The Blatten Glacier Disaster

Before.........

.... and after

There is a fascinating piece of reportage (with spectacular animation) on the BBC web site, relating to the recent disaster in the Swiss Alps.

https://www.bbc.co.uk/news/resources/idt-c7f929de-96a9-45e5-b1bb-31de82fce72d

Thank goodness there was no loss of life, since the idyllic village had already been evacuated, prior to the catastrophic event.  I thought, before I looked into this, that the "glacier collapse" took place in the upper part of a regenerated glacier, like that of Supphellebreen at Fjaerland in Norway -- but no, this was a very small and very dynamic independent glacier (Birch Glacier) in a high mountain environment.  High rates of snow accumulation, steep slopes, and rapid ice flow under the influence of gravity, on slopes dominated by frost shattering and rockfalls. Permafrost melting and rainfall in the Alps (as distinct from snowfall) were contributary factors in causing additional debris mobility.   

The old photos show a substantial fan of debris close to the village, with no clear terminal or other moraines.

There is no doubt at all that collapses like this will now occur with increasing regularity in all of the high mountain environments where there are thousands of vulnerable glaciers of this type.......

(For very good enlargements of the images, just click on them.)

The other evening.......

 Thanks to Lynne for this photo taken at the beginning of my talk the other evening at Canolfan Bethlehem, Newport.  There was an excellent response from the audience, which included many who have also heard MPP reporting on his "discoveries" during and after his September digs in North Pembs.

Just in -- the following comment:  ".........really enjoyed your talk last week. It was so engaging that I don't think anyone minded the hard pews! We thought the talk was a nicely balanced assessment of the pros and cons of all 'the available theories' about how the Bluestones were transported. You have, as one of my bosses used to say, 'relentless pounding logic' on your side. Very well done.

An Irish erratic near Cardigan?

 

I found this small erratic of Carboniferous Limestone in the Irish Sea till at Gwbert, near Cardigan, today.  It has two beautiful brachiopod fossils in it, and as befits a far-travelled stone its surface is covered in striations.  

Where has it come from?  The best bet is that it has come from somewhere in central Ireland, and limestones rich in braciopods seem to be especially common in the Burren area on the west coast.  Here is an example:

However, from what we know of past iceflow directions, a source somewhere near Dublin seems more likely:

Geological map opf Ireland -- the light blue tint shows the area of Carboniferous Limestone outcrops.

If the erratic really did come from Ireland, there must have been much more mixing of ice streams and erratic material in the Cardigan Bay -- St Georges Channel area than has been previously recognized............

We also have to consider Anglesey and the  North Wales coast as source areas, although the outcrops there are of very limited extent.  This is from the GeoMon Global Geopark web site:

.............highly fossiliferous limestones outcrop all long the east coast southwards from Lligwy to Penmon [and along the coast of North Wales from the Great Orme to Prestatyn]. These rocks were laid down in cycles as the sea transgressed and retreated as many as 11 times over North Wales. On Anglesey, only four of these cycles, which consist of limestone followed by sandy beds and then mudstone were deposited. The rocks are rich in brachiopods and corals and often exhibit palaeokarstic surfaces and rarer sandstone pipes.

An Anglesey origin for the erratic is, on balance, most likely since this accords most closely with the ice flow pattern shown on the map above.

An interesting dilemma.........

Gwbert raised beach platform

 

Down on the Teifi Estuary this morning checking out the situation on the east side of the river mouth. There used to be amazing exposures of Irish Sea till here (back in the 1960's) but they were destroyed with the building of new coastal defences and a new caravan park.  

The Irish Sea till is still there, in patches, resting on the old raised beach platforms which are still visible.  These are the counterparts of the raised beach platforms exposed at Poppit, on the other side of the river mouth.  There are occasional exposures of till, fluvio-glacial materials and slope breccia, but because there has been so much slumping it's almost impossible to see stratigraphic relationships. 

The higher parts of the raised beach platform seem to be well above the influence of current HWM coastal processes, so  I interpret the smoothing and rounding of bedrock undulations to glacial erosion prior to the deposition of the till.

The glaciated summit of Carn Llidi

 

 

Thanks to Hugh Thomas for posting this great pic, taken on the summit of Carn Llidi nearSt Davids.  Ice-smoothed summit mounds.  In the distance is Ramsey Island, also with glaciated summits -- the source of a great range of glacial erratics found in mid and south Pembrokeshire.

The latest on the bluestones..........

 

Tonight, 7 pm, at Canolfan Bethlehem, Newport.....

