THE BOOK
Some of the ideas discussed in this blog are published in my book called "The Bluestone Enigma" -- available by post and through good bookshops everywhere. Bad bookshops might not have it....
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Sunday, 21 September 2014

Drover's Roads and summer farms


There are some amazing new images on North Pembrokeshire on the web -- from satellite imagery obtained earlier this year -- presumably in the early spring.  These have nothing whatsoever to do with Stonehenge or the Ice Age, but I thought I'd share them anyway!  With the sun very low, and with long shadows, lots of landscape details stand out clearly.

The upper image shows the old Drover's Road (used in particular in the late 1700's and early 1800's) running between Carn Goedog and Carn Breseb, en route towards Carn Alw and Eglwyswrw.  Many thousands of animals must have been driven this way, heading from the rich farmlands of Pembrokeshire towards the growing industrial towns of the Midlands.  The trackways are quite spectacular.

The lower image is a classic one, showing Hafod Tydfil, on the northern flank of Preseli.  Any farm in Wales which has "Hafod" in the name must have started as a summer settlement, used for grazing in the summer months when the land close to the home farm (or "hendre") was needed for the growing of crops. The Norwegian saeter was very similar, as were the transhumance cottages in the Alps.   Hafod Tydfil must have started as a very small hovel, but eventually a farmhouse was built here, and it was farmed as a viable unit for many years.  Ronald Lockley lived and farmed here for a while after WW2.  Now the farmhouse is ruinous, and the fields are just used as permanent grazing -- but the place still stands out as an "island" of cultivation in the midst of the wilderness.  I was caught in a thunder storm here once, and was stupid enough to take shelter near that big clump of trees.......



Saturday, 20 September 2014

Stonehenge -- did the rhyolite fragments come from bluestone monoliths?

(Thanks to Rob for drawing our attention to this article from 2013.  It reports that Ixer and Bevins have now been involved in a "lumping" exercise by combining the three rhyolite groups A-C into one single category which has quite a lot of variation within it.  Makes a change from the "splitting" which geologists usually do.  Doing a lumping exercise has the merit of simplicity, since we are all confused enough as it is, but there is also a danger of creating complacency and causing non-geologists to assume uniformity where there is none.  I am even more confused because the authors now seem to assume that all three types of foliated rhyolite from Rhosyfelin were to be found on a single monolith at Stonehenge which has now been destroyed.........  we will no doubt have that explained in due course.  See also this post:
http://brian-mountainman.blogspot.co.uk/2013/01/the-rhyolitic-debitage-around-stonehenge.html
But what is especially noteworthy in this article is the contribution from Mike Pitts, who makes exactly the same point as I am making below.  A link to the paper is added at the end of the original post.)


The rhyolite outcrops at Rhosyfelin. A good place for making Mesolithic microliths and Neolithic axes?  That's a question worth asking.......

 Weights and specimen numbers from the Stonehenge Layer.  These graphs have no statistical significance, but they are interesting.  These are just some of the total number of fragments examined from all contexts

Let's agree with Rob Ixer and Richard Bevins that some of the rhyolite debitage in the Stonehenge landscape has come from the Pont Saeson area near Brynberian --  and more particularly from the Rhosyfelin locality.  Of the 4000 or so "bluestone" fragments examined, over 1200 (approaching 30% by number) of those have been made of foliated rhyolite similar to those identified around Rhosyfelin.  That's  about 19% of the total, by weight -- and surprisingly, that figure is greater than the 16% for spotted dolerite. Bear in mind that there are far more spotted dolerite orthostats than there are rhyolite ones -- so as Rob and Richard have pointed out, that means that any rhyolites in the Stonehenge area have been bashed about in preference to bashing about the spotted dolerites.  Maybe that's simply because it was easier to do, since flaky and fractured rhyolites are easily broken up, and dolerites are far harder.......   Interestingly, there is no segment on the diagram above for unspotted dolerite.

Given that there is huge sampling bias here (archaeologists have only examined a few parts of the Stonehenge debitage / soil layer and have automatically homed in on "interesting" samples while rejecting "boring" ones) we can say certain things about the material that HAS been collected and examined.

