The Larkhill bluestone pebble

The Durrington bluestone pebble, with a slice taken off it for analysis.  The facets are very well weathered, and I do not think  they are a result of human working......

Enough of Waun Mawn for the moment.  I picked up on a comment on one of the discussion threads which mentioned a piece of bluestone found in a posthole numbered WA 95.  Apparently, it was found between two radiocarbon dated layers and was therefore shown to have been in position around 7,000 yrs BC -- which places it solidly back in the Mesolithic.  In other words, it was in position at a time when the archaeologists insist that there were no bluestones present on Salisbury Plain........... very inconvenient.

I have tried to track down the evidence, and have found a Wessex Archaeology Report on Durrington and Larkhill, which places posthole WA 95 near the Larkhill Medical Centre, at grid ref 412600 144900.  There is a reference to 1999 WA research, and in one of the frelevent reports Matt Leivers of Wessex Archaeology is mentioned.

See also:

https://brian-mountainman.blogspot.com/2016/11/understanding-of-stonehenge-transformed.html

https://sketchfab.com/3d-models/durrington-bluestone-object-3457e4b573914410a63e05d0df7b1f30

This may or may not be the same bluestone pebble which I referred to in a past post:

https://brian-mountainman.blogspot.com/search?q=+Bluestone+pebble+Durrington

Front and back faces and profile view of the pebble.  It is about 7 cm across, with 4 sides.  Note the heavily abraded surface and the facets -- it I had picked this up near a glacier front, I would have found it to be a perfectly normal component of a glacial deposit........

When I first featured this pebble Rob Ixer told us that it was made of foliated rhyolite, similar to the rhyolite of the Pont Saeson / Rhosyfelin area.   I'm not aware of any more accurate provenancing than that.........

In the descriptions, it is said to have come from the vicinity of two postholes -- but it is not recorded as having been actually embedded in either of those holes.  It may of course have just turned up in the debris being thrown out of one of the pits.  It's dated in the literature as either Neolithic or Romano-British, but I do not know whether that is simply "assumptive" dating -- based on the fallacious reasoning that the stone could not possibly have been in either of these pits earlier than "the arrival of the bluestones."  In "Stonehenge for the Ancestors", Vol 1, p 177, there is a reference to a "discoidal tool of group C rhyolite from a Romano-British ditch".  If that is the same pebble, it is a pretty strange way to describe it..........  There is a reference to a WA publication by Thompson and Powell in 2018.

I'd like to know more about this rather interesting pebble.  Does anybody have more information from Wessex Archaeology, or elsewhere?  Where is it now?

It's worth reminding ourselves that there are bluestone pebbles and fragments scattered all over the Stonehenge landscape.  See this map, which has appeared in a number of publications:

Source -- Stonehenge for the Ancestors, Part 1, free digital download.  It's very detailed, and does not reproduce well at a small scale.

Bearing in mind that this map shows only the bluestone fragments that have been found and recorded in placed where digging has gone on, we can safely assume that no part of the Stonehenge landscape is free of bluestone pebbles and / or fragments.   On almost all occasions I can recall, the "fragments" (they are never referred to as pebbles or stones) are assumed to be in secondary  positions, and assumed to be no older that Neolithic -- with no evidence cited.  They are also assumed ALWAYS to be chips broken off  Stonehenge bluestone monoliths that have been used for tool-making or otherwise destroyed.  What I would like to know is "How do these bluestone bits and pieces relate to superficial deposits such as the clay-with-flints?"  

There are lots of research projects needed on Salisbury Plain, and one of them is a systematic survey of the bluestone debris, with rigorous recording of field data and assumption-free interpretation. Until that work is complete, I think that when people say "There are no bluestones on Salisbury Plain, and therefore the glacial transport thesis is dead",  I think I will reply "There are lots of bluestones on Salisbury Plain, and they look as if they might belong to a very old and degraded glacial deposit."

PS.  More and more intriguing. There is a number on the base of the pebble, which looks like 74411 --5653 --36.  Presumably the pebble is in the Wessex Archaeology collection.

This is the WA description:

The ‘bluestone’ object is a bifacial lithic with polishing and flaking. It was found in a possibly Romano-British feature, next to two Late Neolithic posthole alignments at MOD Durrington. It resembles objects made out of ‘bluestone’, the same as some of the Stonehenge stones. A number of ‘bluestone’ objects have been found across the Stonehenge Landscape, even though not local to the geology.
It is unknown when the object was created, or how it came to be buried at Durrington. Its proximity to the Neolithic posthole alignments could suggest a similar prehistoric date. However, the association with the Romano-British feature could suggest a later curation of the artefact, taken as a memento or trophy.
A section was taken to identify the geology of the rock and shows its original midnight blue colour when it was freshly made. The exterior surface is the result of 4500 years of weathering and wear.