Erratic dispersal modelling -- the Irish Sea Ice Stream

Modelling erratic dispersal accounting for shifting ice flow geometries: A new method and explanations of erratic dispersal of the British–Irish Ice Sheet
R. L. Veness, C. D. Clark, J. C. Ely, J. L. Knight, A. Igneczi, S. L. BradleyVersion of Record online: 15 May 2025

https://doi.org/10.1002/jqs.3720

https://onlinelibrary.wiley.com/doi/epdf/10.1002/jqs.3720

ABSTRACT: Glacial erratics are geologically distinctive rocks transported away from their source area by ice sheets and deposited in lithologically different bedrock areas. They have attracted much scientific curiosity with >24 000 observations across the British Isles. A common misinterpretation is that they took a nearly direct line of transport from source to resting position, neglecting to change ice flow directions during ice sheet growth and decay. To rectify this, we sequentially modelled erratic time‐space trajectories at 1000‐year timesteps using ice flowlines in an empirically constrained ice sheet model simulation to predict erratic deposition areas. We addressed the processes of entrainment and deposition by combining all potential trajectories into a single footprint of possible locations. Erratic dispersal is predicted for three geologically distinctive lithologies; Shap Granite of Northern England, Galway Granite of Ireland and the Glen Fyne igneous complex from Scotland. The footprint of predicted trajectories compared against 1883 observations of erratic locations was found to successfully explain 77% of the observed erratics. Most erratics were explained by flow directions during ice retreat; however, some required earlier ice divide shifts to produce potentially long‐duration, multiphase pathways. Our analysis demonstrates the possibility of explaining many erratics without explicitly modelling the complex processes of entrainment and deposition.

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

This is an interesting paper in which the authors test a modelling exercise agtainst "ground truthing" for the distribution of erratics from three different bedrock sources -- one in Ireland, one in northern England, and one in western Scotland.   Figure 4 (at the head of this post) shows the latest version of the streamlines of the Irish Sea Ice Stream as far south as the Bristol Channel, predicting where distinctive erratics from the Loch Fyne igneous complex might be found.

See this post:

https://brian-mountainman.blogspot.com/2024/08/possible-altar-stone-sources.html

and this:

https://brian-mountainman.blogspot.com/2024/08/in-praise-of-ailsa-craig.html

This new work has a bearing on the Altar Stone debate -- including the possibility that it might have come from one of the ORS sandstone outcrops in the Midland Valley of Scotland or the Southern Uplands.   We already know a lot about the distribution of Ailsa Craig erratics -- this new work suggests that other erratics from much further north -- around Loch Fyne -- might also have found their way into the Bristol Channel and onto the coasts of SW England.

I must admit to being very intrigued by the postulated streamlines for South Pembrokeshire and the Bristol Channel and by the positions of the arrow tips.  There is no ground truthing to show that there ever was a significant ice edge position where it is shown on Figure 4.  And of course it is wildly improbable that erratic-carrying ice ever did swing round in Carmarthen Bay and move north-westwards onto the coast of SE Pembrokeshire -- ie directlly opposite to the direction of ice flow across the rest of the county.   The model that created the map clearly needs some tweaking........

The joy of quartz

An old wall on Parrog, Newport, topped with heavily abraded quartz boulders

A new wall on the other side of the road, also topped with abraded boulders -- in this case probably recycled........

On one of our walks on the Parrog in Newport, the other day, I was reminded of the fact that people just love quartz boulders and cobbles. In and around Newport they are used all over the place, mostly as wall toppings.  They are for the most part not "fresh" and angular, with sharp edges, but rounded or sub-rounded.  They have been for the most part collected from either beaches in the vicinity ( to the west of Parrog) or from old glacial and fluvio-glacial deposits.  Before the days of effective field clearance, the ground surface was littered with quartz boulders...............   

These boulders have not been used for ritual or religious purposes, or even for the enhancement of status  -- they have been used simply because they are ornamental and nice to look at.  They have not been "fetched" from quartz quarries or sacred places.  It's all about aesthetics...............

This brings to mind our discussions on this blog about the famous (infamous) quartz "facade" at Newgrange, made of boulders and cobbles rescued from the spoil when the work of "restoration" was under way.  Whether or not there was originally a quartz facade, most authorities seem to accept that the white boulders (some with cream colouration, some greyish, and some reddish) were used simply to enhance the appearance of the mound.  As I have argued before, the argument that the boulders were quarried from 60 miles away, in the Wicklow Hills, has never been supported by convincing evidence.  It;s much more likely that the boulders were simply collected up in the local landscape around the Newgrange site.

http://www.carrowkeel.com/sites/boyne/newgrange2a.html

Work in progress on the Newgrange site.  A perfect quarry.  Whitish quartz boulders were picked out specifically for the purpose of creating the white facade.

Fluidity and viscosity

 I came across this image of flowing lava in an eruption on Hawaii in 2010.  Lava is extremely hot, becoming more viscous as it cools down.  The fun thing is that ice behaves in a similar fashion when it is flowing at an optimal rate -- but then it ceases to flow when the temperature rises, so that melting, and the conversion to water, destroys the flow structures which are not dissimilar to those of flowing lava.

Lava flows, and glaciers, tend to seek out depressions and fill  them -- subsequently overflowing via cols or low points in the depression rims.

Most of the movement of ice occurs through internal deformation and basal sliding -- but there is also brittle fracture which results in crevasse formation, and the creation of shear fractures and thrust planes partucularly in cold or polar ice.

Here are a few images of flowing glacier ice in Arctic Canada and Alaska:

I have seen similar ephemeral features on small glaciers in East Greenland.

On smooth igneous rock surfaces

 This is one of my favourite photos, taken on the granite coast of Brittany, not far from Roscoff.  Look at the lovely smooth rock surfaces. This reminds us that not all smooth surfaces are glaciated or wave washed. Here we are about 20m above sea level, on a coastline that was not (as far as we know) ever affected by glacier ice during the Quaternary.

