The West Angle enigma (1): the stratigraphy

Three photos of the drift cliff / main exposure at the back of West Angle beach.  As we can see, the vegetation cover has varied over the decades -- and every now and then it is "freshened up" by extreme winter storms.  If you are a geologist or a geomorphologist, what you see is partly a matter of luck.......

One of the most difficult sites in the British Quaternary is at West Angle, near the mouth of Milford Haven.  It is considered by all workers (and there are many who have published) to span a very large part of the Late Quaternary.  Some, including DQ Bowen, think that there are signs of TWO glacial episodes represented here, with glacial and periglacial deposits separated by a raised beach of probable Ipswichian (last interglacial) age.  In the early 1900's there was a clay-pit here, worked for clay which was used in an adjacent brick-making kiln, but following the closure of that operation the clay-pit has been abandoned and is overgrown, and the adjacent sedimentary exposures at the back of the beach have become degraded and very messy.  There are many slumps, and many places where human interference has destroyed the natural stratigraphy.  It's difficult to see what on earth the section looks like, let alone to decide what it all means.....

The earlier workers, including Leach and Dixon (1921) had the advantage of being able to examine the stratigraphy in the clay-pit.  They recorded the sequence as follows:

8.  Angular stony loam - head?  3 ft
7.  Sand with abundant rounded bedrock flakes (?!!) plus erratics (including one from N Pembs) -- 4 ft
6.  Well bedded gravel and sand -- 2 ft
5.  Buff laminated loam including erratics -- 5 ft
4.  Dark blue loamy clay with wood and plant fragments -- 5 ft
3.  Irregular loam, sand and fine gravel  - 3 ft
2.  Grey clay or loam -- 1.5 ft
1.  Clean buff sand -- 1 ft

This sequence has been mis-reported by other researchers to suggest that till was found in the pit beneath raised beach materials.  However, the Geological Survey surveyors were very experienced, and  they did not refer to the gravel and shingle (6) as a raised beach deposit; and neither did they refer to the grey clay and loam (2) as a glacial deposit.

Back in the 1960's and 1970's David Unwin, David Bowen and myself, all working independently with other fieldworkers, measured and described the site, and undertook excavations, but we all seem to have seen slightly different things!

When I organized excavations here in 1965, we managed to dig a couple of metres below present beach level, exposed the raised beach, and found just "basal sand" beneath it.  The sand acts as an aquifer, and is disturbed by flowing water -- so our trenches filled with water so quickly that we could not discern any structures.

David Unwin also described the raised beach, and showed its relationship with other deposits as follows:

David Unwin's sketch of the main exposure at West Angle (north part).  RB = raised beach.

David Unwin's section (south part)

David shows nothing beneath the raised beach deposit, and he shows a complex unconformity on one side of which is a reddish till (?) on which he undertook various fabric analyses.  I have not seen those results, and I don't think they were ever published.  There is one big mistake on the southern part of his sketch section, and that is his portrayal of all the beds as dipping southwards.  In fact the beds are virtually horizontal, and some of them have a very slight dip northwards, from the valley side out into the valley floor.  This is an important point for the interpretation of the sequence.  

My own detailed section for the site is very long and thin, and is difficult to reproduce  --  but here it is:

Click to enlarge.  The locations of our six exploratory trenches are shown, and it is possible to match at least some of the deposits in the sequence with the Unwin diagrams.  The sands, silts and clays exposed in the southern part of the section (and including organic-rich layers) are highly enigmatic -- are they estuarine, lacustrine, colluvial or fluvial?  

The sharp and unconformable contact between these fine sediments and the more varied reddish deposits with clasts occurs close to point E on my diagram; I studied this closely, and here is my record of what the junction looks like:

Unconformable contact between non-glacial and glacial (?) deposits close to point E in the cliff exposure.  The metre scale on the right shows surveyed altitude above OD.  The displacement of the sedimentary layers is about 1m on slip face (2) and about 30 cms on slip face (3) -- suggestive of fracturing and slippage under permafrost conditions.

 My own observed stratigraphic sequence is this:

10.  Made ground and soil
9.    Dark red stratified horizon
8.    Dark red diamicton (non-stratified)
7.    Orange silt and clay series
6.    Grey silt and clay series
5.    Peat and peaty silt
4.    Stony grey silts -- up to 1.5 m thick
3.    Ferruginous bedded sands and gravels -- up to 1.5 m thick
2.    Rounded pebbles / beach shingle in a sandy and gravelly matrix -- up to 1.8 m thick
1.    Sand layer -- more than 1 m thick

It's difficult to tie in this sequence to that of Dixon (1921) -- although Bowen (1977, Table 3) tried to do just that.  

David Bowen has published extensively on the Pleistocene correlations of South and West Wales, and has referred in a number of publications to the fact that like Dixon he has seen 1.5 m of till at the base of the succession.  He says (1977) that "Dixon's till has been re-exposed and a succession directly comparable to his re-established" -- but no adequate supporting evidence has ever been published, and the bulk of Bowen's mentions of a West Angle till simply consist of references to his own past assertions.   As for the sequence described by myself and David Unwin, a promised "radical revision" written by Ribbon and Bowen has never been published......... so we do not know whether an Irish Sea till has been securely tied in through stratigraphy to the base of the sediment sequence.  I suspect that Bowen's observed till is the same as that which I observed adjacent to cutting B.  I am quite certain that the till which I observed is considerably YOUNGER than the raised beach.

I now think that the band of orange clay shown by Dave Unwin and myself is not a primary sedimentary feature but a weathering or secondary feature. I have learned from looking at scores of other sites in West Wales that horizons such as this exist beneath glacial deposits -- not because these horizons have been exposed to the atmosphere, but because this is where there has been water concentration, leaching and also precipitation of chemicals once held in solution. A virtually identical orange-coloured layer exists beneath the Irish Sea till at Abermawr.  But clearly there has been a "cut" here, with pre-existing sediments eroded away and replaced with later sediments that are themselves slumped or faulted. Are we to interpret these as glacial deposits incorporating overridden sediments and far-travelled erratics laid down in a highly fluid ice-marginal environment? I suggest just that.

