Wales Devensian Map revised

This is a high definition map -- click to enlarge...

This is a recent revision of the Wales glaciation map, from many sources.  The valley glaciers are shown in blue -- at the maxima of the glaciations these would of course have been submerged or incorporated into the ice of the Welsh ice cap -- although there would have been some streaming within individual troughs at various times.  The arrows are reasonably good representations of ice movement directions, both for Welsh Ice and for Irish Sea ice.  That having been said, I am still working on the story for the N Pembs coast, and as indicated on earlier posts, I think the ice directions need revision here.

 This is an attempt by Patton et al (2012) to portray the thickness, area and volume of the Welsh Ice Cap during the Devensian.  The "peak" of the glaciation is assumed to be around 23,000 years ago, but because of the complexities of glacier dynamics there is often a lag, and it seems that the ice on the south Wales coasts might have reached its maximum extent around 20,000 BP.  After that, as we can see from the graph, there was a very rapid phase of deglaciation, with huge volumes of ice melting away over the course of a few centuries.

MPP on the glacial transport theory

On p 268 of his book Prof Marker Pearson gets on to the glacial transport hypothesis.  (I'm happy to accept that it still is a hypothesis, in the absence of any killer facts....)

He starts off by referring to Judd and Kellaway and their ideas about glaciation -- although he can't resist throwing in Kellaway's rather extreme Pliocene glaciation idea, just to show what a nutter he is.  (James Scourse did exactly the same thing in the big Stonehenge book a few years ago;  it's known in the trade as the Aunt Sally syndrome.... you put up some rubbish just in order to knock it down.)  Anyway, MPP then refers to the evidence for glaciation,  somewhat selectively, and appears convinced by Chris Green's conclusion that since he didn't find any "glacially derived material" in certain of the river terraces on Salisbury Plain, the chalklands of Wiltshire cannot ever have been glaciated.  Things are not quite so simple, as I have pointed out many times.

He refers to Chris Clark and myself as glaciologists, which we are not.  He then cites Chris as saying that there is a "distinct lack of any evidence" that the ice advanced into south-west England at all.  That, to put it mildly, is absolute nonsense -- as I have said many times before.  Does MPP not do any reading for himself on glaciology or glacial geomorphology?  There is ABUNDANT evidence that the ice of the Irish Sea Glacier crossed the Bristol Channel -- he only needs to read my book called "The Bluestone Enigma" to see some of that evidence, accompanied by references and photographs.  There are plenty of other tomes too.  He then throws in the red herring of the last glaciation, claiming rather disingenuously that glacier ice did not extend beyond Wales around 27,000 years ago.  The glacial maximum was well after that, and the Devensian ice really did extend well beyond Wales, having been shown by James Scourse and others to have reached the Scilly Isles and well into the Bristol Channel.  In any case, the real issue is not how the Devensian Irish Sea Ice Sheet behaved, but how the Anglian ice sheet behaved, maybe 450,000 years ago.  And when we look at THAT ice sheet, the glacial geomorphology community is in agreement that the ice extended AT LEAST as far east as Bathampton Down, the Mendips and the Somerset Levels.  MPP should at least have the good grace to accept that a mottley collection of chips, stones, boulders and pillars (of all shapes and sizes) made of around 30 different rock types, all from the west or north-west, just MIGHT constitute evidence of glaciation on Salisbury Plain..........

By the way, on p 285 of the book MPP publishes a nonsense glacial map -- which seems to be based on one of the maps in a paper by Chris Clark and others.  It purports to represent the BIIS about 27,000 years ago, whereas it is labelled in the original paper as having a date of 23,000 years ago.  The glacial maximum was later still, around 20,000 years ago.  Furthermore, the strange glacial lobe projecting into the Celtic Sea is deemed by glaciologists as being inherently unlikely, given what we know of the laws of ice physics.  In this citation, as in others, a bit more care and a bit less haste might have been appropriate........  and in particular, if he wanted to use a map, MPP should have used a map showing ANGLIAN ice limits as far as we know them, more or less on the lines of the maps at the head of this post.

Tunnel vision and flights of fancy

Over Christmas I had a chance to look at the MPP tome on Stonehenge, having previously dipped into it and found it -- shall we say? -- less than convincing scientifically.  I have previously voiced my concerns about the MPP conclusions on Bluestonehenge and on the idea that Stonehenge is where it is because that is where a few "periglacial stripes" happened to coincide, more or less, with the alignment of the rising sun on the summer solstice.  And I'm on the record as saying, many times, that MPP and other senior archaeologists do their subject more harm than good by breezing off into the realms of fantasy at the slightest opportunity, whatever doubts there might be about the evidence on the ground.  Maybe they don't have doubts, these guys?  Maybe they have such confidence in their own abilities that they just KNOW when they have enough "evidence" to produce a working hypothesis and to turn it instantly into a ruling hypothesis.......

Anyway, away from tunnel vision and on to the chapter about the origins of the Bluestones.  It starts rather bizarrely with a consideration of the bluestone fragments found by Stone and others to the NW of Stonehenge, at Fargo Plantation.  The fragments found thus far are of rhyolite and sandstone -- which does not of course mean that there is no dolerite in the area.  Absence of evidence is not evidence of absence, especially since the digs in that area have been of very limited extent.  Anyway, MPP immediately whizzes off on the idea that there might have been a stone circle somewhere near Fargo Plantation.  How he makes the great leap from a few bluestone chips to a "lost stone circle" is a mystery to me.  (He did it at Bluestonehenge as well, creating in his own mind a bluestone circle even though there are NO bluestone traces of any type -- so far -- in that locality.)  Might it not be rather more reasonable to assume that there might just have been some bluestone erratics lying about in that area at the end of the Cursus, which early inhabitants broke up because they were in the way, or used for making implements?

On to the Preseli Hills.  MPP gives a nice summary of the dozen or more distinctive rock types represented in the Stonehenge assemblage, and also cites the geological work of Rob Ixer, Richard Bevins and Peter Turner.  Anyway, having accepted that there are lots of different rock types, the author moves on to an explantion of how they were moved -- immediately assuming that this was down to human agency.  He argues, in familiar style, that big stones are moved for assorted ritual reasons in many communities throughout the world -- and therefore assumes that they did it here as well.  This is the old "They did it there, therefore they probably did it here too" argument of which we get sick and tired on this blog.......

One interesting thing is that MPP claims that archaeologists are now "fairly sceptical" about the great ocean-going voyages beloved of Atkinson, Darvill and Wainwright.  I don't see much sign of that scepticism in the literature, but let that pass.  So the stones were moved overland, not just 80 of them, but maybe hundreds of them -- many of which were lost or broken in transit.