It is sometimes difficult to be sure of the origin of "glaciated slabs" unless there are striae or glacial grooves present.  On rock surfaces that have been exposed for thousands or even millions of years, a multitude of processes can operate in smoothing off sharp edges, rounding corners and eliminating rocky projections.   The age of a rock surface has a great deal to do with how it looks, as any desert geomorphology textbook will tell you........

Mind you, if a lump of rock in West Wales (or for that matter on Salisbury Plain) is genuinely derived from a Neolithic quarry, around 5,000 - 5,500 years ago, it sure as eggs would not look like this:

Stone 37, courtesy Simon Banton

The increasingly bizarre defence of Bluestone Orthodoxy

Our old friend Tim Daw continues his one-man defence of the bluestone quarrymen, mostly on his blog, which I ignore for most of the time.  He clearly likes to follow my utterances and writings, and posts rather frequent and very aggressive ripostes, while  in some cases being very reluctant indeed to mention me by name.  Weird, that.  Maybe he is afraid I might sue him..........  he need have no concerns on that score, since (unlike some of his cronies) I actually believe in the merits of open academic debate.

But the one-man hit squad is now behaving in a way which can only be described as bizarre.  First, back in March he hired an anonymous "referee" to review my two papers on the Limeslade erratic, and published it on his blog, here:

https://www.sarsen.org/2025/03/peer-reviewing-john-2025.html

Anonymous peer reviews in circumstances such as these are of course completely worthless, and I refuse to engage with this one.  If a reviewer does not wish to publish his / her name alongside disparaging and insulting comments, why should anybody take them seriously?   Shame on him / her for taking part in this grubby little stunt.  Maybe Tim wrote the review himself in spite of denying that he had anything to do with it?  Maybe it was written by a committee of aggrieved academics (Ixer, Bevins and Parker Pearson come to mind) and then put in the public domain with the pretence that it represented the opinion of somebody who is an "independent expert" in the field?  Who knows what goes on in the shadows..........

Then in April 2025 Tim published an anonymous rant entitled:  "A Critical Review of "Carn Goedog on Mynydd Preseli Was Not the Site of a Bluestone Megalith Quarry": Another Glacial Fantasy Masquerading as Scholarship."

https://www.sarsen.org/2025/04/a-critical-review-of-carn-goedog-on.html

Again there was no mention as to the name of the author, who spat out a great deal of  bile beneath a cloak of anonymity.

Then Tim wrote a riposte on the matter of far-travelled Bristol Channel coastal erratics, referring to my Limeslade erratic paper published in QN 162 (June 2024).   Tim's piece was clearly designed to show that the "high level erratics" cannot have been carried by glacier ice but must have been transported on ice floes and carried uphill by human beings.  (The ice floe transport idea is of course also promoted by James Scourse and others in previous publications.)  The latest blog post is here:

https://www.sarsen.org/search?updated-max=2025-04-21T13:49:00%2B01:00&max-results=7&start=7&by-date=false

and it refers to an "important article" -- written modestly by himself -- on the Researchgate web site:

https://www.researchgate.net/publication/390953838_Critical_Analysis_of_Claims_Regarding_High-Level_Glacial_Erratics_in_the_Bristol_Channel_and_the_Implication_for_the_Glacial_Transport_Theory_of_Stonehenge_Bluestones?channel=doi&linkId=6804ba5cdf0e3f544f42e7c7&showFulltext=true

This is referred to as a "preprint", which means of course that it has not been reviewed or assessed for quality.   Suffice to say that it is a very strange piece of work, filled with misunderstandings and unwarranted assumptions and obsessed with the 100m contour.  Boulders and erratic fragments found over that altitude are deemed to be worthy of consideration, and erratics beneath it are discounted as irrelevant.  The important work of Madgett, Inglis and others is cited but effectively discounted, as is my article in QN 164 (February 2025).  The reference list is strongly biased and selective.  There is no mention of the work of Bennett et al (2024), who are in no doubt that the ice of the Irish Sea Ice Stream did affect the coasts on the southern shore of the Bristol Channel.

 I just cannot understand what Tim is on about here;  why is he so obsessed with demonstrating that flowing glacier ice did not affect the Bristol Channel coasts, when everybody knows that the evidence demonstrates otherwise?

Then, also in April,  Tim published three further reviews of my papers on Rhosyfelin, Carn Goedog and Waun Mawn:

https://www.sarsen.org/2025/04/a-review-of-brian-johns-2015-paper.html

https://www.sarsen.org/2025/04/a-review-of-brian-johns-2024-paper.html

https://www.sarsen.org/2025/04/a-review-of-carn-goedog-on-mynydd.html

No authorship is revealed for any of these weird critiques, and so they can be dismissed without further ado.  They might of course have beern generated through some AI programme, but that does mot make them any more meaningful, since we do not have any idea what prompts and editing adjustments there might have been, and we have no sight of any of the reviews that might have been commissioned from the same AI source for articles written by MPP and his team.  Now THAT would be an interesting exercise...........