The presumption is that this is a man-made "object"  -- and that seems to me to be a very strange characterisation, given its surface characteristics. Polishing and flaking?  Artefact?  A memento or trophy?  Yet more interpretative inflation, based on the unsupportable assumption that the pebble could not have been here before the Neolithic. From a careful look at that nice 3D animation, this is a perfectly ordinary small glacial erratic.

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

PS.   Tim Daw has done a post on this pebble on his blog, and seems fairly certain this came from Durrington.. He has cited the following from WA:

"A discoidal 'bluestone' object with heavily ground and flattened edges was found in the tertiary fill of the northern terminal of Romano British ditch 6256 (slot 5145), 7 m from the intersection of the two Late Neolithic posthole alignments (at posthole 5047). The object, which has a rounded trapezoid shape, is 64 mm wide, 67 mm long and 18 mm thick. It is made from a slab of stone that has developed a light grey surface patina, although a fresh break in one corner suggests a poorly developed conchoidal fracture and is a dark grey colour when freshly worked.

Further, thin section petrography shows the artefact to be manufactured from rhyolite with a 'sub- jovian' texture, texturally one of the most extreme (and hence characteristic) of the Craig Rhosyfelin rhyolitic rocks. In hand specimen, this rock-type would be very distinctive.

Relict flake scars confirm that the blank was subjected to rudimentary bifacial flaking around the edges, although it is less certain by how much the sides of the object result from flaking or are products of natural fracture. The edges of the object are all heavily ground, with a distinct flattened facet around the circumference. This flattened facet is a sufficiently recurring feature of similar objects of the type to indicate that it was an original feature and not a subsequent alteration to the edge. Grinding also extended across both sides of the object by as much as 11 mm from the edges. The function of the object remains unknown. 

"Elsewhere at Durrington in another Romao-British context there were found: "18 pottery disks clipped into roughly circular shapes. Suggestions for their use include spindlewhorl production, gaming counters or even ‘pessoi’ for cleaning after defecation." 

That description is rather disappointing, with all those references to "an object" rather than a pebble, and an underpinning assumption that it is worked or fashioned either as a "pessoi" of for some other wholesome purpose.  As I said above, I have seen thousands of similar pebbles close to glaciers, and I suppose I could have described them in a similar fashion if had been minded to.  People seem unaware of how glaciers affect and "fashion" the stones that are transported and dumped by ice.........

Bluestone and sarsen at Durrington

The Durrington MOD site "bluestone lithic" -- possibly rhyolite or ash?  The fresh rock is exposed where a geological slice was taken off for lab analysis.  It's certainly not spotted dolerite......

Thanks to Tony for drawing attention to this -- a short report on what was found during investigations at the old MOD HQ at Durrington prior to development as a housing estate.  The site is about 1 km north of the Durrington Walls scheduled monument

https://www.wessexarch.co.uk/our-work/mod-durrington

There is also a longer published report:

Along Prehistoric Lines: Neolithic, Iron Age and Romano-British Activity in the Former MOD Headquarters, Durrington, Wiltshire
By Steve Thompson and Andrew B. Powell
Published by Wessex Archaeology, 2018

Among the probable Neolithic finds, ..........."the most impressive, at least in size where the pieces of worked sarsen stone blocks found in the posthole alignment, the largest weighing in at 15 kg, with two smaller fragments, interpreted as broken flakes, being found alongside it. The use of sarsen as a material to construct stone circles such as Stonehenge and Avebury may suggest this material had some importance to the occupants of Neolithic Durrington, however it is suggested that the stone was discarded after being unable to be worked further. It is also broadly contemporary with the sarsen phase of Stonehenge, however it is possible sarsen was more commonplace than it is today as a number of solitary standing stones are known locally."

Then we find this, also in a Neolithic context;

A piece of worked ‘bluestone’ known as a biface was found in a later ditch close to the intersection of the two posthole alignments. This object is similar to ones found at Stonehenge and is almost certainly of Neolithic date. However, whilst it is likely to have been brought to the site at this time, it could equally be a Romano-British curio or trophy. ‘Bluestone’ is a key material of non-local rocks, many of which were brought from Wales, and most famous for its use at Stonehenge and the ritual activity taking place there.

This is interesting, in spite of the all too typical assumption that the bluestones found in the area must have been "brought from Wales".......

