Topographic controls over ice stream behaviour

They are coming thick and fast.  Yet another paper relating to the deglacial phase of the Devensian Irish Sea Ice Stream.  This is a very technical paper, somewhat difficult to penetrate, but again there is very useful information in it.  Underpinning the conclusions of the authors are more luminescence and cosmogenic age determinations, particularly from the SE coast of Ireland.  I remember visiting those sites almost 60 years ago in the company of Francis Synge and Frank Mitchell..........

The new work is very relevant to West Wales because whatever went on here was mirrored pretty closely on the other side of St George's Channel.  So the sequence of glaciation and deglaciation over there will give us more than a few guidelines......

The model now looks like this:  Maximum extent into the Celtic Sea around 27,000n years ago.  Then extremely rapid (300–600 m per year) retreat from maximum extent, a slowing of retreat (26 m per year) during the period 25.9–24.2 ka, ice margin stabilization (3 m per year; 24.2–22.1 ka), rapid retreat (152 m per year; 22.1–21.6 ka), and finally a return to slower retreat rates (21 m per year; 21.6–19.5 ka).  The right-hand diagram reproduced above shows the assumed ice edge positions looping across St George's Channel towards Pembrokeshire in phases 1-7, each one tied to a specific Irish location.  Quote:  "Our Bayesian age model indicates that initial ice marginal retreat onto the southern Irish coast occurred at 25.9 ± 1.4 ka (Boundary 2). Retreat of the ISIS from the southern coast of Ireland is constrained by the modeled age (Boundary 3) of 25.1 ± 1.2 ka. Deglaciation to the Wexford coast, and associated deposition of the Screen Hills complex, occurred between 24.2 ± 1.2 ka and 22.1 ± 0.7 ka (Boundaries 4–7)."   So this must have been the critical period for the wastage of ice from western Pembrokeshire.  Let's hope that dating work is planned for some of the key Pembrokeshire sites...........

Now I'm going to have another gripe about the flowlines on the left-hand and middle maps.  The easternmost flowlines in the area under scrutiny cannot be correct; and it is ironic that in a paper devoted to topographic controls and trough geometry the authors are showing ice flowing from NNE towards SSW where there appears to be no topographic control whatsoever, and where the laws of ice physics say that flow must have been from NW towards SE,or perpendicular to the ice edge.  I will keep on banging on about this until somebody shows me some evidence that I am wrong.  Heyho -- all good fun!

On balance, another great contribution from members of the BRITICE-CHRONO research team.

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

https://pubs.geoscienceworld.org/gsa/gsabulletin/article/531364/Trough-geometry-was-a-greater-influence-than


Trough geometry was a greater influence than climate-ocean forcing in regulating retreat of the marine-based Irish-Sea Ice Stream (2018)
by David Small, Rachel K. Smedley, Richard C. Chiverrell, James D. Scourse, Colm Ó Cofaigh, Geoff A.T. Duller, Stephen McCarron, Matthew J. Burke, David J.A. Evans, Derek Fabel, Delia M. Gheorghiu, Geoff S.P. Thomas, Sheng Xu, Chris D. Clark

