement actually are.........

What got me thinking about all of this was a poem read out by "the canal boat laureate" Jo Bell, at a very pleasant PENfro Festival literary lunch yesterday.  Not everybody knows that Jo used to be an archaeologist (before she received enlightenment) and that she has actually written poems that are to do with her past.  I was very much struck by these lines:

"Record what you can see
And not what you expect......"

She suggested that that piece of sound advice should apply to poetry as well as to archaeology and other disciplines.  Well, on this blog I have always tried to show rather than tell, by putting evidence in front of anybody who may be interested, for critical comment and respectful debate.  What I have always had a big problem with, on the matter of the Rhosyfelin "Neolithic Bluestone Quarry" and on other matters, is that certain archaeologists have done a lot of telling and not a lot of showing.  And I have grave concerns that for much of the time they have been recording "what they expected" rather than "what they could see."  Come hell or high water, this is a Neolithic Quarry, and if it takes us ten years, this is what we will show........  We are now in the fifth year of the digging programme at Rhosyfelin, and we have not seen a single piece of "showing" and evidence presentation in print in a seasonal dig progress report or anything else.  Just not good enough, guys......  simply from the point of view of your own self-interest and academic reputations, to get this far into a project without any of your ideas being scrutinized and tested, except by those who are within the "bubble", is downright foolhardy.

By the same token I have to admire the geologists -- particularly Rob Ixer and Richard Bevins.  On some matters I find their evidence less than convincing, but that's the way of the world.  At least they have published, and their papers are out there, freely available for the rest of us to scrutinize.  And we have had some good knockabout fun with them, on this blog, thanks to our mysterious friend Myris.

How long will it be, I wonder, before hard evidence gets in the way of a rather good story?

Stonehenge DEBU (date of earliest bluestone use)

Following up on Tony's recent comment about the relevance of Bluestonehenge, I too have looked at Wikipedia for guidance!  (Yes, I know that's a naff thing to do, but most Wikipedia entries are pretty reliable, since nonsense tends to be kicked out and replaced by people who consider themselves to be experts!)

So here's what the entry says:

https://en.wikipedia.org/wiki/Bluestonehenge

The monument has been tentatively dated to between about 3000 and 2400 BC, although radiocarbon dating of antler tools found at the site has only provided an approximate date of 2469 to 2286 BC for the dismantling of the stones.[5] Tests on an antler pick found at the bottom of a stonehole have so far failed due to inadequate collagen in the sample.[6][7]

Excavation revealed several stone settings that are thought to have been erected some time between 3400-2500 BC, due to two flint chisel arrowheads in a style commonly used during that period being found. It is estimated that there may have been as many as 27 stones in a circle 33 feet (10 m) wide. Charcoal was found in some holes, suggesting that burning may have taken place there.[8] One suggestion is that the henge was a site for cremations.[7] Within the stone circle there were imprints of the bases from the original stones, which have been compared to the bluestones located in Stonehenge and have been found to have matching dimensions.[original research?]

The name "Bluestonehenge" is derived from the discovery of small stone chips in some of the stone settings. These bluestones are also found in Stonehenge and consist of a wide range of rock types originally from Pembrokeshire West Wales, some 150 miles (240 km) away.[2][9] Archaeologist Mike Parker Pearson suspects that any bluestones in the circle may have been removed around 2500 BC and incorporated into Stonehenge, which underwent major rebuilding work at about that time.[7]

The stone circle settings were surrounded by a henge, comprising an 82-foot-wide (25 m) ditch and outer bank which appears to date from approximately 2400 BC.[7] Unlike Stonehenge, there do not appear to be any significant solar or lunar orientations within the monument.[8]

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So MPP appears to be convinced that the bluestones were moved some time after 5400 yrs BP and were in place here by 5,000 - 4,400 yrs BP --  up to 27 bluestones?  They were then moved to Stonehenge around 4400 yrs BP for incorporation into the monument.....

So this would, if correct, give us a DEBU (date of earliest bluestone use) of between 5,400 and 5,000 yrs BP.  The problem is, as we have pointed out many times on this blog, there there does not appear to be a shred of evidence to support this theory apart from some putative stones holes that appear to have contained stones which later appear to have been taken away.

When were the bluestones first used at Stonehenge?

With Prof MPP no doubt planning to reveal his 20 or so Rhosyfelin radiocarbon dates to the world on Wednesday next, it's worth reminding ourselves of the sequence of events as currently understood.  

The piece below was posted on this blog back in Oct 2011 -- shortly after the Rhosyfelin dig started.   The interesting point to come from the chronology assessments is that Prof MPP favours a very early (Middle Neolithic) use of bluestones at Stonehenge, around 5,000 years ago, in Stage 1, when they were placed in the Aubrey Holes.  The evidence for that seems a bit scanty, but one line of argument is that the holes were of  remarkably similar dimensions to the Q and R holes which were (by common consent?) later used for a bluestone setting.  Another argument is that the holes were too big for timber posts and therefore held stones of bluestone size (rather than of sarsen size -- sarsen monoliths would have required much bigger holes).  Then there is the evidence of crushed chalk and other debris, suggesting a great pressure exerted from above -- and the cremation evidence, which is somewhat equivocal.