The AI question comes up again in a very strange article published in Researchgate with the joint authors shown as Tim Daw and "Groc":

https://www.researchgate.net/publication/390662999_A_Review_of_Brian_John's_Three_Papers_on_Bluestone_Quarrying_Sites

It turns out that Groc is an AI bot, and that his (???)  contribution was prompted and edited by Tim. In other words, it is a meaningless exercise which has no value as a piece of independent and unbiased research.

What on earth is this article doing on the Researchgate web site?  I am contacting the moderators to check out what their policy on AI might be, and to ask for the removal of something that makes no pretence at all to represent original scientific thought or process.

So there we are then.  Tim's mission of character assassination continues at an accelerating pace, but at least he has the good grace to use his own name.  But it's sad to see that he now has to resort to AI to do his thinking for him.  As for those who use Tim's blog site to  publish abusive rants directed at me personally while sheltering beneath a cloak of anonymity, they are beneath contempt.  And shame on Tim for allowing it to happen. 

.

Another top Pembrokeshire erratic

 

 

This is one I forgot about -- at Martin's Haven, on the lane leading down to the departure point for the Skomer boats. 

It's an inscribed stone,  and it looks to me like an Ordovician dolerite erratic from the St David's Peninsula.  It may be water worn, but to me it looks like just another glacial erratic.........

Newport lecture, May 22nd

 

As one archaeologist said to another.........

 Thanks for Hugh Thomas for posting this one.  Very instructive.......

Inaugural Rhosygilwen Easter Lecture: The Bluestone Mystery

 

I'm honoured to be invited to give the inaugural Easter Lecture at Rhosygilwen tomorrow evening (7.30 pm) -- on the subject of the Stonehenge bluestones.

I'll talk about the modern mythology invented by Prof MPP and others, and scrutinize the science of the stones, some of which is I think pretty sound and some of which is distinctly dodgy.

I'm hoping for a good turnout, and I'll be using the evening to raise money for my favourite charity -- which is SHELTER.

If you live in West Wales, feel free to come along and join the fun........

Another Welsh Triad: the Three Great Preseli Bluestone Disputations

The bluestone quarrying myth:  three sites and three detailed rebuttals

Just published:


Brian John (2025). Carn Goedog on Mynydd Preseli Was Not the Site of a Bluestone Megalith Quarry.  Archaeology in Wales,  March 2025, 14 pp 

https://www.researchgate.net/publication/390565216_Carn_Goedog_on_Mynydd_Preseli_was_not_the_site_of_a_Bluestone_Megalith_Quarry 

Abstract

This paper examines the hypothesis that Carn Goedog, a prominent tor on the north flank of Mynydd Preseli in Pembrokeshire, Wales, was the site of a Neolithic quarry from which Stonehenge bluestones were extracted on a large scale. The dolerite sills in the area are geochemically heterogenous, with multiple outcrops. Claims of “precise provenancing” of Stonehenge spotted dolerite fragments to Carn Goedog are questionable. Geomorphological studies on the tor reveal that pillars suitable for use as monoliths are restricted to a few small areas, difficult to access. Frost-shattered blocks dominate. Many have sub-rounded edges, suggesting long-term weathering and redistribution by glacier ice. Moulded and smoothed surfaces indicate that the influence of over-riding ice associated with the Irish Sea Ice Stream has been considerable. Examinations of the supposed “Neolithic quarry” site reveal that many of the “engineering features” may be natural. The materials referred to as stone artefacts are not obviously related to quarrying activities, but may instead point to a history of intermittent occupation. The soft shale “wedges” supposedly used for extracting pillars from the rock face may be natural and are ubiquitous. Radiocarbon dating does not appear to support the quarrying hypothesis. Thus the evidence for a Neolithic quarry at Carn Goedog is poor. If blocks and pillars of spotted dolerite were indeed extracted and transported away from the vicinity of the tor in prehistory, the agency is most likely to have been glacier ice.

This is the first detailed examination of the Carn Goedog quarrying hypothesis to be published in a peer-reviewed journal.  Thanks are due to the Editor of the journal, and his anonymous reviewers, for their perceptive and constructive comments which have improved the paper.

With the publication of this article we complete the scrutiny of the  thre crucial sites that have been cited over and again in support of the quarring / lost circle / human transport hypothesis of Parker Pearson et al.    At Craig Rhosyfelin, Waun Mawn and Carn Goedog we have examined the geology, geomorphology and archaeology, and have found a multitude of assumptions and speculations but nothing in the way of hard evidence to support what is now seen as an extended and convoluted myth invented by a small team driven by a ruling hypothesis.

The two earlier papers can be found here:

John, B S, Elis-Gruffydd, D & Downes, J, 2015b, Observations on the supposed Neolithic Bluestone Quarry at Craig Rhos-y-felin, Pembrokeshire, Archaeology in Wales 54, 139-148.

https://www.researchgate.net/publication/286775899_OBSERVATIONS_ON_THE_SUPPOSED_NEOLITHIC_BLUESTONE_QUARRY_AT_CRAIG_RHOSYFELIN_PEMBROKESHIRE

John, B S, 2024a, The Stonehenge bluestones did not come from Waun Mawn in West Wales, The Holocene, 34 (7), 20 March 2024.

https://www.researchgate.net/publication/379121966_The_Stonehenge_bluestones_did_not_come_from_Waun_Mawn_in_West_Wales

As we have pointed out many times before on this blog, Parker Pearson, Bevins, Ixer and their colleagues have pretended, in one publication after another, that their ideas are not just widely accepted but free of any scrutiny or criticism from any direction.  That is just plain silly, as well as demonstrating a cavalier disregard for academic convention.  It is a mystery to me why this small group of academics living in their own little bubble have been allowed to get away with it by a complacent and conniving academic establishment.  Are they all so obsessed with their acceptance of the establishment narrative that they cannot accept that "other interpretations are available"?  Are they all blissfully unaware of the extent of their own delusions?

