Caldey Island — the Ballum's Bay till must be Late Devensian

Google Earth image of Ballums Bay, Caldey Island.  The till exposure is at the head of the gulley, top left.  The edge of the raised beach platform with cemented sediments coincides approximately with the black line.

 

 Ballums Bay from the east (from near Small Ord Point).  The beach, backed by the gully containing till, is right of centre. To left of centre we see remnants of raised beach platforms with cemented beach materials, breccia and sandrock, overlain by a terrace of more recent materials.

Following my note about the interesting QN article by John Hiemstra and others, I have been digging into my records of Caldey Island, and have found a number of photos that might be of interest.  I have several pics of the till exposure which has been investigated and now described in the QN piece, but we'll leave those to one side for the moment.  Of more interest to the debate about age are the photos of the cemented materials found on the old wave-cut platforms immediately to the south.

The platform is seriously broken up, cut by gullies and other inlets affected by ongoing wave action, and with steps and assorted vertical and overhanging sections.  Like the other wave-cut platforms on the limestone coasts of South Pembrokeshire, it appears to be a composite feature, representing erosion at a number of different levels between present HWM and +5m.  The raised beach platform is a mess -- appearing very old, with segments of many different ages.  Ipswichian?  My guess is that it is much older, and that it has been modified across several interglacials.  

                            

Raised beach platform remnants on steeply dipping Carboniferous Limestone strata on 

the south side of Ballums Bay

Cemented brecciated limestone debris incorporating raised beach boulders and cobbles on one of the highest rock platform remnants, Ballums Bay south.

Comparison with other platform remnants is instructive.  See these posts on Broad Haven South and Lydstep:

https://brian-mountainman.blogspot.com/2018/04/the-raised-beach-at-broad-haven-south.html

https://brian-mountainman.blogspot.com/2018/11/on-significance-of-cementation.html

Let's take a look at the cemented deposits.  There can be no doubt that these are all older than the Ballums Bay till.  The raised beach, limestone breccia and bedded sandrock are intimately associated, although they do not all appear in all exposures.  For example, in the extensive high raised beach platform near Lydstep Point cemented breccia and cemented sandrock are both found, but I have been unable to find any traces of cemented raised beach cobbles.

Key Quaternary locations on Lydstep Headland (note that there is a mistake on this map.  The raised beach platform is in the bay to the west, behind Whitesheet Rock.  To be corrected.....)

 

Complex cemented deposits on the limestone raised beach platform on the south side of Ballums Bay.   Here we see abundant raised beach cobbles, layers of sandrock, and masses of limestone rockfall debris and slope breccia. 

Bedded sandrock resting on slope breccia and raised beach cobbles., south side of Ballums Bay.   All cemented with carbonate cement -- with some traces of manganese oxide cement.

The South Pembrokeshire Quaternary regional stratigraphy (based on my own observations and those of Dixon and Leach) is as follows:

8. Sandy loam and blown sand
7. Upper head (uncemented)
6. Fluvioglacial sands and gravels -- traces
5. Till from Dewisland (Devensian) glaciation -- many coastal exposures
4c. Lower head (cemented in some localities)
4b. Cemented sands (sandrock)
4a. Head incorporating raised beach cobbles (cemented)
3. Cemented raised beach
2. Older glacial deposits -- mostly destroyed, but exposed at Lydstep (Black Mixen)
1. Raised beach platform (complex modifications over several interglacials?)

If, as suggested by John Hiemstra and his colleagues, the unconsolidated till at Ballums Bay is of Anglian age (but periglacially redistributed or redeposited), it must be older than the cemented raised beach deposits.  So why is it not cemented like deposits 2, 3 and 4 in the regional sedimentary sequence?  It does not make sense.  The authors seem to be suggesting that the original till is the same age as the ancient cemented till at Black Mixen -- that does not make sense either.  The fresh till at Ballums Bay lies in a limestone gully, just like the fresh till at Lydstep, so the two deposits must be related.

https://brian-mountainman.blogspot.com/2018/05/devensian-till-at-lydstep.html 

In addition, the Ballums Bay till looks like the fresh till exposed in many clifftop locations on the south Pembrokeshire coast -- and it lies in the same stratigraphic position, overlain only by unconsolidated blown sand or sandloess, as in the Isles of Scilly.  It must also be the same age as the till exposed near the Caldey landing stage, which is reddish in colour, sandy and gravelly in texture, matrix supported, and contains a similar mix of erratic cobbles.

Till exposure near the Caldey landing stage.  At the base, broken Carboniferous Limestone bedrock.  Above that, 1.3 m gravelly and sandy fresh unconsolidated till. Above 

that, c 1m of sandy loess and soil.

Brecciated limestone slope deposit or "head" above broken Carboniferous Limestone bedrock, near the Caldey landing stage.  This is uncemented, and appears to underlie the Devensian till.  It is probably of Early Devensian age, and correlated with many other slope deposits in West Wales which underlie till and fluvioglacial materials.

