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Monday 23 December 2013

Chips off the old block

The main sites referred to in the latest paper -- mostly debitage sites

"Chips off the old block: the Stonehenge debitage Dilemma", by Rob Ixer and Richard Bevins, Archaeology in Wales 52 (2013), pp 11-22

Another new paper from the "provenance hunters" Rob Ixer and Richard Bevins -- this time published in "Archaeology in Wales". To quote the authors at the outset:

Within this century there has been a renewed interest in the lithology of the Stonehenge bluestones, both for the standing orthostats and also for the vast numbers of broken bluestone material, now referred to as debitage. Increasingly it has been recognised that there are a number of interesting problems associated with this debitage found within the ‘Stonehenge Landscape’, most notably their original geographical provenance, their internal Stonehenge provenance (matching debitage to parent orthostat), the reason for their presence and finally explanations for the apparent mismatch between the lithologies of the (above-ground) bluestone orthostats and the debitage both in terms of type and numbers. A fundamental initial step in answering most of these questions is to try to match debitage fragments from well constrained contexts to their parent orthostat.

So the debitage (c 4000 rock fragments and c 100 thin sections examined) is the focus here.

The authors also state, with respect to origins:

In relation to the explanation for the debitage, amongst the main anthropogenic contenders are the following: (a) that it is wastage from the dressing of the orthostats, (b) that it is true debitage associated with the later reuse of the orthostats as ‘quarries’ for axe manufacture, (c) that it is made up of ‘knock-offs’ from later souvenir hunters or amulet collectors. The favoured non-anthropogenic explanation is that some of it comes from (glacial) erratic background material, some of which was not incorporated into the Stonehenge stone settings (John, 2008). Of course, it is quite possible that all of these explanations are partly correct; they are not mutually exclusive.

With resepect to the main Stonehenge bluestone lithologies, they say:

The main bluestone orthostat lithologies are either spotted or non-spotted dolerite (the authors suggest 3 groups -- BJ) but within the outer bluestone circle there are 12 non-dolerite bluestones (used here in the sense of any non-sarsen, proven or potential, Stonehenge orthostat material), including both standing orthostats (SH38, 40, 46 and 48) and buried stumps (32c, 32e, 33e, 33f, 40c, 40g, 41d, 42c) (Atkinson, 1979). Of these, 32e is described as a rhyolite, 40c as a calcareous ash, 40g and 42c as micaceous sandstones and 32c, 33e, 33f and 41d as altered, dark olive-green ash (Atkinson, 1979; Thorpe et al 1991). In addition the Altar Stone is a calcareous sandstone of probable Devonian age and unlike any other lithic from Stonehenge (Ixer and Turner, 2006). 

The bluestone debitage comprises spotted and non-spotted dolerite, a restricted set of rhyolite and rhyolitic tuffs, informally known as ‘rhyolite with fabric’ and more formally as Rhyolite Groups A –E (Ixer and Bevins, 2011b), a variety of argillaceous and calcareous tuffs (informally known as ‘volcanics with sub-planar texture’), and a numerically far smaller group of sandstones including (Lower) ‘Palaeozoic sandstone’ and ‘micaceous sandstone’. Other non-bluestone lithologies are very rare and mainly restricted to disturbed or modern contexts and are not discussed further. 

The authors are circumspect, but from previous work there appear to be at least 15 different lithologies in the frame.  There appear to be nine different rhyolites -- represented in the orthostats and in the debitage.  The Altar Stone (Devonian sandstone) is unique among the orthostats, and there are just 3 debitage fragments that appear to match it.  All the other sandstone debitage fragments are from other sandstones -- probably Lower Palaeozoic, and possibly from North Pembrokeshire........

Rhyolite orthostats 38, 40 and 46 appear to be different, and unusual in that there appears to be no debitage related to them.  Orthostat 48 (made of Group E rhyolite) does have some debitage related to it.  There are abundant fragments of debitage in Rhyolite Groups A-C -- assumed to have come from Craig Rhosyfelin, but as yet no related orthostat has been found.  The authors speculate in this paper, not for the first time, that there may be a match either in stump 32d or 32e.