Anyway, we now have three key sites and three key rebuttals of the narrative developed by MPP and his team.  For how much longer, I wonder, will they continue to inhabit their fantasy world before they are forced to confront reality?

Archaeological mythology and the Welsh Triads

• One of the Three Fantastical Places of 
• Powerful Stone.........

In Wales, things come in threes.  To quote from the Prydain Wiki:

The Welsh Triads (Welsh Trioedd Ynys Prydein, literally "Triads of the Island of Britain") are a group of related texts in medieval manuscripts which preserve fragments of Welsh folklore, mythology and traditional history in groups of three. The triad is a rhetorical form whereby objects are grouped together in threes, with a heading indicating the point of likeness.

https://prydain.fandom.com/wiki/Welsh_Triads

According to Wikipedia:

Some triads simply give a list of three characters with something in common (such as "the three frivolous bards of the island of Britain" while others include substantial narrative explanation. The triad form probably originated amongst the Welsh bards or poets as a mnemonic aid in composing their poems and stories, and later became a rhetorical device of Welsh literature. The Medieval Welsh tale Culhwch and Olwen has many triads embedded in its narrative.

https://en.wikipedia.org/wiki/Welsh_Triads

I remember reading the classic work of Rachel Bromwich many years ago, and being greatly intrigued by it. What's not to like about the three princes of the Court of Arthur, or the three bulls of battle of the Island of Prydain, or the three arrogant ones, or the three atrocious assassinations, or the three great illusions?  

See also:

https://www.maryjones.us/ctexts/triads2.html

Bearing in mind that tales and myths are not necessarily old, and they they continue to be created, we come to the three Great Fabricators, Michael of the East, Robert of the Middle and Richard of the West.  And behold the tale of the Three Fantastical Places of Powerful Stone, known as Rhosyfelin, Carn Goedog and Waun Mawn..........

Monolith extraction pits at Stonehenge?

The honeycomb chalk debris surface.  I have seen no convincing evidence that demonstrates that these pits and hollows (or at least some of them) are not genuine stone extraction pits.

There has been some discussion lately, on social media, on the possible occurrence of one or more deep pits at Stonehenge, in amongst the stone settings -- indicative of the extraction of use of large stones.  This is not a new idea -- indeed, I had a discussion with Nick Snashall about this some years ago.

https://brian-mountainman.blogspot.com/2016/08/extraction-pits-solution-hollows-post.html

In that discussion, I was not at all convinced by the argument that genuine extraction pits are genuinely different in kind (ie in morphological features) to other pits that are man-made either as sockets or to accommodate packing stones etc...........

See  also:

https://brian-mountainman.blogspot.com/2013/08/where-did-stonehenge-sarsens-come-from.html

https://brian-mountainman.blogspot.com/2018/03/stonehenge-always-was-bit-of-mess.html

https://brian-mountainman.blogspot.com/2019/02/were-some-stonehenge-sarsens.html

The honeycomb characteristics of the chalky ground surface beneath the Stonehenge layer and other accumulations of detritus have always suggested to me that at least some of the surface indentations and elongated hollows might mark the places from which noth sarsens and bluestones have been extracted and rearranged.  There is the matter of the "stone 16 pit"......... or a pit that might have held stone 56......

In other words, there is a strong possibility that Stonehenge was simply built where it is because that is where the stones (or the bulk of them) were found...........

Some recent discussion has centred on a large "mystery pit" at the centre of Stonehenge, which has shown up in various excavations. Prof MPP thinks it is very intriguing, but Tim Daw thinks it is a genuine extraction pit, used for taking away the Lake House meteorite, which he speculates was found here. I'm not sure what the basis for that speculation might be.  But why could the pit not have been an extraction pit once occupied by one of the larger sarsens or even by one or more bluestones?

To quote Mike Pitts in "Digging Deeper":

https://brian-mountainman.blogspot.com/2018/04/pitts-and-very-ancient-sarsens.html

The idea is that there are two great pits at Stonehenge, larger than any other and both difficult to explain. One of these I partly excavated in 1979, where we found the impression of a standing stone on the bottom, and Atkinson excavated part of it in 1956 (thinking at the time it was the erection ramp for the Heelstone).

The other is near the centre of Stonehenge. It was written about by Mike Parker Pearson and colleagues in Antiquity 2007, as part of their study of the site’s phasing. It’s a problematic thing, as Parker Pearson argues, excavated partly by Gowland in 1901 and partly by Atkinson on two occasions, in 1956 and 1958. There are two radiocarbon dates from samples that appear to be from the pit, but context details are missing and we can’t be sure exactly where they came from, and whether or not they were in pits dug into the filled larger pit; I don’t think we can trust these to age the big pit, which like that by the Heelstone, remains undated.