Here is the crucial discussion on the age of the till, from the QN article by John Hiemstra and his colleagues:

1) In situ Devensian till

This was the scenario we set out to test. Several features certainly favour this origin: (i) ‘foreign’ igneous erratics; (ii) dominance of sandstone clasts mostly probably from outcrops on the west of the island lying slightly south of Bullum’ Bay, which would tally with an ENE flow direction of ice as envisaged by Brian John; (iii) clast form characteristics; and (iv) probable loessic sediment overlying the diamicton without obvious hiatus, consistent with a Devensian origin. There are, however, several drawbacks to this scenario: (i) the very low content of any material that does not have a likely relatively local provenance: (ii) no observed far-travelled erratics or glacigenic diamicton in parts of the island we could access, and also very few such erratics on the beaches; (iii) flow structures atypical of till; and (4) no convincing striations. (The grain fabric evidence is equivocal, neither supporting nor ruling out a till origin.)

(2) Redistribution of pre-existing sediment including any residual Anglian glacigenic sediment during Devensian periglacial conditions

An in situ Anglian till origin is not feasible because raised Ipswichian sea level - probably at least c. +5 m OD (Dutton and Lambeck, 2012) - would have removed any existing sediment from the lower part of the gully where the diamicton lies. An origin by redistribution of regolith and soil as well as any Anglian glacial material by mass flow under Devensian periglacial conditions is, however, plausible. The igneous pebbles could have been derived from two possible transport directions and by two possible sequences of events. (In either case, mass flow would have moved sediment downslope from higher ground in the south of the island to the gully.) One alternative is that they could have been deposited on the island during the Anglian glaciation when many argue that ice from the Irish Sea Basin moved eastwards and southwards across this region. Mass flow processes would then have carried these clasts into the gully. The other alternative is that there is a possible source to the south of Bullum’s Bay of the igneous pebbles in conglomerates of the West Angle Formation of the upper ORS, which is said to be ‘rich’ in such clasts as well as those of some other lithologies (Howells, 2007). In this case, sediment containing clasts derived from mainland sources would have been transported to the island by glacial action, and during the Devensian any remnant glacigenic material would have been carried north(east)wards downslope to Bullum’s Bay by mass flow processes together with any locally eroded material including the igneous erratics. The flow structures, lack of striations, clay-rich texture and grain fabric evidence tally with an origin by periglacial slope processes. Clast rounding could be the result of one or a combination of long-term weathering, residual glacial modification or limited modification acquired during mass flow transport. The clast form characteristics of the igneous clasts would favour a glacial rather than fluvial (i.e. ORS conglomerate) origin, although reconstructing transport history from just four clasts must be treated with caution. Lack of angular clasts from the underlying limestone either in the diamicton or forming the main constituent of a discrete single-lithology periglacial diamicton might appear problematic given the frost susceptibility of this rock type. However, the lack of steep surrounding slopes with exposed bedrock that could act as the source of such material is the probable explanation. (Transport to Bullum’s Bay of the igneous erratics by northward-moving longshore drift during raised Ipswichian sea level is conceivable but their incorporation into the exposed diamicton seems unlikely given the lack of contained marine shells.)

On balance, therefore, we prefer the second scenario to explain the Bullum’s Bay diamicton as it provides a better explanation of the evidence.

In my view, as indicated earlier, the discussion by the authors is not at all convincing, and includes a good deal of special pleading.  The till is not unusual or unique in any way, and like most of the related deposits in South Pembrokeshire, if it looks like a till it probably is a till.  One gets the impression that the authors are rather desperate to demonstrate that the deposit is not an in situ till, and their suggested "drawbacks" are perhaps based on the fact they are not familiar with related deposits, their lithologies and their stratigraphic relationships.  The low content of foreign materials is not at all unusual in Pembrokeshire tills, as I demonstrated in my 1965 thesis. There ARE far-travelled erratics and other tills on the island, as I have shown above.  There are erratics on the beaches.  There are scratches on cobbles which I have interpreted as striations.  And they have not demonstrated that the flow structures seen are "atypical of till" -- this is not a lodgement till or a true flow till, but a till laid down in a wasting ice environment, which was mobile during deposition and then subject to a degree of remobilisation or rearrangement following ice wastage. In that respect it is typical of most of the till exposures of West Wales.

The "preferred explanation" of the till -- namely that it is "a discrete single-lithology periglacial diamicton"  is so convoluted that it is slightly embarrassing!  Is this how the authors would explain the other clifftop diamictons on the south Pembrokeshire coast, or the similar diamictons on the north coasts of the Isles of Scilly?  In my view, if there had been Anglian or other ancient tills littering the ground surface of the Caldey limestone plateau, they would have been "locked in" by interglacial carbonate cementation processes and would not have been available for periglacial redistribution.

Unfortunately, the authors appear to have been so concerned about the implications of fresh Devensian till in this part of the Bristol Channel that they have refused to believe the evidence of their own eyes!  Occam's Razor, chaps.  This looks like a fresh till and it is a fresh till -- and there was Devensian Irish Sea ice in this part of the Bristol Channel around 20,000 years ago.

Finally, this is where some work needs to be done -- in Drinkim Bay, south of Ballums Bay.  I was not able to look at it last time because of tidal and time constraints, but it looks as if there are exposed sediments and platform traces there........

What MPP thinks

Thanks to Tony for drawing this to our attention -- it dates from 2013, but it is still interesting as an insight as to what drives our favourite quarryman........