The reddish till is seen in the cliff face for about 15m north from point E, unstratified towards its base and stratified above. In a QRA field visit in 1969, some experienced Quaternary experts came to the view that because of the relative lack of large clasts in this material, and the frequency of weathered fragments, it must be a re-deposited ancient till, more properly defined as a slope deposit. This view was repeated by DQ Bowen in a number of papers. However, during one later visit to the site, I was lucky enough to discover, close to cutting B (in the gully down to the beach) an excellent exposure of blue clay till with thrust structures and inclusions of rotted bedrock debris. Adjacent to this was another exposure in which the till had a reddish colour with many ORS fragments included, with clearly striated clasts and with lignite and shell fragments too. This was a classic exposure of Irish Sea till, confirming that the ice of the Devensian Irish Sea Glacier did indeed affect this area.

Deposits from this glacial episode are also seen in the northern coves at West Angle -- including a wedge of in situ reddish till in cove number 3 which is packed with fresh striated cobbles, many derived from the ORS.  The till contains flow structures and fluvioglacial lenses, suggesting sedimentation in an ice-marginal environment.

At this stage we should mention two other publications:  one a chapter by Campbell and Bowen in the GCR volume called "Quaternary of Wales" in 1989, and the other  a short paper by CR Morey published in 1997:
Morey, C.R. 1997. A re-examination of the valley-fill deposits at West Angle Bay, Pembrokeshire. Proceedings of the Ussher Society, 9, 164-167.

Campbell and Bowen do not publish any sections or other diagrams of the stratigraphy, and Morey's illustration of the sequence is so generalised and inaccurate as to be effectively useless.  Morey does not accept that there is a genuine raised beach deposit near the base of the succession at West Angle, and nor does he accept that his "reddish brown" layer 4(i) is a till layer, in spite of recording within it clasts of ORS marls and sandstones, dolerites and rhyolites.  He prefers to follow Bowen (1974) in interpreting this as a periglacial head or slope deposit accumulated under permafrost conditions.  He does not explain where all this erratic material might have come from.  Nor does he seem to have examined the fresh till that is exposed in the northern coves of West Angle Bay; such an examination might well have convinced him that Late Devensian ice did indeed reach this locality and must have affected the sedimentas at the head of the main bay.  Campbell and Bowen accept the presence of the raised beach, and its dating as Ipswichian, but are ambivalent on the matter of the "reddish till".  They do however accept the contention by Bowen that there is indeed an exposure of Irish Sea till BENEATH the raised beach.  No evidence is cited in support of this thesis  -- so the jury is still out on the matter.

In 2000 Kenneth Rijsdijk argued that the whole of the sediment sequence at West Angle is of Devensian age, with different layers representing  differing environmental and climatic episodes. 

So we have -- by less than common consent -- a raised beach that appears to be of Ipswichian or Last Interglacial age, and above it a reddish diamicton (which I consider to be till) that must be related to the Devensian Irish Sea till which is found in many locations around the northern and western coasts of Pembrokeshire.  In between those two recognisable deposits we have a suite of clays, silts, sands and gravels with an incorporated layer of peat and peaty silt.  These deposits occupy an equivalent stratigraphic position to the "lower head" or stratified slope deposits assumed elsewhere to be of Lower and Middle Devensian age.  So what were the climatic and environmental conditions which led to the accumulation of these deposits at West Angle?

There are two big questions:

1.  Are there really two tills of different ages at West Angle?
2.  What is the nature of the layers of sands, silts, and peaty loams between the raised beach cobbles and the reddish till?

To be continued.......

----------------------------------

Some key references:

BOWEN, D. Q. (1970). South-east and central South Wales. In: The Glaciations of Wales (Ed. by C. A. Lewis). Longmans, London.

BOWEN, D. Q. (1980). The Pleistocene scenario of Palaeolithic Wales. In: Culture and Environment in Palaeolithic Wales (Ed. by J. A. Taylor), pp. 1-14. British Archaeological Report, no. 76.

Dixon, E.E.L.  (1921)

JOHN, B. S. (1968). Age of raised beach deposits of South-western Britain. Nature, 218, 665-667. 

MITCHELL, G . F . (1960). The Pleistocene history of the Irish Sea. Advancement of Science, 68, 313-325.

MOREY, C.R. (1997(. A re-examination of the valley-fill deposits at West Angle Bay, Pembrokeshire. Proceedings of the Ussher Society, 9, 164-167.
http://ussher.org.uk/journal/90s/1997/documents/Morey_1997.pdf

PHILLIPS, L . (1974). Vegetational history of the Ipswichian/Eemian Interglacial in Britain and Continental Europe. New Phytologist, 73, 589-604.

RAWITSCHER, (1945). The hazel period in the post-glacial development of forests. Nature, 156, 302-303.

Stevensen, A.C. and Moore, P.D. (1982). Pollen Analysis of an Interglacial Deposit at West Angle, Dyfed, Wales. The New Phytologist. Vol. 90, No. 2, pp. 327-337.

TURNER, C. (1970). The Middle Pleistocene deposits at Marks Tey, Essex. Philosophical Transactions of the Royal Society of London, B, 257, 373-440.

TURNER, C. & WEST R. G. (1968). The subdivision and zonation of Interglacial periods. Eiszeitalter und Gegenwart, 19, 93-101.

WEST, R . G . (1980). The Pre-glacial Pleistocene of the Norfolk and Suffolk Coasts. Cambridge University Press, Cambridge.

Catling on Neolithic Pembrokeshire

Quite a hefty article from Chris Catling in Current Archaeology for March 2017.  Thanks to Dave and Tony for bringing it to my attention.

It's a strange article -- part review of a chapter in the new Pembrokeshire County History volume, part report on what was said at the latest NPA Archaeology Day, and part opinion piece.  CC follows a line of argument from Tim Darvill -- namely that there has been too much stress in the past on "monument typologies" and not enough on the purposes and intentions on the builders -- in other words, what the monuments meant to the builders.  When  I read that, I thought:  "Here we go again.  Away with hard evidence -- let's have fun with fantasies instead....."