GSA Bulletin (2018) May 28, 2018
https://doi.org/10.1130/B31852.1

ABSTRACT
Marine terminating ice streams are a major component of contemporary ice sheets and are likely to have a fundamental influence on their future evolution and concomitant contribution to sea-level rise. To accurately predict this evolution requires that modern day observations can be placed into a longer-term context and that numerical ice sheet models used for making predictions are validated against known evolution of former ice masses. New geochronological data document a stepped retreat of the paleo−Irish Sea Ice Stream from its Last Glacial Maximum limits, constraining changes in the time-averaged retreat rates between well-defined ice marginal positions. The timing and pace of this retreat is compatible with the sediment-landform record and suggests that ice marginal retreat was primarily conditioned by trough geometry and that its pacing was independent of ocean-climate forcing. We present and integrate new luminescence and cosmogenic exposure ages in a spatial Bayesian sequence model for a north-south (173km) transect of the largest marine-terminating ice stream draining the last British−Irish Ice Sheet. From the south and east coasts of Ireland, initial rates of ice margin retreat were as high as 300−600 m a−1, but retreat slowed to 26 m a−1 as the ice stream became topographically constricted within St George’s Channel, a sea channel between Ireland to the west and Great Britain to the east, and then stabilized (retreating at only 3 m a−1) at the narrowest point of the trough during the climatic warming of Greenland Interstadial 2 (GI-2: 23.3−22.9 ka). Later retreat across a normal bed-slope during the cooler conditions of Greenland Stadial 2 was unexpectedly rapid (152 m a−1). We demonstrate that trough geometry had a profound influence on ice margin retreat and suggest that the final rapid retreat was conditioned by ice sheet drawdown (dynamic thinning) during stabilization at the trough constriction, which was exacerbated by increased calving due to warmer ocean waters during GI-2.

CONCLUSIONS

The geochronological data presented here allow us to test a conceptual model of ISIS deglaciation in south and east Ireland inferred from the sediment-landform assemblage record. Integration of new geochronological data using Bayesian age modeling produces a conformable age model that supports the conceptual model of deglaciation, with extremely rapid (300–600 m a–1) retreat from maximum extent, a slowing of retreat (26 m a–1) during the period 25.9–24.2 ka, ice margin stabilization (3 m a–1; 24.2–22.1 ka), rapid retreat (152 m a–1; 22.1–21.6 ka), and finally a return to slower retreat rates (21 m a–1; 21.6–19.5 ka).

This timescale strongly suggests that aspects of ISIS behavior during deglaciation displayed a complex relationship to external climatic forcing. Extremely rapid advance of the ISIS to its maximum extent, and its subsequent retreat at 26–25 ka is not directly correlated with distinct climate forcing in the North Atlantic region. Such behavior may be explained as a dynamic instability in response to overextension of the ice stream to the maximum limit that rendered it vulnerable to rapid retreat. Similarly, the stabilization of the ice margin at the Screen Hills spans a time of distinct warming (GI-2) with the subsequent rapid retreat occurring during colder conditions of GS-2. The stabilization at the Screen Hills is the most distinct change in pace of ISIS retreat evidenced by the data presented here and it occurs where there is a step-change in the con ning trough geometry highlighting the important role that this plays in condition- ing ice margin retreat. However, contrary to this, the ISIS subsequently underwent rapid retreat without major changes in trough geometry. We speculate that this represents a delayed response of the ice margin to the climate forcing of GI-2. Overall, changing trough geometry and internal feedbacks related to the overextension, retreat, and stabilization of the ISIS appear to obscure the role of external drivers such as climatic forcing.

The conceptual model and geochronological data presented here provide evidence for specific ice margin behavior during overall deglaciation that provides a testing ground for numerical models that likely require high resolution representations of grounding line dynamics. As contemporary ice streams in Greenland and Antarctica evolve in response to anthropogenic climate change they will undergo retreat that is conditioned both by climatic forcing and their internal dynamics. Our data highlight the potential for the evolution of rapid ice margin retreat to be highly nonlinear and conditioned strongly by trough geometry.

Luminescence (optical) dating of cobbles in fluvioglacial deposits, Isle of Man

Here is another important paper, with a major advance that needs to be applauded -- the ability to date cobbles and boulders contained within fluvioglacial sediments (or glaciofluvial sediments, as we are supposed to call them these days...).  The authors have based their study on the Isle of Man, and have shown that the retreating or wasting  Irish Sea Ice Stream front evacuated this area around 20,000 years ago.  This contributes to the emerging narrative.  There are still some anomalies and things that do not quite fit, but that's only to be expected.