The enterprise, according to MPP, might have involved relays of stone movers, with around 50 people assigned to each stone -- and with a task force of 4,000 people working at any one time.  He claims that there might have been high status attached to involvement in the "bluestone expeditions" -- rather as high status was attached to the carrying of the Olympic Flame in the run-up to the 2012 Olympics.  So people might even have been competing with one another to take part -- rather than looking on involvement as a penalty or as some sort of penal servitude undertaken by slaves.  Really warming to his task, MPP then suggests that as many as 100,000 people might have been involved -- ie the whole population of Southern Britain.  Come now, MPP, calm down...........

I must go and make some soup.  To be continued.....

Rhosyfelin Pleistocene Stratigraphy

The 2012 excavation, seen from near the higher part of the rock face --- the top of the sedimentary sequence is seen in the steps cut into the slope on the left.

I was looking at my photos from this summer, and happened on these.  They reminded me what an interesting stratigraphy MPP and his team have discovered at Rhosyfelin.  There is a real story in them thar sediments........  and by the way, I still see nothing at all that would make me think any of this is down to human agency.

 Stained and semi-rounded erratic (?) at the base of the 2012 excavation.  I suspect that this is at the top of a layer of till.

Blocks and rubble with some rounding of edges, at the base of the scree / rubble layer.

Coarse head with pseudo-stratification, resting on scree and rubble.  At the junction there is a darker layer which might be rich in organic material.  Is this rich enough to provide a sample for radiocarbon dating?

 The lower part of the sedimentary sequence, exposed in the lower part of the 2012 excavation pit.  This is not far from the pit deemed to have held a standing stone.  This is a very interesting stratigraphy, with at least six layers representing changing environmental conditions.  At the bottom is a reddish stained clay-rich layer that might be till.  Above that is a fine-grained layer containing streaks of darker (organic?) material.  Is this a deposit dating from Lake Brynberian?  Then there is a thin layer of broken head.  Above that is another layer of finer sediments incorporating broken rock debris, capped by a thin head layer and then another darker-coloured layer with finer sediment.  Probably the two holes mark the positions from which samples have been taken for C14 dating.

The Stonehenge Solutional Rills

The "periglacial stripes" -- viewed across the slope.  Note that the channels are more than a foot deep.

 The so-called "periglacial stripes" -- acknowledgement to Aerial-cam.  Note that these stripes are aligned -- more or less -- on the axis of the Avenue and on a line drawn through the Heelstone and the Slaughter Stone to the centre of the stone monument.  Significant?  Probably not.....

 The "micro morphology" of the Stonehenge site.  The contours are just 25 cm apart, showing how Stonehenge is located on a slight spur.  the Slaughter Stone and the Heelstone are clearly visible, as are the ridges which define the Avenue.  The open pit shown in the B/W photo above is located very close to the junction between the north-point line and the cross piece.

I have been giving more thought to the famous "periglacial stripes" at Stonehenge, the alignment of which is deemed by Prof MPP to be the reason why Stonehenge was built where it was.  I have argued before that this is fanciful in the extreme, since there are -- in all probability -- stripes like these all over the Stonehenge landscape. Most of them are of course NOT aligned to the Avenue or the midsummer sunrise solstice, but are aligned perpendicular to the contours, wherever those may be.

See my previous post"

http://brian-mountainman.blogspot.co.uk/2012/10/are-there-more-periglacial-stripes-at.html

MPP keeps on referring to the stripes as "periglacial" -- presumably on the basis of what he has been told by Mike Allen and Charly French.  On p 243 of his new book he refers to freeze-thaw conditions and to sediments created from the "grinding of chalk by ice into a clay flour."  Having gone along with this to a certain extent, and having pondered on this blog about periglacial stripes and how they are formed in current areas of permafrost,  I have to admit to being worried about the precise processes that might have operated here, on gradients that are very gentle indeed.  And my brow has been furrowed even more by trying to work out  how and why this ground-up "clay flour" might have been formed during the Pleistocene -- and what role it might have played in landscape modification.  Are we talking about mechanical processes, or chemical ones?

At any rate, I have now come to the view that these ridges and channels are not periglacial at all, but are simply solutional rills developed over many millennia by the straightforward process of rainwater runoff downslope being concentrated into rills or channels which are then deepened over time.  In geomorphology these are referred to as "rillenkarren" where they occur in limestone terrain -- for example around Malham in the Pennines or on the Burren in Ireland.  Have a look at the photos below:

 Rillenkarren on the surface of Carboniferous Limestone near Malham Tarn.  Note the sinuous shapes of both the rills and the ridges.

Rillenkarren on the floor of the Carlsberg Cavern in New Mexico.  Here the channels are formed by solution processes downslope from the points where aggressive groundwater drips from the roof of the cave.

Rillenkarren on the surface of chalk exposed in France.  Note that there are very close similarities between these features and those seen around Stonehenge.

In Carboniferous Limestone areas rillenkarren tend not to be very long because limestone is heavily jointed or fractured -- and where these weaknesses intersect with solutional rills running downslope the flowing water is diverted sideways, giving rise eventually to a highly complicated terrain of clints and grikes, sometimes with the tortuous channels cut to a depth of several metres.

On a gently sloping chalk surface there are fewer joints and other structural features -- the chalk body is often "massive" and coherent.  This means that these gently meandering channels may extend for hundreds of metres downslope, unto the gradient is so low that the rills cannot be maintained or deepened any longer, with the water simply ponding in hollows or sinking into the ground.

Much as I enjoy writing about periglacial processes, I really cannot see any role for them in the formation of these gullies -- and I suggest that the process of deepening the Stonehenge solutional rills has gone on for many hundreds of thousands of years -- sometimes faster, sometimes more slowly, as climatic conditions and water tables have changed.

Charly or Mike, if you are reading this, I would appreciate some information on your thinking -- why have periglacial processes been invoked here, when there really is no need for them?

Rhosyfelin Jan 2012

This is a blow-up of part of Phil's picture, taken last winter after the first season's excavations near the lower part of the rock face and before the much larger 2012 excavations (which removed more of the vegetation and soil from higher up in the gully). 

One thing that shows up here is the rough fan-shape of the sediments coming down onto the main valley floor from the gully.  There has been a lot of sediment movement here -- and this is of course confirmed when we look at the thickness of the material which has accumulated over the litter of scree and broken blocks.

More pics from Rhosyfelin

Photo showing the rocky ridge that projects out into the valley.  This is the flood plain -- the river is on the left.  The main valley curves away to the left of the rocky outcrops, and to the right of it (where the excavations have been done) there is a smaller gully running up the valley slope.