Were my misgivings borne out by what followed in the article?  Well, yes and no.  I liked the points about the diversity of Neolithic monuments, the need to adapt to local materials and locations, and to "show off" to the neighbours.  But I found the arguments about "propped rocks" or sub-Neolithic chambers, a bit strange -- and I'm not sure that it gets us anywhere to imagine that prehistoric men were seeking to imitate nature in their early stone settings -- on the basis that strange rock formations or arrangements might have been created not by nature but by some lost race of giants or gods.  It's just as likely that the Neolithic inhabitants of the Pembrokeshire landscape were perfectly indifferent with regard to rock outcrops, tumbled crags, erratics and scattered stones.  CC says that "many propped rocks occupy impressive settings"  -- you could just as well say, in my experience, that just as many of them do not.  As far as I am concerned, propped slabs occur all over the place, in places where slabs were found.  Perfectly simple.

Were monuments intended to be seen from afar?  This is a much discussed topic, and CC does not add anything new on this.  Were the simplest monuments "statements of occupation"?  Well, of course they were -- nothing very significant about that.  People built things on the land they occupied, then as now.  On dolmens with "lifted capstones" obviously much more labour was involved -- and of course there was more technical skill and more ambition.  Portal dolmens were more complex still.  There are some interesting points about the evolution and re-fashioning of monuments like Pentre Ifan over time, but the author seems uncertain whether the Pembrokeshire monuments arose out of a multitude of contacts with other parts of the Neolithic world, or whether (as TD seems to be arguing) each one is essentially unique.

Were the monuments set into sacred and secular zones, as Prof MPP has argued?  In partial answer to that, CC argues that some megalithic monuments in Pembrokeshire are set into the landscape "as counterpoints to natural features".  He cites Garn Turne and Carn Bica  as being counterpoints, where natural features have been enhanced and modified.  I disagree completely with this fanciful search for significance -- you could just as well use similar language for any construction in any landscape.  Portal tombs, he says, look out over sea and mountain.  Of course they do -- where else are they supposed to look?

CC repeats the hoary old myth (invented by Darvill and Wainwright) that there is a strong association between megaliths and springs in Pembrokeshire and that this is the basis of the "healing bluestones" fantasy.  There is no such association, and I wish people would stop repeating it uncritically.

CC then comes on to the Neolithic preference for particular rock types, and claims that there was an "astonishing" knowledge of geology, with Neolithic geologists travelling vast distances to source preferred stones.  But he does not adequately differentiate between tool manufacture and megalith building.  As far as I can see, in Pembrokeshire there has been NO preferential use of specific rocks in any of the types of dolmens found in the landscape.  Always, people used whatever was to hand in the vicinity.  That point has been made by many experienced archaeologists.

CC concludes "Rock in prehistory was something living and resonant with meaning", and argues that instead of collecting hard evidence and working on "typology" archaeologists should become more concerned with meanings and the search for significance.  Hmmm -- from where I stand, there is too much fantasy as it is, and we hardly need more of it.   This article really adds very little to what we knew already, but the illustrations are pleasant enough. 

Case dismissed for lack of evidence.

Devensian till at the Blue Lagoon, Abereiddi

One does not often see exposures of Devensian till on the north Pembrokeshire coast, except in valleys and bays where till is often found as a "plug".  However, there is a splendid exposure at Abereiddi, near the famous flooded quarry called the Blue Lagoon.  Above are a couple of photos.

As we can see, the clifftop till is here about 3m thick, resting on broken shale bedrock.  The till is full of rounded, striated and faceted cobbles and erratics.  The matrix is clay-rich, but more gravelly in patches.  There is some iron-staining, but by and large the larger stones are fresh in appearance, just as they are in all of the other Devensian till exposures in North Pembrokeshire.

I'm not making any particularly new point here.  This is just for the record.......

Llansteffan and the Altar Stone

Thanks to Geraint Owen for further information on the Senni Beds.  He has studied the Craig Ddu section in detail, and from his descriptions, and the work of  Ixer, Bevins and Turner, I am now more than ever convinced that the Altar Stone might well have come from Craig Ddu near Llansteffan. Below I reproduce some of the key info on the Senni Beds from the big report by Barclay et al 2015.
 It's clear from the published work that the Altar Stone has significant differences from the Cosheston Sandstones around Mill Bay (Milford Haven) and significant similarities with the sandstones described from Craig Ddu.  The samples are not identical, but that is not surprising;  we do not know the precise positions from which all the samples have been taken, along a rock exposure c 400m long and 20m high.

For the moment, until further work is done, I think we can assume that the Altar Stone has probably come from the Llansteffan Peninsula and maybe even from the Craig Ddu exposures. That makes perfect sense, since the eastern Preseli hills and the Llansteffan Peninsula are on pretty well the same Irish Sea Glacier flowline.  All of the speculation about the Altar Stone having come from somewhere along the A40 road between Llandeilo and Sennybridge becomes redundant.

  

Flow lines and erratic trails -- reconstruction by Olwen Williams-Thorpe, after Kellaway.  Note that the pinkish coloured flowline crosses both Preseli and the Llansteffan Peninsula.

 ==========================

Big BGS report on ORS stratigraphy.  It provides a more formal correlation of Cosheston Group and Senni Formation:

BARCLAY, W J, DAVIES, J R, HILLIER, R D, AND WATERS, R A. 2015. Lithostratigraphy of the Old Red Sandstone successions of the Anglo-Welsh Basin. British Geological Survey Research Report, RR/14/02. 96pp.
It's a free download from the BGS website.

Extract:

4.2.5     Senni Formation

Name
Derived from the Senni Valley (Glyn Senni), Powys, south-central Wales. The name Senni Formation supersedes the traditional Geological Survey name Senni Beds (Cantrill in Strahan et al., 1904). In the Clee Hills, the formation was previously named the Clee Sandstone Formation.