The conclusion of the paper is as follows:

Although the evidence is very incomplete the hypothesis is, that, for the non-dolerite bluestones, above-ground orthostats have no debitage and so have suffered little systematic removal of material, (the recent observation by Abbott and Anderson-Whymark (2012, 25) that the bluestone circle bluestones are largely undressed partially supports this suggestion) whereas the most abundant classes of debitage belong to (now buried) ‘slighted’ orthostats and are the result of a purposeful destruction possibly by those with an axe to grind. But here is the rub; most of the ‘slighted’ orthostats comprise ashes, tuffs (‘volcanics with sub-planar texture’) and sandstones, ‘soft’ lithologies that would be difficult to work into tools. These proposals can, should and will be further tested.

As for the future, the authors say:

Sampling that would provide longer term provenancing data should begin with buried orthostats SH40g and SH42c, noted by Atkinson as micaceous sandstone. This would allow comparison of these two orthostats with the Altar Stone and with the (Lower) ‘Palaeozoic sandstone’ debitage to determine if either is the parent for any of the sandstone debitage. This should then be followed by sampling buried orthostats 32c, 33e, 33f and 41d, noted by Atkinson as altered, dark olive-green ash. This would allow comparison of these with two or more classes of ‘volcanic with sub-planar texture’ debitage, again to establish any relationship. Finally, sampling the remaining standing and buried dolerite orthostats would allow for new petrographical and geochemical analyses to complement the on-going programme of sampling in situ Preseli sources.

All in all, another interesting piece of work, confirming the very large number of lithologies represented among the bluestone orthostats and the bluestone debitage, and confirming the point that much of the debitage has not apparently come from the dressing of stones still present in the bluestone settings.  Quite reasonably, the authors therefore suggest that many stones might have been completely smashed up, and that the debitage comes largely from those.  I would have liked more discussion of non-anthropogenic origins for the debitage -- maybe we would have had it if the paper had been submitted to a geological journal instead of an archaeological one.  From where I stand, I still see an assemblage of erratic materials that have come largely from West wales.  I also see considerable areas of the Stonehenge landscape that have not yet been excavated -- and I assume that new and undiscovered rock types may well be represented in these areas.  The number of lithologies represented in the Stonehenge landscape seems to be going up all the time, and there is a lot of provenancing still to be done.  And EH must get up off its backside and accept that if some of the major problems surrounding the bluestones ever are going to be answered, there MUST be a proper sampling programme on the bluestone orthostats themselves.  ALL OF THEM!


Dean said...

Quoting Myris on 19 September 2013 12:59 ( )
”...only I have seen vast amounts of debitage, most is small, less than 15 grms in weight,(the volcanics with sub-planar texture are almost all smaller than that) and rounded slivers.

What explains the rounded slivers found in the debitage? Surely these are NOT “chips off the old block”!

BRIAN JOHN said...

Good point, Dean.I wonder if a shape analysis has been done on these fragments and slivers? I suppose that anything anthropogenic should be angular and sharp-edged -- but rounded or sub-rounded fragments are difficult to explain by human processes -- and we have to ask therefore whether some of the debitage might be derived from gravels incorporating water-rounded of glacially-rounded materials......

chris johnson said...

The "rounded slivers" would be interesting to know more about, and non-intrusive.

Personally I do not think we will learn anything significant by doing keyhole surgery on 4 buried orthostats. We might in fact do harm. My limited experience of seeing geologists in action is that they whack off of big bit of whatever it is they want to look at and, in this case, after digging a big hole.

What might they find? 1) No connection to Rhosyfelin. This will not prove that another orthostat is not linked - we do not know how many bluestones there were even. 2) A connection to Rhosyfelin. This takes us no further. 3) A connection to somewhere else entirely. This would be interesting but hardly likely after looking at 4000 pieces of debitage and finding no new connections.

Geocur said...

Agree Chris , I’ll be only too happy to discover the results of the provenancing , it will provide a scratch to the mental itch but that’s all .
We are speedily using up our generations share of intervention at Stonehenge if not already well past it , nothing new there though .

BRIAN JOHN said...

Disagree with you guys on this. You don't need big holes -- we know exactly where these stumps are, and very small holes will be fine. Then you just need a core sample -- Myris will no doubt tell us how large that needs to be for provenancing purposes.

