Some of the ideas discussed in this blog are published in my new book called "The Stonehenge Bluestones" -- available by post and through good bookshops everywhere. Bad bookshops might not have it....
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Sunday 30 September 2012

The mystery of Stone 32e

Thanks to Rob for annotating the top photo.  These are all from the old Atkinson collection --  and 32e is the one which is assumed to provide a possible match for some of the Stonehenge debitage and maybe some of the samples from Rhosyfelin.  That's the one closest to Atkinson's head in the lower photo.  Now that worries me a bit, since it doesn't look anything like as flaky and foliated as 32d, next to it, and 32c, closest to the camera in the top photo.  And it doesn't look anything like the famous "proto-othostat" at Rhosyfelin either.

Note that these three stumps are packed very closely together -- with gaps of less than a foot in each case.  The honeycomb of intersecting sockets is very complex indeed.  So if these three stones ever were "complete" and standing as part of the bluestone circle, they must have created an impression of being almost a "wall" of stone -- unlike the other stones of the bluestone circle (what's left of it, if it ever was complete) which are more widely spaced.....

The standing pillar which we can see in the photos is bluestone 33.

Another Stonehenge puzzle...

Posting problems

Apologies all for the problems with posting over the last week.  I've just returned from a week in Tuscany (those defended hilltop villages are AMAZING!!) and discovered that my laptop was not picking up the majority of posts -- just some of them.  No idea why.......  anyway, on my return, I found more than 20 posts on my home computer, and have now put all of them onto the site.  There may be some duplication and confusion as a result..... but I hope that a sense of good order will soon return!  Thank you all for your contributions.

Thursday 27 September 2012

The Glaciation of Rhosyfelin

A glacial erratic with a distinct orange-coloured patina -- exposed among the litter on the floor of the 2012 dig at Rhosyfelin

I'm often asked what the evidence of glaciation is in the Rhosyfelin area.  Well, there is plenty of it about.  The upper part of the Brynberian Valley (in which the rocky crag is located) has been glaciated on at least two occasions, and probably more.  The glacial episodes about which we know most were the Anglian (about 450,000 years ago) and the Devensian (reaching its peak around 20,000 years ago.)  The former was almost certainly the time of the GBG (Greatest British Glaciation) and in the latter the Irish Sea Glacier was very extensive and may even have extended beyond the Devensian limit in some areas.  The Wolstonian / Saalian Glaciation was probably extensive, but traces of it are very difficult to differentiate from those of the Devensian, as Chris Clark, Phil Gibbard and many others have pointed out.  So let's put that to one side for the moment, while allowing the possibility that it might have done some work, at the very least, in modifying the landscape of West Wales.

Suggested limit for the Irish Sea Ice in the Devensian period.  The glacier came in from the north and north-west.  The dotted area shows the suggested extent of the Preseli ice cap, which would have been contemporaneous.

During both the Anglian and Devensian glaciations, the ice of the Irish Sea Glacier came into this area from the N and NW.  First, what do we know about the Anglian ice extent?  It has been accepted for more than 100 years that the ice inundated the whole of Pembrokeshire and that it flowed up the Bristol Channel  -- and for well over 50 years it has been known that it impinged upon the coasts of Devon, Cornwall and Somerset.  This is indisputable -- and if any archaeologist or geomorphologist tells you otherwise, do not believe them. So the ice was very thick indeed -- maybe up to 600m thick -- as it flowed across this area.   Was entrainment of blocks of stone or monoliths possible at this time from the crags at Rhosyfelin?  Yes -- without a doubt.  I have covered this possibility -- and indeed likelihood -- many times before on the blog. Large glaciers and ice sheets can and do entrain large blocks on the up-slope flanks of upland barriers where glacier bed conditions are just right.  So entrainment was more likely to have happened on the northern flank of Preseli than either on the summit or on the southern flank, where the glacier bed at the peak of glaciation was most likely to have been frozen to its bed. This is a matter of ice physics or glaciology -- not a lot to do with geology, although obviously tors and rocky crags will have made perfect entrainment locations.  One of the problems with Rhosyfelin is that we do not know how much bigger the pre-glacial crag might have been.  It might well have been 10m or more higher than it is today.  Thousands of tonnes of the famous foliated rhyolite might have been removed.  At the moment, we have no way of telling -- but we are working on it.........

The deep gorges of the Brynberian and Nevern Valleys.  Rhosyfelin is the rocky spur on the western flank of the valley near the base of the photo.  These valleys have many features in common with the subglacial meltwater channel complex of Cwm Gwaun and Nant y Bugail.  There are other rocky crags in the Nevern Valley at Felin y Gigfran.

There is also a strong possibility that the river gorge around Rhosyfelin and Pont Saeson was cut initially during the Anglian Glaciation by torrents of glacial meltwater flowing subglacially or on the edge of a wasting ice mass, as the Irish Sea Glacier was breaking up.  In addition to the main gorge, there is a strange subsidiary channel which is both looped and humped -- and this is typical of the subglacial meltwater channels in North Pembrokeshire.  Sometimes these channels are simply swept clean of debris by the sheer force of meltwater flowing through them, at very high hydrostatic pressures.  I would not fancy the chances of any Anglian deposits (either glacial or fluvioglacial) surviving in the area, given that almost half a million years has elapsed -- but I would not rule this out entirely.