The lump of bluestone doesn't look much like a typical "biface artifact" to me, but there is a great 3D animation on the Wessex Archaeology web site:

https://sketchfab.com/3d-models/durrington-bluestone-object-3457e4b573914410a63e05d0df7b1f30

This is the description:

The ‘bluestone’ object is a bifacial lithic with polishing and flaking. It was found in a possibly Romano-British feature, next to two Late Neolithic posthole alignments at MOD Durrington. It resembles objects made out of ‘bluestone’, the same as some of the Stonehenge stones. A number of ‘bluestone’ objects have been found across the Stonehenge Landscape, even though not local to the geology.

It is unknown when the object was created, or how it came to be buried at Durrington. Its proximity to the Neolithic posthole alignments could suggest a similar prehistoric date. However, the association with the Romano-British feature could suggest a later curation of the artefact, taken as a memento or trophy.

A section was taken to identify the geology of the rock and shows its original midnight blue colour when it was freshly made. The exterior surface is the result of 4500 years of weathering and wear.

This is all quite intriguing.  No doubt the petrology of the stone will have been sorted out by now.  My best guess is that it is a rhyolite or ash.   The "lithic" is very small, and it does not matter very much whether it is from a Neolithic context or a Romano-British one.  I'll hazard a guess that it is a small erratic pebble that has been bashed about a bit -- but I am unconvinced that the "flaking and polishing" are the results of human interference.  They could be natural features -- and its interesting that the weathered crust (assumed to be the result of just 4500 years of exposure) extends across the whole face of the pebble.  One would have expected the Neolithic (?) flaked areas to show up as a different colour -- with a less well marked crust.   It's difficult to tell what is going on here, even on that wonderful animated 3D image!

Anyway, somebody will probably enlighten us.........

PS.  I knew I wouldn't have to wait for long!  Rob Ixer kindly informs us that it is a piece of foliated rhyolite similar to that found at Rhosyfelin in North Pembrokeshire.  So it can be grouped together with assorted other fragments of the same rock type found  in the Stonehenge landscape.  But this is the first one I've seen that looks like a pebble rather than a fragment knocked off a larger stone.

Enhancing the glacial transport theory

Ice flow reconstructions for the Anglian Glaciation of the Bristol Channel region. 

 After Williams-Thorpe, Kellaway and others.

The other day, on one of those endless social media discussion threads, somebody complained that I was a miserable old git unable to come to terms with the "fact" that the glacial transport theory has been comprehensively dismissed.  Assorted senior professors keep on saying the same thing:  and they have been saying it for the last 20 years.  Anyway, I asked said complainant who had done the dismissing, and he failed to reply.  Have I missed something?  The last serious attempt to dismiss the glacial transport theory, as far as I know, was in 1997, when James Scourse was having a go at Geoffrey Kellaway and citing glaciological theory.  That was 24 years ago.  Since then, nothing.  I suppose the principle is that if you keep on saying "the glacial transport theory has been comprehensively dismissed or disproven" enough times, people will come to think it's true, and you don't even have to cite any sources.

https://brian-mountainman.blogspot.com/2019/05/salisbury-plain-and-impossible-glacial.html

The unfortunate thing about James Scourse's 1997 book chapter was that he was seeking first and foremost to dissect Geoffrey Kellaway's ideas in detail -- some of which were unconventional to say the least. But with respect to glaciation as far east as Salisbury Plain, he did use the word "impossible" -- and that is never a good idea, as Olwen Williams-Thorpe and others have pointed out. 

Since the turning of the century a lot has changed, and a vast amount of research has been published, to transform our knowledge of what went on in the Ice Age.  I have summarised and analysed scores of important articles in this blog, dealing with the geology, geomorphology and glaciology of western Britain and its glaciers.  So what's the state of play?

1.  Evidence of erratics and coherent deposits from Flatholm, the Bristol area, the hills around Bath, the Mendip fringes and the Somerset Levels confirms that ice from the west has penetrated far inland from the Bristol Channel on at least one occasion -- and probably several times. None of this was disputed by Scourse in 1997, although he argued that all of the glacial traces to the east of the Bristol Channel coast were "ice-marginal".   We still do not know where the eastern limit of the greatest glaciation was, but glaciological theory suggests it might be somewhere near the chalk escarpment on the western edge of Salisbury Plain.

2.  Computer modelling by Alan Hubbard and colleagues, James Patton and others have indicated that it is perfectly feasible that ice from the Irish Sea Ice Stream (ISIS) actually reached the Stonehenge area.  They do NOT support Scourse's contention that this was "impossible".  

One of the glaciation models -- this is from Edwards et al, 2017.  Patton et al (2016) ran a whole series of models for the growth and decay of the LGM ice sheet.  Modelling work is still in progress.

3.  The size of the Celtic Sea ice lobe is now known to have been far greater than previously appreciated.  Not so long ago, it was thought that the ice edge rested on the Isles of Scilly, but my own fieldwork chimes with that of the BRITICE team to show that it extended far to the south at the time of maximum glaciation -- all the way out to the shelf edge.  If the ice flowed further to the south than previously thought, it must also have spread further to the east.  Again, that chimes with my own recent work in south Pembrokeshire.