Type area
Senni Valley [SN 930 209]

Partial type section
Waterfall exposures [SN 930 209] in a tributary of the Afon Senni (Nant Ystwyth) above Tyleglas.

Reference sections

1.    Heol Senni Quarry [SN 9154 2210], Powys provides a well documented reference section. It exposes about 40 m of grey-green sandstones, with minor siltstones, mudstones and intraformational conglomerates at the top of the formation (e.g. Edwards et al., 1978; Loeffler and Thomas, 1980; Dineley, 1999b; Barclay, 2005e).

2.    Cliffs at Craig Ddu on the western side of the Llansteffan peninsula, Carmarthenshire [SN 32441015](Owen, 1995). These reach a height of 20 m and have continuous exposure for 400 m of beds near the top of the formation.

3.    The stream draining north-westwards across Clee Liberty [SO 583 848–587 844] in the Clee Hills exposes about 140m of the formation (Allen, 1961) and provides a reference section for this area.

Lithology
Mainly of green and green-grey (locally red-brown and purplish green), very fine to medium- grained, micaceous sandstones, mainly channelised, cross-bedded and parallel-laminated, with green and red-brown siltstone and mudstone interbeds, some calcretes and intraformational conglomerates; the formation is characterised by the presence of vascular fossil plant remains and some soft sediment deformation is also present. In the Clee Hills, pale green sandstones are mainly arranged in fining-upwards conglomerate–sandstone–siltstone cycles, with subordinate red or green, sporadically calcretised mudstone/siltstone interbeds (Ball and Dineley, 1952, 1961; Allen, 1961; Greig et al., 1968).

Lower and upper boundaries
The lower boundary is placed at the base of green sandstones, which overlie red-brown sandstones and mudstones of the underlying Freshwater West (formerly St Maughans) Formation. Where mature calcretes at the top of the Freshwater West Formation are present (the Ffynnon/Abdon Limestones), the base of the formation is placed at the top of the uppermost calcrete. The upper boundary is placed where red-brown sandstones of the Brownstones Formation overlie the green sandstones of the Senni Formation, the junction being gradational. In the Clee Hills, Here, the lower boundary of the formation is placed at an erosion surface cut in the uppermost calcrete of the Upper Abdon Limestone, where it is sharply overlain by the basal green sandstones. The upper boundary is a gradational passage into generally coarser-grained
strata lacking in argillaceous beds and in which the sandstones are more variably coloured, these being assigned to the Brownstones (previously Monkeys Fold) Formation.

Thickness
300 to 450 m in the Brecon Beacons and Black Mountain, 150 to 200 m in the Black Mountains and 152 to 167 m in the Clee Hills.

Distribution
From Carmarthen Bay eastwards to the Black Mountain, Brecon Beacons and Black Mountains, and from there southwards to Abergavenny, wedging out north of Pontypool.

Depositional environment
High-discharge, mixed-bedload, sand-dominated, braided stream systems with relatively high sedimentation rates and water-table levels; although the formation is dominated by in-channel deposits, overbank floodplain silt and mud deposition also occurred.

Age
Latest Lochkovian to latest Pragian or Emsian in age.

REFERENCES

OWEN, G. 1995. Senni Beds of the Devonian Old Red Sandstone, Dyfed, Wales: anatomy of a semi-arid floodplain. Sedimentary Geology, Vol. 95, 221–235.

see also:

Also, RG Thomas's opus magnus on the Cosheston Group, which includes petrographic data:
THOMAS, R G, BARCLAY, W J, MORRISSEY, L, WILLIAMS, B P J, and ALLEN, K C. 2006. Enigma variations: the stratigraphy, provenance, palaeoseismicity and depositional history of the Lower Old Red Sandstone Cosheston Group, south-central Pembrokeshire, Wales. Geological Journal, Vol. 41, 481-536.

Rhosyfelin -- Coflein record is corrected

After lots of messages and a good deal of confusion, this is probably as right as it ever will be   -- it should now be almost acceptable to both sides of the argument!! 

I suggested further corrections, but these have been ignored.......


http://www.coflein.gov.uk/en/site/416247/details/craig-rhosyfelin-pont-saeson-craig-rhos-y-felin-rhyolite-bluestone-outcrop

Site Description

Fieldwork in 2011-12 led to the proposal that most of the foliated Stonehenge rhyolite debitage originated from a specific 70m long area called Craig Rhos-y-felin near Pont Saeson. Petrographical sampling by Dr Rob Ixer and Dr Richard Bevins found that 99% of these foliated rhyolites could be matched to rocks found in this particular set of outcrops. Rhyolitic rocks at Rhos-y-felin are distinctly different from all others in South Wales, which suggests that almost all of Stonehenge foliated rhyolites have a provenance of just hundreds of square metres. The results were of considerable significance, and were published in 2011 in the Journal of Archaeological Science.

Excavations between 2011 and 2015 identified Neolithic activity that may have been associated with megalith quarrying, but this is disputed by geologists, who believe that erratic materials were entrained at Rhosyfelin by over-riding glacier ice and transported south-eastwards towards Stonehenge.

Sources:

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

Ixer, R.A., Bevins, R.E., 2011, Chips off the Old Block: The Stonehenge Debitage Dilemma. Archaeology in Wales, 52, 2011, 11-22.

Brian John, Dyfed Elis-Gruffydd, and John Downes, 2015, Quaternary Events at Craig Rhosfelin, Pembrokeshire. Quaternary Newsletter 137, October 2015, p16-32.

Mike Parker Pearson, Richard Bevins, Rob Ixer, Joshua Pollard, Colin Richards, Kate Welham, Ben Chan, Kevan Edinborough, Derek Hamilton, Richard Macphail, Duncan Schlee, Jean-Luc Schwenninger, Ellen Simmons and Martin Smith (2015). Craig Rhos-y-felin: a Welsh bluestone megalith quarry for Stonehenge. Antiquity, 89 (348) (Dec 2015), pp 1331-1352.

L. Osborne & T. Driver, RCAHMW

Here comes Super-Stonehenge........

