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

Thursday, 29 October 2015

Tafarn y Bwlch Visitor Centre




Some serious landscaping work has been done on the site at Tafarn y Bwlch, largely associated with the garden and car parking areas.  This may have been done now because the original planning consent was given in 2008 -- so maybe it needed to be demonstrated that the project was under way, so as to avoid a lapsing of the consent.  That's speculation -- let's hope that work will shortly start on bthe rest of the project including the renovations to the old farm and outbuildings.

What interests me is the use of hundreds of huge glacially smoothed and faceted boulders in the landscaping work.  They are nearly all dolerites and gabbros,  and I reckon that some of them weigh well over 20 tonnes.  Where have they come from?  I'm trying to find out -- but if they have all been picked up locally, on the site, this would confirm that there is a very large moraine here -- of which more anon.



Mesolithic eco home near Stonehenge




 Shock! Horror!  Mesolithic men did not use modern building techniques, but built eco homes in the forest.  This drives one to despair -- an endless stream of completely underwhelming drivel.  It seems that anything with the word "Stonehenge" in it is good for a headline and a breathlessly excited write-up.  One sometimes loses the will to live.....

http://www.theguardian.com/uk-news/2015/oct/29/archaeologists-discover-mesolithic-eco-home-near-stonehenge?CMP=share_btn_fb

Monday, 26 October 2015

Rhosyfelin -- the marketing begins.....



No sooner said than done -- I was just browsing about and came across this, on the National Park web site.  It's a short walk (one of many) in a format suitable for use on iPhones and iPads, or for printing off as a paper copy.  That's the way tourist information is going.

I'm really rather irritated, because in spite of letters to the NPA Archaeologist Phil Bennett, and to the NPA's Chief Executive, warning them to be rather careful about what they say on the subject of Craig Rhosyfelin, they have gone straight into full marketing mode, and to hell with the truth.  So Craig Rhosyfelin is flagged up in the title as "Source of the Stonehenge bluestones"  and then we see:  LOOK OUT FOR: Craig Rhosyfelin crag, source of two of the bluestones from the inner circle at Stonehenge.

On the second page the text reads:  It is here that a number of the famous bluestones were quarried and later taken to Stonehenge – most probably by land on sleds hauled by oxen. 

Needless to say, there is no evidence for any of that.


As an honest taxpayer -- and as somebody who led over 200 walks and talks for the National Park's visitor programme over the years -- I feel somewhat aggrieved that the NPA nowadays apparently has no regard for science or for properly published research work, and prefers to obtain its information from certain professors who stand up and tell elaborate stories in public lectures.

On we go, with the race to the bottom......

Rhosyfelin reverts to nature


After all that quarrying by the MPP tribe over the past five Septembers, all is quiet again down in the valley.  The dig site has been filled in and re-seeded, and this is what it looked like about a month ago.  The big "pseudo proto-orthostat" is still exposed, as is much of the rock face and the upper part of the rockfall bank, but all of the interesting sediments and the cut sections are now lost without trace.  That's a pity, given that there is going to be a considerable controversy over the coming months about what is there and what it all means.  So the evidence is no longer available for scrutiny by independent experts, and people will have to depend upon the reliability -- or otherwise -- of what appears in print.

Thank goodness I have been able to post scores of photos of the site onto this blog, which specialists can search for and examine. If necessary, of course, new trenches can be dug and boreholes can be put down, but great care will have to be taken because in some places the top 2m or so of sediments will be infill shunted in from the big spoil heap which was located adjacent to the dig.

Before long, this will all be green again, until somebody or other moves in with picnic tables and information boards........

New Preseli Visitor Centre -- work commences


 The new Visitor Centre at Tafarn y Bwlch will be located just off the bottom right of the photo.

Back in 2008 local businessman Mr Llew Rees obtained planning permission from the Pembs Coast National Park for the building of a new Visitor Centre at Tafarn y Bwlch, adjacent to the cattle grid on the north side of Mynydd Presely, where the Newport road branches off the B 4329.