This brings us to the extraordinary flat face of the Rhosyfelin cliff -- revealed in spectacular fashion as a result of the recent dig.  This does not look to me like a quarried face, and I am currently convinced that it is a long glaciated face, fashioned above all else by moving ice.  I have not seen any striae on the face -- but I have not spent enough time there, and one day I'll go back and take a closer look. Of course, if there are striations on the face, they are just as likely to be Devensian as Anglian -- given that the ice has returned for a second (or third, or fourth) time to the same area.  One intriguing feature is that the direction of ice movement -- as far as we know -- was broadly from the NW towards the SE, which was perpendicular to the alignment of the Rhosyfelin rocky ridge.  So the natural direction for subglacial meltwater flow would have been up the Brynberian Valley rather than down it, if the dictates of hydrostatic pressure were followed.  It is more likely, given these facts, that meltwater flow was marginal, along or near the ice front of a melting glacier.

Did the Irish Sea Glacier cover this area during the Devensian?  I am increasingly convinced that it did (see the map above), and that the ice edge was somewhere to the south of Rhosyfelin, on the northern face of Preseli.  This assumption is based on a lot of evidence, including the presence of apparently fresh striations on Carn Alw, the presence of apparent marginal channels along the hillsides near Carn Goedog, and the fresh moraine near Tafarn Bwlch and Waun Mawn.  There must have been a great lobe of ice pressing in from the N and NW and filling the depression in which Brynberian and Rhosyfelin sit.  As indicated in earlier posts, some geomorphologists have speculated that there was a marginal lake in this depression either prior to the maximum ice advance, or shortly afterwards.  We await detailed stratigraphy and analysis of the sediments in this depression -- all will be revealed in due course.  There is a layer at the base of the sediment sequence exposed during the 2012 excavation which looks as if it might be lacustrine -- I did not have time to examine it properly.  It's only a few centimetres thick --  was it laid down at the bottom of this large proglacial "Lake Brynberian", or maybe on the bed of a much smaller lake confined within the valley, held up my a plug of melting ice somewhere to the north of Rhosyfelin?

The exposures on the flank of the 2012 dig.  There are many layers in the sediments, although the boundaries between them are diffuse.  The finest-grained deposits are at the base of the section, and may indicate lacustrine or slackwater deposition.  Note the accumulated litter in the foreground, where quite large blocks have accumulated beneath the cliff face.

What about the Late Devensian history of the Rhosyfelin area?  Well, we know that there is a great litter of broken debris beneath the cliff face, as we would expect beneath any steep rock face in Pembrokeshire.  If analogies around the Pembrokeshire coast are anything to go by, this litter must have accumulated after about 20,000 BP, with a late peak of frost shattering and periglacial activity around Zone III or the Younger Dryas, around 13,000 - 11,000 BP.  After the melting of the Irish Sea Glacier in this area, we might well have had 10,000 years or more of oscillating cold climate during which considerable damage might have been done to the Rhosyfelin crag -- so it is very difficult to imagine what it might have looked like during the glacier melt episode.

Several points emerge from an examination of the 2012 dig:

1.  The litter of broken rock seems to me to be entirely natural -- including the placement and positioning of the "big Rhosyfelin orthostat."

2.  I think that the dig might now have got down to the top of a till layer.  There are signs of erratic blocks in the litter -- including at least five big blocks of quartz (which might of course be rather local) and a stone with a yellowing surface patina which does not look like a lump of Rhosyfelin rhyolite (see photo at the top of this post).

Four quartz erratics exposed on the floor of the dig.  We do not currently know how far these might have travelled.  The are sub-rounded, and have been subjected to some wear during transport.

3.  I have not seen any sign thus far of any fluvio-glacial material, although I would not rule this out when the dig goes a bit deeper.

4.  A very intriguing feature of the exposed surface of the litter is the degree of rounding or smoothing that appears on the edges of many of the stones.  Naturally, this foliated rhyolite breaks down into fragments and slabs with rather sharp edges -- so something must have been responsible for the wear on the edges.  The only two candidates, realistically, are overriding ice and meltwater flow.  The former is, I think, a possibility, given that the till layer is now being exposed; the stones which we now see at the dig surface may have come from some distance away, or they might just have been overridden in situ. Some accurate provenancing is needed to sort this out!   Another explanation is that there has been a long process of rounding of stone edges by snowmelt, maybe during the many centuries during which frost shattering and scree accumulation were going on.  (I have to admit that I'm a bit confused here -- more work is needed.)

The rounded upper surface of one of the local rhyolite slabs exposed on the floor of the 2012 dig.  Many stones of all sizes are rounded in similar fashion.  What caused this rounding?  Overriding ice, or glacial meltwater?

5.  The thickness of accumulated slope deposits here is quite surprising, given the relatively short length and limited height of the slope to the NW of the dig site (that is the orientation of the steepest part of the slope.)  As mentioned above, the deposit with the finest and most consistent grain size is near the base of the 2m or so of exposed deposits, suggesting a temporary lacustrine or alluvial situation with relatively low-velocity water flow.  Above that, the sequence of deposits is complex, with a great deal of soil and slopewash material mixed with angular fragments, most of which are presumably rather local in origin.  There are several layers which appear rich in organic material -- and for which radiocarbon dates will presumably be obtained.  It will be interesting to see what comes out of these investigations.

In summary, we have traces of at least two glaciations here, with most of the major erosion and landscape development attributable to the earlier one, and most of the deposition of superficial deposits attributable to the later one.  There is undoubtedly a great deal more to be discovered, and I hope that MPP has some good geomorphologists on board to help him in the task of unravelling what actually went on.

If MPP wants to make use of the above material, he is welcome to do so, as long as he acknowledges the source.