Talking of hokum, as we do quite often on this blog, wait for it....... here comes the latest blockbuster for Sky TV.  It's called "Britannia".  It will be broadcast this year, and featuring large will be a sort of Super-Stonehenge around which the drama involving Druids, Celts and Romans will swirl, no doubt with plenty of magic, monsters, and blood and gore.  Historical accuracy cannot be guaranteed.......

For those who like this sort of thing, here is the key info, put out by the publicity people:

Full credits for Britannia -- 10 episodes coming up in 2017

http://www.imdb.com/title/tt5932548/fullcredits?ref_=tt_ov_st_sm

Britannia is an epic drama set in 43AD as the Roman Imperial Army - determined and terrified in equal measure - returns to crush the Celtic heart of Britannia - a mysterious land ruled by warrior women and powerful druids who can channel the powerful forces of the underworld. Or so they say.

http://www.radiotimes.com/news/2016-12-07/first-look-at-david-morrissey-and-kelly-reilly-in-epic-new-historical-drama-britannia

Sky and Amazon partnership  -- filming in Czech Republic and Wales 2016.

The international distribution rights (excluding the US) for Britannia will be handled by Sky Vision, Sky’s international production and distribution arm. WME and Sky Vision negotiated the deal with Amazon.

Commenting on the show, Jez Butterworth said: “Besides being hard, hard warriors, the Celts have a belief system which makes them almost invincible. It’s a deep, heavy magic. Last time the Romans tried to invade, the mighty Julius Caesar took one look, turned round and went straight home. Now, almost a century later, the Romans are back. I’m fascinated in what happens when gods die. When an entire, ancient faith stalls, topples, collapses - and a whole new one grows in its place. New names, new faces, to suit the new times. Here we have a  war between two pantheons - the Roman gods v the Celtic gods. It’s the Heavyweight Clash of All Time, the one which most shapes who we are today. And we see it all from a human perspective, of individual survival, ambition, courage, lust, loss, revenge. All the stuff the gods have always loved us humans for the most!”

Kelly Reilly said: "I am thrilled to be joining the production of Britannia, a story rooted in the heart of our ancient history. Collaborating with great creative minds is what I love most about my job, and having one of Britain’s leading playwrights, Jez Butterworth, come on board to bring Celtic Britain alive has made this a fiercely exciting project. The vision is big and bold and beautiful, and I can’t wait to get my hands dirty.”

David Morrissey added: "I have been a fan of Jez's writing for a long, long time, so to get the chance to work with him on this epic tale is very exciting. His dialogue and storytelling are second to none. I am also really looking forward to working with the brilliant cast that has been assembled for Britannia - I just hope I get a nice horse!"

Anne Mensah, Sky’s Head of Drama said: “This is one of the most ambitious dramas we’ve ever made and one of the most exciting. Jez Butterworth has written an incredible drama that is entertaining and emotional but also asks important questions about what drives men and women to stand and fight. This is a battle for the heart of Britain like you’ve never seen before.”

Roy Price, Vice President, Digital Video and Amazon Studios, said: “We’re thrilled to be collaborating with Sky on our first series entirely produced overseas. Our customers will experience a cinematic world with bold characters anchored in a ruthless period of history.”

April 1st comes early this year....

Our friend Paul Sanday is doing another talk in Newport about his claim that he has found "The Welsh Stonehenge" -- full coverage in the local press.  Ah well, it's a free world, and I suppose his ideas are no wackier than many others featured in the Stonehenge debate over the years......

http://www.countyecho.co.uk/article.cfm?id=109765&headline=Geologist%20stumbles%20across%20%E2%80%98Welsh%20Stonehenge&sectionIs=news&searchyear=2017

I think Paul is having a jolly time here, just seeing how much outrageous nonsense he can get a gullible public to accept as "scientifically" based.  Not sure what this all does for the reputation of geology....... maybe that's a problem for geologists to address!

Wolstonian glaciation of west Wales: an hypothesis

In a previous post, I suggested that there is now so much evidence of strange goings-on in the glacial record of Pembrokeshire that it may well be time to reinstate the Wolstonian as a serious and extensive glacial event.  Here is my earlier post from a month ago:

https://brian-mountainman.blogspot.co.uk/2017/01/time-to-bring-wolstonian-in-from-cold.html

As I have suggested on many occasions, the old Wolstonian limit, as proposed by assorted researchers including Gibbard and Clark, does not make any sense, at least in Wales, so anything has to be an improvement. To repeat -- my reasoning is as follows:

1.  The orientation and scale of the Gwaun-Jordanston meltwater channel system cannot be explained as a product of Irish Sea ice coming in from the N and NW, either during the Anglian or Devensian glaciations.   The channels must have been eroded at a time when there was a strong hydrostatic gradient from E towards W -- that is the undoubted direction of meltwater flow.  So there must have been Welsh ice flowing from east to west.

2.  There are anomalous striae on the north Pembrokeshire coast, which have always puzzled me since they run approx E-W.  All other striae match the expected directions of Irish Sea ice across the north Pembrokeshire coast.  I have not been able to work out the relative ages of the assorted striae, but some of the anomalous ones might well be of Wolstonian age.

3.  The glacial and fluvioglacial deposits that scatter the Devensian "ice free area" south of Mynydd Preseli have to be explained somehow.........  some are very rotten, as at Llangolman, suggesting a pre-Devensian age.

4.  The ancient till deposits at West Angle, Lydstep and maybe New Quay may well be of Wolstonian age.

5.  The frequency of Ceredigion grits and coarse sandstones in the glacial deposits of the Nevern Estuary in Newport suggests to me that they were deposited far out into Cardigan Bay during a Wolstonian glaciation, and then picked up and redeposited by Irish Sea ice during the Late Devensian.

6.  The deep downcutting of Milford Haven may also be partly a result of large quantities of glacial meltwater flowing westwards at the end of a Wolstonian glacial episode on the lines shown on the above map.

What do others think?  Comments very welcome.