It would have been nice if the interviewers had been capable of critical thought and independent scrutiny, to the extent of asking him about his "evidence" for bluestone quarrying -- but maybe that would have been too much to ask.

https://pia-journal.co.uk/articles/10.5334/pia.401/

Mike Parker Pearson is the Institute of Archaeology’s newly appointed Professor of British Later Prehistory. In this interview he reflects on his experience at the birth of post-processualism, current problems and opportunities in modern archaeology, and the subject for which he is best known: Stonehenge.
Williams, T.J.T. and Koriech, H., 2013. Interview with Mike Parker Pearson. Papers from the Institute of Archaeology, 22, pp.39–47. 

DOI:http://doi.org/10.5334/pia.401

I just love all this stuff about post-processualism........ it goes some way towards explaining why MPP and his colleagues seem to think that evidence is really rather unimportant, and that narratives are all that matter.......

Caldey Island till — and this blog becomes respectable

The current version of my map showing the proposed Devensian ice edge in Pembrokeshire.  This was published last year, and I still think it is more or less correct......

The Ballums Bay till exposure which has been examined by John Hiemstra and his colleagues

Erratics from the Ballums Bay till

In the latest peer-reviewed issue of Quaternary Newsletter (June 2019) there is an article published by  assorted craggy academics whom I greatly respect:

John F. Hiemstra, Richard A. Shakesby, Geraint Owen and Simon J Carr, 2019.  CALDEY (‘KALD EY’ IN OLD NORSE) WAS LITERALLY A ‘COLD ISLAND’, BUT WAS IT UNDER DEVENSIAN ICE?

Quaternary Newsletter Vol. 148 June 2019, pp 21-31

It’s behind a wall at the moment — available only to QRA members, but I hope one or another of the authors will put it onto Researchgate or Academia.edu.

They were responding to a call I made some time ago for some “bright young things” (in other words,  enthusiastic young glacial geomorphologists) to take a look at South Pembrokeshire in general and Caldey Island in particular, with a view to sorting out the glacial sequence there.  Since they have done a lot of work on the Gower Peninsula — not so very far away — they were understandably intrigued by my identification of a Devensian till on Caldey, since to accept it as such would imply a major realignment of glacial limits in the Bristol Channel region.  It’s a detailed and highly professional paper which is also good-humoured, and that’s something one always likes to see.  But one very interesting feature of it is the citation of this blog on a number of occasions in the text.  The authors have clearly read many of my entries relating to Caldey Island and the Bristol Channel, and they have taken them seriously.  So I thank them for that.  Finally, an acceptance that a blog like this can be competent and capable of contributing to academic debate......

The paper starts with a summary of the various views on ice limits in the Bristol Channel and the SW approaches; my latest proposed Devensian limit is shown, but it is erroneously labelled as the “Cardigan Bay ice lobe”.  I have never called it that, and have referred to it on a number of occasions as the Bristol Channel lobe or the Carmarthen Bay lobe. That’s a minor point.  But the authors do correctly refer to my view that the Devensian ice cannot, according to glacial theory and ice mechanics, have reached far to the south of the Scilly Isles without also pushing far to the east in the Bristol Channel and also impinging on the coasts of Devon and Cornwall.

The bulk of the paper deals with the small exposure of reddish till (which I refer to as the ORS facies) in Ballums Bay towards the eastern end of the island.  Following a field visit in 2016 the authors subjected the till (or diamicton, if you want to call it that) to a host of analytical procedures, after which they conclude that it is indeed a till.  But what sort of till, and of what age?  They consider two alternatives: Anglian or Devensian?  They argue quite convincingly that the till is probably Devensian, then they argue less convincingly that it might be Anglian, and then come down with the conclusion that the latter (older) age is to be preferred.

Much as I respect John Hiemstra and his colleagues, I do not agree with them. They have omitted two very important lines of evidence in their discussion:
1.  The regional context from Ballums Bay, other parts of Caldey, and the nearby mainland;
2.  The presence of cemented deposits in the neighbourhood, including raised beach and brecciated slope deposits and ancient till which are vastly different in appearance from the unconsolidated sandy till at Ballums Bay.

On the first point, there are other exposures of fresh till on the island, including one near the island landing stage. There are also abundant other exposures of fresh and unconsolidated till on the cliff tops of south Pembrokeshire and in coastal embayments, as I have shown in a series of posts on this blog.  (In fairness to John and his colleagues, most of these posts were published last year — maybe after this article was written.). These other deposits have not been analysed in detail, but they lie in the same stratigraphic position as the Ballums Bay till, and share many of the same physical characteristics.  They are not clay-rich lodgment tills but flow tills and ablation till subjected to varying degrees of "rearrangement" or redeposition following initial emplacement.  If these deposits are of Anglian age, why are they not overlain by Ipswichian interglacial deposits and periglacial and other deposits dating from the Devensian cold period?
See these posts:

https://brian-mountainman.blogspot.com/2011/08/devensian-till-at-bullums-bay-caldey.html  (this is the post which is cited in the new QN article)

https://brian-mountainman.blogspot.com/2011/08/glaciation-of-caldey.html

https://brian-mountainman.blogspot.com/2018/08/south-pembrokeshire-devensian-till.html

https://brian-mountainman.blogspot.com/2018/04/the-devensian-ice-limit-in.html

https://brian-mountainman.blogspot.com/2018/04/strange-till-near-stackpole-head.html

https://brian-mountainman.blogspot.com/2018/08/more-south-pembrokeshire-till-locations.html

https://brian-mountainman.blogspot.com/2018/04/even-more-south-pembrokeshire-till.html

https://brian-mountainman.blogspot.com/2017/03/the-south-pembrokeshire-lgm-again.html