1.  We are talking about very small weights here.  What is the total weight of all the rhyolite fragments examined?  Perhaps Rob will tell us, but it may be no more than a few kilos.  The weight of a few small stones or axes?  I take the point that Rhosyfelin was not an established source of axes, and that there is no known "axe group" identified by the Implement Petrology Group with the right petrological characteristics, but that does not mean that Rhosyfelin was not used by some individuals as a source of material for the making of axes.  If that happened, those axes (which may not have been very good ones) could also have been traded, brought to Stonehenge, and then destroyed because they were unfit for purpose.  (Forgive me.  I feel a story coming on.......)

2.  I'm not sure why it should be assumed that because there are "Rhosyfelin rhyolites" in the debitage at Stonehenge, they must have come from one or more destroyed orthostats.  That's a reasonable hypothesis, given those enigmatic stumps that look as if they are made of the right material (32d and 32e, if we have the numbering right) -- but it's also a perfectly reasonable hypothesis to suggest that the fragments might have come from "inconvenient" pebbles, chunks or boulders that happened to be lying around in the Stonehenge landscape and which were simply smashed up because they were in the way or were of no use.

3. There are three different rhyolite fabrics in the frame here.  These are, as defined by Ixer and Bevins in 2011:

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.

Forgetting about Groups D and E for the moment, they say "the other three groups are significant in percentage terms both by weight and number."

I accept that there is considerable variation in the characteristics of the rhyolites across the rock face exposed at Rhosyfelin.  But do all three types occur on this single rock face?  From my careful reading of the paper, I am not sure that this has been established.  So even if some very accurate provenancing can be demonstrated (ie to within a few metres) the possibility remains that substantial amounts of the Stonehenge rhyolitic debitage have come from other sampled or unsampled locations across the Pont Saeson area either from currently exposed rock outcrops or from others that are currently invisible.  (Even if you look at the published thin sections showing the "Jovian fabric" about which all the fuss has been made, the samples from Stonehenge and Locality 8 are similar but NOT identical, as the authors recognize.)


Top image -- Jovian fabric from Locality 8 at Rhosyfelin.  Bottom image -- Jovian fabric from one of the Stonehenge samples. The fabrics are similar but not identical, as Ixer and Bevins point out.

My point is that no matter how good the geological provenancing of these rhyolite fragments may be, the orthostat obsession has led to the quarry obsession, and that in turn has led to all sorts of skulduggery in the interpretation of perfectly natural features observed during the 2011-2014 digs.........  Ah, geology as the root of all evil!

Quotes from the Ixer / Bevins papers called "Chips off the Old Block" and "CRAIG RHOS-Y-FELIN, PONT SAESON IS THE DOMINANT SOURCE OF THE STONEHENGE RHYOLITIC ‘DEBITAGE":

** Since 2008 there has been a systematic lithological investigation of debitage found within the Stonehenge Landscape; most of these lithic fragments were re-examined in April 2013. Just over 4000 bluestone debitage fragments weighing between 0.1 and 8500g have been lithologically classified macroscopically, the majority being from the April 2008 Darvill and Wainwright excavation within the Stonehenge stone circle (3657 fragments) but also including lithics from the Heelstone Ditch excavations (171) (Pitts, 1982; Ixer and Bevins, 2013), the Stonehenge Avenue including Trenches 44 (20) and 45 (71), Aubrey Hole 7 (54), and from surface finds and test pits in the area close to the western end of the Stonehenge Greater Cursus (31) (Ixer and Bevins, 2010). ............  In addition small numbers of bluestone fragments have been identified from locations in the vicinity of the Stonehenge Landscape although no bluestones have been identified from West Amesbury Henge. In addition over 100 thin sections, polished blocks and polished thin sections have been described for the major non-dolerite classes of debitage and these have been compared with polished thin sections from all the sampled bluestone orthostats.