Wednesday 26 September 2012

The Rhosyfelin litter

Click on the picture to enlarge

This picture of the inner (upper) part of the Rhosyfelin dig 2012 shoes a very steep bank of litter or broken stone accumulated to quite a high level on the rock face, with no clear organization or arrangement of stones.  Entirely natural, as far as I can see.  What is more interesting is the broken stones which we can still see in position ABOVE the cliff, with the turf tumbling down over them.  Most of them are lying flat, rather than being on edge -- as we would expect if they have come down from higher up, moving down and over the little cliff face under the influence of gravity.

This reinforces my view that many of the stones now exposed on the floor of the dig have not been levered from the cliff face but have come down from the crags above. Many of them have simply accumulated as scree -- other stones might have slid down over snowbanks, since this gully is a perfect place for snowbanks to accumulate during periods of cold climate.

Thursday 20 September 2012

About turn on Garn Turne

One of the most interesting things about the evening at Brynberian was the presentation by Colin Richards on the 2012 excavations at Garn Turne, some way away from Rhosyfelin and in the southern Preseli foothills.  The key feature is the massive 80 tonne capstone at the heart of a portal dolmen.  Previously, Colin has maintained the line that the capstone was moved from the rocky crag at the top of the hill by our sturdy ancestors, and indeed his team started to dig into a hollow near the summit which was assumed to be the place from which the stone was taken.  However, when they excavated there, they discovered that it was nothing more than a buried wartime lookout or some such thing, even including a concrete slab.  (I think that's what he said....)  So that was ruled out, and after this year's dig the conclusion is that the huge recumbent stone has simply been used in the place where it was found.  That's a major turnaround in interpretation, and great respect is due to Colin Richards for that......

Two really interesting things have come out of the dig. 

First, that there are TWO dolmens here, in the same place.  The first (a small one) used as a capstone the boulder we can see in the photo immediately to the right of the tree shadow, slap in the middle of the portal to the second -- later -- dolmen which used the 80-tonne capstone.  So there is multiple use here, with at least two generations using the same site.

Second, the huge second capstone has been raised bit by bit, through the use of long levers (wooden poles) and packing stones to hold it up as it was raised laboriously, inch inch, from its original bed.  The grooves can still be seen, in which the ends of the levers were placed.  They were no fools, these fellows, since they used exactly the same technique as I use in my garden when I am trying to shift a 2-tonne erratic boulder which is projecting inconveniently through the ground surface...........

So there we are then.  This time we have a glacial erratic used at the place where it was found, not all that far from its source.  Colin also confirmed what Steve Burrow has said -- that the tradition in Wales was not to move large capstones, but to use them in the places where they have been dumped by ice or else where they occur at natural rock outcrops.  Now what was I saying about that all those months ago.....??

The Rhosyfelin Railway Track

This is exactly where the "rails" are supposed to be.  The big recumbent stone is on the left, and the cliff face is off the photo to the right.  So the slope runs down from right towards left.  Rails?  Sorry chaps, but I see no rails -- just a jumble of broken scree.

Rhosyfelin 2012

I couldn't get over to the dig site yesterday, but thought I'd better zap over early this morning before the hole gets filled in....  met one of the archaeologists there, and managed to have a quick look around.  Here are some of my photos:

This shows the whole dig site -- rock face to the left, rubble and big stone in the centre, and the banks cut into the thick sediments on the right.  We are looking up the slope towards the head of the gully.

This is the rock face, seen from higher up the gully.  You can see from the change in colouring just how much of it has been covered up -- before this dig -- with sediments and vegetation.  The cliff is effectively now twice as high as it appeared originally.

This is the "damaged" or "crushed" stone just beyond the downslope edge of the large stone they refer to as an "orthostat".  Yes, it is damaged, but it seems to me that the damage is no more or less than we see on scores of other stones on the site.  Is the damage fresh enough to be attributed to Neolithic quarrying activity, or is it a natural consequence of frost-shattering during one of the periglacial phases to have affected this area?

This is the enigmatic socket that has everybody puzzled.  It's a few feet across.  Did it really hold a large standing stone, or was it a storage pit or something that had another purpose?  MPP is convinced it held a stone for c 4,000 years, and that the stone was finally toppled or removed around 500 AD.  Evidence eagerly awaited...

This is the so-called "activity floor" where traces of charcoal, burnt stone etc were found.  Assumed to be traces of an Iron Age encampment.....

The deep vertical crack in the rock here is said by Richard Bevins to be the sampling point for the most accurate match yet between the Rhosyfelin crag and some (how much?) debitage from Stonehenge.  So the claim is that there is a piece of provenancing here which is accurate to within a metre or two.  I want to see chapter and verse on that, since unless you have a 1m sampling grid over a wide area it is pretty hazardous to make that sort of claim.  The that as it may, this is very skilful provenancing by Rob and Richard.  The problem is that this does not look like a place where even a small boulder has come from, let alone a massive orthostat.  If you look at the whole rock face it is incredibly smooth, and I think it is glaciated.  I think also that the great mass of the debris here has not come from the rock face but from ABOVE it -- I think that glacial and periglacial processes combined have led to a collapse or series of collapses of material that has crashed down from the upper part of the slope where there are still many gorse bushes etc.  Maybe some mountaineering is called for in the winter, when the vegetation has died back a bit.

Well well, this is all getting rather interesting........

Wednesday 19 September 2012

An evening in Brynberian

 The 2011 dig -- showing the big stone which has caused more excitement than is really justified, and the litter of smaller broken stones banked up against the rock face.

A photo taken by Linda Norris, showing how much bigger the 2012 dig is, and showing the great bank of rubble and slabs between the big stone and the rock face.