Photo taken from high on the valley side, looking down at the rocky ridge and the Brynberian river valley.  The main valley floor is on the right.  The road runs down towards the main valley (and the ford) via the deep gulley where the excavation pits were dug.

Thanks to Phil for these two excellent photos taken at Rhosyfelin -- they show the landscape features very well.  The focus of attention is the gully in the centre of the lower photo, to the left of the rocky ridge.  Once we know exactly what processes have operated in this gully, and what the time sequence may have been, we have the Rhosyfelin story unravelled........

These are very high definition photos -- click to enlarge and see the details.

Happy Christmas everybody!

None of the things that happen on this blog actually matter very much -- but there are things in life that DO matter to everybody.  So in that spirit, may we wish you all a joyful Christmas and peaceful New Year -- with whatever prosperity may be appropriate in these austere times......

Those sacred springs..........

As followers of this blog will know, I have often had cause to investigate the claims by Profs Darvill and Wainwright that the eastern end of Preseli (especially the area around Carn Meini) was full of sacred springs, even back in the Neolithic, and that this gave rise to the idea that the rock around these springs was also special or magical -- thereby giving a incentive for the locals to quarry it from Carn Meini and cart 80 or so bluestones all the way to Stonehenge.

Type in "sacred springs" into the search box on this blog and you'll see some of my previous posts.  One of them is here:
http://brian-mountainman.blogspot.co.uk/2011/03/carn-meini-manufacturing-of-magic.html

A few days ago a lady called in for a chat about her research.  She is acting as a field researcher for a new book on the sacred springs of West Wales, mapping them very carefully, finding the locations of "lost springs" and trying to work out why certain saint's names were given to them, in addition to asking whether some of them might have been pre-Christian.  I was able to help her with some of the locations and names.  We got talking about various parts of Pembrokeshire, and she confirmed that in eastern Preseli there is not a single sacred spring in the area referred to by the two professors.  To the best of my knowledge there are only two or three that actually have names, and they are not saint's names.  So the idea that the area was "specially revered" is in her view sheer invention, and this matches what both Robin Heath and I have been saying.

It's funny how senior archaeologists keep on inventing the evidence which they need to support their preposterous fantasies............  maybe they expect people to believe them, just because they have the word "Professor" in front of their names?

The Loveston Erratic

Many thanks to Adrian for this -- it can be found on his blog here:

http://pdboyinsuffolk.blogspot.co.uk/

Adrian mentions that it is from the north, and that it is locally called "The Loving Stone" which is natural enough, given its location at Loveston Farm.  It certainly looks igneous -- but I don't recall any mention of it in the Geol Survey reports.

Much appreciate those grid references, Adrian!  I'll try to check them out one day.  Nice to see some original research being published here.......

Bedd Morris standing stone back in place

Good news for all megalith maniacs -- the Bedd Morris standing stone in Pembs (which was knocked over by a reversing car some months back) is now back in position again.  

Our friend Prof GW took part in a little dig at the site, while the going was good, which is excellent.  It doesn't look as if they found anything interesting -- not even the bones of the dastardly robber who is supposed to have been buried there, with his little dog.

So there we are then.
 
http://www.bbc.co.uk/news/uk-wales-south-west-wales-20669802

Castell Mawr, Rome and Mecca

 Was Castell Mawr once the centre of the western world?  It's starting to look that way, at least to some people with rather vivid imaginations........

A little bird tells me that in the latest issue of "Current Archaeology" there is a report by Chris Catling called "Stonehenge Blues" -- summarising MPP's unofficial inaugural lecture (October 29th 2012) as newly appointed Professor of British Later Prehistory at the UCL Institute of Archaeology.

Apparently MPP is saying that Stonehenge was built to celebrate 'the merging of two or more polities'.   Nothing new there -- he has been saying that for some time, without of course having any evidence to support the idea.  Catling says a scenario is now being created in advance of OSL dating of soil from Castell Mawr, designed to determine how long ago soil minerals were last exposed to daylight.  (I'm not sure how those dates, whatever they may be, will contribute to this political debate, but let that pass......)  The scenario says that the Stonehenge bluestones were originally quarried in west Wales, and erected as a stone circle at Castell Mawr.  They were later moved to Salisbury Plain, says MPP, and used to create a new monument at the centre of the newly unified Neolithic world.

Apparently, when asked by a member of the audience whether the merger was voluntary or enforced, MPP said 'who knows?' - but then added rich spice to the theory by saying that if it was a forced merger, one shouldn't make assumptions about who had been conquered by whom.  So the possibility is being thrown out here that Neolithic people from Wales brought their bluestones  (and perhaps their cremated ancestors) to Salisbury Plain to mark their victory over the people of the east.........

All very jolly.  The only problem is that there is no evidence in support of any of it, and as far as I know not even any evidence of a stone circle at Castell Mawr.  They looked for standing stone sockets this year, but according to two of the diggers to whom I talked, they didn't find any.  Well, what the hell -- why let the lack of evidence get in the way of a jolly good story?  Haven't we heard that before..........?

More on the Nevern Estuary erratics

Chips off one of the erratic boulders in the Nevern Estuary.  This is a high-definition photo, so you should be able to examine the rock quite carefully.....

One of the larger Nevern Estuary felsite (?) erratics, sitting on an exposure of till.

Further to my earlier post about the strange erratics in the Nevern Estuary opposite  Newport,  I have been looking again at the old map (made about 1940) by JC Griffiths, which shows his proposed ice movement directions across NE Pembrokeshire, which coincide broadly with those which I recently proposed.  My earlier post is here:

http://brian-mountainman.blogspot.co.uk/2012/02/mystery-erratics-on-newport-beach.html

In other words, Griffiths thought that the last ice might have come from the NNE or NE (in other words, it was Welsh Ice) rather than from the N or NNW (in which case it would have been Irish Sea Ice.

Griffiths noted two main erratic types found in the area -- "Cader and Arans felsite" and "Green Harlech Grit."  There is certainly some greenish grit in the erratic pebbles in the till exposed in the estuary -- and I am increasingly convinced that the larger erratics on the foreshore are similat to those found elsewhere in the area by Griffiths.  The trouble is that "felsite" is a very broad term, used widely in the good old days but no longer accurate enough to tell us what we want to know about the texture and origins of the rock we may be looking at.

But I am mindful of Rob's warnings that nothing other than proper petrography will do here -- and mindful that one must not go on visual identifications alone..........

Developments awaited....