Suggested Wolstonian limits of the Welsh ice cap.  That ice cap must have been similar to the modelled Devensian ice cap, but it was probably thicker, with more active ice streams in all of the major radiating valleys.  It was also substantially more extensive. It is assumed that the Irish Sea Glacier was at the time less powerful than during the Anglian and Devensian glaciations -- but there must have been contacts between these two ice masses in the NW, N and NE sectors. 

Hardangerjokul -- on the way out......

This is a fantastic oblique image of Hardangerjokul in Norway.  As we can see, it is a perfect plateau ice cap, with just one outlet glacier that has shrunk do much that it no longer drops over the trough head near the left edge of the photo.  The ice in the centre of the ice dome is still about 300m thick, but the highest point on the ice cap has dropped by 15m since 1925, and the edge is retreating at a dramatic rate every year.  The Norwegian weather service is now predicting that the ice cap will melt away completely within 50 years, if the current rate of climate warming continues.......

Llandre Gravel Quarry -- where is the Penfro Till?

 The flooded Llandre Gravel Quarry, not far from Clynderwen, well inside the "Devensian ice-free area".  Gravels (heavily iron-stained) can be seen in the exposures on two sides of the quarry.  There us no current exposure of till.

Not long ago I  put up a post about the Penfro Till Formation, and wondered where its type locality is really located and just how old it is.  Is it, indeed, just one formation,or are assorted tills of various ages all lumped together rather unreliably?  I am beginning to suspect that the latter is the case.

https://brian-mountainman.blogspot.co.uk/2017/02/penfro-till-formation.html

I called in to have a look at the quarry today  -- it's very close to the road, near a big animal shed belonging to Llandre Egremont Farm and a few hundred metres north of the point where the road passes under the Gelli railway bridge. Grid reference:  SN 092202.  I wasn't able to achieve much, and I couldn't dig away at the gravels without risking life and limb........ but the gravels are at least 3m thick and are heavily iron-stained. But they do not appear to be anything like as rotten as the gravels exposed at Llangolman.  I'm not even sure that they are fluvioglacial -- they look like river gravels to me -- with most pebbles under 5 cm in diameter and with just a few larger clasts.  I think the gravel pit is cut into a remnant of an old river terrace with its top no more than 2m above the present valley floor.  I would hesitate, therefore, to give this site any great geomorphological significance, or assume that it will help us in unravelling the Ice Age history of this area.  I'll take a look at it again in the summer, when hopefully it will be dry enough for me to do a bit more work on the gravel faces.

Higher up the slope, adjacent to the animal sheds, there is an exposure of rotted bedrock and slope deposits or head -- but no gravels or till.

This is certainly not a good enough site to be a type locality for anything.  I might revise that judgment in due course, once I have hoofed about a bit more.

Postscript

I have discovered another gravel pit, at SN093203, about 300m from the one described above.  It's at an altitude of c 44m, on a broad spur above the river valley.  Let's call it Llandre No 2 quarry -- I shall go and check it out.......

Trough head emergence

A great photo from James Lea, showing the emergence of a trough head at the landward end of an East Greenland fjord.  This is a bit strange, because there is an undoubted trough head, but no obvious ice stream flowing to the edge of it.  Maybe, further in from the ice edge, something has happened to cut off the ice supply?

Rhosyfelin -- bad news from the rock face?

I reported back in August that some cosmogenic dating was about to be done at Rhosyfelin -- and I assumed that a number of samples would be taken which would help to sort out the chronology there.  I assumed that samples would be taken from the big "picnic table" slab and from assorted positions on the rock face, so as to establish when assorted parts of the face first became exposed to cosmic radiation.  In particular, the so-called "extraction point" so beloved of Prof MPP deserves serious investigation.

https://brian-mountainman.blogspot.co.uk/2016/08/rhosyfelin-more-good-news-from-rock-face.html

Well, I heard on the grapevine not long ago that NO samples were taken from the rock face and that the only feature sampled was the big stone.  If that is true, this appears to be a pretty meaningless exercise, since ages for the faces of the stone cannot now be interpreted alongside any "control" dates from the crag itself.   One, or all of the dates, from the stone could be wildly misleading, since nothing will be known about inherited exposures, dates of burial, amount of overshading by trees or cover by turf, moss and bushes.

Very disappointing -- but maybe we should not be too surprised, since good science has been in very short supply at Rhosyfelin.

Apparently the dates may be reported in the summer.  Let's see what transpires......

Rhosyfelin entrainment area

 Oblique air photos from Toby Driver (RCAHMW), from the Coflein web site.  I have added approximate ice directions on each photo, and on the lower one we see the approximate outline of outcropping foliated rhyolite. Click to enlarge.

One might have some gripes with the updating of records on the Coflein (RCHAMW) web site, but we have cause to be thankful for the amazing collection of oblique air photos by Toby Driver  -- which keeps on growing!  These two excellent photos have been added to the Coflein Rhosyfelin record, giving us a new perspective on the likely rhyolite entrainment area at the time of the Anglian glaciation.

As we can see from the lower photo in particular, there is a relatively large area of outcropping foliated rhyolite here.  It is quite possible that overriding ice during the Anglian glaciation could have picked up or entrained slabs, pillars or rhyolitic debris from within and indeed beyond the area enclosed by the white line.  As we have said many times before on this blog, the geologists have not demonstrated beyond reasonable doubt that some of the material in the Stonehenge debitage came from within a few square metres of the tip of the Rhosyfelin spur, and we can assume that prior to the Anglian glaciation (ie three glaciations ago) the upstanding rhyolite crags here must have been much more prominent than they are today.  Where has all the material gone?  Well, much of it is littered across the landscape downglacier from here, and some of it appears to be at Stonehenge.......

Postscript:

Since I have been accused (rather aggressively) of getting this whole issue all screwed up, of failing to do proper fieldwork, and totally misunderstanding the local geology, I went back to source.  I found that, according to Ixer and Bevins, the foliated rhyolite rocks are indeed exposed in the Pont Saeson - Rhosyfelin area in pretty well the exact area shown on the lower photo, ie within a distance of c 150m from the tip of the spur.  I am unaware of any published evidence that contradicts this.