Well, I turned up last evening to the packed village hall in Bynberian to hear the presentations from Colin Richards and Mike PP.  Very jolly fellows, both of them  - and I say that without a hint of sarcasm.  The presentations were interesting and informative -- and they were pretty up-front about everything.  And I refrained from making any comments at all in public, having been exhorted on all sides to be on my best behaviour.  I was very proud of myself.  And that was in spite of the speakers steadfastly refusing even to utter the words "glacial erratics" -- almost as if they might have caused grave offence among the members of the audience.......  Of course, most of the audience turned up hoping to get a jolly good story, and that was what they got -- with the borders between fact and fantasy very blurred indeed.  That having been said, I found that both Colin and Mike were a good deal more circumspect than they were last year in the language that they used.  On this occasion, my blood did not boil.  So maybe we are making a little progress.......

I also visited the site at Rhosyfelin, and had a long chat with Colin, whom I found very straightforward and open. 

First of all, the site.  The dig is now ENORMOUS -- they have extended in all directions, although I don't think they have gone any deeper than last year, since I'm keen to see if there are fluvioglacial gravels (or even till) beneath the slope deposits which they have been investigating.  They have been carefully removing all of the fine material around the broken rock debris that litters the "floor" of the excavation, as seen in the old pic above and in the other pic (from this year) below.

The key features which MPP is using in support of his quarry hypothesis are as follows:

1.  An elongated stone perpendicular to the lower end of the big recumbent stone which has a damaged upper surface.  MPP argued that this damage is the result of other big stones being dragged over it before the current big one was left where it is. My view?  The stone certainly does have a broken upper surface, and it is conceivable that the damage was done by a big stone -- or several --  being dragged across it.  But I'm intrigued by how rounded and moulded it is -- and I am pondering on whether quite a lot of the stones exposed at the bottom of the dig have actually been moulded by over-riding ice.  I was really struck by this moulding when I looked at the dig -- but it has not been commented on by the archaeologists.  Human versus natural?  50:50

2.  The hammer stones and mauls found here and there in the dig.  I haven't examined them myself, and I 'm not sure where they have come from, but a photo was shown purporting to be of one of them insitu, embedded in the midst of a litter of angular stones.  The other archaeologists to whom I spoke said that these stones are fractured and damaged by percussion --  and for the moment I'm prepared to accept that they know what they are talking about.  Not sure what rock types they are made of -- but if they are genuinely foreign, that would strengthen the MPP case.  Human versus natural?  75:25

3.  There is an Iron Age date (around 500 BC?) from charcoal (?) somewhere on the site, which I suppose shows that at that time there were people around here, making fires.  Date obtained in 2011?

4.  The elongated "railway lines" or "sliding stones" shown in the photo in MPP's book, and along which big stones were supposedly slid sideways down the slope from the cliff face.  I couldn't see them last year, and I couldn't see them this year either.  More fantasy than fact? Human versus natural?  20:80

5.  A huge stone pit or socket, reputed to have held a big standing stone held in place with packing stones.  You can glimpse the edge of this pit at the extreme L edge of Linda's photo.  I have to accept that this is real, rather than just an artifact created by the diggers -- but it is quite an anomaly.  Nobody seems to know what to make of it.  It's a very strange place for people to have put up a standing stone -- down near the floor of a wooded valley, close to a rocky crag.  MPP thinks that a big standing stone or monolith was in position here until the Iron Age, when it was removed or smashed up.  No trace of it today -- unless the stones found in the pit are the remnants of it.  Human versus natural?  90:10

6.  A strange "activity surface" in the flattish area behind the people in Linda's photo.  MPP seemed to suggest that this was another Iron Age feature -- with flints, chips, flakes, charcoal and burnt stone in a quite extensive spread of debris.  Then, after 500 AD, the site was covered with hillwash and slope deposits.  So -- traces of human activity, certainly -- but quite the wrong age to be used in support of the "Neolithic Quarry" hypothesis.  MPP argues, of course, that the standing stone and this evidence of Iron Age occupation (even if for a very short time, in a seasonal winter camp, maybe) shows that the site was revered as a quarry site from which sacred stones had been taken long ago ---- and hence that there must have been USE of this site over many thousands of years.   Hmmm -- that sounds pretty fantastical to me -- and I wouldn't mind having a bit of evidence to support the idea.


That seems to be the essence of the "case for the Quarry" -- although the geology evidence is jumbled up in the argument too.  Richard Bevins was at the lecture, and I had a good chat with him about provenancing etc.  I'll cover that in another post.  But for the moment I'll say that the geological evidence is neutral -- it is nothing more and nothing less than an interesting piece of geological detective work, and it does nothing to support the Quarry Hypothesis.

In summary, there is clear evidence of human occupation of this site -- I have no wish to deny that.  But whether there was NEOLITHIC occupation is quite another matter.  There do not as yet seem to be any radiocarbon dates to support occupation around 3,500 BC -- which is the date which MPP now speaks of as the date for the "first known presence of bluestones in the Stonehenge area."  That's a very long time ago -- 5,500 years ago.  Is it really likely that Iron Age tribes in this area would have continued to revere a site first used 4,000 years earlier?

Far more questions than answers.  Currently, my thinking is that this site has nothing whatsoever to do with the human transport of big stones to Stonehenge -- but that it might have been used intermittently for the fabrication of implements, given the lovely sharp edges which this rhyolite gives.  so in that sense, it might have been a quarry or a factory.  Later on, some Iron Age people used this sheltered site against a craggy rock face in a wooded valley as an encampment -- maybe over the winter months.