The exposure of reddish Caldey Island till near the landing stage.  This has similar colouring and other characteristics as the Ballums Bay exposure

On the second point, it’s a pity that the authors have not visited Lydstep and Black Mixen.  If they had, I venture to suggest that they would have come away convinced that there are TWO tills in South Pembrokeshire, one cemented with calcium carbonate or iron oxide / manganese oxide cement, and the other unconsolidated.  Both tills are visible at Lydstep.  If the Ballums Bay till had been laid down during the Anglian Glaciation, I am convinced that it would by now have been solidly cemented, given that it rests on Carboniferous Limestone.  Only 50m away, on the south side of the bay, there are solidly cemented brecciated slope deposits which appear — by correlation with other S Pembrokeshire exposures — to be of Ipswichian or Early Devensian age.  If the Ballums Bay till is even older, and deemed to be of Anglian age, why is it not also cemented, located as it is in a gully where water flow -- and thence carbonate precipitation -- would have been considerable?

Solidly cemented Anglian (?) till at Black Mixen, Lydstep.

See these posts:

https://brian-mountainman.blogspot.com/2018/03/lydstep-headland-key-quaternary-site.html

https://brian-mountainman.blogspot.com/2018/05/lydstep-ancient-till-site-confirmed.html

https://brian-mountainman.blogspot.com/2018/05/devensian-till-at-lydstep.html

https://brian-mountainman.blogspot.com/2018/11/on-significance-of-cementation.html

So this is a detailed and welcome paper, which draws attention to an important site — but some of the lines of reasoning are questionable, and I think the authors have got their tentative conclusion all wrong!

Suggested relationships of ice masses during the LGM in the Bristol Channel area (my map, not that of Hiemstra et al)

PS.  In 1905 EL Dixon wrote of Bullum's Bay: "..... the glacial deposit appears to overlie the raised beach, although the exposure is obscure, and the evidence of superposition is not so conclusive as in Gower." (Summary of Progress for 1905, Mem Geol Surv, p 70).  This is my impression too -- but excavation will be needed to establish where the till lies with respect to the cemented limestone breccia just around the corner towards the south.  Is there a cemented raised beach too?  I think so, but I must look back at my field notes for reassurance.  I'm surprised that the authors of the new paper make no mention of the local sedimentary stratigraphy -- which in itself suggests a Devensian age for the till:

6. Modern soil
5. Sandy loess or brickearth (c 1m thick)
4. Reddish till with ORS and other erratics (c 3m thick).  This is the till now analysed.
3. Blocky broken limestone head (up to 2m thick)
2. Concreted raised beach and included angular limestone fragments (up to 50 cms thick)
1. eroded raised beach platform up to 10m above MSL.

There is nowhere where you can see this full sequence, but bits of it (including other patches of till) can also be seen in the cliffs to the south of the main exposure.

New bluestones papers

There are two new bluestone papers (or at least, papers mentioning bluestones) in the WANH magazine recently published.  The first one, by Andrew Powell, is about discoveries made beneath the old road surface adjacent to Stonehenge.  Rob Ixer was brought in to look at the characteristics of some of the debitage;  there is an appendix in which a number of samples are discussed, including some which are of igneous or volcanic origin.  Four of the discovered fragments are assigned with complete certainty to Rhosyfelin, but we are not shown any thin sections, and we may therefore dismiss the provenancing as wishful thinking.  Not for the first time.  Other samples have probably come from other locations within the north Pembs outcrops of Fishguard volcanics, either within Preseli or further afield.  There is one lump of rhyolite weighing in at around 500 g -- it does not look like a piece knocked off during the shaping of the bluestones at Stonehenge, and one wonders whether there are abundant other bits of "bluestone litter" lying about which might have come from ancient glacial deposits. This, of course, is one of the scenarios which certain geologists steadfastly refuse to consider......... 

In the second paper, Ixer and his colleagues look (again!) at the Altar Stone and related samples and debitage, and admit that the previous emphasis on the infamous sample 277 may well have led to confusion and even erroneous conclusions.  They suggest that other samples probably have come from the Altar Stone or from debris related to it.  They also push the idea (yet again) that the Altar Stone came from the Senni Beds near the eastern end of the South Wales outcrop, maybe near Abergavenny.  But as far as I can see from the article, there is no evidence of any sort to support this contention.  Other researchers are also looking into the problem of the Altar Stone -- watch this space........

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

Along the road to Stonehenge: investigations of the Stonehenge Avenue and within the World Heritage Site
by Andrew B. Powell
with contributions by Phil Harding, L Higbee, Rob Ixer, Matt Leivers, Inés López-Dóriga, Lorraine Mepham and David Norcott, and illustrations by Rob Goller. 