We are getting too precious about the stones here -- personally, I want to see a small hole drilled in every single stone for the purposes of building a petrology data base for the whole stone monument. You can fill in the sample holes after taking the sample so that you won't even see where the sample has been taken from.

Once that data base is in place, we can have a proper scientific debate about where all the stones have come from, and how they got from there to here...... that will be real progress from the endless speculations that we have at the moment.

geocur said...

Brian , it's not a matter of being precious about a bunch of stones ,it's about being responsible and not interfering unnecessarily .We could have done with people being more precious in the past ,at Stonehenge and elsewhere but curiosity has killed quite a few cats that future generations will never have the pleasure of meeting .
I imagine the stones will be provenanced in the next decade , if not sooner ,and I'll be more than pleased to discover the results,but it may mean that something else gets put on the back burner and it is also taking up yet more of this generations share of a finite resource .The results will satisfy the curiosity of small group for a short time ,including myself ,"so they (32 d and or e)came from CRF after all " being my guess ,but whether that guess is right or wrong matters little , they will not answer "how they got from there to here " .

chris johnson said...

To quote the famous Dr Ixer:

"Too often the request to identify and provenance artefacts (especially lithics) appears to have a poorly defined purpose, to be an afterthought or perhaps sought for the appearance of completeness."

I think this is a fair description of many of the pleas made here regularly for more digging in the circle. What is the question that needs answering?

MPP and the team seem to have their question clear. They look in Pembrokeshire for connections and the science is pointing the way.

Dean said...

What would we know by sampling the 'buried candidate', stump 32e/d? We would know the Rhosyfelin rhyolite fragments in the debitage did or did not come from any of the Stonehenge orthostats standing or buried.

If the Rhosyfelin rhyolites do not match any of the orthostats how did they get to Stonehenge? And why are some of these pebbles 'rounded slivers'? These are the questions some would rather not have to answer!

”We are speedily using up our generations share of intervention at Stonehenge if not already well past it “

Does each generation have a limited right and allotment to the truth? Some people just don't want the truth and would use any excuse to avoid it!

TonyH said...

Yes, Brian, I am sure Rob Ixer and his devoted team need only very small core samples from the Stonehenge orthostats in order to carry out their wonderful scientific scrutiny of the rock for provenancing purposes. Remember, there are precedents for this if only in the analogous sense: skeletons are sampled for carbon dating purposes, for example. Any holes in either skeleton or rock can be re-filled for presentation purposes.

geocur said...

"Does each generation have a limited right and allotment to the truth?"

An not uncommon misunderstanding of what was actually said Kostas .

geocur said...

Tony,the problem isn't the eventual cosmetic appearance of stones or bones.In the case of the stones it hardly matters at all.
Despite advances in the past couple of decades in the amount required for sampling ,and the far more detailed info becoming available ancient bone in particular needs to be to conserved. We have lost enough from just a few generations ago .The barrow diggers/vandals that destroyed so much for posterity were also " truth " seekers .

BRIAN JOHN said...

Geo -- I am not sure what you are saying here. To quote: "We are speedily using up our generations share of intervention at Stonehenge..." That sounds dangerously close to saying that we should suppress our instincts for investigation in favour of respect / reverence / aesthetics... or something else.

Since when has any generation had a ration of research time and intervention on anything? The very idea is preposterous. Scientists will investigate whatever appears to them to be important. Others (like EH) might argue that they would prefer not to know certain things, for the sake of keeping controversy alive and keeping "mysteries" going -- incidentally very good for keeping the fee-paying members of the public interested in visiting Stonehenge. As far as I am concerned, the more intervention at Stonehenge, the better. If there are unsolved mysteries and questions, it is in the nature of mankind to seek to get in there to sort them out and find answers.

And why should you or I or anybody else feel guilty for the misdemeanours of our ancestors? It seems to me that the geologists who have been looking at Stonehenge recently have been very responsible and respectful to the fact that Stonehenge is an icon that needs to be preserved and protected.

Dean said...


Fundamental logic! Logical conclusions to a statement are part of that statement and its intent. Your unrelenting attacks on Kostas do not surprise me. But do not interest me either!