On the other hand, my understanding is that Darvill and Wainwright argued that the bluestones did not get used at Stonehenge until Stage 2, when they were placed in the Q and R holes around 4,500 years ago, in the Late Neolithic.  They propose that this happened after the erection of the sarsen trilithons but before the erection of the sarsen circle.  

There seems to be more agreement about what happened after that.  In Stage 3 (c 4350 yrs ago) (Copper Age) there may have been some rearrangement of the bluestones inside the trilithons.  In Stage 4 (c 4,100 yrs ago) (Early Bronze Age) the bluestones are thought to have been taken from the Q and R holes and placed in their "final" positions, first in the outer bluestone circle, and then in the bluestone oval or horseshoe.  In Stage 5 (c 3600 yrs BP) (Middle Bronze Age) the Y and Z holes were dig, maybe with the intention of putting bluestones into them, but in the event nobody ever got round to doing it............

That is the chronology as far as I understand it from Prof MPP's 2012 book.  So, if you believe in the human transport theory,  the favoured story is that the bluestones were carried from Wales in the Middle Neolithic, around 5,000 years ago.  Of course, as we have said many times before, the presence of that dolerite boulder in Boles Barrow pushes the "earliest bluestone use date" back to around 5,500 years ago. 

All comments on the accuracy of the above will be welcomed! 

===================== 

Did the Aubrey Holes hold 56 bluestones?

Sunday, 9 October 2011

 

   

I found this report from 2008 on the research council web site -- and it struck me that the discovery in Aubrey Hole 7 of "crushed and compacted chalk" by MPP and his team is about the only evidence we have that the holes once held bluestone pillars. The report says that a similar feature was also found in 3 other Aubrey Holes in earlier excavations. But how do we know that this compaction was not simply done by a ramming device, with the purpose of creating a firm base in the hole for whatever was due to be placed in it? (eg cremated remains). No bluestone fragments, as far as I know, have been found in the Aubrey Holes -- so the pillars (if there were any) could well have been small sarsens rather than bluestones. But MPP builds up a large hypothesis here -- not for the first time -- on what seems to me to be very flimsy evidence. He even speculates now that the stone circle of 56 bluestones had a diameter of 87m -- and that that stone circle might well have been carried from Preseli, where it was previously set up at Waun Mawn. He also says that when the Neolithic transport gangs had carried that stone circle lock, stock and barrel (or maybe minus the 3 stones that are still there) from Waun Mawn to Stonehenge, and put them all up in the Aubrey Hole setting, they later dismantled the whole thing and moved the stones in towards the centre of the monument, where they were supplemented by another batch of stones from the wild west (bringing the total up to 82), and then built into the later bluestone circle and horseshoe settings.

Type in 'Waun Mawn" in the search box for my previous posts on this topic.......

Does anybody know of any other evidence that supports this wacky theory, or is is just as wild as I think it is?

==========================
From the AHRC web site -- a report of a project funded with £500,000.

Changing the meaning of Stonehenge 

09 Oct 2008 
AHRC-funded excavation of Aubrey Hole  could change Stonehenge’s meaning

A new excavation of Stonehenge, funded by the Arts and Humanities Research Council, has revealed that an Aubrey Hole – one of a circle of pits surrounding the stones at Stonehenge – had probably held a standing stone.
The excavation of Aubrey Hole 7 was directed over one week in August 2008 by Mike Parker-Pearson, Mike Pitts and Julian Richards for the Stonehenge Riverside Project. The project, sees a collaboration involving five UK universities and over 200 archaeologists, and is funded by a £500,000 research grant from the AHRC.
Professor Mike Parker-Pearson at the University of Sheffield says, “If all 56 pits had held stones, this would have been one of the first and largest stone circles in the country, made of Welsh bluestones in 3000BC. A recent claim that these stones arrived at Stonehenge in 2300BC would then relate to the time when the bluestones were moved into the centre of the site 700 years later. Stonehenge’s history as envisaged since the 1950s is overturned.”
The pit had already been excavated twice: when discovered in 1920, and again in 1935 when all the cremated human bone found earlier at Stonehenge was reburied. Recovery of this bone for modern examination was the prime goal of the new dig (the bone was in excellent condition, and study will begin over the winter).
Another reason was to look at the Aubrey Hole itself – the first to be seen open since 1950. It was believed that these pits had been dug for oak poles, but Parker-Pearson had revived an old interpretation that they had held bluestones: the evidence of crushed and compacted chalk had been recorded in 1920 in three of the pits. He says, “Aubrey Hole 7 had crushed chalk on its base indicative of a standing stone. This had been missed by archaeologists twice before: it seems likely that similar evidence still survives in other Aubrey Holes. We propose that very early in Stonehenge’s history, 56 Welsh bluestones stood in a ring 285 feet 6 inches (87m) across”. He concludes, “This has sweeping implications for our understanding of Stonehenge.”
The new evidence from Aubrey Hole 7 suggests megaliths were present throughout Stonehenge’s existence. The first three radiocarbon dates for human cremation burials, obtained in May from the only bones then available for study, range between about 3000 and 2300BC. Contrary to claims made in the recent BBC Timewatch film, which promoted a theory of Stonehenge as a healing centre built after the practice of cremation burial had ceased, standing stones and burial of the dead may have been prominent aspects of Stonehenge’s meaning and purpose for a millennium.
Ends.
Media Contact: Emi Spinner, Communication Officer,  tel: 0117 9876 770 / 07854 005662

