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Sunday, 22 September 2013

Enough debitage to make an orthostat?

In thinking through this issue of whether the foliated rhyolite debitage at Stonehenge came from the far west as an orthostat, or a boulder, or as smaller fragments suitable for trading, I discovered this diagram from some months ago:


These diagrams refer of course only to the samples collected by assorted diggers over the years -- so the captions should refer to "that part of the Stonehenge Layer sampled thus far" -- and we cannot tell whether the proportions of rock shown here are typical of the whole, or strongly biased towards particular rock types because of the chosen locations of digging sites.

Note that the proportions of rhyolite and subplanar rhyolite are very small indeed.  Perhaps Rob and Richard can tell us what the total weight of foliated rhyolite fragments gathered up thus far actually is.  Five kilos?  Ten?  A hundred?  If there really was a foliated rhyolite orthostat -- or several of them -- at Stonehenge, as certain archaeologists would have us believe, where are the remains of it?

If something like the "one that got away" (the proto-orthostat that rests amid the rubble at Rhosyfelin) ever did exist at Stonehenge, we might expect debris totalling several tonnes to be present in the debitage.  Why do we not see it?

13 comments:

BRIAN JOHN said...

Kostas -- comment dumped. You know why.

Constantinos Ragazas said...

Brian,

As Myris says and Chris agrees, the “killer question” is how the foliated rhyolite (and other) fragments got to Stonehenge.

I have been raising this issue here for over two years now. And no explanation put forth by anyone can sensibly explain this. Other than my hypothesis: [deleted]

Kostas

Myris of Alexandria said...

Lovely to see those diagrams but they have not been published anywhere and are unlikely to be as they were an interim augenblick.
When something is published then the correct gloss can be applied. Until then, the AS the 'tribal rock musical' says, 'the rest is silence' itself perhaps a steal from Hamlet?
So sorry not yet. ,'The lit's the thing to capture the conscious of the king'
M

Constantinos Ragazas said...

Myris,

Does it really matter where truth is told? Not to truth! But these trully beautiful diagrams beg the question: How did such variety and amount of stone fragments, many of which don't match any of the SH orthostats, got to Stonehenge?

Kostas

chris johnson said...

"many of which don't match any of the SH orthostats", Kostas asserts.

Actually from the data presented it seems the vast majority of debitage fragments are the same type as the monument stones.

BRIAN JOHN said...

You are right, Chris -- as we might expect. Most of the debris appears to be from broken sarsen stones and dolerites. The really exotic rock types are present in very small quantities.

Constantinos Ragazas said...

Chris,

I was refering to types and not to numbers of stones!

Am I surprised there are smaller stones in the debitage that match SH orthostats? Absolutely not. If natural transport brought the big stones to Stonehenge, why wont the same transport bring little stones of the same type to Stonehenge?

But the killer question concerns all the other fragments (like the Rhosyfelin foliated rhyolites) in the SH debitage that DO NOT match any of the Stonehenge orthostats. Their presence in the debitage begs for explanation. My hypothesis explains these. What is your favorite made-up story for these?

Kostas

Myris of Alexandria said...

Kostas let us hope that I and Bevin' s paper 'Chips off the old block' in a couple of months will help clarify the situation. You will need to read this bit of the primary literature.
As with the Stonehenge Layer you has half grasped secondary interpretations of what was written/intended.
M

chris johnson said...

I wonder if anything more is known about the slate? A big (and distinctive) slate mine at Rosebush is only 3 miles SW of Carn Goedog, and as we discussed inconclusively several months ago..

BRIAN JOHN said...

Chris -- there is slate all over the place in North Pembs. Since the igneous rocks of the area were intruded into shales and mudstones, there are great thicknesses of metamorphosed rocks around all the intrusions -- the main feature being slates of all colours and qualities. Rosebush is just one of scores of commercial slate quarries in NE Pembs. Pembs slate was used for the Palace of Westminster and for the big public buildings in Cathays Park, Cardiff.

Constantinos Ragazas said...

Myris,

I have always sought and welcomed corrections to my ”half grasped secondary interpretations of what was written/intended”. More effective to correct than to argue corrections are needed, however.

My observations of a year ago concerning the NW Rhosyfelin Rockface and this Crag being engulfed in water are now being confirmed by the evidence Brian has been presenting here. A year ago these same insights and observations were severely criticized by him and others. So I rather trust my sensible reasoning on such matters than on what is written in peer-reviewed literature. Too much knowledge is as misleading as too little.

Can you give us a hint as to the carbon dates MPP has been holding from us? Brian thinks these are very old (Pleistocene) while I think these are rather young (Iron Age perhaps). While MPP seems to hint at this -- all the dates are Holocene and none Pleistocene; Iron Age hearths; need to dig deeper to reach the Pleistocene glacial till; etc.

We need to know these dates and where they were sampled in order to make more sense of MPPs Rhosyfelin “quarry” discovery. Or to completely debunk it!

Kostas

BRIAN JOHN said...

Kostas -- please stop putting words into my mouth. The crag was not "engulfed in water" -- the signs are that there was a small meltwater channel here, probably used for a short while at the end of the Anglian glaciation and again at the end of the Devensian, maybe around 18,000 years ago. And I do not "think" that the C14 dates are Pleistocene -- if they are mostly from the Holocene, fair enough. What I want to know is the stratigraphic contexts so that we can make some sense of the stratigraphy and possible settlement / camping history at the site.

I fear that your reasoning is somewhat erratic, to say the least.....

Constantinos Ragazas said...

Brian, quoting from your "inconvenient truths" post:

[...] we can see that the [Rhosyfelin] dig site is on the floor of a small meltwater channel, [...] its use by meltwater [...] might go some way towards explaining the long, smooth, regular wall which others tend to refer to as "the quarry face."

[photo caption]: looking along the rock face of the spur towards the top end of the meltwater channel. In the far distance the channel loops round to the left and rejoins the main meltwater channel now occupied by the Brynberian River.


If meltwater channels ran along both sides of the spur, wont the spur be engulfed by water? Your guess such meltwater channel was ”small” belies the long, several meters tall, very smoothly cut NW Rockface!

Your own evidence points to Rhosyfelin being engulfed in water. The only question is when. I argue more recently and possibly postdating Stonehenge (Iron Age perhaps) while you argue in favor of Pleistocene dates. Here is another quote from your post:

In the Moylgrove lecture, MPP also dismissed the idea that the excavation had reached a layer of till. He said that if there was till present, it must be much deeper down. I have news for him.

Since MPP has not released the carbon dates we can only speculate here. But from various comments MPP has made (e.g. no Pleistocene dates; Iron Age use; need to dig further and deeper, etc.) suggests to me the dates are much younger than MPP needs to have for his “quarry” explanation. That may go a long way explaining MPP's “erratic behavior” with his concealed dates.

Brian, what is confirming my observations of a year ago re:Rhosyfelin Crag is the evidence your are presenting. Certainly I don't expect you to confirm anything I may argue!

Kostas