Wilts Archaeology and Natural Hist Mag, vol. 112 (2019), pp. 197–216

ABSTRACT

Archaeological mitigation works undertaken for the Stonehenge Environmental Improvements Project involved the excavation of two sections across the Stonehenge Avenue within the line of the former A344 road. This showed that while the Avenue’s banks had been levelled during the road’s construction it appears to have had little impact on its ditches, which in form, fills and contents closely match previously excavated sections on either side of the road. Excavation of the edge of the Heel Stone ditch also showed limited impact.

Works in the area of Airman’s Corner, close to the new Stonehenge Visitor Centre, which included the lifting, restoration and relocation of the Grade II listed Airman’s Cross memorial, and of a milestone, revealed a large quarry-like feature. This may have provided embankment material for the Salisbury to Devizes road (A360) at the point where it crossed a dry valley, as part of improvements to the road when it was turnpiked c. 1760. At some later date, the partly infilled quarry was used as a burnbaking site, at which turves were burnt to produces ashes for spreading on land newly turned from pasture to arable, a change in agricultural practice that was to cause lasting damage to many archaeological sites in the Stonehenge landscape.

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

Alternative Altar Stones? Carbonate-cemented micaceous sandstones from the Stonehenge Landscape
by Rob Ixer, Richard Bevins, Peter Turner, Matthew Power and Duncan Pirrie .

Wilts Archaeology and Natural Hist Mag, vol. 112 (2019), pp. 1-13

Abstract

The six-tonne recumbent Altar Stone is perhaps the most enigmatic of all the Stonehenge bluestones, differing markedly from the others in size, tonnage, lithology and origin. It has therefore had more than its fair share of speculation on all of these aspects and many questions remain: was it always recumbent, was it a singleton or half a twin, where did it come from? Clearly it is not from the Preseli Hills hence the debate as to its geographical origins for over a century. However, any provenancing of the Altar Stone must rely on a detailed and accurate lithological and petrographical description. New descriptions of material labelled ‘Altar Stone’ held in museum collections and a re-evaluation of suggested Altar Stone debitage using automated scanning electron microscopy and linked energy dispersive analysis using QEMSCAN technology suggests that modification of the published petrographical descriptions is needed. A new ‘typical Altar Stone’ description is provided including the presence of early cementing barite and a better characterisation of the clay content. These new data should continue to narrow the search for the geographical origin of the Altar Stone, one that is expected to be at the eastern end of the Senni Formation outcrop, an outcrop that reaches as far east as Abergavenny in the Welsh Marches.
https://s3.amazonaws.com/academia.edu.documents/37280878/38_knock_offs.pdf

Waun Mawn and the Stonehenge fantasy

Waun Mawn -- stone sockets or handy little holes created by the archaeologists?

REVIEW

Waun Mawn stone circle: the Welsh origins of Stonehenge
Interim report of the 2018 season

By Mike Parker Pearson, Josh Pollard, Colin Richards, Kate Welham, Dave Shaw, Ellen Simmons and Adam Stanford

https://www.bluestonebrewing.co.uk/wp-content/uploads/2019/05/Waun-Mawn-2018-interim-report-lite.pdf

This is a strange interim report — with some bits pasted in from a 2017 Report, and other bits clearly inserted just to please the funding organisations and selected parts of the archaeological establishment. The whole thing is delivered with a degree of certainty that borders on arrogance — and as in the other publications from this team, there is no mention of the fact that there is a major dispute going on with regard to the “bluestone quarrying” issue, which is of course crucial to the matter of the supposed Waun Mawn “great stone circle.” (Readers of this blog will recall that the discovery of a circle of bluestones became necessary because the radiocarbon evidence from Rhosyfelin and Carn Goedog was so confusing and inconclusive that nobody could make head or tail of it. As far as most of us are concerned, the quarrying hypothesis was actually falsified by the radiocarbon evidence produced from the two sites by the diggers themselves — but they steadfastly refuse to acknowledge that……. So on they plough, in the hope that somebody out there still believes them.)


—————————————
Here is the summary:

Summary

One of the great mysteries of prehistory is why Stonehenge’s ‘bluestones’ came from over 140 miles away in west Wales. While Stonehenge’s sarsen stones are thought to be local to the Avebury area, 20 miles to the north, the smaller bluestones (mostly weighing 1-3 tons) came from the Preseli hills of west Wales. Our aim is to find out why Stonehenge was built of stones from such distant sources.

Over the last seven years, the Stones of Stonehenge project has identified and excavated two of the outcrops from which bluestones were quarried in c.3300-3000BC, before these megaliths were erected at Stonehenge in its first stage in c.3000-2920 BC. Archaeologists and geologists have hypothesised that Stonehenge’s bluestones might have first been erected as a stone circle in west Wales, that was later dismantled and moved to Salisbury Plain, rather than being brought directly from their quarries.

Archaeological excavations at the partial stone circle at Waun Mawn uncovered stone holes of two of its four remaining monoliths and revealed 12 further features extending beyond the ends of the arc of monoliths. Six of these features were holes for standing stones removed in antiquity. Radiocarbon and optically stimulated luminescence (OSL) dates are awaited for samples taken from these features at Waun Mawn.

Together with the four remaining monoliths at Waun Mawn, the six stone sockets excavated in 2018 form part of a former stone circle with a diameter of c.110m. This makes Waun Mawn the third largest stone circle known in Britain.