Bevins et al, 2012
Journal of Archaeological Science 39 (2012) 1005e1019
Provenancing the rhyolitic and dacitic components of the Stonehenge landscape bluestone lithology: new petrographical and geochemical evidence
Richard E. Bevins, Rob A. Ixer, Peter C. Webb, John S. Watson
Department of Geology, National Museum of Wales, Cathays Park, Cardiff, Wales CF10 3NP, UK

Quote:
We conclude that currently the only dacitic or rhyolitic lithology which can be matched with any degree of confidence between the Stonehenge landscape and a specific source area is the so-called ‘rhyolite with fabric’ lithology, which matches with foliated rhyolitic rocks exposed in the Pont Saeson area of north Pembrokeshire, in particular including those from Craig Rhos-y-felin. This is now correlated with some confidence in terms of petrography, whole-rock geochemistry and mineral (zircon) chemistry.

-------------

Rob Ixer and Richard Bevins. 2011. Craig Rhos-y-felin, Pont Saeson is the dominant source of the Stonehenge rhyolitic ‘debitage’. Archaeology in Wales, 50, 21-31.

Quotes:
In the Pont Saeson area the Fishguard Volcanic Group comprises a strongly foliated to foliated and lensoidal rhyolitic rock the like of which is not seen elsewhere in the outcrop of the group across the 32 km of strike section from Pen Caer in the west to Crymych in the east. These very distinctive rhyolitic rocks can be traced for no more than 150 m from the northeasternmost end of Craig Rhos- y-felin.
Although there are subtle but distinct differences between different rhyolitic outcrops at Pont Saeson, including those on Craig Rhos-y-felin, they share a distinctive petrography that is unrecognised from elsewhere in the Fishguard Volcanic Group. Texturally all are foliated usually with an associated lensoidal fabric where deformed lithic clasts occur and carry a similar dominant mineralogy, although, in addition, some outcrops have rare, unusual minerals.
Although the degree of foliation is strong to very strong, the associated lensoidal fabric varies from weak but pervasive to very strong.......

Those other sarsen stones

 The Cuckoo Stone (Simon Banton)

 

 The Bulford Stone (Simon Banton)

 

This is an interesting short article from Simon Banton  -- follow the link to the original, with illustrations.  Simon makes the point that the "shortage"of sarsens in the Stonehenge landscape is often cited in support of the thesis that the stones were collected from the Marlborough Downs. On the other hand, as pointed out by Andrew Goudie and many others, the shortage of large sarsens within striking distance of Stonehenge can also be interpreted as a sign that most -- if not all -- of the big, useful ones were collected up during the "stone setting" phases of the monument.  Also, as I have suggested many times, because there are only 53 or so sarsens at Stonehenge,  that may well mean that they ran out of stones which were close enough to fetch, and then gave up on the whole project, leaving it incomplete. 

 =======================

Other Sarsen Stones near Stonehenge and Woodhenge

Simon Banton
https://blog.stonehenge-stone-circle.co.uk/2017/02/05/other-sarsen-stones-near-stonehenge-and-woodhenge/
--------------------------

Sarsen boulders lie scattered in substantial “drifts” across the landscape of the Marlborough Downs near Avebury.

By contrast, close to Stonehenge there are almost none. This is one of the reasons why most archaeologists believe that the large sarsens for the monument were not locally sourced.

There are, however, a few examples of substantial sarsens dotted about Salisbury Plain within a couple of miles of Stonehenge. And there are tantalising hints that others used to exist.

The most obvious, and easily accessible, is the Cuckoo Stone. This stone is about 2m long by 1.5m wide by 1.5m thick and lies in the field immediately west of Woodhenge.

The Stonehenge Riverside Project excavated around the Cuckoo Stone in 2007 and discovered that the stone once had been set upright right next to the hollow in which it had originally formed.

Close by were two neolithic pits containing pottery worked flint, deer antlers and animal bones, dating to between 4000BC and 2000BC. A series of three burials were also found close by, dating to around 2000BC.

The stone remained a focus of activity right down to Romano-British times, and a small square wooden building – most likely a shrine – was built immediately to its southwest. Coins and pottery found in the ploughsoil date this to between 200AD and 400AD.

The other readily accessible sarsen is the Bulford Stone which lies in an arable field east of Bulford Village. It’s rather larger than the Cuckoo Stone at 2.8m long and again the excavation evidence shows that it too was once stood upright next to the hollow in which it formed.

It’s also closely associated with burials from the neolithic, the pottery found here dates to between 2300BC and 1900BC. The grave goods found were remarkable, including a flake of transparent rock crystal from either South Wales or the Alps and a “mini megalith” carved from a piece of limestone.

Lying in the northern ditch of a badly degraded long barrow within the Salisbury Plain military training area (and therefore not accessible to the public) are three more sarsen boulders.

They vary in size and – being half buried in the turf – are difficult to see, but the largest seems to be almost 2m long.

This long barrow was excavated by John Thurnam in 1864 who found an early neolithic burial on the original ground surface and an later Beaker burial just below the top of the mound.

Subsequent digging by the military in the early 20th century has almost obliterated the barrow but its outline can still be made out.

There is some debate about whether the sarsens lying in the ditch were originally part of the structure of the long barrow or if they were dragged there by farmers clearing fields at some later date. The stronger possibility is that they were part of the structure.

John Britton in his “Beauties of Wiltshire (1801)” says:

“About two miles north of Amesbury, on the banks of the Avon, is Bulford. Near this village are two large stones of the same kind as those at Stonehenge. One of them is situated in the middle of the river, and, as I am informed, has an iron ring fixed in it; but the waters being very high I could not see it.”