This is a fantastic site -- exactly where I would have built a Visitor Centre had I been 40 years younger and somewhat wealthier.  So -- the best of luck to Mr Rees, and all credit to him for being prepared to invest in the local community and to provide something for which there will certainly be a great demand.  There will be a 60-seat cafe, educational facilities, toilet facilities, an information display, tourist information point, with extensive car parking and maybe a depot for mountain bike hire etc.  You can walk straight out of the site onto the common, with the northern flank of Preseli opening up in front of you.  The old farmhouse (somewhat ruinous) will be converted for use by the site manager and his family, and the newer buildings will go to the NE of the farm, near a realigned entrance from the road.  You can see the plans on the National Park web site -- look for Application 07/600 (2008).

Just to the north of the site are the standing stones of Waun Mawn, and Craig Rhosyfelin is less than 4 km away, past the village of Brynberian.  Then we have the Bedd yr Afanc chambered cairn and other glacial and archaeological features galore.......  I can already see the student field parties lining up to use the facilities here!

The recession has caused the project te remain in cold storage from 2008 until now -- but now work has started, and we can already see some of the details emerging.  The landscaping work already looks impressive -- I'll shortly post some photos.







The Gower raised beaches




I came across these and other splendid images on Jessica Winder's blog site, which can be found here:

https://natureinfocus.wordpress.com/2013/01/01/ancient-gower-shells-raised-beaches/

They are reproduced here with her kind permission.  She has 20 photos from the Gower raised beaches in this file,  from a number of different sites.  Many of these deposits are cemented, and the main species of shell are Patella and Littorina.

There used to be references to "the Patella Beach" and "the Littorina beach" and there was an assumption that they were at different altitudes.  Nowadays it is assumed that all the beaches date from the last (Ipswichian) Interglacial, around 130,000 - 100,000 years ago. 

The Paviland Moraine: its bearing on the bluestone debate


The Paviland Moraine (pecked line) runs for almost 10 km inland of the south coast.  It is best seen  just inland of the coast at Port Eynon Bay (after Bowen, 1985). Port Eynon Bay is the southernmost bay on Gower.  The moraine has an arcuate form and may be up to 40m thick.  The north-facing flank is steeper than the south-facing flank, according to the 2015 QRA Field Guide.  Bowen's presumed Devensian ice limit is shown by the dashed line.

The Paviland Moraine in western Gower is widely cited as one of the oldest glacial constructional features in the UK -- and for many years Prof DQ Bowen has promoted the idea that it is of Anglian age, on the basis that it LOOKS very old and that it contains till and clasts of many sizes that appear to be heavily weathered.  Also, it lies beyond or outside the Late Devendsian ice margin reconstructions made by Bowen and many other workers over the years. It also rests on a ridge crest not far from the famous Paviland Cave, within which a human skeleton has been found and which has been dated to the Middle or Late Devensian.  The thinking has been, for many years, that if people were inhabiting the Gower caves at this time, the ice margin could not have been located in the vicinity.  I have done various earlier posts on this topic:

http://brian-mountainman.blogspot.co.uk/2012/02/paviland-and-ice-edge.html

http://brian-mountainman.blogspot.co.uk/2011/08/monster-from-daylight-rock-1.html

http://brian-mountainman.blogspot.co.uk/2011/08/monster-from-daylight-rock-2.html

http://brian-mountainman.blogspot.co.uk/2012/02/arthurs-stone-gower.html

On the QRA / GLWG field trip the other day, we visited the Paviland Moraine itself, and while it is singularly unspectacular (essentially a low capping of till and other sediments on a limestone rock ridge more or less parallel with the coast) it does have an irregular crest line and a nice "micro morphology" of low ridges, hollows, valleys, hummocks and steps which is rather convincing.  In short, the moraine is no more "degraded" than any of the Devensian constructional features in South Wales (like the hummocks in the Moylgrove-Cardigan area) which can be dated with a fair degree of certainty.  As soon as I saw it, I thought: "If somebody wants to tell me that this is a Devensian feature, I would be inclined to believe it."  Also, John Hiemstra and his colleagues showed us a very convincing sections from an 11m core through the moraine, showing that the contained clasts are quite fresh, and free of the weathering crusts that might be expected if there had been almost half a million years of weathering since deposition.  The other very convincing argument for a Late Devensian age for this feature is the presence of "plugs" of chaotic fluvioglacial debris at the mouths of Western Slade and Eastern Slade valleys, suggestive of pulses of very turbulent and even catastrophic meltwater flow from an ice margin in close proximity.  The debris exposed in the cliffs is very fresh, and cannot have been emplaced here if a Devensian ice margin had been located  several kilometres to the north, on the other side of the limestone ridge.