Both of these could be explained as filled natural hollows that once contained larger local sarsens. To the north-east, we may be looking at the stone that was dug out and raised, the Heelstone. To the south-west, we can only guess. It’s such a large pit, it might have held the tallest stone, trilithon Stone 56 which now stands at the end of the pit. I suggested Stone 16 as a possible candidate, because of its odd shape.

The last glaciers of the Wicklow Mountains

This is an interesting article which looks at the evidence for the last small glaciers in the Wicklow Mountains,  in Younger Dryas / Zone III / Loch Lomond / NS  times, around 12,000 years ago.  There are interesting comparisons with other Irish mountain areas and with Scotland, where the extent of this new glacierisation was much more dramatic.

These small glaciers -- just seven of them -- can be classified as cirque glaciers, and the authors incorporate evidence of three types of associated moraines, each one dependent upon certain glaciological conditions.   Three of the studied glaciers do not look much like cirque glaciers at all, but more like elongated snowpatches or snowfields on NE-facing steep slopes where snowdrift accumulations occurred. Were these really small glaciers (with flowing ice capable of transporting detritus) or were they small firn fields fronted by pro-talus ramparts or ridges of frost-shattered debris that simply slid down the snow surface from exposed cliff edges? I would have liked something in the article about stone and boulder shapes in the three moraine types, which might have given us a clue........

But these are small matters, and the cosmogenic dating evidence presented by the authors (based on the sampling of morainic boulder surfaces) is rather convincing.

Lauren Knight, Clare M. Boston, Harold Lovell, Timothy T. Barrows, Eric A. Colhoun, David Fink, Nicholas C. Pepin.  05 March 2025 
Restricted cirque glaciers in the Wicklow Mountains, Ireland, during the Nahanagan Stadial (Greenland Stadial-1/Younger Dryas). 

Journal of Quaternary Science  

https://doi.org/10.1002/jqs.3699

ABSTRACT

In Ireland, the Nahanagan Stadial (NS) was characterised by cirque glacier, plateau icefield and mountain ice cap expansion and is named after the cirque glacier type-site of Lough Nahanagan in the Wicklow Mountains. This period is broadly equivalent to the Younger Dryas Stadial and Greenland Stadial-1 (GS-1: ~12.9–11.7 ka). Here, we provide the first evaluation of the full extent of NS glaciation in the Wicklow Mountains by combining solar radiation modelling, mapping of glacial geomorphology, 10Be and 26Al cosmogenic surface exposure dating, 3D glacier reconstructions and analysis of snowblow and avalanching potential. We identify seven sites that hosted cirque glaciers at this time. Glacier extent was very restricted, with most glaciers only partially filling their cirques. Equilibrium line altitudes (ELAs) ranged from 470 ± 5 m a.s.l. (Lough Nahanagan) to 721 ± 5 m a.s.l. (Lough Cleevaun), with an average ELA of 599 m a.s.l. Higher snowblow and avalanching contributions at sites with lower ELAs demonstrate local topoclimatic influence on glacier growth and preservation alongside regional climate. The Wicklow Mountains provides a good example of marginal cirque glaciation during GS-1 and the importance of local topography and microclimate for sustaining glaciers in some mountain areas of Britain and Ireland.

One would expect similarities between the Wicklow situation and that of Wales -- and indeed there are a number of known "late cirque glaciers" in Snowdonia (Eryri) and in the Brecon Beacons.   The only small glacier of equivalent age in Pembrokeshire was that of Cwm Cerwyn, close to Foelcwmcerwyn:

https://brian-mountainman.blogspot.com/2012/02/pembrokeshires-last-glacier.html

There are two other locations, both on the Preseli north face, where I think there might have been small Younger Dryas nivation hollows, firn fields or  mini-glaciers.  But the evidence is very subtle, as suggested in this post:

https://brian-mountainman.blogspot.com/2020/09/an-enigmatic-landform-on-north-slope-of.html

The hunt for the Morvil Scottish erratic.....

Today, on a fine sunny winters day, we went up into the mountains on a hunt for the "Scottish erratic"............

Quote:  Erratic clasts, including gneissic rocks from northern Britain, for example at Morvil Farm [SN 037 307], Puncheston, confirm an Irish Sea provenance.

Reference: Burt, C., Aspden, J., Davies, J., Hall, M., Schofield, D., Sheppard, T., Waters, R., Wilby, P., Williams, M. (2012). Geology of the Fishguard district: a brief explanation of the geological map Sheet 210 Fishguard. British Geological Survey.

https://webapps.bgs.ac.uk/memoirs/docs/B06909.html

As far as I know, there are no gneissic rocks in Pembrokeshire, so to find an erratic of Lewisian gneiss from the island of Lewis would be quite something.  Mind you, there are also gneissic rocks on Skye, Iona and the NW Scottish mainland -- including some areas near the Irish Sea Glacier ice shed, from which there was a southward flow of ice.  There vare some related rocks in Ireland as well.  