Old OS maps of the area show where this stone in the river once lay, but sadly it has now been removed and its present location is unknown to this author (please get in touch if you have any information about or pictures of it):

“…an interment which was lately discovered above Durrington Walls, by a shepherd, who in pitching the fold, found his iron bar impeded in the ground : curiosity led him to explore the cause, which proved to be a large sarsen stone, covering the interment of a skeleton”

There are other references to large local sarsens from antiquarian reports – one is mentioned by Sir Richard Colt Hoare in the early 1800s:

… and another by the Rev. Allan Hutchins from about the same time:

“In a field, not far from the road which leads from the Amesbury Turnpike into Bulford, is a Barrow of chalk facing the parish and standing by itself… When I came nearly to the virgin earth in this Barrow, my progress was impeded by an immense oval sand stone, underneath which was a skeleton, a beautiful lance head, and a handsome drinking cup”

Perhaps there are still more to be found. Certainly it seems that sarsen boulders of “large” or even “immense” size are not unknown in this part of Wiltshire so maybe the idea that the sarsens of Stonehenge were brought from the Marlborough Downs shouldn’t be accepted at face value.

Curiously the Cuckoo Stone, the Avon Sarsen and the Bulford Stone all lie precisely on a straight line, with the Avon Stone being 1500 yards from the Cuckoo Stone and 1450 yards from the Bulford Stone.

But that’s another story……….

Royal Commission -- a cavalier disregard for the truth

Well over a year ago, I wrote to the Royal Commission in Wales (RCAHMW) to complain about serious misrepresentations in the Coflein site description for Craig Rhosyfelin.  I reported this in a blog post:

https://brian-mountainman.blogspot.co.uk/2015/11/rhosyfelin-official-record.html

I won't repeat the same points here.  But I pointed out that the report of the site, written by Toby Driver and L. Osborne, misrepresented the work of both the geologists and the archaeologists, and made unsupportable assertions and speculations concerning the significance of the site.  It is also seriously out of date, given that there are now three peer-reviewed articles about the site, none of which is mentioned.  The site also has a RIGS designation, which should be mentioned.

I am not impressed, since RCAHMW has neither acknowledged my submission nor amended the entry that was on the site in 2015.  How long does it take to amend a web site entry?  Two or three minutes, at the most.  Could it be that there is an inconvenient truth out there somewhere, which is not universally acknowledged?  Could it be that the archaeological establishment in Wales does not actually WANT the true situation at Rhosyfelin to be reported and placed on the record?

This is an official site, sponsored and funded by the Welsh Government.  We deserve better than the unquestioning perpetration of fantasies.

The Welsh Stonehenge? Hmmm -- or maybe not.......

I went to a talk not long ago by geologist Paul Sanday on the subject of the Welsh Stonehenge.  Paul (he of the aurochs and sledge theory) chatted amiably about Stonehenge, the bluestones, the alignments, the "quarries" and assorted other things -- demonstrating, sadly, that people should not stand up and give talks on things that they do not fully understand.  Paul's lack of awareness of the basic literature was more than a little embarrassing -- or maybe he knew it but just chose to ignore it for the sake of telling a good story?  It's a good job I didn't take any notes, or we would be here for a very long time........

Anyway, the basis thesis seemed to be that the accepted geology of the bluestones (as described by Ixer and Bevins, and many others) is all wrong, that the bluestone and stonehenge time sequence is all wrong, and that there was once a bluestone circle (later dismantled and shifted to Stonehenge) at a wondrous new location called Castell Mawr.  This is Paul's "Welsh Stonehenge".  Trouble is, Castell Mawr is very well known, and has been for many years.  It is well described in all of the databases and archaeological publications, including Coflein and Archwilio (and on this blog) and all the evidence points to it being a perfectly normal  Iron Age defended feature which is far too late to have anything to do with Stonehenge or the bluestones.  Mike Parker Pearson and his team have dug there rather recently, looking for stone sockets and other traces of Neolithic or Bronze Age occupation, and came away having found nothing interesting.  Was Paul really blissfully unaware of this recent work?  The best that we can say is that there might have been an earlier henge structure beneath and within the Iron Age ramparts.

Anyway, he provided no evidence of any kind in support of his thesis, apart from something very dodgy about the amount of earth excavated from the Neolithic Stonehenge ditch being exactly the same as the amount of earth excavated from the Iron Age ditch at Castell Mawr.  Oh dear......

Moving rapidly on........

Penfro Till Formation

I'm increasingly intrigued -- and concerned -- about something labelled as "The Penfro Till Formation" in the official stratigraphic lexicon.  This label is applied to all of the glacial deposits lying outside the supposed Devensian limit in South Wales -- we have done several posts on this.  According to Prof David Bowen, this formation is a part of the "Albion Glacigenic Group".  I'm not sure where the type section is supposed to be -- it might be Pencoed in Glamorgan, and it might just be West Angle Bay in Pembrokeshire, or the old gravel pit at Llandre, near Clynderwen.  All of the glacial and fluvioglacial deposits in the south Pembrokeshire Devensian "ice-free" area are included.  These are well shown on the BGS mapping -- this is a small scale map and one enlarged section:

Apart from the smaller exposures shown on these maps, there are two extensive ones -- let's call them the Clynderwen Gravels and the Templeton Till.  I need to get at them in order to describe them properly........

In this discission we need to include the Llangolman deposits already described on this blog:

https://brian-mountainman.blogspot.co.uk/2014/10/pre-devensian-glacial-deposits-south-of.html
https://brian-mountainman.blogspot.co.uk/2015/04/llangolman-gravel-pit-angian-fluvio.html
https://brian-mountainman.blogspot.co.uk/2015/01/if-ever-there-was-case-for-osl-dating.html
https://brian-mountainman.blogspot.co.uk/2014/12/fluvio-glacial-gravels-around.html
https://brian-mountainman.blogspot.co.uk/2014/12/ancient-till-at-llangolman.html

The signs are that many -- if not all -- of these deposits are heavily weathered, and look different from the fresh glacial and fluvioglacial deposits of north and west Pembrokeshire.  But are they all of the same age?  Could some of them date from the Wolstonian glaciation and some from the Anglian?

https://brian-mountainman.blogspot.co.uk/2017/01/time-to-bring-wolstonian-in-from-cold.html

Whaever the truth of the matter,  we need much better field research and cosmogenic dating before the matter of the "Penfro Till Formation" can be sorted out.