Finally, a word about artificial significance.  Archaeologists don't think about it often enough.  We could also call it sampling bias.   I am pretty convinced that MPP and his colleagues have invested this site with significance because they have decided in advance that it is a Neolithic quarry site.  It is perfectly reasonable to think that if they had visited almost any sheltered craggy site in a north Pembrokeshire valley (and there are many of them) and subjected that site to this level of scrutiny, they would have found virtually the same assortment of features -- including a litter of large blocks and slabs, and even traces of temporary encampments in the Iron Age.

To be continued......

Monday 17 September 2012

Bad feeling coming on.....

 This is a photo of the section between the rock face and the recumbent monolith.  
Rails?  I see no rails.......

Oh dear -- I have just got my long-awaited copy of MPP's latest tome.  On looking at the pictures first, as one does, I immediately came across the photo opposite to the base of page 199.  There the caption is a classic piece of MPP speak -- "clear evidence of bluestone quarrying" -- "they then moved the monolith...." and so forth.   Everything stated as fact, and even a reference to these wonderful stone "rails."  Quote:  ".... they then moved the monolith from the rock face along stone "rails" on which it still rests."

How do people like him get away with this sort of stuff?  Don't publishers have editors these days?  Here we go again.  Hubris over scholarship, and pseudo-science even before I have read a word of the text.  I'm not sure that I'm looking forward to reading the book..... but maybe somebody has to do it.

Fragments from the rumour mill

What with the PENfro Book Festival at Rhosygilwen (chairman, for my sins) life has been a bit hectic lately.  So I still haven't managed to look in on the dig at Rhosyfelin.  And the other dig up the road, at Castell Mawr.  Anyway, the rumour mill has been at work, and has spat out a few fragments of gossip.

1.  At Castell Mawr, the search continues for the village that provided the quarrymen that provided the labour for digging out the stone that ended up at Stonehenge.  If you see what I mean.  So the assumed Iron Age fortified site (which is very spectacular) needs to be established to be much older -- preferably Neolithic.  I'm pretty relaxed about that -- I imagine that many of the Iron Age sites will have older settlement traces beneath and around them.  There is a lot of work going on there -- aimed at finding older "disappeared" ditches and embankments etc.  Rumour has it that some very large post holes have been found there -- so we will no doubt have the place renamed at Durrington Fach before very long........

2.  At Rhosyfelin -- the quarry hypothesis is still very much alive and kicking, and MPP is very happy that he has hammerstones and "railway lines" to show to the world.  By railway lines, my mysterious informant presumably means a sort of trackbed of elongated stones over which a large stone might be moved?  Anyway, all will be revealed in due course...

3.  Apparently there is at least one Iron Age radiocarbon date from the site -- in a position that appears to have stratified sandy and gravelly materials on top of it.  That is quite intriguing -- must go and have a look at it.  If the date is correct, that means there has been some alluvial process going on over the last 2,000 years or so.

Bouncy Henge

Thanks to Phil for this photo of the latest craze -- Bouncy Henge which is on tour all over the UK, complete with bands and concerts and so forth.  There is also a very elaborate web site with videos, sound tracks etc.  All very jolly..... but if you want wacky reconstructions, give me Achill Henge any day, which exists for non-mercenary reasons and makes of sort of statement about social and political control, freedom of expression etc.

Anyway, nice picture, Phil.  Did you bounce?

And of course, being serious (well, sort of) for a moment, we have the intriguing possibility that the sarsens and the bluestones were bounced along on air bags or inflated sheep's stomachs etc by the ingenious builders of that splendid edifice.

Wednesday 12 September 2012

MPP to report on latest Pembs digs

MPP and the boys are back in town -- and may be digging at Rhosyfelin and Carn Goedog as we speak.  I hope they have some geomorphologists with them this time.  I'm available -- at a very reasonable rate.......

Might well roll along on 18th to see what's occurrin'......

 Stonehenge's Preseli link

Tuesday 11th September 2012

Perhaps one of the greatest mysteries surrounding Stonehenge is the origins of the stones themselves. How did bluestones from the Welsh Preseli Mountains become the construction material for the site of Stonehenge built some 5000 years ago?

Professor Mike Parker Pearson of University College London is leading a collaborative project involving universities from across the UK in looking at this enigma. Their work has brought them back to Preseli in search of the quarries and sites that may be the start of the longest journey for megaliths anywhere in prehistoric Europe.

Following initial investigations in 2011 the team have returned to excavate a quarry site at Brynberian, North Pembrokeshire.  On Tuesday 18th of September at 7pm, at Brynberian Old School, Professor Mike Parker Pearson will be presenting a talk on the results of the project so far.  Everyone is welcome to attend and there will be a small charge to cover refreshments.

Tuesday 11 September 2012

More Quarry Fantasies

Thanks to Rob Ixer for forwarding this article, published in Mineral Planning magazine -- a journal presumably read by mining and quarrying engineers and such like.  It's an interesting and brief introduction to the recent geological research relating to the bluestones, and all credit to Rob for that, but I have to say that some of its central assumptions and assertions are very poorly supported.  The strap line under the main title is not encouraging -- it refers to "the discovery of the first secure Stonehenge-related quarry."  As Rob and other readers of this blog will know, I think that is nonsense, and will continue to think do until somebody comes up with some decent evidence that there really is a QUARRY at Rhosyfelin.  On the basis of the evidence thus far placed in the public domain, the evidence is just not there -- and I am more than a little surprised that a serious geologist should go along with a rather fanciful story trotted out by archaeologists who seem to know little about geology and even less about geomorphology ..........