As in the paper by Glasser et al (2018) there is a recognition that the edge of the Irish Sea Ice Stream wrapped itself around the SW coasts of Pembrokeshire and pushed into Cardigan Bay.  Bur again I take exception to the easternmost arrow or flowline in the big lobe south of St George's Channel.  Ice does not flow parallel to ice edges.  In Pembrokeshire the ice did ot flow NE towards SW.  It flowed NW towards SE, as we would expect from the laws of physics.  The same would have been true of the ice edge further south.

But that's a minor niggle.  Very useful stuff.

Luminescence (optical) dating of cobbles in fluvioglacial deposits, Isle of Man

https://livrepository.liverpool.ac.uk/3022823/1/jenkinsetal2018.pdf

A new approach for luminescence dating glaciofluvial deposits - High precision optical dating of cobbles
G.T.H. Jenkins, G.A.T. Duller, H.M. Roberts, R.C. Chiverrell, N.F. Glasser
Quaternary Science Reviews 192 (2018) 263-273

Abstract

In recent years luminescence dating has increasingly been applied to date glaciofluvial sediments, but uncertainties about the degree of bleaching of the luminescence signal at deposition make dating of such sediments challenging. Here we test a new approach for luminescence dating of glaciofluvial sediments, based on the analysis of rock cores drilled from granite cobbles, and compare the luminescence ages generated against independent age control.

Luminescence measurements from rock slices in cobble-sized clasts can be used to reconstruct the extent of bleaching, thereby giving greater confidence in the ages produced. This study illustrates that another important advantage of using cobbles is that at depths of 2 mm or more below the cobble surface >90% of the total dose rate arises from the cobble itself, making the dose rate insensitive to the water content of the sediment matrix. Ordinarily, uncertainties in estimating water content during burial are one of the largest sources of uncertainty in luminescence dating methods, and hence reducing the reliance upon the dose rate could be particularly advantageous for glacial deposits, where water contents can potentially be large and highly variable.

Measurements of cobbles from Orrisdale Head, Isle of Man, demonstrate that the luminescence signal was completely bleached to depths of up to 12 mm into the cobble. Sampling of orientated cobbles from lithofacies diagnostic of bar-top environments was used to maximise the chances of exposure to sunlight. The upper-faces of these orientated cobble surfaces appear to be bleached to a greater depth than the lowermost faces. Data from 45 rock slices from these cobbles were tightly clustered, yielding a mean age of 20.7 ± 0.3 ka that is in agreement with independent age control. One of the well-bleached cobbles shows evidence of two discrete exposure events, potentially recording both the advance at 26.2 ± 0.8 ka, and retreat at 20.7 ± 0.3 ka, of the Irish Sea Ice Stream.

Delusions of infallibility.....

You have to larff.  Something from my grate hero Molesworth.  He tells his despotic and psychopathic teacher Dr Kurdling that North America actually exists.  Foolhardy but noble.....

KURDLING:  Fie child you speak with conviction.  Stand forth and bend over WHACK WHACK WHACK WHACK ow gosh ow gosh that will teach you not to alter the ignorance of a lifetime.

Nothing much changes.  When those in positions of authority or power feel that their fondly held beliefs are under threat, they will do whatever is allowed within the rules (or maybe outside them) to maintain the status quo.  Bad mistake.....

Major progress on Devensian ice limits and dating

It's great to see the publication of two big new articles on the Devensian of Wales which move forward our understanding of both the sequence of events (with new dates) and the nature of deglaciation.  This is the first article, which I shall refer to as Glasser et al (2018).

