THE BOOK
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....
To order, click
HERE

Thursday, 14 June 2018

Historic document from 2000



Ah -- this brings back happy memories! A Western Mail press cutting from April 2000, in the early stages of the Millennium Stone Pull.

This reminds us that when the pullers started with the project, all wore yellow gloves and PULLED on the ropes.  But many found that very hard work, getting rope burns and blisters on their hands -- and so after a while the organisers developed a sort of harness for each puller, with a bar in front of the chest and a connection behind onto the main haulage rope.  So those who were drawing the stone along were facing forward and PUSHING --  and were able to use their body weight much more effectively.  The men with the levers who walked along behind the stone were there to lever the loaded sledge back into position when it slid sideways -- as it did with alarming frequency.

In spite of these innovations, and the use of modern ropes and friction-reducing Netlon to increase sliding efficiency on asphalt roads, the stone pull was still an unmitigated disaster, proving without a doubt to all of those involved that the hypothetical human haulage of 80 bluestones from Presell to Stonehenge was just about as reliable as the "aliens from outer space" hypothesis.








Wednesday, 13 June 2018

Meanwhile, in the Brecon Beacons


Thanks to Phil for 4 images of the cirque called Craig Cerrig-gleisiad (glitter-stones crag) in the Brecon Beacons.The top one looks south into the Taff Valley; the second one looks out of the cirque, over the lip, towards Brecon and Hay on Wye in the distance; the third looks into the cirque, with the headwall in the distance.  The last photo, below, shows the inside of the cirque with Pen y Fan and Corn-du in the distance.



There are some very spectacular glacial features in the Beacons, all well recored and studies over the years. The ice divide in this area seems to have been very mobile -- apparently shifting about in all compass directions during the course of the Devensian.





Monday, 11 June 2018

More from the ice divide



Purely by chance, this was posted on Facebook today by Stephen John (no relation).  Fabulous image -- taken on the remote upland road to the Elan Valley.  Again, this is typical ice divide terrain, maybe covered by relatively stagnant and cold-based ice for most of the Devensian cold episode.  That means maybe 50,000 years of ice cover, with remarkably little landscape modification.

Craig Rhosyfelin -- "the monolith extraction point" -- again


Fracture scar left when a small slab (maybe 5 cms thick and c 20 cms wide) fell away relatively recently.  The scar edges are sharp and fresh.

I applied some close scrutiny to the "monolith extraction point" at Rhosyfelin on my last visit -- referred to by Mike Parker Pearson and colleagues as located in a "recess."  There isn't any recess there, and there is no evidence at all that a single stone might have been taken from the point at which MPP has charmingly posed for a thousand photographs.

As I have pointed out before, the rock face here has several prominent fracture scars which must have been created when small slabs of foliated rhyolite fell away and accumulated at different times at the foot of the crag.   If they were present in 2011, these must all subsequently have been carted away and dumped by the archaeologists, who were interested above all else in the 5 years of digs in looking for monoliths capable of being carted off to Stonehenge or to "proto-Stonehenge".  It's possible, of course, that some of the slabs broke away while the site was affected by glacier ice and torrents of meltwater;  they may have been incorporated into overriding ice, or moved downstream before being dumped.  They must all have been quite small, and easily modified or destroyed.


A very old fracture scar on the same face; note how heavily abraded the outer edge of the scar is.  The slab that dropped away from above it must have parted company wit the rock face many thousands of years ago.


Another clean fracture, also heavily abraded.  A late Devensian feature?


Irregular fracture scars towards the base of the exposure.   Several slabs have fallen away here, one c 6 cms thick and probably another around 4 cms thick.  Again the scars are heavily abraded -- suggesting the action of either ice or meltwater.

The sample that was taken away for cosmogenic exposure dating about 3 years ago must have come from somewhere on this face.  The dating must have been completed long since -- I wonder why the result has never been published?  But then nobody likes to publish inconvenient evidence, do they?

More comments about the book....



Two more comments from senior academics. (By the way, I did not make them up.)   I'm quite encouraged.  Of course, there will be negative and aggressive reviews in assorted journals from people with vested interests and maybe from some who don't wish to take my arguments on board.  Such is life....

"..........your recent book The Stonehenge Bluestones. Excellent! I believe you! I read it from cover to cover.  Your demolition job on the Bluestones did me good. ‘Assumptive research’ is more common than one might expect … and embedded assumptions create vast barriers, dams, holding up research … YET flexibility is unwelcome!"

"Only had a quick browse so far but seems you've done a grand job updating... Excellent stuff." 

Thursday, 7 June 2018

Stonehenge -- rhyolite in a Mesolithic context?

Pit 9580 -- from p 46 of Cleal et al, 1995

On looking through Ros Cleal's mammoth tome the other day, I came across a rather interesting reference to a "rhyolite chip" in what appears to be a Mesolithic context.   This would not, of course, be the first time that a piece of bluestone has been uncovered in a pre-Stonehenge context.......

In Chapter 4 ("Before Stonehenge") Michael Allen makes use of the unpublished notes of Martin Trott, working for Wessex Archaeology at the behest of English Heritage, to study those famous post holes in the old Stonehenge car park.