Glacier art

This is a polar glacier in North Greenland, taken at the time when the spring melt is setting in -- notice the meltwater puddles on the sea ice in the fjord.  Click to enlarge.

Another subglacial tunnel with a wonderfully scalloped roof.  Not sure where this photo was taken.  Click to enlarge.

OK. This is a bit of fun.  Interesting iceberg. No further comment needed.  I hesitate to suggest this, but click to enlarge......

Devensian Welsh Ice in North Pembrokeshire

Had a Eureka moment the other day, when I was sitting on top of Carningli, drinking my cocoa and gazing northwards, taking in the fantastic view of Cardigan Bay -- I could see Aberystwyth, Plynlimon, Cader Idris, Snowdonia, Llyn and Bardsey.  Most impressive......

Anyway, I realized that the experts have got it all wrong, and that during the Devensian NE Pembrokeshire was not so much affected by Irish Sea Ice as Welsh Ice.  The most up-to-date publication to portray the position of the Devensian ice edge is that of Etienne et al in 2006.  Their map is shown above.  We are talking about an ice edge position here at around 20,000 years ago.

We will forgive the authors of the article for showing the ice edge as a smooth line -- they were generalising.  But there is no way that the actual ice edge will ever have looked like this. it will have been much more closely adapted to the lie of the land, with fingers into the lowlands and embayments where the higher land acted to divert ice to right or left.  Another summary of this ice edge position is here, showing the local topography rather more clearly:

That's one of my maps, made while I was pondering on the southernmost extent of the Irish Sea Ice and coming to the conclusion that there are so many ice-smoothed slabs and perched blocks on Carningli and Dinas Mountain that the ice must have flowed across the whole of that upland area and reached the spectacular meltwater channel (a very old one) called Cwm Gwaun.  You will also notice that the lime on the map by Etienne et al is about a mile further south than mine.  You will also notice that on both maps there is an assumption that the ice has come in from the N or NNW.

But I have been very worried by the morainic accumulations at Cilgwyn and Waun Mawn, and have been wondering how Irish Sea ice managed to bend around the eastern flanks of Carningli and Carnedd Meibion Owen in order to leave these deposits where they are, when it melted.  Ice can do extraordinary things, but if it can, it prefers to do things the simple way.

So I have got it wrong.  The ice has actually crossed NE Pembs from the N or NNE, meaning that it was propelled by the Welsh Ice Cap rather than by the Irish Sea Ice Sheet.  This is my new scenario:

Suggestions for ice movement directions at the peak of the Devensian Glacial episode in NE Pembrokeshire.  On the map, the blue arrows represent Welsh ice and the orange arrows represent ice from the Irish Sea Glacier.

There is a great deal of evidence in support of this scenario:

1.  Strong evidence of ice streaming on the ice-smoothed slabs on the NE-facing edge of the Carningli upland, overlooking Newport.  This evidence is best explained by ice coming from the NE.
2.  The morainic accumulations at Cilgwyn and Waun Mawn are best explained by ice pressing in across the Brynberian lowlands from the NE.
3.  The evidence of ice smoothing and perched blocks at Carnedd Meibion Owen is best expolained by ice movement from the NE.
4.  The enigmatic accumulations of fluvioglacial sands and gravels in the Monington area (near Moylgrove) are best explained as accumulations on a wasting ice contact edge, between Irish Sea ice to the west and Welsh ice to the east.

Note the "excrescences" or rough areas on this image of the Monington area, just to the NW of the centre of the image and also to the SW of the centre.  These are the accumulations of sands and gravels, exploited today in two gravel pits.  Note that elsewhere the land surface appears smooth. (Thanks to Henry Patton)

5.  Till deposits exposed on the beach at Newport since recent storms have considerable quantities of red, purple and pink sandstone clasts in them -- suggesting strongly a North Wales origin.  There are also strange metamorphic rocks in the Nevern estuary on the foreshore (samples sent to Rob Ixer) which I strongly suspect as having a N Wales origin.

6.  There are faint traces of marginal channels on the north face of Preseli which suggest an ice gradient sloping westwards.  Again this suggests ice coming from the NE.

This does not alter the fact that there might have been a later slight advance of Irish Sea Ice across the Pembrokeshire coast in this area  since there is heavy clay till at Gwbert, Parrog and other places which appears to be a very typical Irish Sea till.  There are also striae on the coastal rocks at Gwbert and Parrog which show that ice has come across the coast from the N and NNW.

This is just a start.  I have to give this much more thought.......

The relevance of all this as far as archaeology is concerned?  Quite considerable, since both Rhosyfelin and Carn Meini  (and Preseli generally) are in the frame here.  If we can tidy up on the details of chronology and the precise sequence of geomorphological episodes in this region, that will help us greatly in determining what happened at these sites which certain people are pleased to call "quarries."  By the way, Glacial Lake Brynberian is still in the frame here, as seen in the map at the top of the page.  (It's the lake shown as overflowing via the Rhosddu Channel at 220m asl.  I'm not convinced about that overflow, and that needs to be looked at..........)

New Stonehenge chronology not all that new....

 I have had a quick look through the new ANTIQUITY article about the revised radiocarbon chronology for Stonehenge.  First of all, credit where credit is due -- the authors have had a pretty noble crack at sorting out a horizontal and vertical nightmare scenario at Stonehenge, trying to fit radiocarbon dates into some sort of context that makes sense.  And the chronology that they come up with does seem tom me to be sensible, on the whole.  However (there always is a "however") the evidence does not always match up with the assumptions of conclusions reached, and I cannot help thinking that there is a degree of "fitting evidence into assumptions" which does not make for good science.  But then, fantasy always was a part of archaeology, and probably always will be......

What is a bit more worrying is the apparent mismatch between what the article shows and what has been put out in the press release by the learned professors.

1.  The idea that  the bluestones were brought to the site late -- ie after the building of the sarsen trilithons -- is not supported by either the evidence on the ground or by anything in this article.

2.  The Darvill idea that the bluestones were the preserve of sheep and cow farming Beaker People whereas the sarsens were the preserve of earlier pig farming Neolithic tribes is entirely unsupported by any evidence, either in this paper or anywhere else, so far as I can see.

3.  There is nothing here to support the Darvill idea that the sarsens came from nearby "quarries" around 2,600 BC.

4.  There is nothing here in support of the idea that the bluestones "were probably imported from Wales."

5.   Are they now suggesting that there were far more than 80 bluestones on site -- ie an original shipment of c 80 and another batch of 25 from Bluestonehenge?  That's over 100 bluestones........... this idea is fantastical in the extreme, and there is nothing to support it.