**  Although there are subtle but distinct differences between different rhyolitic outcrops at Pont Saeson, including those on Craig Rhos-y-felin, they share a distinctive petrography that is unrecognised from elsewhere in the Fishguard Volcanic Group. Texturally all are foliated usually with an associated lensoidal fabric where deformed lithic clasts occur and carry a similar dominant mineralogy, although, in addition, some outcrops have rare, unusual minerals.

**  Almost all (>99.9%) of the Stonehenge rhyolitic ‘debitage’ can be petrographically matched to rhyolitic rocks found within a few hundred square metres at Pont Saeson and especially to those found at Craig Rhos-y-felin. However, it is possible in a few cases, where the petrography of these Welsh in situ rocks is so distinctive, to suggest an even finer provenance to within square metres, namely to individual outcrops.

**  Well over 1200 rhyolitic lithics belonging to Groups A – C have been identified and their distribution is widespread throughout the Stonehenge Landscape including close to the Stonehenge Greater Cursus area but no parent orthostat has been securely identified although hitherto unsampled buried stones SH32d or SH32e are strong candidates. The majority of the rhyolite lithics are small struck flakes but at least one large rough out weighing 190g (April 2008 excavation context 12/10; Roman) has been recognised.  It is interesting that it does not belong to any of the established axe groups established by the Implement Petrology Group (Clough and Cummins, 1979, 1988). 

 ===========================

Addendum

A re-examination of rhyolitic bluestone ‘debitage’ from the Heelstone and other areas within the Stonehenge Landscape
by Rob A. Ixer and Richard E. Bevins, with a contribution from Mike Pitts
Wilts Arch & Nat Hist Mag 106 (2013), pp 1-15.

https://www.academia.edu/4036994/Lithics_from_Heelstone_Ditch_area_Stonehenge

ABSTRACT

Recently it has been proposed that the Stonehenge rhyolitic debitage can be distributed into five petrographical groups (A-E) (and that at least three of them (A-C) are from rocks cropping out at Craig Rhos-y-felin). This supersedes an earlier classification scheme of this important category of Stonehenge material. The earlier 1980s scheme, based on lithics found close to the Heelstone, divided the rhyolites into two groups (A and B) and sub-divided the larger into two further
sub-groups (Bi and Bii). Re-examination of this earlier material together with other Stonehenge rhyolites has allowed the two schemes to be compared and integrated.
The original 1980s Group A lithics are identical to the present Group B, (both are small groups). This group is described in detail so completing the petrographical descriptions of the Stonehenge rhyolitic debitage. Despite bearing feldspar megacrysts this group shares sufficient petrographical characteristics with rocks from Craig Rhos-y-felin to support the view that that location is the geographical origin of the group.
Lithics belonging to the 1980’s groups Bi and Bii, however, are randomly distributed amongst the present A and C groups and there are no strict correspondences. The designation Bi and Bii should therefore be abandoned.
Using the new scheme it should now be possible to map more precisely the distribution of the rhyolitic debitage in the Stonehenge landscape to inform such questions as to the number of rhyolite orthostats originally present and their fate.


Extract from the contribution by Mike Pitts

Such issues of context are extremely important if
we are to understand the significance of the different
types of stone used at Stonehenge. Context has been
conspicuously absent from most debate, which has
focussed on whether the smaller megaliths were
brought to Stonehenge from Wales, or found lying
on Salisbury Plain. Debris at Stonehenge or nearby
is typically treated as if it were a proxy for megaliths.

Distinctions between different types of bluestone are
assumed to matter only to modern scientists, not
to the people who built or used Stonehenge. None
of this is helpful (archaeologists and geologists are
equally at fault).

It is notable that all the samples matched in this
study to Craig Rhos-y-felin come from debitage and
not from megaliths (although Ixer and Bevins (2011a
and b) have suggested that buried megalith SH32e
may also come from Craig Rhos-y-felin). One of the
distinctive features of the rhyolitic rocks is that they
are flinty – they have a good conchoidal fracture.
That makes them relatively easy to break up, if they
are standing as monoliths at Stonehenge. But it also
makes them suitable for making portable artefacts.
There are flaked bluestone ‘tools’ from Stonehenge
(including some from the stone floor). Which of
these are made from debris created when stones
were dressed on site? Which are made from broken
up megaliths? And which were made in Wales and
brought to Stonehenge by people visiting, perhaps
on a pilgrimage of some kind? Clearly the distinction
has important implications for how we understand
Stonehenge.