Some thoughts on the article:

1.  I don't agree with the definition of a bluestone as a Stonehenge foreign stone once used as an orthostat.  I have always defined a bluestone as ANY foreign or non-sarsen rock found in the Stonehenge environs, and I suspect that most geologists and geomorphologists would agree with me on that.  To limit the bluestone debate to orthostats is to allow the archaeologists to dictate the agenda; if one is really seeking to understand how the environment has evolved, and what processes have worked upon it, we MUST consider the contents of the regolith and the debitage.  Indeed, in a recent message Prof Danny McCarroll suggested to me that the REALLY interesting stones at Stonehenge are not the othostats but the smaller stones, fragments, chips and flakes -- since they are much more likely to have arrived in the Stonehenge area by natural rather than human agency.  (After all, even if our Neolithic ancestors were intent upon moving stones about, would they have bothered to cart about baskets or bags full of rather nondescript stones and pebbles, over great distances?  Answer: probably not.)

2.  With respect to Preselite, "A number of possible quarry sites are being sought along the northern edge of those hills".  Now why on earth was that remark added to the article?  It may be true, but it is actually counter to the thrust of the article, which strongly suggests multiple sites and sources -- and hence glaciation, erratic transport and deposition.

3.  Orthostat 48 -- what do we know about that?  Most recently it is described as a rhyolitic crystal-vitric-lithic ash-flow tuff from an unknown source, with no known matching material in the Stonehenge debitage (or at least, in that part of the debitage that has been investigated.)   It's an interesting recent development that one of Stone's collected stones from the Cursus Field matches the orthostat.

4.  With respect to the rhyolite debitage at Stonehenge with the distinctive "Jovian" structure, allowing an "almost impossible provenance of ten squares metres" to near point 9 at Rhosyfelin, I do not think that statement is justified by the evidence thus far presented in print.  I have said that before, and I will say it again.   If I had refereed the paper I would have pointed that out, and asked for more information.  So in turn the statement "The archaeologists were told where to dig" is a sort of self-fulfilling prophecy. If you have a sample from an accurately located sampling point, and then tell somebody to go digging adjacent to it, of course you are going to find more or less the same rock type.  That should be a surprise to nobody.  (By the way, I am confused -- on the photo above, point 9 is a long way from the Rhosyfelin dig site, and point 8 is adjacent to it ......)

5.  And what did the MPP team find when they dug as instructed?  "They found, just a few metres from site 9, a large proto-orthostat, a large joint block set for its journey to Salisbury Plain".   Sorry Rob, but that is a thoroughly unscientific comment, and you should not have made it.  It doesn't matter what your objectives might have been in writing this article, or what sort of readership you were expecting, slapdash comments like that do no good to anybody.  What those guys found was a large elongated slab of rhyolite embedded in a mass of broken scree and other debris typical of the debris to be found under almost any rocky outcrop in Pembrokeshire --- I suspect that neither you nor I have seen any evidence to justify saying any more than that.  If there is more evidence, it should long since have been placed in the public domain.  I say to you what I would say to any scientist:  "Show me the evidence, and I might start to believe you -- if you do not show it, I am not prepared to accept your assurances about anything."

6.  The article refers to ".... the first secure Stonehenge-related quarry site, confirming that man moved the bluestones." Rubbish. Rob, did you really write that?  I don't believe a word of it, until you show me the colour of the evidence.

7.  Re the final paragraph, I agree that "there remains a degree of lithological randomness inherent in the presence of the other types of rhyolitic tuff and sandstone bluestones" at Stonehenge.  OK, one thinks, now the author is getting to grips with the problem.  But then he says:  "Could it be that the monoliths are a mixture of quarried stone augmented by randomly chosen rocks just to make up the numbers, so making Stonehenge among England’s earliest jerry-built public buildings?"  Why this strange obsession with quarries and quarrying?  And why should a geologist seem to have a problem with coming to the obvious conclusion -- namely that the strange assemblage of orthostats and stony debris is most easily explained as a consequence of natural processes (ie glacial processes) operating during the Pleistocene?  I think I might just about go along with the statement about the "degree of lithological randomness", but since glaciers obey the laws of physics no less than rivers or winds, the randomness may be more apparent than real, in that we have not got round to finding satisfactory explanations for the presence of stones that currently appear to us to be disorganized and scattered about.  Never fear -- enlightenment will come..... and as far as I can see, there are perfectly rational glaciological explanations for the presence of almost all of the bluestones so far identified at Stonehenge.

8.  "....... are there further, undiscovered, quarries silently hiding among the Welsh bracken and flowering foxgloves, feint (sic) echoes of carefully organised stone and social structures?"   Hmmm -- no comment.


Here is the article, with full acknowledgement to the magazine:

Digging into Stonehenge’s past

Mineral Planning, issue 143 / October 2012, p 13

The provenance of Stonehenge’s rocks has been a subject of heated
debate for many years. Rob Ixer explains how the
contents of a small box led to the discovery of the first secure Stonehenge-related quarry

The precise number, identity, geological provenance and pre-historical significance of
the various Stonehenge bluestones (any non-sarsen rock-type that was used as a
Stonehenge orthostat) have been, and will always remain, contentious. This has been especially
true in the past couple of years.

Although these 4-6-tonne bluestones are overshadowed by the larger, sandy-coloured
and locally derived sarsens (a type of indurated sandstone) that make up the
photogenic trilithons and arches of the outer circle and inner horseshoe, they have more to
tell us about Stonehenge’s origin and history. These rocks are once again the centre of
much debate about how they reached Salisbury Plain; even those who believe they
were man-hauled to Wessex, rather than carried by glaciers, are now arguing about the
route they took.