6.  I don't understand what Darvill is on about re the late arrival of the bluestones, since in the text of the article (he is after all one of the authors) there are quite frequent references to bluestones in the earlier Aubrey Holes and also at Bluestonehenge.  (Regarding Bluestonehenge, there is no evidence that there ever were bluestones there, but let that pass.....)

7.  I don't see any evidence in this article for any gap between the erection of the sarsen trilithons and the first setting of bluestones.  But I do understand that from a purely practical standpoint, if you are putting up a stone monument you would put up the big stones in the centre first, while there were no smaller stones getting in the way.  Once you have got those up, you put the smaller orthostats into the ground around the trilithons.

The radiocarbon chronology doesn't seem to be all that different from chronologies published before, except for the thesis that the big sarsens went into ground earlier than previously supposed.  Nothing new and affecting the numbers or origins of bluestones is published here -- and certainly there is nothing here to dent my long-standing beliefs that the bluestones are glacial erratics, that they were in this area long before Stonehenge was ever thought of, that Stonehenge was never finished, and that there never were enough stones available to fulfill the ambitions of the builders.

-------------------------------------
Please read the complete article.  There is a great deal of interesting info about phases and dating results, and about sarsen settings and earthworks etc.  Leaving those to one side for the moment, let's concentrate on the bluestones.  Right then.  Very selective extracts:

"........within the enclosure, a circle of Aubrey holes, which may have held stones
and/or posts; four Station stones; two roughly concentric rings of pits known as the Y and
Z holes (barely visible on the surface); the sarsen circle; the double bluestone circle set in the
Q and R holes (not visible on the surface); the outer bluestone circle; the trilithon horseshoe;
the bluestone oval now visible as a bluestone horseshoe; a central bluestone circle (not visible on
the surface); and, lying in the centre, the ‘Altar’ stone. ‘Bluestone’ is an archaeological term
popularised in the early twentieth century to refer to what had previously been called the
‘foreign’ stones (i.e. any stones that are not locally derived sarsens). The portmanteau term
‘bluestone’ thus embraces a range of dolerites (including the well-known spotted dolerites),
tuffs, rhyolites and sandstones. Except for the sandstones (Ixer & Turner 2006), the other
bluestones derive from the Preseli hills of north Pembrokeshire (Thomas 1923; Thorpe
et al. 1991; Darvill et al. 2009; Ixer & Bevins 2010)."

[[My comments:  Cleal et al said bluestones were brought from Wales at end of Phase 2 -- ie about 2600 BC?  Double bluestone circle then built (Phase 3i) using Q and R holes.  Sarsens came later, and used in Phase 3ii
 From an examination of the intersecting sockets etc in the 2008 dig, "other possible relationships cited in support of the double bluestone circle pre-dating the sarsen circle and trilithon horseshoe can also be disputed."
Pitts and MPP think (like Hawley) that the Aubrey Holes once held pillars -- presumably bluestones.  The authors seem to be supporting that.....]]

Proposed new chronology:  

Stage 1 (3000-2620 BC)

"Digging of 56 Aubrey holes around the inner edge of bank, possibly to hold bluestones and/or posts."
"Stones were probably present at the site from its inception. Re-excavation in 2008 of
Aubrey hole 7 suggested that this hole may have held a standing stone (Pitts 2008a),
supporting Hawley’s original proposal (1921: 30–31). The stone that stood in stonehole 97
outside the north-east entrance, together with the stones that occupied stoneholes B and C,
all presumably sarsens, may also tentatively be assigned to Stage 1. The stone in stonehole
97 sat within a filled linear depression which might have been a solution hollow formed
beneath a recumbent sarsen (Pitts 1982, 2008b: 15)."
"Some of the Aubrey holes had cremations inserted into their upper fills perhaps after the removal of stones or posts. Culturally, these activities are associated with the users of Grooved Ware pottery. The ring of about 25 monoliths popularly known as ‘Bluestonehenge’ beside the River Avon at
West Amesbury was probably constructed during this stage although a robust date for its
construction has not yet been obtained (Parker Pearson et al. 2010)."

Stage 2 (2620 - 2480 BC)

At the outset:  "Trilithon horseshoe comprising five sarsen trilithons set up in the centre of
the site with SW–NE solstitial axis (midwinter sunset/midsummer
sunrise). Double bluestone circle of between 50 and 80 bluestones set up
outside the trilithon horseshoe with a shared SW–NE axis. Sarsen circle
comprising 30 shaped uprights linked by 30 lintels built outside the
double bluestone circle. Altar stone perhaps placed within the trilithon
horseshoe."
"Outside the trilithon horseshoe, the double bluestone circle was created, marked by the Q
and R holes. The axis of this arrangement is the same as the trilithon horseshoe, with an
entrance passage on the north-east side (Cleal et al. 1995: figs. 81 and 82). Around the east
side of the double bluestone circle, the bluestones were set within dumbbell-shaped sockets
as radially set, paired stones. Q hole 13 was examined in 2008 (Darvill &Wainwright 2009:
12) but found to have been heavily disturbed by later cuts. On the south and west sides,
only a single line of stoneholes was detected by Atkinson, leading him to suggest that the
structure was perhaps never completed (1979: 204). It is possible that some of the Q and R
holes on these sides were eroded away by later activities (Darvill’s preference). Alternatively,
there was never more than a single circuit in this area (Parker Pearson’s preference).
Some or all of the Q and R holes might once have held the bluestone pillars formerly
standing in the Aubrey holes and moved into the centre of the monument in Stage 2. It is
further assumed that the bluestones used for the double bluestone circle were later reused
in Stage 4 to form the structures known as the bluestone oval and the outer bluestone circle.
This could explain why at least three of the bluestones at Stonehenge are topped with tenon
projections, why two have pairs of mortise holes (and were therefore formerly lintels), and
why two have tongue-and-groove joining. From the positions of the two bluestone lintels in
later arrangements, they may have been used to frame entrances into the double bluestone
circle on the north-east and south sides, echoing the two entrances through the enclosure
ditch. How many of the other bluestones in the double bluestone circle were dressed is not
known. There are no dated samples associated with the construction of the double bluestone
circle, although a sample from the backfill of an unidentified Q hole provides a terminus post
quem for its slighting in Stage 3 of 2465–2220 cal BC (OxA-4901:Marshall et al. 2012: fig.
22), suggesting that it was built in Stage 2."
"The Altar stone, a former standing stone lying prone, is traditionally associated with the trilithon horseshoe because of its position and is therefore tentatively included in the Stage 2 structure though it could date to any point before the collapse of the great trilithon on top of it. The great trilithon collapsed after the building of the Stage 4 bluestone oval (2205–1925 cal BC: Last bluestone horseshoe:Marshall et al. 2012: fig. 22) but before the earliest plans were made of Stonehenge in the seventeenth century AD. Thus the Altar stone could have been laid in its current position at any point between the Neolithic and the early modern era."