The empty sockets contained the imprint of the monoliths that had each stood in these holes. They range in size from 0.2m across to 0.6m across and were mostly held in place with packing stones before their removal at some point in antiquity before the growth of peat. The largest of these stones had an unusual pentagonal-shaped base which can be matched with Stone 62 at Stonehenge. A large flake of dolerite that appears to have become detached from the Waun Mawn monolith during its erection or removal, is of the same type of rock as that of Stone 62 at Stonehenge.

Further links with Stonehenge are provided by the discovery that one of the former standing stones on the northeast sector of the circle, singled out by its construction on a mound, is potentially aligned from the circle’s centre towards either midsummer solstice sunrise or northern major moonrise. The stone’s location is enhanced by its placement on top of a low artificial mound. Secondly, the diameter of Waun Mawn circle is the same as the diameter of Stonehenge’s perimeter ditch; no other Neolithic monuments in Britain are known to share this diameter.

Like the other great stone circles of Britain, Waun Mawn is expected to date to the Neolithic around 3000 BC. Together with a Neolithic causewayed enclosure at Banc Du, a Neolithic palisaded enclosure at Dryslwyn, and seven Neolithic tombs, it forms a major ceremonial complex within the Preseli hills and their environs. This provides a new insight into the significance of the source of Stonehenge’s bluestones, and raises interesting new questions about the relationship of this complex with that on Salisbury Plain, such as why Stonehenge was built out of one or more second-hand monuments.

————————————————————————

Let’s ignore that for the moment and concentrate on the meat of the report.

Research goals as identified by the team:

"The project’s overall goals are:
1. To investigate the source area of Stonehenge’s bluestone monoliths in the Preseli hills, identifying megalith quarries and locating other Neolithic sites and monuments associated with bluestones.
2. To discover whether the bluestones were incorporated initially into one or more Pembrokeshire monuments before being transported to Wiltshire.
3. To explore the quarrying of the bluestones in Preseli and their subsequent use, including their journey to Stonehenge, to clarify the purpose of Stonehenge.

In 2017 our specific goal was:
1. To establish whether an arc of four standing stones (Waun Mawn) forms the remains of a dismantled Neolithic stone circle where bluestones were first erected before being moved to Stonehenge."

At the outset there is a bland statement that certain of the Stonehenge bluestones have been accurately provenances to the Rhosyfelin and Carn Goedog; that is a falsehood — the geologists have made certain claims, but the provenancing is not at all certain. Then they say: "Remains of megalith-quarrying at these two outcrops have been dated to the period shortly before 3000 BC.” As pointed out above, this is also a falsehood — the dating points to intermittent occupation of the sites over a long period of time, but it does NOT point to megalith quarrying.

There follows a description of the geographical setting of Waun Mawn, carefully engineered to demonstrate a likelihood that something of Neolithic significance should be sited here! There is an assumption that Waun Mawn was once covered by blanket bog — I doubt that. There is reference to the underlying bedrock of Aber Mawr shales or meta-mudstones, but no mention is made of the immediately adjacent outcrops of dolerite — presumably because it is the intention of the research team to demonstrate that all of the large stones on this site were carried in from a long way off, rather than simply being picked up from a few metres away. What is the point of this strange and unscientific obsession?  I have been very critical of this “induced blindness” before, here:

https://brian-mountainman.blogspot.com/2018/05/waun-mawn-and-invisible-dolerites.html

This is interesting:
"Magnetometer and earth resistance surveys at Waun Mawn in 2011 failed to identify any sub-surface features that might be stone sockets extending the length of the arc, and these negative results were put down to the problems created by podzolisation. Further surveys in 2018, employing electro-magnetic induction, ground-penetrating radar and earth resistance, also failed to identify any significant anomalies that could be interpreted as stone holes of a dismantled stone circle.”

 It does not seem to have occurred to the team that the failure to find a stone circle may have simply been down to the fact that there isn’t one now and that there never was one…………..

Nonetheless, they battle on with utter conviction. and in the following section. Under “Findings” they make no attempt to present their evidence or to interpret it in a scientific or empirical fashion. That’s not their style. Instead, they say that in addition to the holes belonging to two recumbent monoliths, they have found 12 new “features” which are described with complete conviction thus:
"Six of these features were holes for standing stones removed in antiquity. Together with the four remaining monoliths, they were part of a former stone circle with a diameter of 110m. This makes Waun Mawn the third largest stone circle known in Britain."

The “features” are described in turn, with no discussion or analysis of the “evidence”. There are copious references to sockets, ramps, packing stones, infills, imprints and so on, with particular emphasis concentrated on stoneholes 007, 015, 021, 030, 017, 037 and 091.  I have examined all of these, and have found them singularly unconvincing — and no attempt is made by the authors to show us that the “sockets” and associated features are in any substantial way different from a multitude of other slight pits and depressions across this moorland — and indeed others exposed during the 2017 and 2018 digs. Where are the controls? And where is the reasoned argument pointing to these features being man-made? As the authors admit, they have discovered no artefacts in the pits and there is no clear archaeology which might help their arguments.

The largest of the 2018 excavations -- is that a stonehole?  Some people think so....