These are questions that future research can
approach through excavation in Wales and at
Stonehenge and study of the debris. Very limited
excavation at Stonehenge would allow modern
identification of the stumps and other pieces of
megalith at the site, and perhaps the matching of
some to Ixer and Bevins’ rhyolitic groups. The
dressed dolerite fragment and apparent tools from
the 1979–80 excavations suggest that re-excavation of
Hawley’s stone dumps would be productive, despite
the lack of context. The search for sarsen quarries,
too, is critical.

A good start, as Ixer and Bevins suggest, would
be to re-examine all previously excavated rhyolitic
debitage. As they say this needs to reach beyond
Stonehenge. Over 30 years ago I compiled a list
of Stonehenge-type rocks found away from the
monument, noting that there had been ‘surprisingly
little consideration of the stones imported to the site
for use as megaliths’ (Pitts 1982, 124–126). Perhaps
now this might change.



The point about Rhosyfelin rhyolites being used for tool making is a good one, and needs to be answered.  Mike also wonders why we should always assume that the debitage at Stonehenge has come from monoliths rather than from other stone debris or from broken up tools which were imported onto the site by traders or visitors.  In my view this is much more likely than the "smashed monolith" hypothesis.  After all, why would the Stonehenge builders go to the trouble of carrying a rhyolite monolith (or several of them) all the way to Stonehenge in the knowledge that it was no use at all as a standing stone, and then to smash it up on site?  It would have been far simpler, if they were more interested in rhyolite tools from Rhosyfelin, to do the work at Rhosyfelin itself, leaving all the debris behind.  Back to my point -- was it the tools that were smashed up, rather than the monoliths?







Friday, 19 September 2014

The buried stones at Durrington Walls



The map above is from Tim's blog -- the purple line shows where the stones are located. 

Here is an extract from his site, for those who are interested in the throwaway line in the recent BBC Stonehenge programme:

http://www.sarsen.org/2014/09/durrington-walls-dragons-teeth.html

This relates to part of the southern bank at Durrington Walls.  It appears that there have been no excavations so far in order to check out whether these really are recumbent buried stones, or something else entirely........  no doubt Tim will report on any developments.

Using powerful ground-penetrating radar, which can ‘x-ray’ archaeological sites to a depth of up to four metres, investigators from Birmingham and Bradford universities and from the Ludwig Boltzmann Institute in Vienna have discovered a 330 metre long line of more than 50 massive stones, buried under part of the southern bank of Durrington Walls.
“Up till now, we had absolutely no idea that the stones were there,” said the co-director of the investigation Professor Vince Gaffney of Birmingham University.
The geophysical evidence suggests that each buried stone is roughly three metres long and 1.5 metres wide and is positioned horizontally, not vertically, in its earthen matrix.
However, it’s conceivable that they originally stood vertically in the ground like other standing stones in Britain. It is thought that they were probably brought to the site shortly before 2500BC.
They seem to have formed the southern arm of a c-shaped ritual ‘enclosure’, the rest of which was made up of an artificially scarped natural elevation in the ground.
The c-shaped enclosure – more than 330 metres wide and over 400 metres long – faced directly towards the River Avon. The monument was later converted from a c-shaped to a roughly circular enclosure. (source)