Stage 3 (2480 - 2280 BC)

"Bluestones (perhaps from Bluestonehenge) arranged as the central bluestone
circle within the trilithon horseshoe."
"The stone circle at West Amesbury known as Bluestonehenge was
dismantled and a classic henge with bank and internal ditch about 35m in diameter was
constructed there around the area in which the circle had previously stood. It is possible, but
unproven, that the 25 or so pillars (interpreted as bluestones on the basis of their imprints)
were taken to Stonehenge for use in Stage 3. The positioning of an arc of five stoneholes
(WA3285, 3286, 3700, 3702 and 3402) imply a central bluestone circle (Phase 3iii in Cleal
et al. 1995: 206–209, fig. 109), which has the appropriate radius and spacing for a circle
transplanted from Bluestonehenge beside the Avon."
"Culturally, some at least of the changes during Stage 3 may be associated with people
who used Beaker pottery. As well as the distinctive Beaker-style burial in the ditch already
referred to, more than 200 sherds of Beaker pottery have been recorded at the site but only
rarely in stratified contexts."

[[My comments:  NB.  This directly contradicts what Darvill is saying in the press release about the Beaker People being responsible for the bluestone haulage and use.  If Beaker influence is only seen in Stage 3, what about all the activity involving bluestones in Stages 1 and 2?]]

Stage 4 (2280-2020 BC)

"Central bluestone circle and double bluestone circle dismantled and re-built as bluestone oval of c. 25 monoliths inside the trilithon horseshoe and the outer bluestone circle of between 40 and 60 monoliths in the space between the trilithon horseshoe and the sarsen circle.
Major rearrangements of bluestones in Stage 4.  Quote:  "It is assumed that the 80 or so stones used to construct the bluestone oval and the bluestonecircle represent the reuse of bluestones from earlier structures at or near Stonehenge.  Certainly, these two sources would provide about the right number of stones, although the possibility of further material derived directly from West Wales cannot be ruled out.  Only 43 of them survive on the site as stones or stumps. Some pieces of bluestone were
worked on site into tools of various kinds, as indicated by discarded rough-outs. Other
bluestones were broken up much later, during Roman times and perhaps after (Darvill &
Wainwright 2009). Indeed, it seems highly likely that removal of at least seven pillars at the
northern end of the bluestone oval, to create a bluestone horseshoe (Atkinson 1979: 80–82;
Cleal et al. 1995: 231), was actually carried out in the Roman period. Culturally, users of
Beaker pottery were responsible for the activities represented in Stage 4."

Stage 5 (2020 - 1520 BC)  

"Extensive use of Stonehenge with working of some bluestones into artefacts."
"Bluestones and, to a lesser extent, sarsens were being broken up during Stage 5 as clearly shown by the debris associated with a working floor and small structure just outside the earthwork enclosure west of the Heel stone."

This is awaited:

MARSHALL, P., T. DARVILL, M. PARKER PEARSON & G. WAINWRIGHT. 2012.
Stonehenge, Amesbury, Wiltshire: chronological modelling.
English Heritage Research Report 1/2012. Available Not yet) at
http://research.english-heritage.org.uk/report/?15075

New Timeline for Stonehenge

Thanks to Rob for drawing attention to this.  Must peruse the article carefully in ANTIQUITY, to see how much this journalist has got right, and how much of it is wrong.  I notice that Rob is credited with being the researcher who discovered the origin of the bluestones, which is very flattering for him, even if it is not necessarily correct....... but what the hell...

I notice immediately that there is the assumption that the bluestones were imported from Wales at a particular time which the authors think they can date, and that there is absolutely no questioning of the human transport theory.  More on that anon.....

I also notice that they now think the bluestones were carried by the Beaker People --- which makes the "heroic enterprise" a good deal later than earlier estimates.  Expect further posts.

--------------------------
Article: 
Building Stonehenge: A New Timeline Revealed

Tia Ghose, LiveScience Staff Writer
http://www.livescience.com/25157-stonehenge-megaliths-timeline-enigma.html
Date: 30 November 2012 Time: 01:23 PM ET

Ancient people probably assembled the massive sandstone horseshoe at Stonehenge more than 4,600 years ago, while the smaller bluestones were imported from Wales later, a new study suggests.

The conclusion, detailed in the December issue of the journal Antiquity, challenges earlier timelines that proposed the smaller stones were raised first.

"The sequence proposed for the site is really the wrong way around," said study co-author Timothy Darvill, an archaeologist at Bournemouth University in England. "The original idea that it starts small and gets bigger is wrong. It starts big and stays big. The new scheme puts the big stones at the center at the site as the first stage."

The new timeline, which relies on statistical methods to tighten the dates when the stones were put into place, overturns the notion that ancient societies spent hundreds of years building each area of Stonehenge. Instead, a few generations likely built each of the major elements of the site, said Robert Ixer, a researcher who discovered the origin of the bluestones, but who was not involved in the study.
"It's a very timely paper and a very important paper," Ixer said. "A lot of us have got to go back and rethink when the stones arrived."

Mysterious monument

The Wiltshire, England, site of Stonehenge is one of the world's most enduring mysteries. No one knows why prehistoric people built the enigmatic megaliths, although researchers over the years have argued the site was originally a sun calendar, a symbol of unity, or a burial monument.

Though only some of the stones remain, at the center of the site once sat an oval of bluestones, or igneous rocks (those formed from magma) that turn a bluish hue when wet or freshly cut. Surrounding the bluestones are five giant sandstone megaliths called trilithons, or two vertical standing slabs capped by a horizontal stone, arranged in the shape of a horseshoe.

Around the horseshoe, ancient builders erected a circular ring of bluestones. The sandstone boulders, or sarsens, can weigh up to 40 tons (36,287 kilograms), while the much smaller bluestones weigh a mere 4 tons (3,628 kg).

Past researchers believed the bluestone oval and circle were erected earlier than the massive sandstone horseshoe.

But when Darvill and his colleagues began excavations at the site in 2008, they found the previous chronology didn't add up. The team estimated the age of new artifacts from the site, such as an antler-bone pick stuck within the stones. Combining the new information with dating from past excavations, the team created a new timeline for Stonehenge's construction.

Like past researchers, the team believes that ancient people first used the site 5,000 years ago, when they dug a circular ditch and mound, or henge, about 361 feet (110 meters) in diameter.