The six-figure grid reference given by Burt et al is not adequate, and after hunting around Morvil Farm, along the road and in the adjacent paddocks today I found plenty of dolerite erratics, but nothing made of gneiss......  I might go and take another look when the weather is warmer.

To find a gneissic erratic here, at an altitude of 210m high up in the foothills of Mynydd Preseli, would be almost as exciting as finding the "shelly drift" high up (c 400 m asl) above the North Wales coast at Moel Tryfan.....

https://brian-mountainman.blogspot.com/2014/09/the-shelly-sands-and-gravels-at-moel.html

Citation mistake: St Lawrence Estuary boulder movements

Apologies to Guillaume Marie for the mistake in the citation of his article, in my recent QN note on the Limeslade Boulder.  In the text, the citation should be "Marie, 2022" and not "Guillaume, 2022".

This is incorrect in the reference list:

Guillaume, M. (2022) Boulder transport by ice in the St. Lawrence Estuary (Canada): Influence of shore platform geomorphology and ice-foot development, Marine Geology 449, 106815.

and it should be: 

 Marie, G. (2022) Boulder transport by ice in the St. Lawrence Estuary (Canada): Influence of shore platform geomorphology and ice-foot development, Marine Geology 449, 106815.

The mistake probably arose because of the confusion of having a christian name as a surname.  It has happened to me on a number of occasions too!

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

Response: The provenance of the Limeslade igneous erratic: a matter of no importance?
Brian John
Quaternary Newsletter 164, pp 19 - 27 (February 2025).
https://www.qra.org.uk/quaternary-newsletter/quaternary-newsletter-current/


https://www.researchgate.net/publication/389436022_Response_The_provenance_of_the_Limeslade_igneous_erratic_a_matter_of_no_importance

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

This is an interesting presentation nby Guillaume:

https://www.researchgate.net/publication/341653982_Boulder_transport_by_sea_ice_on_a_rock_coast_of_St_Lawrence_marine_estuary_Canada

Submerged forest exposures at Abereiddi

 

Many thanks to Ruth Crofts for these photos, taken at Abereiddi after one of the winter storms had exposed quite a large expanse of the submerged forest at Abereiddi.

These photos are important bcause they show a stratigraphy of three layers:

3.  Peat bed incorporating tree roots and branches and other detrital debris

2.  Purple clay layer which is clearly "churned"

1.  Buff clay layer which contains many erratic clasts of all shapes and sizes

It is possible that the purple layer is the weathered "cap" of the layer below, but the churning is quite spectacular.  In this situation we cannot be dealing with a violent liquified mud flow -- and the interpretation must be that this is a periglacial feature, created at a time of permafrost.  In the lowest layer I think we are looking at a deposit of the Irish Sea till, similar to that of the Abermawr exposure some miles to the east.  

So my interpretation here would be:  Late Devensian glaciation and deposition of Irish Sea till  >>> late glacial cold climate episode with permafrost and creation of involutions  >>>  Holocene temperate conditions with peat growth and climax woodland  >>> sea level rise and inundation of the woodland and peat bed, probably within the past 5,000 years.

The submerged forest stratigraphy -- multiple sea level oscillations

Relative sea-levels in the Bristol Channel area over the past 12,000 years -- after Bell, Lambeck, 

Shennan and others

This is an interesting thesis concentrating on sites on the Gower and along the Glamorgan coast.  It argues that in the period of Mesolithic and Neolithic settlement there were multiple oscillations of relative sea level -- transgressions and regressions -- leading to coastal changes from saltwater marsh to freshwater lagoons and peat beds with some forest cover.  Although the thesis does not go into mechanisms, this all demonstrates a delicate balance between isostatic recovery rates and the post-glacial (Holocene) eustatic sea level rise. 

This is the context within bwhich we have to try and understand the nature and the sequence of deposits beneath the submerged forest.........

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

Changing Tides:
The Archaeological Context of Sea Level Change inPrehistoric South Wales
Thesis submitted for the degree of PhD Cardiff University
Department of Archaeology and Conservation School of History Archaeology and Religion
September 2018

Rhiannon Philp

https://orca.cardiff.ac.uk/id/eprint/118952/14/2019philprphd%20118952%20DPR.pdf

Quote from Introduction:

According to nationally applied models, sea levels rose by around 55m between 10,000 and 6000 years ago (Lambeck 1995; Shennan and Horton 2002). After this period, the models suggest that sea levels stabilised around modern day levels (Bell 2007e,10). Archaeologically this gives the impression that sea level change affected Mesolithic communities more than those in the later prehistoric periods and that coastal ranges were similar to the modern day by the Neolithic period. However, when archaeological evidence is brought into the mix, it is clear that prehistoric experience of sea level change is not so clear cut. Archaeological and palaeoenvironmental evidence from intertidal zones around Britain, including the Severn Estuary (Bell et al. 2000b; Bell 2007b; Bell 2013c), Langstone Harbour (Allen and Gardiner 2000a), Hullbridge (Wilkinson and Murphy 1995) and the Isles of Scilly (Charman et al. 2016c), has shown that despite the apparent reduction in sea level rise, the effects of fluctuating sea levels (both transgressions and regressions) were felt throughout the prehistoric periods, from the Mesolithic through to the Iron Age and beyond within humanly perceivable timeframes (Bell 2000c, 19). This is unlikely to have been in the form of catastrophic events. Rather, despite early Holocene movements appearing significant, archaeological evidence suggests prehistoric coastal populations would have experienced very gradual and fluctuating change with an average of 1cm rise per year (Shennan et al. 2009).