 A one-metre section of the 11m core, laid on its side.  The sediment here is reddish brown in colour, with large clasts set in a matrix of gravel, sand and silt.  There is less clay in the matrix than there is in the lower part of the core.  This is clearly a till.  Note that the clasts (sliced through by the drill) are clean, with no weathering crusts.

So I'm convinced that the Paviland Moraine is Late Devensian in age.  Whether this represents the MAXIMUM extent of Devensian ice on the Gower is another matter -- I reckon the jury is still out on that one.  But there is no reason in principle why there should not have been intermittent human habitation of the Gower caves round about the time that the Devensian ice coming out of the South Wales Valleys was at its maximum. 

 Now we come to the relevance of all this for the bluestone transport debate.  Here is a 1994 quote:

"New evidence confirms the suggestion that the Llanddewi Formation of Gower (Bowen, 1969b) and its Paviland Moraine should be correlated with the Anglian (Bowen et al., in preparation). This, however, represents glaciation from due north, and does not support the hypothesis of an Anglian ice-sheet (~450 ka) that transported 'bluestones' from Preseli to Stonehenge (Kellaway, 1971; Thorpe et al., 1991). Cogent arguments have been assembled against this hypothesis (Kidson and Bowen, 1976; Green, 1973;(in press); Darrah, 1993), and are supported by a 36Cl age determination on an igneous rock from the Stonehenge collection in the Salisbury Museum. This shows that it was still buried at its source outcrop during the Anglian (400 ka), and did not become exposed by denudation to the atmosphere until the Late Devensian (Bowen et al., in preparation), after which it was presumably quarried by prehistoric people and taken to Stonehenge."

Bowen, D.Q. (1994) Late Cenozoic Wales and South-west England.  Proc Ussher Society 8, pp 209-213.  (Scott Simpson lecture 1994)

Leaving the highly controversial 36Cl dating issue to one side, what Bowen is arguing here is that if the Anglian ice from the South Wales valleys was able freely to press across Gower as far as the position of the Paviland Moraine,  there could not have been Irish Sea ice in the vicinity -- and if there was no Irish Sea Ice here in the Anglian, it cannot possibly have transported bluestones from Pembrokeshire all the way to Stonehenge.  (The gradient of the Irish Sea Glacier must have been continuous from Preseli, across the tip of Gower and all the way to Somerset.)

That is all perfectly logical IF THE PAVILAND MORAINE IS REALLY OF ANGLIAN AGE.

If, however, that dating is faulty, as it now appears to be, and if the moraine is just another Late Devensian feature, Gower could well have been overridden by Irish sea Ice during the Anglian and the bluestones could well have been transported from Preseli to Stonehenge.  There must have been Irish Sea erratics lying around on Gower, or contained in ancient deposits, when the Late Devensian ice from the valleys arrived and flowed across the peninsula from north towards south.  This would tie in with the observations of George, Bowen and many other researchers that are scattered Pembrokeshire erratics in raised beach deposits and in the head which in places underlies the Devensian till and fluvioglacial materials.  The situation is very similar in Pembrokeshire, and in Devon and Cornwall, where ancient erratics (and sometimes very large boulders) sit on the raised beach platform and are incorporated into slope and other deposits that pre-date the LGM.

It all slots together.......



 This is the BRITICE map for West Wales, including Pembrokeshire and the Gower.  The cream-coloured area was supposedly ice free during the LGM.  Note that most of Gower is shown as ice-free during the Devensian (the dotted line shows the supposed limit) -- but the mapping here is now shown to have been based upon the flimsiest of evidence, with the old dating of the Paviland Moraine responsible for a multitude of sins.

This map from Thorpe et al (which assumes that the Anglian Irish Sea ice reached Salisbury Plain) shows that the big ice stream must have crossed much of Pembrokeshire and Gower en route.  This explains the presence of Pembrokeshire erratics on Gower, at Pencoed and on the Vale of Glamorgan.   The ice was much more limited in extent during the Late Devensian, when ice from the valleys of the Nedd, Tawe, Tywi and Taf flowed broadly southwards, but with much variation induced by topography.  Sometime near the peak of this very recent glaciation, the Paviland Moraine appears to have been  formed.