Let Dr Ixer et al determine the scientific value of sampling the stones, as they have requested. I doubt if this is merely a mental itch for them as it is for you.

geocur said...

Brian , I wasn't saying anything like you suggest most of your response consists of straw men .There was no mention of research or the rationing of it ,to suggest so ,is preposterous .The comments were obviously in relation to archaeological investigations .
Archaeology is destructive , once you have dug that trench you can never return to the original state . We have learnt from the mistakes of previous generations but there was no request or need for you to feel guilty.Its too late for much of Stonehenge but that is why there will be something left for future generations to excavate , to a far higher standard and with more sophisticated tools .
Fortunately ,scientists cannot investigate whatever may be important to them ,that 's why we have and need research and ethical councils controls are necessary on any discipline that involves the biosphere and physical environment .
The EH conspiracy comment is worthy of Kostas .Further intervention is ,if anything , in their interests .
Find answers by all means ,feel free to discover the extent of glaciation in the area around Stonehenge ,or elsewhere ,all with an interest would be glad to see the results .
The geologists were indeed respectful and responsible and Stonehenge does need to be protected and preserved , did I suggest otherwise?

geocur said...

Dean/Kostas , in that case your "logical conclusions " were wrong .

Once again a misrepresentation and misunderstanding ,the itch metaphor was in relation to curiosity and had no bearing on scientific value ,which wasn't even mentioned . Another example of an illogical conclusion .

BRIAN JOHN said...

Geo -- if you make broad statements you must expect people to seek to understand them and to draw conclusions as to what you mean. There is no point in you then -- not for the first time -- complaining and accusing people of misunderstanding things or putting words into your mouth -- or of putting up "straw men." Waste of everybody's time...

That having been said, I accept that archaeological digs are rather destructive, and that the regolith once disturbed is gone for ever. And yes, I do agree with you that consents for future digs have to be carefully allocated, and that new, less invasive techniques might well come along.

As for the "EH conspiracy", I have said before -- and so have plenty of others -- that it suits EH rather well to maintain a situation in which there are many questions and not many answers. Ever heard of marketing?!!

Geo Cur said...

Brian , you said " I am not sure what you are saying here." Wouldn't it have been more reasonable to ask for clarification rather than go off on a tirade with the straw men ?
When I complain of people putting words in my mouth , it is easily checked , if the complaint has no justification then I can easily be shown to be wrong .

Archaeo digs are , simply , destructive .Even archaeos who were always aware of that are starting to see the point of some restraint .
I have little interest in EH ,I only ever hear of complaints , most probably justified but any future excavation at Stonehenge must only be in their own interest .Once again , despite the itches ,I welcome whoever restrains the cats .

chris johnson said...

The history of archaeology is full of instances of digging things up to see what we find. I think in future the questions we want answering should be defined precisely and should have a sufficient weighting to compensate for the inevitable collateral damage.

There is always going to be damage. The science around e.g. particle analysis and e.g. dna is advancing very quickly and we will be much more capable in 20 years time than we are today. The question we ask today has to be important enough to justify the possibility of damaging something we might need to analyse in the future.

In the case of the 2 or 4 orthostats people want examined we cannot formulate any sensible question.

Most people who think logically already conclude that the debitage comes from deliberate breaking of bigger stones. Finding a link or no link between some debitage and one of the four orthostats does not take us any further. It does not change anything we might do subsequently or alter any hypothesis - it is frankly a complete waste of time, money, and the opportunity to do more sensibly directed excavation.

And Dean/Kostas: I thought we agreed not to feed trolls here so unless you prove some real-life identity or Brian is prepared to validate your bona fides, I am not going to help educate your evident misconceptions or enter into a debate.

TonyH said...

Brian said:[29 Dec above]:"As for the "EH conspiracy", I have said before - and so have plenty of others - that it suits EH rather well to maintain a situation in which there are many questions and not many answers.Ever heard of marketing?!!"
Is it me, or is it just a coincidence that MPP worked for quite a long period for English
Heritage prior to 1990? [source: introduction to MPP's Lunchtime Lecture]

Anonymous said...

Stonehenge Storm damage!


BRIAN JOHN said...

Nice one, Pete....... Happy New Year!!

chris johnson said...

Nice one.
Happy new year all.