But the new analysis suggests around 2600 B.C. the Neolithic people built the giant sandstone horseshoe, drawing the stone from nearby quarries. Only then did builders arrange the much smaller bluestones, which were probably imported from Wales. Those bluestones were then rearranged at various positions throughout the site over the next millennium, Darvill said.

"They sort out the local stuff first, and then they bring in the stones from Wales to add to the complexity of the structure," Darvill told LiveScience.

The new dating allows the archaeologists to tie the structure to specific people who lived in the area at the time, Darvill said. The builders of the larger sandstone structures were pig farmers found only in the British Isles. In contrast, the bluestone builders would've been the Beaker people, sheep and cow herders who lived throughout Europe and are known for the distinctive, bell-shape pottery they left behind.

The new timeline "connects everything together, it gives us a good sequence of events outside, and it gives us a set of cultural associations with the different stages of construction," Darvill said.

=====================
"Stonehenge remodelled"
Timothy Darvill, Peter Marshall, Mike Parker Pearson & Geoff Wainwright
ANTIQUITY 86 (2012): 1021–1040

Stone haulage and the diffusion of innovations

Now here's an interesting thought.  Last night I gave a talk to the Haverfordwest Civic Society about the "Bluestone Wars" and I had a very interesting chat with members of the audience afterwards about the diffusion of culture and technical innovations.  I had made the point in my talk that if (as TD, GW and MPP insist) Neolithic tribesmen collected up and transported 82 stones from west Wales to Stonehenge, we should assume that this would have been a technical peak in a history of long-distance stone haulage.  This would have been a massive technical (and maybe cultural) innovation -- we would expect to find in the archaeological record traces of the early introduction of the innovation, then a peak of some sort, and then a decline.  Instead of that, we find nothing -- no history of long-distance stone transport beyond maybe a few miles (there are some examples that seem to be well founded) -- and indeed, as we have argued before on this blog, in Wales the megalithic rule that seems to apply is this:  big stones are used more or less where they are found.

I remember from my days as a student that we had assorted lectures relating to cultural diffusion.  But that was a VERY long time ago, and things have moved on.   So I did a bit of digging, and came across this interesting entry on Wikipedia:

http://en.wikipedia.org/wiki/Diffusion_of_innovations

There are other entries on cultural diffusion and trans-cultural diffusion. No doubt there are vast archaeology tomes devoted to this topic.   If you look at the graph above, and apply it to long-distance stone haulage, you see that -- according to the model -- there should be an innovation phase, with early adopters catching on; and then a sort of critical mass phase where the majority adopt the new technique; and then a late majority, coinciding with a peak or a plateau; and finally a period during which the laggards (most remote or backward communities) eventually catch on......

If you look at the market share you eventually reach saturation, when 100% of the population has adopted the technique.  In reality, of course, you do not get isolated episodes like this, because once you have a new technique it does not just rise and fall, but it is improved and modified, and gives rise to better and newer techniques. So there are lots of overlapping curves.

Back to Stonehenge, and long-distance stone haulage.  Why is it that when we look at the archaeological record we see no evidence of innovators, early adopters, majority adoption, and laggardly adoption in remote areas?  It is a total aberration, with no development phase and no phase of decline.  So instead of a "normal" curve as on the graph above we have just an incredibly short episode (a few hundred years) during which (according to our archaeological friends) 82 very large stones were hauled over a very long distance across incredibly hostile terrain and/or water.  Nothing before, nothing after.  That's what these eminent professors want us to believe.

Apply the same test to the GW/TD idea that the stones were sacred or magical, and were revered for their healing power.   Nothing --  no evidence on the ground, no evidence of innovation, adoption, or decline in beliefs of this type.

Apply the same test to the MPP idea that the stones were revered because they embodied the spirits of the ancestors, and needed to be transported to a specially sacred site (Stonehenge) as an act of tribute or respect or reverence.  Again, nothing --  no evidence on the ground, no evidence of innovation, adoption, or decline in a culture of ancestor worship.

Sorry chaps -- it just doesn't make sense.....  It all defies logic, as it defies the evidence on the ground.  So forget it, and move on.

Rhosyfelin crags

Another nice pic from Rhosyfelin -- thanks to Chris. He says this was taken about 40m upstream from the "quarry" -- presumably on the other side of the ridge, where the crags are "overhanging" and more precarious.

OK -- Chris wonders how crags as delicate as this can survive glaciation and assorted other destructive earth surface processes.  Fair enough -- this is one of the great questions of glacial geomorphology.  I won't pretend that I have an easy answer on tap.  There are delicate crags all over the place, in areas which HAVE been glaciated quite recently.  There are crags like this at Felin y Gigfran, at Nant y Bugail neat Trecwn, and in Tycanol Wood -- not to mention all those delicate crags up on the top of Preseli.  In other places the crags are not so delicate -- they are smoothed off, and have obvious traces of glacial erosion on them.  This is the classic beetling fragile precarious craggy rock in Pembrokeshire -- the Precambrian rhyolite crag at Maiden Castle, near Treffgarne:

Parts of this crag are so fragile and delicately balanced that they look as if a decent storm might blow them down -- let alone an Irish Sea Glacier.  We geomorphologists assume, therefore, that this crag was not affected by Devensian ice, and that the central part of Pembs was beyond the ice limit during the last glacial episode.

On the other hand, if a glacier is cold-based rather than warm-based it has the extraordinary capacity to PROTECT landscapes and even very delicate tors from the processes of glacial erosion, which are concentrated into zones where streaming occurs -- where the ice moves at high velocity.   This has happened in parts of the Cairngorms, in North Wales, on Dartmoor, and on the uplands of Preseli.

Back to Rhosyfelin.  There are several possibilities.  

One, the crags as we see them today might have been fashioned by frost-shattering and other periglacial processes after the Devensian ice retreated from the area around 20,000 years ago.  We have quite a long period to think about here -- about 10,000 years in fact, when the climate was warming only very gradually.  The climate was still very severe -- probably permafrost was present for much of the time, and it got even colder during the Older Dryas and Younger Dryas episodes before the real Holocene climate warming set in.

Two, the crags might indeed be very old, having survived beneath the Devensian ice because the valley was filled with largely stagnant ice, with more active glacier ice shearing or streaming over the top.

Three, we might be looking here at the fractured remains of a crag which has been extensively broken up by plucking and entrainment processes during the Devensian.  (This is the sort of mechanism which I think will have affected this crag during the Anglian Glaciation, leading to the entrainment of material from Rhosyfelin into the ice which moved SE and E towards Somerset and Wiltshire.)