Sunday, 25 October 2015

Occam's Razor on the Gower

Some of the members of the QRA / GLWG Field Trip to Gower, 22 - 25 October, near Horton in Port Eynon Bay

The Gower Peninsula, near Swansea, has a rather interesting location, since it has probably been affected at various times by both Welsh ice and Irish sea ice, and since it lies close to the margin of Devensian ice derived from the southern part of the Welsh ice cap.  Somewhere, around 20,000 years ago, the glaciers flowing down the valleys of the western coalfield skidded to a halt.  They reached Carmarthen Bay and Swansea Bay, that's for sure, but where was the ice edge on the Gower?

The glacial and fluvioglacial deposits in this area consist predominantly of sedimentary rocks -- sandstones, grits, conglomerates, shales, and mudstones from the ORS, NRS, Millstone Grit, Coal Measures and Pennant Sandstone.  And a lot of Carboniferous Limestone too, since that is the locally outcropping rock across much of the peninsula.  There are some igneous and metamorphic erratics from the west -- particularly in western Gower, but in the bulk of the thick glacially-derived materials looked at, they are extremely rare.  So the assumption is that these erratics have come from largely destroyed earlier glacial deposits related to the action of the Anglian (?) Irish Sea Glacier.

For decades, the story of the Quaternary on the Gower has been complex and confusing -- with a multitude of suggested ice edge positions and with a multitude of chronologies to go with them.  Now, at long last, it appears that common sense is breaking out.  Researchers based mostly in Swansea University have studied most of the key coastal and inland sites and when I joined the field trip yesterday, leaders John Hiemstra, Danny McCarroll and Rick Shakesby gave a coherent and convincing new interpretation of the events of the Late Quaternary.  Essentially, what they are saying is this:

1.  There are not multiple interglacial raised beaches on Gower, as suggested by DQ Bowen, but one raised beach which is sometimes cemented and sometimes not, and which occurs at a range of different altitudes depending on precise locations on peninsulas, in bayheads etc.  The beach always contains well rounded pebbles and in some places it is very rich in shell fragments and even complete shells.

2.  There is plenty of evidence of a prolonged periglacial episode following the formation of the interglacial raised beach, since here and there we see many metres of pseudo-stratified slope deposits or "head" above the raised beach and beneath the glacial and fluvioglacial materials.  (This is exactly the sequence we see in Pembrokeshire.)  Sometimes the head is cemented, and sometimes not.

3.  The glacial sediments exposed in the cliffs at Rotherslade, Horton and elsewhere are not ancient deposits moved into place by periglacial and slope deposits, but fresh materials emplaced at or very near a Late Devensian ice edge.  (There was a lot of discussion amongst field trip experts about whether some of these deposits were indicative of actual ice-contact situations, with chaotic and even catastrophic flowing and emplacement of till and mixed fluvioglacial materials at a time of rapid ice wastage, or whether they were carried from an ice margin some way away and deposited as "plugs" of debris with till-like characteristics in episodes of turbulent and high-velocity meltwater flow.  The jury is still out on this....)

4.  The Paviland Moraine near Horton, which has been interpreted by DQ Bowen as well beyond the Devensian ice margin (and hence a very ancient glacial feature) contains material which is no more ancient than any of the other glacial and fluvioglacial materials exposed in the cliffs.  It should therefore be re-interpreted as a Devensian feature -- deposited maybe during a long ice edge stillstand at this position, on a ridge not far from the southernmost tip of Gower.

More on some of this anon, when I have had a bit more time to examine my photos and to look at the excellent "Quaternary of Gower" Field Guide prepared by the field trip leaders.

Lecture on the Stonehenge Bluestones

Happy to give a puff for this one -- a lecture by Richard Bevins at the Wilts Museum in Devizes.  Thanks to Tony for the alert.....

LECTURE: Old Stones, New ideas: Sourcing the Stonehenge Bluestones

2:30 pm, Saturday, 21 November, 2015
Wiltshire Museum, Devizes

A Saturday afternoon lecture by Richard Bevins.
Stonehenge is arguably one of the most famous prehistoric monuments in the World. It is renowned for the enormous size of the sarsen monoliths used in its construction which comprise the Outer Circle and Outer Horseshoe. It is generally agreed that these stones were sourced from the Marlborough Downs area, some 30 km to the north of Stonehenge. However, a set of smaller stones, comprising the Inner Circle, the Inner Horseshoe and the Altar Stone, are exotic to the Salisbury Plain area; these are the so-called bluestones, and have been the subject of investigations since the latter part of the 19th Century. Early petrographical studies recognised that the bluestones largely comprise a range of altered volcanic, intrusive and tuffaceous rocks with rarer sandstones but could not provide a definitive source.