With regard to two of the recumbent stones, Richard Bevins has stated that the largest one (of unspotted dolerite) is likely to have come from Cerrigmarchogion. He then says that the smallest recumbent stone (of speckled or spotted dolerite) might have come from Mynydd-bach. Are these simply opinions or has Richard actually undertaken sampling and petrographic analyses? It remains to be seen how strong the evidence might be for these two bits of speculative provenancing.

This is interesting, with respect to “stonehole 091”: "Its extraction hole was then filled with a sequence of secondary fills containing over 40 struck dolerite flakes. One of these was a large stone flake (22.9cm x 8.4cm) aligned longitudinally along the eastern side of the extraction ramp. With its weathered cortex on its exterior face, it may have been an unintentional removal, detached from the standing stone as it was pulled out of the hole. As with all the other flakes from stonehole 091, it is of unspotted dolerite…….” Are these genuine struck flakes, or are they simply dolerite fragments contained within the local till that covers the whole site? Having seen some of the things referred to as “artefacts” at Rhosyfelin and Carn Goedog, I admit to a degree of scepticism! It would not be at all surprising to find dolerite fragments and cobbles within the local till. We may or may not ever get to see the evidence.

This is also interesting: "Artefacts found in close proximity (within 2–3m) of stonehole 091 consist of a flint scraper (SF40), a piece of worked flint (SF1) and a trimmed circular mudstone disc (SF3). The mudstone disc is very similar to three such artefacts found in Neolithic levels at Carn Goedog megalith quarry.” Two bits of flint and a “mudstone disc” may or not be artefacts — let’s see how strong the evidence is when and if it is published.

Other attempts to demonstrate human involvement in the creation of micro-features include reference to an “artificial mound” and a “sunken trackway” which seem no less fanciful than the "engineering features” described at Rhosyfelin and Carn Goedog.

Later, in the discussion, we get another gigantic leap of the imagination: "The pentagonal-sided imprint of the standing stone (BJ: presumably that means the one stone still standing) is highly unusual and can be matched in size and shape by just two bluestones at Stonehenge. One of these, Stone 62, is also of unspotted dolerite. Quite possibly, Stone 62 is the stone that stood originally in stonehole 091 at Waun Mawn.”

The "pentagonal" remaining standing stone at Waun Mawn.  Was one like this taken from pit 091 and then put up again as stone 62 at Stonehenge?  The latest MPP speculative leap...........

Then this: "The fact that Waun Mawn stone circle has the same diameter as the perimeter ditch of Stonehenge is also highly suggestive of a close link between these two monuments. No other Neolithic monument in Britain shares this same diameter.” Well, yes and no — there are many approximate concentric rings at Stonehenge, and many stone settings from other parts of the UK can be “matched” with one or another of them. The Waun Mawn circle — if there was one —was substantially larger than the largest stone setting at Stonehenge.

The conclusion is typical of the MPP team:

"The confirmation of Waun Mawn as one of Britain’s former great stone circles changes our understanding of the considerable significance of the Preseli region during the Middle–Late Neolithic. The importance of north Pembrokeshire in the Early Neolithic has long been recognised on the basis of the extraordinary concentration of portal dolmens and other megalithic tombs in this area (Lynch 1972; Barker 1992), recently enhanced by Darvill and Wainwright’s excavations of a causewayed enclosure at Banc Du (Darvill et al. 2005: 22–3; 2007; Darvill and Wainwright 2016: 75–6) and a palisaded enclosure at Dryslwyn (Darvill and Wainwright 2016: 76).

"Around 3000 BC, there was further activity both at the bluestone megalith quarries of Craig Rhos-y-felin and Carn Goedog (Parker Pearson et al. in press) as well as at the Banc Du causewayed enclosure where its ditch was re-cut in 3105–2915 cal BC (Darvill et al. 2005: 22–3; 2007; Darvill & Wainwright 2016: 75–6; Whittle et al. 2011: 526–7), coinciding with the ending of megalith-quarrying at Carn Goedog and with the erection of bluestones in the Aubrey Holes at Stonehenge. The recognition that Britain’s third largest stone circle was built here in Preseli, a stone’s pull from two bluestone quarries, leaves us in no doubt that this was one of the great religious and political centres of Neolithic Britain when the bluestones were taken to Stonehenge. Whether Waun Mawn stone circle was left unfinished may give us a major clue to the social circumstances that led to the remarkable decision to move up to 80 bluestones to Stonehenge.”

Every sentence in there deserves to be carved up or ripped to shreds — but now I’m fed up. Suffice to say that there may have been a more extensive stone setting at Waun Mawn, a bit like that at Castlerigg or Swinside.  Then again, maybe not. The evidence presented thus far is, to put it mildly, less than convincing. And there is NOTHING at Waun Mawn to suggest any link at all with Stonehenge.

https://brian-mountainman.blogspot.com/2018/05/castlelrigg-and-swinside.html

Interim 2018 dig report from the "great circle" hunters.........

Courtesy of Bluestone Brewery, just up the road, the interim report from MPP et al on the 2018 dig is now in the public domain.  He confirms that there will be no dig this year, but expresses the hope that the diggers will be back in 2020.  Here we go again.........