Then we have the other complicating factors of snowmelt, fluvio-glacial streams and even possible lake waters affecting this valley.

Work in progress...........

Rhosyfelin -- is it a quarry site?

Below I have posted a short note written by Phil Morgan, in which he considers the question of whether Rhosyfelin really does have a man-made quarry there, or whether everything is natural...... I happen to disagree with many of the things that Phil says, but discussion is always good!

1.  I quite accept that where quarrying is contemplated, it makes more sense to take stones from sloping walls where things will slide down under some degree of control, rather than from overhangs where there is great danger.  So from that point of view the rock face at Rhosyfelin which looks down on the dig site is "suitable." This wall faces NW, as Phil says.

2.  I don't agree that there would have been less freeze-thaw activity under a periglacial climate regime on the NW face than on the SE face.  I think there may well have been more on that side, since with westerly winds predominating in this area, the SE face would have been relatively more protected by lee-side accumulations of snow, which inhibit freeze-thaw processes and frost shattering.

3.  Orientation of big blocks.  Phil mentions that there are 4 blocks lying at right-angles to the rock face -- I don't see that.  If you look at all my photos on this site, and at the Gigapan, what you see is a jumble of fallen and broken blocks and scree with no preferred orientations.  So I don't agree that this tells us anything at all about human involvement.  I agree it would be interesting to know how many of the blocks have fallen directly down from the higher parts of the rock face, and how much downslope movement there may have been -- ie movement broadly parallel with the rock face. A factor which Phil doesn't consider at all is the influence of ice and snow-banks in all of this -- scree slopes in high-latitude or periglacial environments are very complex indeed, with snow, ice and running water all playing roles and with rocks falling down onto ice or snow and then sliding or settling later on.  Believe me -- I have crawled about on such slopes many times in my wild youth!

4.  The large block and the rails.  Again, I don't agree with Phil.  It could perfectly well have fallen and slid on ice or snow into its present position.  No human agency needed -- and there are no rails either, as I have pointed out.  Has anybody suggested that the longish stones beneath the big "orthostat" are made of mudstone?  They look like perfectly ordinary local rhyolite to me.....

5.  Heather as an indicator of quarrying activity?  Sorry Phil, but there is heather all over the place in areas which have not been quarried. I don't believe a word of what you say here.

In short, I see nothing here or anywhere else to shift me from the view that this jumble of rocks, large and small, is entirely natural.

Rhosyfelin -- is it a quarry site?



Figure 1 – Stope


1). Quarry workers are concerned over where rocks fall, nature cares not.

Gold mining practice utilises ‘Stopes’, where large caverns are excavated to access the gold bearing veins. The ore veins seldom exist at a convenient angle for extraction, resulting in the sides of the stope forming steep angles with the ground, (Figure 1)

When mining operations form these steep angles the sides of the workings are named the ‘foot’ wall and the ‘hanging’ wall. The safer rock face to work is the foot wall side for the product slides down-slope to the floor, whereas when working the hanging wall there is always the danger of the side collapsing and falling vertically, which could cause injury.

The Neolithic stone gatherers would have disliked being struck by falling stones and they would have realised that working the Craig Rhos-Y-Felin outcrop from the ‘foot’ wall side, (north-west face), would be the safer option.


Figure 2 (below) – Craig Rhos-Y-Felin ‘Foot-wall’.






Figure 3 (below) – Craig Rhos-Y-Felin ‘hanging Wall’.






2). Considering the actions of ‘freeze-thaw’

The photo only shows the dig in the area of the north-west face of the outcrop, the face that would have been least exposed to the actions of freeze-thaw; whereas the ‘hanging’ wall, (south-east face), which would have been more susceptible does not appear to have the same smooth finish of the foot wall.

It may prove beneficial to place a small trench below the south-east face to examine any debris for similar large blocks of rock. If no such blocks are found then it would again support human activity.

3). Orientations of the larger stone blocks.

Gravity is unable to differentiate between human quarrying and natural quarrying; it is logical to think that the quarried material comes to rest in the same manner for both activities, and that the orientations would not favour either quarrying method.

However, it is unusual that there are four blocks lying at right angles to the rock face. I suggest that a search be made to see if the upper surface of each block correlates with the rock face immediately above it. If it does then it is more likely that it was wrenched from the solid with it rotating about its base as it fell, indicates human activity, (figure 4).





If the underside of each block correlates with the solid rock then it is more likely to have become detached by natural means and slid down the rock face, (Figure 5).

It is normal, and best, practice when removing rock from the solid, to work to a free face, which in this case would be to work from the top of the outcrop vertically downwards. Therefore, the above correlation test should initially be applied to the upper portions of the outcrop.

The method used to separate the blocks is unknown but the use of water to expand wooden wedges inserted in the natural joints of the rock would work, especially if combined with the use of levers and ropes.

4). The large block lying parallel to the rock face.

It is thought that this slab is too far from the rock face to have come to rest after falling by human or natural means. Therefore, it is reasonable to say that it has been moved.

Mention has been made of this stone resting on ‘rails’, however this could be purely by accident. It is suggested that the ‘rails’ be examined to verify whether they are made of the same rhyolite as the igneous outcrop, or of some foreign stone, particularly mudstone.

Mudstone becomes slippery when wet, especially when under load. The pressure breaks down the rock surface which forms a lubricating interface.

Craig Rhos-Y-Felin is situated in the Fishguard Volcanic Group of rocks, however, the mudstones of the Aber Mawr Formations are reasonably close and southwards, upstream of the Afon Brynberian.

If the rails are formed from mudstone this would again support the human activity principle.

5). Heather as an indicator of human quarrying activity.

A study has been made of the use of heather as an indicator that quarrying has been conducted by humans. Craig Rhos-Y-Felin formed a part of this study and proved to be an ideal candidate for human quarrying.

Briefly the study has shown that heather, which has an affinity for acidic soils, flourishes on man-made, acidic, scree slopes, while refusing to grow on identical, and adjacent, natural scree.

It seems the reason for this abnormal activity is that, generally, natural scree slopes have been formed by freeze-thaw during past ice ages, when no plant life could survive. However, all human quarrying activity has to have taken place after the last Ice Age when plant life could survive.

The heather at Craig Rhos-Y-Felin grows only on the igneous outcrop, (figure 6).

Figure 6 – Heather and gorse growth at Craig Rhos-Y-Felin.







It is thought that the combination of orientations of the four rock slabs, the changed direction of the fifth slab, the use of ‘rails’ possibly made of imported mudstone combined with the presence of heather indicates that this area has been quarried by human hand.

Phil Morgan, Inc. Eng.
18th September 2012