However, it was the seminal paper by H.H. Thomas in 1923 that persuasively demonstrated that the spotted dolerite component of the bluestones could be sourced to outcrops exposed towards the eastern margin of Mynydd Preseli in southwest Wales, citing the tors Carn Meini and Cerrigmarchogion as the most likely sources. Thomas also argued that other lithologies in the bluestone assemblage, notably the rhyolites and the ‘calcareous ash’, could be sourced in the same locale, in particuar from Carn Alw and the northern slopes of Foel Drygarn respectively.

The first major investigation of the geochemistry of bluestone assemblage was by Richard Thorpe and team who compared whole rock wavelength-dispersive X-ray fluorescence spectrometry analyses from both orthostats and debitage at Stonehenge with whole rock analyses from Mynydd Preseli
.
Using petrography, mineral chemistry and whole rock geochemistry Richard Bevins and Rob Ixer have re-examined the proposed source of the bluestone rhyolites and determined that Carn Alw, as proposed by Thomas, is not the source of bluestone rhyolite; instead they argued that the majority of the rhyolite debitage from the Stonehenge Landscape (but not the four rhyolitic/dacitic standing or recumbent orthostats) comes instead from a prominent outcrop called Craig Rhos y felin, located on low ground to the north of the Mynydd Preseli range in the vicinity of Brynberian. More recently they have re-examined the spotted and non-spotted dolerites and concluded that a large % of the dolerite fragments and cored samples from Stonehenge come from Carn Goedog rather than Carn Meini.


Biography
Dr Richard Bevins as Keeper and Head of the Department of Natural Sciences at the National Museum Wales in Cardiff is responsible for Strategic leadership for collections and research related activities within the Department.

Qualifications, memberships and relevant positions:
BSc (Hons) Geology (Aberystwyth University), PhD (Keele), Fellow (Geological Society of London), Chartered Geologist (CGeol), Fellow (Society of Antiquaries of London), Honorary Lecturer (School of Earth & Ocean Sciences, Cardiff University), Chair, Geological Society of London’s Geoconservation Committee, Member of the Geological Society of London’s External Relations Committee, Chair of the British Geological Survey’s National Geological Repository Advisory Committee.

References
Primary research area is centred on the the Caledonian igneous history of Wales and related areas, as well as on their low-grade metamorphism. More recent work has focussed on extending the petrology and geochemistry of altered igneous rocks from Pembrokeshire into a re-examination of the source of the Stonehenge bluestones.

Selected Publications:
Bevins, R.E., Ixer, R. A. & Pearce, N.J.G. 2014. Carn Goedog is the likely major source of Stonehenge doleritic bluestones:evidence based on compatible element geochemistry and Principal Component Analysis. Journal of Archaeological Science, 42, 179-193.

Ixer, R.A. & Bevins, R.E. 2014. Chips off the old block: the Stonehenge debitage dilemma. Archaeology in Wales, 52, 11-22.

Bevins, R.E., & Ixer, R. A. 2013. Carn Alw as a source of the rhyolitic component of the Stonehenge bluestones: a critical re-appraisal of the petrographical account of H.H. Thomas. Journal of Archaeological Science, 40, 3293-3301.

Bevins, R.E., Ixer, R. A., Webb, P.C. & Watson, J.S. 2012. Provenancing the rhyolitic and dacitic components of the Stonehenge landscape bluestone lithology: new petrographical and geochemical evidence. Journal of Archaeological Science, 39, 1005-1019.

Parker Pearson, M., Pollard, J., Richards, C., Thomas, J., Welham, K., Bevins, R.E., Ixer, R., Marshall, P. & Chamberlain, A. 2011. Stonehenge: controversies of the bluestones. In L. García Sanjuán, C. Scarre and D.W. Wheatley (eds) Exploring Time and Matter in Prehistoric Monuments: absolute chronology and rare rocks in European megaliths. Proceedings of the 2nd European Megalithic Studies Group Meeting (Seville, Spain, November 2008). Menga: Journal of Andalusian Prehistory, Monograph no. 1. Seville: Junta de Andalucía. 219-50.