The authors have used luminescence and cosmogenic dating, and have also incorporated information from other studies.  The most interesting feature is the conformation (the evidence looks pretty strong) that the maximum extent of the Irish Sea Glacier occurred about 27,000 years ago -- that's a full 7,000 years earlier than I and many others have assumed in the past.  the second feature -- suggested by others in the past -- is that the behaviour of the Irish Sea Glacier was out of step with that of the Welsh Ice cap, which seems to have remained in existence as a major feature until it started to retreat around 20,000 years ago.  This all has major implications for our understanding of Devensian events in SW Wales, where some territory was affected by Irish Sea Ice, some was apparently ice-free, and some was affected by the ice of the Welsh ice cap.  Just one small gripe -- I would have liked a consideration of the role of local ice caps, as suggested by Henry Patton and others -- but that's a small point.  Overall, this is an excellent and highly influential paper.  Read it!

This is one of the "context" maps showing the suggested extent and flowlines of the Irish Sea Ice Stream (ISIS) and the Welsh Ice Cap.  What is particularly pleasing is the apparent acceptance that the ice edge was not somewhere offshore to the west of the Dale Peninsula and Milford Haven, but in the vicinity of Caldey Island.  I have been arguing for this for years, and have presented evidence on this blog in the form of photos and descriptions of fresh glacial deposits (admittedly very thin and patchy) all along the south Pembrokeshre coast and even on Caldey Island itself.  Maybe somebody does pay attention to what  appears on this blog.......

But I don't particularly like the ice stream arrows in the outer part of the Bristol Channel and the zone of the NE and SW of the Isles of Scilly.  Ice does not flow parallel to an ice edge except in highly constrained environments, as I have repeatedly pointed out.  So the ice along this sector must have been flowing towards the ice edge from the NW, not from the N or NNE.  More work needed on all of this, chaps.......

With respect to the Devensian ice edge in the Preseli district, we have discussed the BGS reconstruction (above) many times, and have decided that it is more or less correct.  I still think the Devensian ive overtopped at least part of Carningli - Dinas Mountain, and I think it reached Gernos-fawr, but let's argue about that some other time.......

This is the reconstructed ice edge from Glasser et al for this area.  As we can see, it's very similar.  the ice edge is dated to about 27,000 yrs BP, and it's suggested that there was still an ice cover on the upland north of the Nevern Valley, bounding the accumulating fluvio-glacial deposits around 26,500 years ago.  The sands and gravels in the quarries of Pantgwyn and Trefigin are dated to 26,700 years old.

Relevance for the two famous sites of Carn Goedog and Rhosyfelin?  Well, Carn Goedog is shown as having been glaciated on its lower (northern) flanks, but as having its summit or topmost crags possibly above the ice surface.  (The small circles on the map show tors or rock surfaces thought to have been unaffected by Irish Sea ice on this occasion.  Cosmogenic dates are clearly needed to decide exactly where the ice edge was.)  Rhosyfelin is shown as well within the glaciated area, where we would expect to find till, fluvioglacial deposits and signs of glacial activity on rock surfaces.  Exactly what we do find............  But another thing that interests me is the confirmation of a catastrophic ice edge collapse, with the ice edge retreating across about 10 km of countryside in only 500 years.  That's pretty dramatic, and the amount of meltwater produced would have been phenomenal.  We would expect quite substantial meltwater erosion, including the use of old meltwater channels, maybe the cutting of new ones in softish sediments, and the smoothing and rounding of exposed bedrock surfaces affected by the full force of the torrents.  Exactly what we find at Rhosyfelin..........

Below we reproduce the beautiful map which illustrates many of the key points from the article. I will no doubt refer to it again in the future.  Click to enlarge.

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Late Devensian deglaciation of south-west Wales from luminescence and cosmogenic isotope dating

N. F. GLASSER, J. R. DAVIES, M. J. HAMBREY, B. J. DAVIES, D. M. GHEORGHIU, J. BALFOUR, R. K. SMEDLEY and G. A. T. DULLER

JOURNAL OF QUATERNARY SCIENCE (2018)

ISSN 0267-8179. 