My attempt to portray the LGM extent of ice in the SW part of the British Isles.  In a previous glaciation, we know from the distribution of glacial deposits that the ice was more extensive than this in the inner reaches of the Bristol Channel and elsewhere.

4.  From the work of Prof Dave Evans and others, we now know that Dartmoor supported its own ice cap on at least one occasion during the Ice Age, and if there was glacier ice there, climatic conditions must have been quite suitable for glacier ice to reach Salisbury Plain.  There are abundant erratics (which must be glacial in origin) across SW England, and especially on the coasts of Devon and Cornwall, as itemised in my book "The Stonehenge Bluestones".

5.  There can be little doubt that the bulk of the 43 Stonehenge bluestones have most of the characteristics of glacial erratic boulders and slabs.  Only a few of them can be described as pillars. Apart from a few that have been worked, they are faceted and heavily abraded, and carry thick weathering crusts. They have none of the characteristics of quarried stone.  This matter was not considered by Scourse (1997) when he argued for the human transport of the bluestones.

6.  The fact that most of the Stonehenge bluestones have come from the north slope of Mynydd Preseli in Pembrokeshire chimes with glaciological theory, which predicts that there must have been a "zone of enhanced erosion and entrainment" just in those areas where bluestone provenances have been established by Ixer and Bevins. Research in northern Finland also shows that where overriding ice encounters a hill barrier such as Ounastunturi (or indeed Preseli) erosive capacity is enhanced on the up-glacier side.

7.  It is still true that no "free boulders" or monoliths classified as bluestones have been found across the Stonehenge landscape, except at Stonehenge.  However, there is the Boles Barrow bluestone anomaly which suggests that at least one bluestone boulder was present on Salisbury Plain  long before Stonehenge was built.  There are also thousands of bluestone "fragments" scattered across the landscape, and as pointed out by Olwen Williams-Thorpe and others, it is perhaps too convenient to refer to all of these as "fragments of destroyed monoliths".  Some of the fragments deserve to be referred to as pebbles, and some appear to be in Mesolithic or early Neolithic contexts.  Analyses of these fragments in the past have been bedevilled by assumptions that there was a "bluestone arrival date" ( if not several), and by dubious assignments of fragments to secondary or tertiary sediments or fills, for example in the Stonehenge ditch and in the Aubrey Holes.

8.  Ongoing research into the "clay-with-flints" and other sediments on Salisbury Plain suggests the incorporation of several different  materials, some of which have the characteristics of degraded glacial tills.

9.  Recent work on the glaciation of the Celtic Sea shelf by the Irish Sea Ice Stream has shown that the Devensian ice surface gradient was exceptionally shallow, dropping from +750m in the Irish Channel to +400m in St Georges Channel to -200m at the southernmost ice edge about 500 km away. There must have been substantial lateral spreading and gradient reduction on the ice surface once it was clear of the constriction between North Pembrokeshire and the coast of SE Ireland.  It was proposed by Prof Geoff Boulton many years ago that this was because of the soft and saturated sediment bed on what had been the sea floor, facilitating a high rate of bed deformation, lubrication and basal sliding.  This has been confirmed by subsequent work by James Scourse and the BRITICE team.  So could the ice from the west have surmounted the chalk escarpment on the edge of Salisbury Plain? Since the Plain has a surface altitude of 200m-250m, an ice front capable of surmounting the chalk scarp must have had a surface altitude of c 300m.  That could not have happened in the late Devensian glaciation, but it would have been perfectly feasible in the Anglian, at a time when the whole of Preseli must have been deeply inundated by ice, with a glacier surface at c 750m. The soft sediments of the Somerset Levels would have facilitated ice movement eastwards from the Bristol Channel.

I am not aware of any research (published or unpublished) within the last 24 years that conteracts or contradicts the above points, and I believe that the case for a glacial incursion onto Salisbury Plain (by ice carrying North Pembrokeshire erratics) is stronger now than it ever has been. 

Reproduced from "Stonehenge for the Ancestors" (2020).  The Boles Barrow boulder (or piece of it) now stored in Salisbury Museum.  The argument rages on about whether it ever was at Stonehenge, or ever was in a Neolithic long barrow near the western edge of the chalklands..........

 

The rhyolite pebble that may or may not have come from a Mesolithic context at Durrington

Links:

https://en-gb.topographic-map.com/maps/ddp/

https://brian-mountainman.blogspot.com/2020/10/on-lateral-spreading.html

http://publications.thebritishacademy.ac.uk/pubs/proc/files/92p271.pdf