Small grey box

The cause is a recent re-examination of the contents of a little box of stones collected by
JF Stone in 1947 from plough soil close to the Stonehenge Greater Cursus and donated to
the Salisbury and South Wiltshire Museum. Many of the ten or so stones – none of which
are bigger than a fist – were found to be texturally and mineralogically distinctive.
Initial investigations showed none of these matched any of the standing bluestones:

*The Altar Stone, the largest at Stonehenge, is a possibly fallen, calcareous sandstone from
somewhere between the Brecon Beacons and south-west Wales, but not from Milford
Haven as previously thought.

* ‘Preselite’, the local name for altered spotted/unspotted dolerites, are the most
abundant Stonehenge bluestones and are very similar to outcrops on the high Preseli
Hills in south-west Wales. A number of possible quarry sites are being sought along
the northern edge of those hills.

*Rhyolitic lavas and volcanic tuffs, including the distinctive orthostat 48 (SH48) with its
pumice fragments and visible feldspar crystals. Only four volcanic lava bluestone
orthostats survive and earlier suggested origins are incorrect; their source is
probably from close to the Preseli Hills.

*In addition, there are a number of buried orthostats, including rare hard sandstones
and calcareous tuffs. There are also tens of thousands of bits of debris lying just below
the surface of Stonehenge and its immediate surroundings, ranging from 10kg to less
than a gram. This debris had only been subject to two small lithological studies.

All of these Stonehenge rocks had been described on a few occasions in the 20th
century, notably in the 1980s and later by the Open University (and colleagues) in 1990. They
were rigorously re-described initially by Dr Rob Ixer, of the University of Leicester,
accompanied after 2009 by Dr Richard Bevins, keeper of geology at Amgueddfa Cymru,
National Museum of Wales, to provide a standard set of descriptions.

A large and systematic study was set up to build on this work. This included detailed
petrography, complementary whole rock and detailed mineral geochemistry of Stone’s
stones by Ixer and Bevins, in partnership with colleagues from Aberystwyth and the Open
Universities, together with lithic assemblages found within Stonehenge and its immediate
environs, collected over the last two centuries, plus all the debitage from 21st century
excavations, as well as dedicated geological in situ collecting from south-west Wales.
New in situ sampling, down from the northern slopes of the Preseli Hills, showed
some of Stone’s stones and Stonehenge rhyolitic debitage could be matched to highly
unusual rocks from the Pont Saeson area and in particular to a 70m rocky outcrop called
Craig Rhos-y-felin. Stonehenge material was being provenanced to an area of less than a
square kilometre. Subsequently matching the distinctive
‘rhyolite with fabric’ debitage (first seen in Stone’s stones) from Stonehenge to very
detailed sampling along the Welsh outcrop showed that rocks from the extreme north-
east of Craig Rhos-y-felin (‘site 9’) were identical to Stonehenge rhyolites showing the
'Jovian’ texture. This suggests an almost impossible provenance of ten squares metres.
The archaeologists were told where to dig. In September 2011, Professor Mike Parker-
Pearson of Sheffield University and his team cleared the vegetation from the northern end
of Craig Rhos-y-felin and excavated. They found, just a few metres from site 9, a large
proto-orthostat, a large joint block set for its journey to Salisbury Plain.

So the contents of a 60-year-old box led to the discovery of the first secure Stonehenge-
related quarry site, confirming that man moved the bluestones. But the initial
assessment of Stone’s stones was wrong, because in June 2012, one of the rocks was
recognised as coming from bluestone SH48, making it only the fourth piece of debitage
from thousands investigated that could be matched to a specific bluestone orthostat.

Lithological randomness

However, even if many of the bluestones come from a couple of outcrops on the top and
northern slopes of the Preseli Hills and even from a very small area within those outcrops
(as has been shown for Craig Rhos-y-felin and strongly suggesting they were quarried) there
remains a degree of lithological randomness inherent in the presence of the other types of
rhyolitic tuff and sandstone bluestones. Could it be that the monoliths are a
mixture of quarried stone augmented by randomly chosen rocks just to make up the
numbers, so making Stonehenge among England’s earliest jerry-built public buildings?
Or are there further, undiscovered, quarries silently hiding among the Welsh bracken and
flowering foxgloves, feint echoes of carefully organised stone and social structures?

Dr Rob Ixer is a geologist at the University of Leicester

Were the builders of Stonehenge herders, not farmers?

An interesting discussion -- and it questions the widely-held thesis that Stonehenge was so elaborate, and needed such a sophisticated organizational and social structure to make it happen, that it can only have been built by a settled and stable community with large agricultural surpluses.  Well, I have been arguing for a long time that it was never actually finished -- so maybe that in itself leads to questions about just how settled and well-organized the builders really were.  I imagine that this one will run and run......

Herders, rather than farmers, built Stonehenge

from stonehengenews

The ancient builders of Stonehenge may have had a surprisingly meaty diet and mobile way of life. Although farming first reached the British Isles around 6,000 years ago, cultivation had given way to animal raising and herding by the time Stonehenge and other massive stone monuments began to dot the landscape, a new study finds.

Stonehenge in southern England may have been built by herders, not farmers, suggests a new analysis of crop remains from the last several millennia.

Agriculture’s British debut occurred during a mild, wet period that enabled the introduction of Mediterranean crops such as emmer wheat, barley and grapes, say archaeobotanists Chris Stevens of Wessex Archaeology in Salisbury, England, and Dorian Fuller of University College London. Farming existed at first alongside foraging for wild fruits and nuts and limited cattle raising, but the rapid onset of cool, dry conditions in Britain about 5,300 years ago spurred a move to raising cattle, sheep and pigs, Stevens and Fuller propose in the September Antiquity.

With the return of a cultivation-friendly climate about 3,500 years ago, during Britain’s Bronze Age, crop growing came back strong, the scientists contend. Farming villages rapidly replaced a mobile, herding way of life.