Parchmarks at Stonehenge in 2013

There's a mention of the parchmarks paper on Tim's web site, here:

http://www.sarsen.org/2014/08/antiquity-article-on-stonehenge.html

Antiquity Issue 341 - September 2014

Simon Banton, Mark Bowden, Tim Daw, Damian Grady and Sharon Soutar

Parchmarks at Stonehenge, July 2013.... Volume: 88 Number: 341 Page: 733–739

Despite being one of the most intensively explored prehistoric monuments in western Europe, Stonehenge continues to hold surprises. The principal elements of the complex are well known: the outer bank and ditch, the sarsen circle capped by lintels, the smaller bluestone settings and the massive central trilithons. They represent the final phase of Stonehenge, the end product of a complicated sequence that is steadily being refined (most recently in Darvill et al. ‘Stonehenge remodelled’, Antiquity 86 (2012): 1021–40). Yet Stonehenge in its present form is incomplete—some of the expected stones are missing—and it has sometimes been suggested that it was never complete; that the sarsen circle, for example, was only ever finished on the north-eastern side, facing the main approach along the Avenue. A chance appearance of parchmarks, however, provides more evidence.

The Altar Stone-- recumbent or erect?


I just noticed in this image of a "Pristine Stonehenge" from the recent BBC programme that the Altar Stone is shown here (in the shadow) as recumbent -- ready to be used for ritual slaughters and other nasty going-on..  I know Aubrey Burl always argued that it was meant to be recumbent and had never been set upright in a socket -- but others (like Tony Johnson) have insisted that it was simply the biggest of the bluestones, knocked over during a nasty sarsen accident.

I haven't kept up on this issue.  What is the latest thinking?

Operation Stonehenge - Part 2

"Operation Stonehenge -- what lies beneath?"  Part 2. BBC2 18th September.

Once again, a strange mixture of fantasy and fact, with assorted gruesome reconstructions of the brutal lives led by our highly sophisticated ancestors...... and the shaman looked like the sort of fellow one wouldn't have liked to get on the wrong side of.....

But some interesting information.  A few thoughts:

1.  It was simply assumed that the sarsens all came from the Marlborough Downs -- no attempt to support that hypothesis with actual evidence.  I was not convinced.

2.  It was suggested by Katy Whitaker that all the sarsens were beaten with hammer stones over every square inch of their surfaces, to give a pristine white surface which must have made the whole monument -- when complete -- a truly spectacular appearance.  Nice pictures, but I was not convinced.



3.  Wolfgang Neubauer suggested that the sarsens were dragged from the Marlborough Downs by the most direct route possible, which means along the route of the Avenue -- although it was not there at the time.  There was mention of "glacial striations"  -- by which I suppose they meant the wonderful periglacial stripes.  But it was unclear from the commentary whether they thought that the dragging of the sarsens caused the grooves and scratches shown in the surveys, or whether they simply used these existing grooves to ease the transportation by sledges etc.  All speculation, and of course meaningless if the sarsens were really collected up in the Stonehenge area.


4.  Tony Johnson demonstrated how Stonehenge was laid out with the aid or ropes and pegs.  All fair enough, but that does not demonstrate that Stonehenge ever was finished or accurately built......

5.  The crop marks -- interesting evidence which MIGHT show that there were pits at some of the locations where stones are assumed to have been positioned -- but I have problems with this (and so does Kostas) since a place where there is a hidden pit would have deeper soil and one would assume -- better moisture retention in case of drought.  On the images below the lower one is computer enhanced, and is not to be trusted.  Another thing is that even if there were sockets in the places where the crop marks are prominent, that does not tell us that there ever were any stones in them, and this is absolutely NOT "compelling evidence that Stonehenge was completed."  Even if there were big sarsens in these supposed sockets, they could have been moved about and relocated.  If they played about with the bluestone settings over many centuries, is it not possible that they did exactly  the same with the sarsens?


6.  On the bluestones, the commentary said "geological analysis proves they were quarried in Wales" -- which is of course nonsense.   There was remarkably little about the bluestones in the programme, which went on to suggest, with great conviction, that the family of six whose teeth and bones have been analysed actually came from West Wales, providing a link with the bluestones.  That is over-egging the pudding to a considerable extent -- the published evidence does very little to support that hypothesis.

7.  I felt really sorry for the poor fellow who seems to have been crushed beneath a falling monolith, but was greatly relieved to hear that he survived to tell the tale.......  and as for that nasty shaman, the less said about him, the better......

All in all, another curate's egg of a programme, which told us relatively little we didn't know already.