Editors Notes

Arts & Humanities Research Council: Each year the AHRC provides approximately £100 million from the Government to support research and postgraduate study in the arts and humanities, from archaeology and English literature to design and dance. In any one year, the AHRC makes approximately 700 research awards and around 1,000 postgraduate awards. Awards are made after a rigorous peer review process, to ensure that only applications of the highest quality are funded. Arts and humanities researchers constitute nearly a quarter of all research-active staff in the higher education sector. The quality and range of research supported by this investment of public funds not only provides social and cultural benefits but also contributes to the economic success of the UK.

Aubrey Holes

56 pits named after the 17th century antiquarian John Aubrey, were discovered by archaeologists in 1920. Thirty four were excavated 1920–1924 and two in 1950. They average about 3.5 feet across (1.1m) and 3 feet deep (0.9m) – similar to pits in the centre of Stonehenge known to have held bluestones. Their contents included mostly undistinguished artefacts, and pockets of cremated human bone and ash.
The pits’ purpose has been much debated. The original excavators first thought they were dug to hold small standing stones (the Welsh bluestones): the great Egyptologist Sir Flinders Petrie suggested they were a war indemnity paid by a Welsh tribe. But debate followed on whether they had held stones or wooden posts. After the 1950 excavation of two pits, they were believed to have been only for the placement of ritual deposits, with no stones or posts. In the 1960s astronomers suggested they may have held markers to predict eclipses. Since 1995, the standard interpretation has been that, when first dug, they held tall oak posts that had no astronomical function.

Cremation at Stonehenge

About 60 finds of cremated human bone are recorded at Stonehenge, representing some 50 people. Most of what survives has now been recovered in the excavation of Aubrey Hole 7. All such remains had originally been buried in or near Aubrey Holes or the ditch beyond. Pitts has suggested that in total, the cremated remains of some 240 people were buried at Stonehenge. This is by far the largest cemetery of this era we know of in Britain.
After the 1920s excavations had ended, no institution wished to curate the cremated bone, and in 1935 Wiltshire archaeologists William Young and Robert Newall buried them in Aubrey Hole 7. A lead plate with an inscription briefly describing the event was found in August. Today we expect to be able to learn a great deal from these remains, identifying sex, age and health of the individuals, and with a new process we can radiocarbon date them.

Bluestones

The great majority of researchers agree that almost all the bluestones were brought to Stonehenge by people from a small area of Pembrokeshire around the Preseli Hills. There are no stone chips at the bottom of the Aubrey Holes, but large numbers elsewhere on the site. It may be that 56 stones were brought to Stonehenge as natural boulders around 3000BC, and erected in the Aubrey Holes. Only later were some of them (not all) carved to shape, and further bluestones must have been brought to Stonehenge either then or before.
The total weight of all original bluestones at Stonehenge was around 260 tons. The total weight of the sarsens (the larger stones, brought from some 20 miles away) was around 1,700 tons.

BBC Timewatch

These new claims conflict with those made by Timothy Darvill and Geoffrey Wainwright, who excavated at Stonehenge in April. In a BBC broadcast on September 27, they said the first bluestones arrived at Stonehenge in 2300 BC, by which time cremation burial had ceased.
We cannot support the 2300 BC radiocarbon date. It was obtained from a single cereal grain, which most archaeologists would find unacceptable. Items this small can be moved by burrowing animals – Charles Darwin showed the burying power of earthworms specifically at Stonehenge in 1877. It also conflicts with other radiocarbon dates and the known sequence of megalithic construction at the site, which together place the first erection of bluestones in the centre of Stonehenge at an unknown date before 2470 BC.
There are currently only three radiocarbon dates for cremation burials. It is statistically unlikely that the last burial that took place at Stonehenge is amongst those dated, so the most recent date of 2470–2300 BC should not be read as dating the end of that tradition.

Stonehenge Riverside Project

Responsible for major excavation within the Stonehenge world heritage site over the past five summers. Directors are Mike Parker Pearson (Sheffield University), Joshua Pollard (Bristol University), Colin Richards and Julian Thomas (Manchester University), Christopher Tilley (UCL) and Kate Welham (Bournemouth University).
Website at www.shef.ac.uk/archaeology/research/stonehenge