Many researchers have posited that agriculture either took hold quickly in Britain around 6,000 years ago or steadily rose to prominence by 4,000 years ago. In either case, farmers probably would have assembled Stonehenge, where initial work began as early as 5,500 years ago, with large stones hauled in around 4,400 years ago (SN: 6/21/08, p.13).

But if Stevens and Fuller’s scenario of British agriculture’s ancient rise, demise and rebirth holds up, then small groups of roaming pastoralists collaborated to build massive, circular stone and wood structures, including Stonehenge. Shifts from farming to pastoralism, sometimes accompanied by construction of stone monuments, occurred around the same time in parts of Africa and Asia, the researchers say.

“Part of the reason why pastoralists built monuments such as Stonehenge lies in the importance of periodic large gatherings for dispersed, mobile groups,” Fuller says. Collective meeting spots allowed different groups to arrange alliance-building marriages, crossbreed herds to boost the animals’ health and genetic diversity and hold ritual feasts. At these locations, large numbers of people could be mobilized for big construction projects, Fuller suggests.

“A predominantly pastoralist economy in the third millennium B.C. accords well with available evidence and provides a suitable backdrop to the early development of Stonehenge,” says archaeologist Timothy Darvill of Bournemouth University in England. But he believes many large stones were brought to Stonehenge during a later upswing in cereal cultivation, as pastoralism receded in importance.

Stevens and Fuller compiled data on more than 700 cultivated and wild food remains from 198 sites across the British Isles whose ages had been previously calculated by radiocarbon dating. A statistical analysis of these dates and associated climate and environmental trends suggested that agriculture spread rapidly starting 6,000 years ago. About 700 years later, wild foods surged in popularity and cultivated grub became rare.

Several new crops — peas, beans and spelt — appeared around 3,500 years ago, when storage pits, granaries and other features of agricultural societies first appeared in Britain, Stevens and Fuller find. An influx of European farmers must have launched a Bronze Age agricultural revolution, they speculate.

Stevens and Fuller’s analysis offers only a general breakdown of how farming and pastoralism developed in Britain, asserts archaeologist Alasdair Whittle of Cardiff University in Wales. The scale of cultivation, even during times characterized by relatively abundant remains of domesticated plants, remains uncertain, Whittle says.

Even if farmers didn't built Stonehenge, cultivators erected plenty of massive stone monuments, Whittle holds.
Bruce Bower

Link source:

Saturday 1 September 2012

THAT meteorite to go on display

The Lake House Meteorite (which we have discussed earlier) is due to go on display in Salisbury Museum this autumn.  No doubt there will be more interesting discussion of where it was found, and how it got there...........  but since Colin Pillinger is not an archaeologist, forget about the Druids.

I found this on the BBC web site:

14 February 2012

Wilsford-cum-Lake doorstep meteorite 'biggest to fall in UK'

Mystery had always surrounded the origins of a 200lb (90kg) meteorite that had been on the doorstep of a Wiltshire house for more than 80 years.

Experts had wondered if the space rock had initially landed in another part of the world several thousand years ago and had been brought at some stage over to England

However, researchers now believe the 1.6ft (50cm) long rock may have landed 30,000 years ago closer to home - making it possibly the largest meteorite ever found in Britain.

What was known about the rock was that it had been on the step of Lake House near Wilsford-cum-Lake since the early-1900s.

But when the family, who wished to remain anonymous, wanted to sell property in 1991, they decided to take the rock, which they had always referred to as "grandfather's meteorite", to the Natural History Museum.

At the time, museum experts confirmed it as a meteorite but were unable to verify if it had been found in the UK.

It had been assumed the rock, which is four times larger than any other meteorites that had been previously found in the UK, had been collected by the family's grandfather on his travels abroad.
But Professor Colin Pillinger, from the Open University, who has been researching the meteorite's history for more than a year, said there was photographic evidence of the rock being on the steps of the house which predates the family.

He said he was now "99.9% certain" the meteorite had landed in the UK.

"It's very unusual to find a meteorite this big in Britain," he said.

"They are very unstable, they contain a lot of metallic iron which oxidises and the meteorite falls to pieces.

"So the only logical explanation of how such a big meteorite may have survived being on Earth for 30,000 years is that it fell on or near a glacier and was in a deep freeze for 20,000 years."

'Scavenging druids'

Professor Pillinger, famed for his work on the Beagle II Mars explorer, said he believed the low-humidity and freezing conditions would have protected the rock from weathering.

"Then along came some druids, scavenging on Salisbury Plain for strange or interesting stones, and it was picked up and used in a chalk mound," he said.

Professor Pillinger believes the giant meteorite was unearthed in an excavation of a burial mound
"And the 'reducing environment' of chalk - the anaerobic environment - would have prevented the iron from oxidising."

The giant fragment of asteroid is then thought to have been unearthed by a previous occupant of Lake House, who is known to have excavated several nearby burial mounds.

"He was an archaeologist and was digging every barrow up in sight trying to find treasure," said Professor Pillinger.

"And we think he got it out of a barrow and added it to his collection."

The meteorite, known as a common chondrite, is due to go on display at the Salisbury and South Wiltshire Museum in autumn.

Adrian Green, the museum's director, said there was still "a lot of debate" about how the rock came to be on the doorstep of Lake House.

"But it's not uncommon for exotic rocks to be built into burial mounds," he added.

"And it's still covered in chalk which is the bedrock of the landscape.

"And it's colossal - it would take four people to lift it - and it's not aesthetically pleasing, so common sense dictates that this has not been shipped from abroad at ridiculous cost and significant effort, but that it came from the UK."