DOI: 10.1002/jqs.3061   

ABSTRACT:

The Welsh Ice Cap was a dynamic component of the last British–Irish Ice Sheet at the Last Glacial Maximum, but there are few chronological constraints on the pace and timing of deglaciation. This paper presents new geomorphological and geochronological evidence that constrains the timing of the separation of the Welsh Ice Cap from the Irish Sea Ice Stream and the subsequent deglaciation of south-west Wales; and allow these to be assessed in the context of late Pleistocene climatic events. Luminescence ages from glacial outwash sediments south of Cardigan demonstrate that the Irish Sea Ice Stream was receding by 26.7 ka. The subsequent recession of the Welsh Ice Cap is documented by cosmogenic ages from landforms and sediments in the Aeron and Teifi valleys and upland areas. Deglaciation of the Cambrian Mountains was underway by 19.6 ka. Cross-valley moraines and associated deglaciation deposits show that minor re-advances interrupted the recession of the Aeron Glacier twice, and the Teifi Glacier on at least 12 occasions. By 14.9 ka, the Aeron valley was probably ice-free, but the northwards withdrawal of the Teifi glacier had halted in the Tregaron area. The final rapid recession of this glacier into the uplands of central Wales was completed during the Windermere Interstadial (13.5 cal ka BP) when, in common with much of the UK, the whole of Wales is believed to have become ice-free. There is no evidence that the Cambrian Mountains contained ice-free enclaves at the Last Glacial Maximum, as has been previously suggested. The new ages presented here support suggestions that there was rapid change in the configuration of the Welsh Ice Cap between 20 and 17 ka as upland areas became exposed and there was increasing topographic control on patterns of ice discharge.

Who's afraid of the big bad wolves?

About three years ago, in 2015, three harmless old codgers (namely John Downes, Dyfed Elis-Gruffydd and me) spent some time looking at the so-called "Neolithic bluestone quarry" at Rhosyfelin, having developed some concerns about the manner in which the field research by Prof Mike Parker Pearson et al was being promoted through popular lectures, press releases and articles in glossy magazines.  Over four years of checking over what was being exposed in the archaeological dig at the site, we had concerns that the evidence on the ground did not justify the hype -- and so we went over there to take a serious look at the landforms, the micro-morphology, and the sediments exposed.  It would have been better if we had been invited by the digging team to contribute to their deliberations.  But such an invitation was not forthcoming, so we worked independently.  We also wanted to check out quite a long list of "quarrying features" used by MPP in particular to justify the labelling of this site as a quarry used for the extraction of bluestone pillars destined for Stonehenge.

We were so concerned about what we discovered that we wrote an article entitled "Observations on the supposed "Neolithic bluestone quarry" at Craig Rhosyfelin, Pembrokeshire", and submitted it to the peer-reviewed journal called "Archaeology in Wales."  After review, we made adjustments as requested by the referees and the editor, and the paper was duly published in December 2015.  There was a lot of press coverage, largely homing in on the fact that we found no quarrying features whatsoever, and that in our opinion all of the landforms and sediments were entirely natural, requiring no human intervention in their creation.  So -- archaeologists and earth scientists were looking at the same things and seeing different origins. A classic scientific dispute.

Almost three years have now passed since the paper was published, and things are getting really interesting.  On Researchgate, the article has been read more than 1,000 times, which suggests it is rather popular and is deemed to be rather important. (Rubbish papers are lucky if they get 20 reads.......)  It is 100% certain that all of the archaeologists and the two geologists involved in the Rhosyfelin dig have read the paper an have probably downloaded it -- but thus far, in spite of the growing collection of Rhosyfelin articles in print, there has not been a single citation of our work.

As noted in a recent review of my new book by Dr Ian Evans,  '.........John creditably cites the publications of the proponents of the human transport hypothesis and opponents of the glacial transport hypothesis. This is a courtesy which has not been returned in recent papers by his opponents."