Quote from Conclusions:

The evidence has shown that sea level change affected Gower throughout the Mesolithic and Neolithic periods, but not in a linear fashion. Long-lived inundations did not affect either of the sites during timeframes represented in the studied environmental sequences. However, at Port Eynon in particular, there is evidence for at least five instances of direct marine influence during the late Mesolithic period. This led to the deposition of minerogenic sediments and salt marsh indicators within the pollen record. Importantly these transgressive periods were followed by regressions in sea level, leading to the reinstatement of freshwater environments represented by substantial peat deposits. At Broughton Bay, evidence for contemporary transgressions has not been directly identified in the stratigraphic record, although raised levels of salt marsh indicators in the pollen record towards the base of the organic peat deposits suggests an earlier marine phase.

Gabbro erratic on the Abereiddi shore platform

 

This large erratic made of gabbro (?) has been exposed on the washed surface of the intertidal shore platform,  at the northern end of Abereiddi Bay.  Dimensions -- roughly 1m x 1m x 1m.   Normally it is encased in beach sand, but it is exposed now because the beach has been lowered by a metre or so during recent stormy weather.

New exposures of the Abereiddi submerged forest

 

Following the winter storms there are some new exposures of the submerged forest at Abereiddi -- near the stream at the lower edge of the pubble bank.  Just a few traces of the peat bed, with broken branches exposed at the surface.  Normally these features are buried beneath a metre or more of beach sand.  We can't see any stratigraphic relationships at the moment -- but there is a considerable "boulder bed" which looks as if it lies on top of the peat.  I suspect that there is a stratigraphic inversion there, and that these are "old boulders" that have been incorporated into the storm beach and have migrated with it as it has moved inland over the top of the peat bed during the Holocene.  

Or are the boulders in situ, related to a Devensian till deposit that underlies the peat bed?

More studies required........

My riposte to that very silly Limeslade rant

Just published:

Response:  The provenance of the Limeslade igneous erratic: a matter of no importance?
Brian John
Quaternary Newsletter 164, pp 19 - 27 (February 2025).

https://www.qra.org.uk/quaternary-newsletter/quaternary-newsletter-current/

https://www.researchgate.net/publication/389436022_Response_The_provenance_of_the_Limeslade_igneous_erratic_a_matter_of_no_importance

This is in response to the extraordinary rant published by Pearce et al (2024) in QN163:
Pearce, N., Bevins, R., Ixer, R. & Scourse, J. (2024). Comment on "An igneous erratic at Limeslade, Gower, and the Glaciation of the Bristol Channel" by Brian John. Quaternary Newsletter 163, pp 15 - 20.

In that article, they mounted what can only be referred to as an ad hominem attack, designed to demonstrate to the world my ignorance and incompetence, following my note describing some of the preliminary pXRF work done by Steve Parry and Prof Tim Darvill.  In attacking me, Nick Pearce and his cronies also questioned the integrity and competence of an experienced geologist and a senior academic -- and that is never a good thing to do in print, in a widely read journal.

Anyway, I may be old, but I still know what I am talking about, and I'm grateful to the editor of QN for giving me the opportunity to put the record straight. In the text, I point out how bizarre it is for a group of academics to attack a short preliminary note on the grounds that it was not more comprehensive -- especially since they could themselves have done more detailed work on the boulder if they had chosen to do so. 

They also accused me of having a preferred narrative driven by preconceptions, of ignoring clear and contradictory information, and of being ignorant of geological and geochemical processes. I pointed out the deep irony of reading these accusations coming from a team which has, over the last decade, refused to cite any "inconvenient literature" or to accept that any of their ideas are questioned or disputed by anybody else........

Then there was the accusation that I questioned the validity and accuracy of their data.  If they had bothered to read my article more carefully, they would have seen that I questioned their analyses and interpretations, not their data.

There were assorted other criticisms and rather snide asides which I will not bother with here -- they were too petty to justify the wastage of any more of our time.

My final paragraph:

Finally there is the parting shot (p 19) on the matter of John (2024): "This article merely represents a disingenuous cover to justify a rehearsal of the now well-worn and increasingly tedious debate concerning transport of the Stonehenge bluestones." Nothing can be further from the truth. The article as published was expanded and fashioned in response to the constructive comments of the journal editor and referees. The "tedious debate" to which Pearce et al (2024) refer has been fuelled and perpetrated by a stream of journal and popular science magazine articles which they themselves have written, many of them recycling the same basic data, designed to promote the hypothesis that the Preseli bluestones at Stonehenge were targetted, quarried and transported by our Neolithic ancestors. It is unfortunate that they are apparently unprepared to accept that others might question both their evidence and their interpretations.

Anyway, it is good to know that many readers of QN have told me how amazed they were by the vitriolic nature of the attack by Pearce et al, and I think we can take it as read that Pearce, Ixer, Bevins and Scourse have now done far more harm to their own reputations than they have ever done to mine.