I'm a bit pushed for time at the moment, but here is a link for those who want to take a look.  My initial impression is that MPP is as determined as ever to ignore the fact that much of his bluestone quarrying / Stonehenge / Waun Mawn  evidence is hotly disputed.  We have looked at these irregular indentations in the ground before, in earlier posts, and one has to admire the sheer effrontery of these guys in claiming without a shadow of a doubt that they are stone holes or sockets that once held monoliths!  I wonder if any other archaeologists have looked at them, and agreed?  Anyway, enjoy, and I shall come back to this in more detail in due course.

https://www.bluestonebrewing.co.uk/wp-content/uploads/2019/05/Waun-Mawn-2018-interim-report-lite.pdf

By the way, MPP is giving his annual jolly brewery talk early this year, as it happens on my birthday, 27th July.  Happily I shall be away, doing a spot of quiet kayaking in the Stockholm Archipelago.

Anglesey and Pembrokeshire -- both subjected to areal scouring?

A comment from a mysterious contributor the other day has got me thinking about the similarities and differences between Anglesey and Pembrokeshire with respect o the history of glaciation.  They are both lowlands located away from the bulk of the Welsh upland massif and its Welsh Ice Cap which waxed and waned during the Devensian glaciation and presumably during other glaciations as well.  In both regions superficial deposits are thin and scattered, and in both regions there are no marked uplands, and instead a sequence of undulating and gentle ridges and depressions which expose the "grain" of the country -- related in turn to the structures and textures of the underlying rock types.

Anglesey has quite prominent streamlined bedrock features, aligned broadly NE - SW, as noted in this article by Lee et al (2015):

Lee, J.R., Wakefield, O.J.W., Phillips, E. & Hughes, L. 2015. Sedimentary and structural evolution of a relict subglacial to subaerial drainage system and its hydrogeological implications: an example from Anglesey, north Wales, UK. Quaternary Science Reviews 109, 88-105.

http://nora.nerc.ac.uk/id/eprint/509384/1/Lee_et_al_QSR_2015.pdf

Quote:

The Quaternary deposits of Anglesey form a thin and discontinuous veneer that mantles the bedrock. The most prominent superficial deposit is a diamicton containing far-travelled erratic lithologies sourced from bedrock strata within and surrounding Irish Sea Basin. This diamicton is synonymous with the ‘Irish Sea till’ (Greenly, 1919; Campbell & Bowen, 1989; Williams, 2003; Thomas & Chiverrell, 2007; Phillips et al., 2010) which forms part of the Irish Sea Coast Subgroup of the Caledonia Glacigenic Group (McMillan & Merritt, 2012). The till was deposited extensively around the Irish Sea Basin by the Irish Sea Ice Stream during the Late Weichselian (Devensian; MIS 2) glaciation (Figure 1c). The overriding of Anglesey and the adjacent offshore area by the Irish Sea Ice Stream led to the sculpting of the substrate and development of streamlined bedrock features (e.g., streamlined bedrock, roche moutonée, rock-cored drumlins) and sediment- to bedrock-cored (e.g. drumlins) subglacial bedforms (Hart 1995; Thomas & Chiverrell, 2007; van Landeghem et al., 2009; Phillips et al., 2010). These landforms and locally-preserved glacial striae record an overall ice-movement direction from northeast to southwest across Anglesey. The Irish Sea Ice Stream was one of several ice streams that drained the interior of the last British Irish Ice Sheet (Figure 1c) (Evans et al., 2005; Bradwell et al., 2008; Hubbard et al., 2009; Clark, C.D. et al., 2012; Clark, J. et al., 2012). At its maximum extent (c.24-23 ka BP) the ice stream occupied much of the Irish Sea Basin and was fed by glaciers emanating from western Britain and eastern Ireland (Knight et al., 1999; Clark & Meehan, 2001; Hiemstra et al., 2006; Roberts et al., 2007; Greenwood & Clark, 2009; Scourse et al., 2009; Rijsdijk et al., 2010; Clark, J. et al., 2012; Chiverrell et al., 2013).

In Pembrokeshire the "grain" of the country is not so easy to pick up, except in the south.  If you look at the following maps, this is apparent. (Google Earth satellite images are not so easy to interpret, because they have too much clutter on them........)

Low definition LANDSAT image of Pembrokeshire.  On this, the grain can be picked up, but it is much clearer in the south.

A simplified map of the structure of Pembrokeshire, with info extracted from BGS mapping material.

The grain can be tied in with the features of the geology map, but note that the strips of Ordovician igneous rocks in the core of the Preseli uplands are NOT easy to pick up in the satellite imagery.

Now let's tie these images in with what we know about directions of ice movement across Pembrokeshire.

This map incorporates information from many sources on ice movement directions, and can be taken as representing a "best fit" for the Anglian Glaciation, around 450,000 years ago.

This map by JC Griffiths (1940) is based on erratic distributions, taking no account of possible zig-zag routes and movements of single erratics across several glacial episodes.  Note that there are differences with the "Anglian" map above.  

Griffiths has Irish Sea ice coming across the north Pembrokeshire coast directly from the north.  He also shows central and southern Pembrokeshire affected by an ice stream flowing from NW towards SE. On the Anglian map we have a more westerly component, with ice moving from WNW towards ESE.

So what is the evidence for streamlining? I have to say that there is none in north Pembrokeshire, but that in south Pembrokeshire there is a degree of alignment between the "grain" of the country, the known structural trends, rock outcrops, and ice movement directions. Cause and effect?  Now that's very difficult to establish.............