This is truly extraordinary, given that the AiW article was published in the hope that it would stimulate debate and encourage wide scrutiny of all of the papers written thus far about Rhosyfelin and the so-called quarries.  We have done the quarrying proponents the honour of examining, discussing and citing their work; and in response we have a conspiracy of silence.  Parker Pearson, Ixer, Bevins and the other authors appear to have closed ranks and have decided that they will completely ignore our work, although it is fully refereed and published in a mainstream archaeological journal.  

As I have said before on this blog, it goes against all of the traditions and protocols of scientific publishing for an author or group of authors to maintain a pretence of wide acceptance of their findings when in fact there is a major academic dispute going on.  That, in my book, is scientific malpractice, constituting sufficient grounds for an article -- or in this case, several articles -- to be retracted.  We have complained three times to journal editors about the failure of Parker Pearson and his colleagues to cite totally relevant (but highly inconvenient) research by other specialists; and one of the editors even had the gall to suggest that MPP had no obligation to cite our research since "it came from another discipline."

Should we be angry?  I suppose so.  But speaking personally, my main feeling is one of sadness -- and disappointment that quite senior academics are apparently so scared of a relatively simple (and unchallenged) paper by three old codgers that they cannot even bring themselves to accept that it exists.  How pathetic is that?

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

OBSERVATIONS ON THE SUPPOSED “NEOLITHIC BLUESTONE QUARRY” AT CRAIG RHOSYFELIN, PEMBROKESHIRE
Archaeology in Wales, vol 54, pp 139-148, December 2015
by Brian John, Dyfed Elis-Gruffydd and John Downes

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

ABSTRACT

Following the publication of a geological paper by Ixer and Bevins (2011) that provenanced certain rhyolite fragments in the Stonehenge "debitage" to a rocky crag at Craig Rhosyfelin in North Pembrokeshire, Parker Pearson and his archaeological colleagues announced that "the Pompeii of prehistoric stone quarries" had been found at the site. Over the course of five digging seasons they claim to have confirmed the initial hypothesis, although nothing has been published. There has been no geomorphology involvement in the dig or in the interpretation of field findings, and this has caused concern. Because the site is adjacent to a public footpath, and because parts of the excavation have been left open from season to season, it has been possible to conduct independent studies of the landforms and sediments. This paper summarises the new findings. The dig site is located in a small meltwater channel on the NW flank of a rocky ridge. There are abundant traces of glacial and fluvioglacial action, including heavy abrasion of exposed surfaces. The valley wall coincides with a rock face which is interpreted as a natural feature controlled by multiple closely-spaced fracture planes which dip steeply and which are themselves controlled by foliations within the Ordovician rhyolite. There is a long history of rockfalls from the crags above the rock face, and rockfall debris now partly obscures it. Fragile rocky outcrops are still affected by biological and other processes which cause intermittent slope collapses. The rock face is deemed not to be a quarrying face, since there is no trace of human intervention in its evolution. The sequence of deposits at the site is described alongside a set of stratigraphic columns with a photographic record.

Dem bones, dem bones, dem dry bones...... an alternative press release.

This is an "alternative version" of the OU press release which has caused such a lot of trouble in recent days.  I was happy to share it with Andy, over on the Megalithic Portal.  

I have cut out the hype and concentrated on the key findings of the research.  It is actually rather interesting, but it reminds me of the early days of amino acid dating and 36C dating, when correction factors and contamination sources were still being worked out, and when some rather outrageous claims were being made about accuracy and significance......... 

The nonsense (official) version is here:
http://www.ox.ac.uk/news/2018-08-02-new-light-shed-people-who-built-stonehenge

This is a version which extracts all the key evidence and findings from the scientific study:

New light shed on Stonehenge cremated remains
Despite over a century of intense study, we still know very little about the people buried at Stonehenge or how they came to be there. Now, a new University of Oxford research collaboration, published in Nature Scientific Reports, suggests that a number of the people buried at the Wessex site had probably come from the west or the north, but probably not from the south or the east.