Rhosyfelin should have a RIGS designation



Yesterday I sent this out in all directions, and although we are too late to stop the hole being filled in, I hope the request will bear fruit.  These things are never decided in a hurry...... the only consolation, with respect to Rhosyfelin, is that the archaeologists have put down a sheet beneath the spoil being dumped back into the pit, in the hope of returning next year.  So the features are not lost for ever, and can be examined again if somebody finds the funds and the motivation to do more work here.......

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

Dear Colleagues

I am writing with an urgent request for a site review at Craig Rhosyfelin in Pembrokeshire, which is the current location of an archaeological excavation.  This may or may not be important archaeologically, but it is certainly VERY important from the point of view of geology and geomorphology -- and I am seriously concerned that it might be filled in before it can be examined by qualified earth scientists.  THE DIG IS DESIGNATED TO END AT THE WEEKEND, WHICH MEANS THAT THE REMOVED SEDIMENTS MAY WELL BE DUMPED BACK INTO THE EXCAVATION TODAY OR TOMORROW, IF ACTION IS NOT TAKEN.  Most of the evidence required for RIGS notification will then be lost.

Will you please take urgent action to put a hold on the work of the archaeologists and ensure that the site is examined?

The images below** show the essential features of the site, including the glacial meltwater features, the rock face, and the Devensian morainic accumulations and finer-grained sediments which may shortly be buried, thereby making a "rescue assessment" from taking place.

Over to you!

With many thanks

Dr Brian John
18th September 2014


**not reproduced here -- they are familiar to readers of this blog.

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

PROPOSED DESIGNATION AS A REGIONALLY IMPORTANT GEODIVERSITY SITE
Craig Rhosyfelin
Grid Ref SN 117363

Suggested Statement of Interest:

Craig Rhosyfelin is a rocky spur on the flank of a deeply cut meltwater channel now occupied by the Brynberian River.  There is a subsidiary meltwater channel on the northern flank of the spur. The crag reveals (towards its outer end) an unusual foliated rhyolite from the Fishguard Volcanic Series which has been matched with some of the "debitage" at Stonehenge, though not with any existing bluestone monoliths.  There is ongoing debate about the mode of transport of these fragments from Rhosyfelin to Stonehenge.  The sequence of deposits adjacent to the spur includes Late Devensian till and torrential fluvio-glacial materials, rockfall accumulations and scree of various ages, fine-grained stoneless deposits that might have been laid down in a pro-glacial lake, and a distinctive iron-rich hardpan deposit beneath later colluvium and a modern soil horizon.  The site is of great geological, geomorphological and pedological significance, and it deserves RIGS designation.  In particular, it is of national importance for the elucidation of Quaternary chronology.



=================================
Key document:
Pembrokeshire Coast National Park Authority
Regionally Important Geodiversity Sites in Pembrokeshire

http://www.pembrokeshirecoast.org.uk/files/files/dev%20plans/AdoptedSPG/RIGS_SPG_FinalOct11Eng.pdf
3.1 RIGS are a non statutory geodiversity designation. They sit under the Geological
Conservation Review (GCR) sites designation. [GCR sites are considered to be of national
and international importance in relation to British Earth science and geological history. The
GCR are localities already notified or being considered for notification as ‘Sites of Special
Scientific Interest’ (SSSI), and provides legal protection of sites].
3.2 RIGS in Wales are funded and supported by the Countryside Council for Wales. They are
designated outside of the Local Development Plan process by the Regional RIGS Groups. This
Supplementary Planning Guidance provides the location and summary of the Statement of Interest
for RIGS within the Pembrokeshire Coast National Park.
3.3 Regionally Important Geodiversity Sites (RIGS) are advisory designations and are non-statutory.
The Pembrokeshire RIGS were designated in 2009 by the South-West Wales RIGS Group.
3.4 The South West Wales RIGS website can be accessed at www.swwalesrigs.org.uk.
3.5 The web site of UK RIGS groups is www.ukrigs.org.uk. and they can be emailed at
info@geoconservationuk.org