In Pit 9580 (the easternmost pit, very close to the old Visitor Centre), there was a very varied fill of sediments about 1.3 m thick.  The pit seems to have been re-cut and modified several times, the most prominent modification being a transformation into a wide shallow pit (purpose unknown) just 70 cms deep.   Trott described primary, secondary and tertiary contexts.  The most interesting thing about the recut tertiary fill at the top of the sequence (context 9581) is that it contained a piece of rhyolite weighing 62g, at a depth of 20 cm.  Then we come to some circular reasoning -- Allen says:  "this latter find is of some significance as it indicates that this layer was not earlier than, and was probably contemporary with, the dressing of the bluestones (phase 3)."  That is one explanation -- the other is that the rhyolite chip was there when the pit was in use, or was being filled in, very much earlier than Bluestones Phase 3. This latter explanation is supported by the radiocarbon date of 8400 +/- 100 yrs BP obtained from charcoal in the tertiary fill layer.  The layer is pretty well homogenous, and there is no reason to think that the rhyolite chip was introduced and buried here more than 3,000 years after the Mesolithic pit was finally filled.  If it had been, there should be signs of some break in the stratigraphy.

Then it gets even more confusing, since detailed work on the molluscan fauna and on pollen analyses from the side of the opened pit indicate a "hiatus" between the lower parts of the pit fill and the "tertiary fill" near the surface.  Allen and other researchers suggest that there was indeed a break of as much as 5,000 years between the Mesolithic and Neolithic activity.  In the Mesolithic (Boreal) period there was a wooded landscape, and when the sediments of the tertiary fill were emplaced the landscape was much more open.  But is that assumption of a long hiatus based upon the assumption that rhyolite cannot possibly have been present in the neighbourhood during the Mesolithic?  Could the clearance of land and its transformation from open woodland to a grassland area have taken place rather quickly -- or over a few thousand years -- during the Mesolithic, as a result of burning?  Should we believe the radiocarbon date, or treat it as an aberration?

This is all very intriguing -- does anybody have more information?

Ice shed country -- Cambrian Mountains


Llyn Cwm-byr, near Pumlumon

I keep on discovering fascinating landscapes.  I discovered another one the other day, while travelling home from giving a talk in Bishops Castle, in the Welsh Borders.  We took  detour off the Newtown - Aberystwyth road and took minor roads via Devil's Bridge to Pontrhydfendigaid and Tregaron.  I had been that way before without seeing much, but this time it was a real hot summer's day, with blue sky and fantastic visibility.

This is part of Wales's empty quarter, with a rolling -- almost prairie - like -- landscape of broad river valleys, wide depressions with lakes in them, and hilly areas with gentle slopes.   This is the core of the Cambrian Mountains and the main watershed of Wales, with some streams flowing west and others flowing east -- but no glaciated troughs.  During the big glacial episodes this area has been at the heart of the Welsh ice cap -- so there has been very thick ice sitting on this landscape -- but it has done virtually nothing in terms of landscape modification.   The ice has been effectively stagnant, and probably cold-based,  maybe with occasional aerial scouring but no streaming.  The whole landscape reminded me of parts of the basalt plateaux of NW Iceland, except that here there are the remnants of a very old fluvial landscape which has been largely unmodified for millions of years.

Must try to get back there soon, so that I can take a more careful look.......


The Cambrian Mountains of mid-Wales, between Aberystwyth and Newtown.  The undulating "watershed plateau" is clearly seen in the centre of the map.  The brown-coloured area is the highest part of the plateau, around Pumlumon.


Typical landscape on the plateau


Extract from the BGS glacial map of Wales, showing Devensian ice movements at the centre of the Welsh Ice Cap.  Note the outlet glaciers flowing away from the ice-shed area -- the Rheidol and Ystwyth Glaciers flowing west, and the Wye and Severn Glaciers flowing NE and SE respectively.  






Friday, 1 June 2018

Herbert Thomas scrutinized



A new review of Herbert Thomas and his work has just been published in Antiquity journal. Was he a brilliant geologist, or a bit of a charlatan?  I'll report on the detail in due course, but in the meantime here is the Abstract and the reference list -- the latter makes a good check-list of the papers by Bevins and Ixer.  With a bit of luck, the hyperlinks will work........
(As we all know, I don't agree with the authors that they have definitively identified the locations from which some of the bluestones and the debitage at Stonehenge have come -- the best that can be said is that they have narrowed things down to the most likely neighbourhoods.)

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

Retracing the footsteps of H.H. Thomas: a review of his Stonehenge bluestone provenancing study
Richard Bevins and Rob Ixer
Antiquity, May 2018.

Published online: 31 May 2018

Abstract

The long-distance transport of the Stonehenge bluestones from the Mynydd Preseli area of north Pembrokeshire was first proposed by geologist H.H. Thomas in 1923. For over 80 years, his work on the provenancing of the Stonehenge bluestones from locations in Mynydd Preseli in south Wales has been accepted at face value. New analytical techniques, alongside transmitted and reflected light microscopy, have recently prompted renewed scrutiny of Thomas's work. While respectable for its time, the results of these new analyses, combined with a thorough checking of the archived samples consulted by Thomas, reveal that key locations long believed to be sources for the Stonehenge bluestones can be discounted in favour of newly identified locations at Craig-Rhos-y-felin and Carn Goedog.


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