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Wednesday 16 September 2020

Biomechanical processes at Rhosyfelin

Over the last five or six years, I have spent a lot of time on this blog criticising the MPP team (including geologists Rob Ixer and Richard Bevins) for steadfastly refusing to consider the role of Quaternary earth surface processes in the formation of the "quarrying" features at Rhosyfelin and Carn Goedog.  I have also called them out for wilfully ignoring (ie refusing to cite) the two peer-reviewed papers by Dyfed Elis-Gruffydd,  John Downes and myself, and even refusing to accept that there is a scientific dispute going on.  Just as significant is their refusal to accept the role of biological processes -- at Rhosyfelin in particular -- in the formation of the crag and the accumulation of debris on its flanks.  This is cited in the RIGS citation for the site, but the digging team continues to publish papers without making any mention of biomechanical processes, and they have done it again in the book chapter entitled " Long-distance landscapes: from quarries to monument at Stonehenge."

If nothing else, archaeology research at the highest level requires multidisciplinary inputs, and the blinkered approach of the MPP team has to be seen as unscientific, designed to "prove" a preexisting hypothesis by wilfully ignoring everything inconvenient.

A reminder:

From a 2015 post:
Biomechanical processes in a woodland ecosystem

It appears that certain people are very sceptical about the manner in which biomechanical processes operate in woodland ecosystems. Strange, since we see them operating almost every day. At the top of the bank in our garden we have a large ash tree embedded in a stone wall. Every now and then the stone wall collapses and has to be rebuilt, because of two observable processes: the gradual and inexorable process of root expansion, and the rocking of the tree in high winds. Both processes push out very heavy stones, some of them far too heavy to lift.

Above is one of my photos from Rhosyfelin, showing a large block of rhyolite that has already been separated from the rock face because of root expansion and the rocking of shrubs -- in this case gorse and heather.

From a 2018 post:
Biological processes at Rhosyfelin

I'm increasingly convinced that biological processes are -- and have been for a long time -- of great importance in the evolution of the landforms at Rhosyfelin.

If one looks back at the Devensian, and at the history of other crags and rock faces (for example, on the coast) one sees the effects of frost shattering over a period of around 70,000 years -- during which there must have been continuous or discontinuous permafrost and an ongoing process of rock breakage at the surface. Many fracture patterns must have been exploited, with fractures opened or widened by freeze-thaw processes. Then, in the intervals when scrub or woodland vegetation was able to take hold, the expansion of root systems must have continued the work, forcing fractures to widen even further, until failures occurred, accompanied by large and small rock fragments crashing down and accumulating on the flank of the crag. This is what we see in all the photos -- interpreted as quarrying waste by the archaeologists and as natural rockfall or slope accumulations by geomorphologists.

The process continues to this day -- maybe at a faster rate now than in the past, given the nature of the present climate and the occupation of the upper part of the crag by gorse, hazel, willow and other bushes and small trees. Root expansion does part of the work, the the rocking of trees and shrubs in the wind is another very active process.


Further down the valley, biological / biomechanical processes are operating quite prominently, but apparently quite invisibly as far as the MPP team is concerned......


What we see at Rhosyfelin today is the operation of a set of natural processes which have affected the local landscape for something like 20,000 years since the melting of the last remnants of Late Devensian glacier ice.  Biological processes are crucial in the mix, and so here is another interesting question:  in the Rhosyfelin debate, where are the botanists?  I assume that they have been asked by Prof MPP to look for pollen in sediment samples, and to identify nuts and bits of wood and charcoal by looking down microscopes in their labs, but where are they when we need them in the field?


Helen said...

*Perhaps not for publication*

Hello Brian and apologies for the unorthodox way of contacting you.

I switched on the BBC World Service just now and caught the last few minutes of this broadcast:

It's part of a series examining worship of the sun down through history.

I was interested to hear The People's Archaeologist, one MPP, interviewed - at Stonehenge, of course - talking about the alignment of the monument with summer and winter solstices.

What particularly caught my attention was this segment:

Dava Sobel (presenter): The stone age sun-worshippers who erected Stonehenge might have taken their alignment cues from the landscape.

MPP (for it is he): We excavated out of the front of Stonehenge and discovered that the avenue that leads from it, that is on that solstice axis, is actually sat on top of an earlier feature that shares that alignment and our great surprise was that actually that alignment was a natural landform. It wasn't built by people at all and it consists of two ridges of chalk and between them are a series of parallel gullies that were formed in a previous ice age.

Perhaps this is all very old news to you, but I hadn't realised that MPP apparently accepts that - by implication, at least - ice had covered the area to a depth sufficient to cause these striations in the chalk.

I know I'm making assumptions here, but if this avenue-carving ice sheet was thick enough to have such an effect, surely it's not unreasonable to assume that it may also have been carrying assorted erratics on and within it as it passed through? What would have cause these 'gullies' - would the action of ice alone have been sufficient, or would its effects have been enhanced by rocks trapped in its underside?

Apologies if this seems banal to you, but I was under the impression that the orthodox view of MPP's merry band of archaeologists was that the Stonehenge area had not been affected by any ice age (and, ergo, glaciers) at all?

Perhaps I'm confused and should go and take a belated afternoon nap...

Hope all is well with you and yours.

BRIAN JOHN said...

Hi Helen -- MPP has been on about these |periglacial stripes" for years. It's a particularly useless hypothesis -- it does not add anything to our understanding of Stonehenge, and it seems to me that MPP just likes it because it is anice extra wacky bit of the story. "Ice Age| does not necessarily mean glaciation. During the glacial episodes of the Ice Age, various parts of Britain were ice-free, and affected by periglacial / permafrost conditions. MPP argues that the "periglacial stripes" (look that up via our search facility) were formed at a to=ime of frozen ground conditions, much like Arctic Canada today. But he has never demonstrated that they are anything to do with permafrost -- I think they are simply solutional rills cut into the chalk......


'The Botanists and the Diggers should be friends, the Botanists and the Diggers should be friends, then we could have an inter - disciplinary ho - down, like we saw in "Oklahoma!", THE Botanists and the Diggers should be friends........[as should, of course, the Glacial Geomorphologists]'

Will they NEVER learn! A little more WISDOM, a little less Technology, PLEASE.....


With acknowledgements, of course, to Elvis ap Preseli who is no longer around to share my sentiments, but sang a rather similar, if racier, song....