Bevins, R.E., Pearce, N.J.G. & Ixer, R. A. 2011. Stonehenge rhyolitic bluestone sources and the application of zircon chemistry as a new tool for provenancing rhyolitic lithics. Journal of Archaeological Science, 38, 605-622.

Links:
www.researchgate.net/profile/Richard_Bevins2

Saturday afternoon lectures start at 2.30pm and last approx. one hour.

Our Lecture Hall is accessible via a lift if required, has a hearing loop and air conditioning.

Booking:

Essential.

Booking Options
Book online using Paypal
Telephone – 01380 727369
Email – hello@wiltshiremuseum.org.uk
Visit – Wiltshire Museum, 41 Long Street, Devizes

Monday, 19 October 2015

Ceibwr connected pot-holes and cemented sediments

The subsidiary Channel (with linked pot-holes) -- view towards the sea.  Note the foxy-red cemented sediments on both flanks.


One of the larger meltwater channels at Ceibwr.  The channel is on the right.  To left of centre is the ridge which separates the channel from the larger Ceibwr Bay channel.  Note the foxy red cemented sediments on the tip of the spur.  The inner end of the subsidiary channel is seen at the right edge of the photo.  In the foreground we see the bedrock floor of the channel.  Photo: Ben Ashton.


Yesterday I was over at Ceibwr, near Moylgrove on the N Pembs coast, during a pleasant walk along the clifftop.  I was struck once again by the rather interesting landforms and sediments there.  There are two big meltwater channels separated by an elongated ridge.  One of the channels is now occupied by an arm of the sea (Ceibwr Bay) and the other is dry and occupied by the roadway and car parking area.  This dry channel is fascinating, because it contains a smaller channel which is cut into its floor at the seawards end -- as seen above.  Really this small channel is a series of connected pot-holes, excavated out at a time of very turbulent meltwater flow, with large erratic boulders rolling about in enclosed hollows and excavating out very soft Ordovician shales.  Similar boulders can be seen in the foreground in the photo above.

It's tempting to think that the main channels here are of Anglian age and that they have been modified during the Devensian at a time of more limited meltwater flow.  But that would be too simple.  There are solidly cemented tills, frost-shattered periglacial accumulations and fluvioglacial deposits plastered on the inside of the "newer" small channel, and then fresh till sitting on top of these red-stained cemented deposits.  The fresh till has to be of Devensian age.  So how old are the cemented deposits?  Might they date from the Anglian glaciation?  If they do, that means the small channel might also date from the Anglian, and it might be even older.

Solidly-cemented deposits are common in the Moylgrove-Ceibwr area, maybe because groundwater here is very rich in iron and manganese.  So the reddish and black cement is made essentially of iron oxide and manganese oxides.  How long does it take for a deposit to be turned into concrete?

I'm increasingly convinced that these cemented, stained and rotten deposits (for example at Llangolman and Ceibwr) are very old, but they do need to be dated through the use of one of the modern techniques.  Must work on that........

The sediments at the head of the subsidiary channel.  Foxy-red stained and cemented till and other materials below, and grey uncemented fresh Devensian till above.  The boulders at bottom left are residuals left behind when finer sediments are washed away during extreme storm wave conditions and by runoff during periods of heavy rain.


Stained and cemented sediments at the roadside, on the hillside above the subsidiary channel.  Broken Ordovician shales below.


The crust of cemented till resting on bedrock at the Witches Cauldron, near Ceibwr.  Here the cement is so hard that it has resisted wave attack while much of the softer black shale bedrock beneath it has been eroded away. There's a lot of manganese oxides here, so in places the sediments are stained black rather than foxy red.

There is a lot of discussion of the channels and the cemented sediments in this paper by Glasser et al (2004):

Glasser, N. F., Etienne, J. L., Hambrey, M. J., Davies, J. R., Waters, R. A. & Wilby, P. R. 2004 (August): Gla- cial meltwater erosion and sedimentation as evidence for multiple glaciations in west Wales. Boreas, Vol. 33, pp. 224–237. Oslo. ISSN 0300-9483.

I don't agree with all that the authors say -- they don't sufficiently differentiate the uncemented and cemented deposits, and they refer simply to a "pre-late Devensian" episode of sedimentation and cementation.   If I understand them correctly, they seem to think that the cemented materials are mostly fluvial in origin, and relate to a period of very ancient fluvial valley erosion and sedimentation.  I think the cemented deposits are much more varied than that, with ancient till included.