Conducted in partnership with colleagues at the UCL, Université Libre de Bruxelles & Vrije Universiteit Brussels, and the Muséum National d’Histoire Naturelle de Paris, France, the research combined radiocarbon-dating with new developments in archaeological analysis, pioneered by lead author Christophe Snoeck during his doctoral research in the School of Archaeology at Oxford.

While there has been much speculation as to how and why Stonehenge was built, the question of the origins of the people buried there has received far less attention. Part of the reason for this neglect is that many of the human remains were cremated, and so it was difficult to extract much useful information from them. Snoeck demonstrated that that cremated bone faithfully retains its strontium isotope composition, opening the way to use this technique to investigate where these people had lived during the last decade or so of their lives.

With permission from Historic England and English Heritage, the team analysed skull bones from 25 individuals to better understand the lives of those buried at the iconic monument. These remains were originally excavated from a network of 56 pits in the 1920s, placed around the inner circumference and ditch of Stonehenge, known as ‘Aubrey Holes’. They were later reburied in Aubrey Hole 7, and bone samples from this collection have been analysed in the new study.

The small fragments of cremated human bone date from an early phase of the site’s history around 3000 BC, when it was mainly used as a cemetery. Analyses showed that 15 of the 25 people probably came from Salisbury Plain or from other chalklands in eastern England; but the others probably did not live near Stonehenge prior to their death. Instead, the researchers found that the highest strontium isotope ratios in the remains were consistent with living to the west or north, in areas underlain by older rocks. Although strontium isotope ratios alone cannot distinguish between places with similar values, this connection suggests that at least some of these people might have come from western Wiltshire or eastern Somerset. Others might have come from further afield.

Lead author Christophe Snoeck said: ‘The recent discovery that some biological information survives the high temperatures reached during cremation (up to 1000 degrees Celsius) offered us the exciting possibility to finally study the origin of those buried at Stonehenge.’

John Pouncett, a lead author on the paper and Spatial Technology Officer at Oxford’s School of Archaeology, said: ‘The powerful combination of stable isotopes and spatial technology gives us a new insight into the people buried at Stonehenge. The cremated remains from the enigmatic Aubrey Holes and updated mapping of the biosphere also suggest that some people from well-wooded environments moved onto the Wiltshire Downs before they died.’ There are also suggestions in the research that some people were cremated in well-wooded environments away from the chalk downs, and that their remains were later carried to Stonehenge for interment. That supports other research which has suggested that Stonehenge was a burial place of more than local significance.

Rick Schulting, a lead author on the research and Associate Professor in Scientific and Prehistoric Archaeology at Oxford, explained: ‘To me the really remarkable thing about our study is the ability of new developments in archaeological science to extract so much new information from such small and unpromising fragments of burnt bone.'

Commenting on how they came to develop the innovative technique, Prof Julia Lee-Thorp, Head of Oxford’s School of Archaeology and an author on the paper, said: ‘This new development has come about as the serendipitous result of Dr Snoeck’s interest in the effects of intense heat on bones, and our realization that that heating effectively “sealed in” some isotopic signatures.’

The technique could be used to improve our understanding of the past using previously excavated ancient collections, Dr Schulting said: ‘Our results highlight the importance of revisiting old collections. The cremated remains from Stonehenge were first excavated by Colonel William Hawley in the 1920s, and while they were not put into a museum, Col Hawley did have the foresight to rebury them in a known location on the site, so that it was possible for Mike Parker Pearson (UCL Institute of Archaeology) and his team to re-excavate them, allowing various analytical methods to be applied.’

Megalithic Portal takes a look at the strontium isotope ratios.........

Andy Burnham and colleagues have pasted up a series of posts on the already infamous article in Nature Scientific Reports dealing with cremated bones and strontium isotope ratios.

http://www.megalithic.co.uk/article.php?sid=2146414340

I think we can safely assume that Andy is no more convinced by all this stuff about a "West Wales connection" than Mike Pitts and many others including me.........