(Note:  thanks to Myris for correcting me!  I have changed the text to refer to manganese oxides....)

Wednesday, 14 October 2015

Sarsen locomotion


One of my pics from the other day -- showing the glass-fibre sarsen stone on its cradle and rollers, just outside the new Visitor Centre.  No doubt these very large stones were moved from assorted locations (either near or far away) to their present positions, and we have reported often on this blog the latest experimental archaeology work in this field.  What interests me more than the rollers, cradles and sledges is the nature of the rope.  The ropes used to hold the stone in position here are very magnificent -- and very modern and shiny.  But what would ropes have been made of in the Neolithic?  Nettles?  Brambles?  And how strong would they have been?  And how long would they have taken to make?  And how long might they have been in order for very large groups of men to haul extremely large stones across country?

Monday, 12 October 2015

The burning of the books?


After the frustration of watching Wales trying to score a try against the Aussies at Twickenham, we travelled yesterday from Sevenoaks to Nunney, and the nice lady who lives inside our Tom Tom decided that we should travel past Stonehenge.  We didn't have much time, but popped into the new Visitor Centre and took a look at the gift shop and some of the new exhibition items.  We didn't bump into Chris, but maybe that's not surprising since there were thousands of others there at the time......

Anyway, we checked on the availabilty of "The Bluestone Enigma" and were not really surprised to find that it was nowhere to be seen.  We asked the staff about it, and were told that the decision had been made some time ago by EH to discontinue stocking it, in spite of the fact that it had been selling well.  They hadn't informed me of that fact.

I'm not sure whether this signals a burning of the books, or a disinclination to stock anything perceived to be uncomfortable or subversive, or even a decision to cut down on titles more than 5 years old, or even an attempt to take out lots of books so as to make more room for "popular" merchandise.  I'll be generous and assume that the latter is the most likely scenario.  The book section seems to me to have been dramatically reduced in size.  There are lots of other titles I expected to see there -- but could not see a trace of.

Anyway, I'll try and find out what the politics of this might be, and will report back!


Friday, 9 October 2015

Rhosyfelin Mill?


"Rhosyfelin" means "the moor by the mill" or some such thing, and I have always wondered where the mill was or is.  I think we found it a couple of weeks ago, a few hundred yards up the valley, lost in the trees and somewhat ruinous.  To get there, you just follow the public footpath from the archaeological dig site and the ford.

This is far more worthy of archaeological investigation than the "Neolithic Quarry" since it has some quite interesting features which appear to be man-made.  In the winter it will be far easier to explore, when the vegetation has died down a bit.  But there is a sort of walled depression in front of it, which brings to mind the old fulling mill at Pandy, in the Gwaun valley.  ("Pandy" means fulling mill.)

So my working hypothesis is that this is a fulling mill, and not a woollen mill or a corn mill.   I wonder if the National Geographic will sponsor a full-scale research project?  Hmm -- I suspect not.  That worthy journal is probably not that interested in old mills which had stinking ponds full of urine in front of them........




Monday, 5 October 2015

Red sarsens


On the matter of red sarsens, Pete Glastonbury has kindly given permission for me to use this interesting pic -- of red sarsens in a cottage wall. What strikes me is the distinctly foxy red colour -- typical of the iron oxide staining which can occur on rock surfaces when they are underground.

What intrigues me rather more is the pinky colour that sometimes appears on rocks -- presumably that must also be due to oxidation processes, involving different mineral combinations?

Sunday, 4 October 2015

Reddish erratic in Savernake Forest?



Out of the blue, I have received a letter from a gentlemen who once did some work in Savernake Forest, which lies SE of Marlborough.  He was asked by a well-known geomorphologist to investigate and take photos of an apparent erratic boulder with dimensions c 18" x 18' x 12" which lay in the depths of the wood.  He recalls that it was sub-rounded in shape, and it had a reddish colour -- in other words, it was very distinct from the chalk bedrock in that area.    A reddish bluestone?

The grid ref is approx 423166.  The location is more than 25 km to the NE of Stonehenge.  The gentleman concerned is trying to find his photos taken at the time.  I will also try to discover more details......

Has anybody else got any knowledge of possible glacial erratics in that area?  Or has anybody else come across any records that might be of interest?