THE BOOK
Some of the ideas discussed in this blog are published in my book called "The Bluestone Enigma" -- available by post and through good bookshops everywhere. Bad bookshops might not have it....
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Monday, 1 September 2014

Salon gets things slightly wrong



Thanks to Rob for alerting us to this, in Salon.  I note this comment ".........in the absence of permission to take new samples from the bluestone orthostats..."  Yes, it must be frustrating!  But keep asking, chaps.

Fourteen orthotats out of sixty?  Which 60 might they be?  Other orthostats come from Rhosyfelin?  Where did that idea come from?  That is something that the geologists have specifically NOT demonstrated. All they have done is tentatively suggest that some of the debitage might have come from one or two of the buried stumps.  There is also the suggestion that all orthostats are dressed in some way, and that because of the lack of appropriate debitage, the dressing must have taken place elsewhere.  That again is a very dodgy assumption -- as far as I can see, most of the bluestones are not dressed at all, but have just been used in their raw or natural state.  That's one reason why I think they are erratics.  I'd agree that it will be great to get provenances for the non-Preseli stones, but I repeat that I think the attempts to link Stonehenge with the Orkney and Isle of Lewis sites are fanciful in the extreme.
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Salon No 325, 2014 (1st Sept)

Bits of Stonehenge

Another subject that never seems to wane in media popularity is that of Stonehenge and the origin of its component stones. Fellows Rob Ixer and Richard Bevins have published several articles in recent weeks explaining their work analysing the thousands of lithic samples collected at Stonehenge from recent and historic excavations. In British Archaeology, they explain how their work began in the 1980s as part of the team working with our late Fellow Richard Thorpe to compare the geochemistry of the Stonehenge bluestones and data from the Preseli hills of Pembrokeshire. The breakthrough came with their development of a robust method of identifying the unique signature of specific rock outcrops.

Reporting on their results so far, Ixer and Bevins say that, in the absence of permission to take new samples from the bluestone orthostats, they have to work mainly with debitage, and they have to make assumptions about which orthostats this material came from. Despite this constraint, they have been able to pin down the sources of fourteen orthostats out of sixty, and seven come from a single outcrop — Carn Goedog — while others come from Craig Rhos-yfelin, both of them on the northern slopes of the Preselis, facing the Irish Sea. In matching debitage to orthostats, they have also observed that there is remarkably little debitage from some orthostats — what little there is coming from late or disturbed contexts, suggesting post-prehistoric breakage. In other words, the evidence increasingly suggests that there was very little in situ stone dressing, which must have taken place elsewhere.

With all this focus on identifying Preseli quarries, the authors say that it is just as important to identify the source for those stones that do not have a proven Pembrokeshire origin: they single out the Altar Stone — the biggest and most unusual of the bluestones — which they describe as a Devonian calcareous cornstone, showing much white mica, that ‘could be from anywhere in a large tract of south Wales and Herefordshire’. They speculate that it is not coincidental that the Ring of Brodgar and the Stones of Stenness, in Orkney, have a similar geology, and they ask could the Altar Stone be a deliberate reference to the Orkney monuments, and ‘could the beautiful gneiss macehead found at Stonehenge, if the gneiss is Lewisian Gneiss which is quite possible, be a reminder of the spectacular Callanish Lewisian Gneiss stone circles?’ An intriguing thought!

Saturday, 30 August 2014

Icy breath in Death Valley



This is fun -- one of the strangest natural mysteries appears to have been solved.  We never cease to be amazed by natural processes the consequences of which which have been observed and puzzled over, but not previously understood.......

So here we are in Death Valley, one of the hottest places on Earth, having to come to terms with the work of ice.

These boulders, on surfaces with hardly any gradient, appear to move along for no apparent reason, leaving long trails behind them.  The work of aliens?  The trouble is that people have normally looked at them in the summer, when temperatures can be up over 40 degrees C.  The research team decided to look at them in the winter, when temperatures are often well below zero -- and lo and behold, they saw them move!  What happens is that very thin sheets (just a few mm) of ice form on the saturated playa floor, with temperatures sometimes not low enough for freezing down to the ground beneath.  So the thin ice sheets rest on a film of water, and when the wind blows, the ice sheets move gently, applying enough pressure on stones and boulders to overcome friction and move them too.  There isn't much friction because the playa floor sediments are saturated and slushy -- so the stones move along and leave "plough marks" behind them.  In the spring, the water all evaporates away, and desert conditions reappear, and lots of people come along and take photos like the one above!

Here are two other images from the original research paper, showing how changes of wind direction cause the thin ice sheets to move in different directions:





 One rock moved 224m during a single winter.  Notice that not all the stones and boulders were moved during the period of observations.  Individual stone movement depends on a variety of factors -- including the depth to which it is embedded in the sediments, the mobility of the slushy surface layer, the depth of the water film, the thickness and coherence of the ice sheet, and the strength and persistence of the wind. 

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This is a report from the Nature web site, with a link to the article itself in PlosOne journal:

http://www.nature.com/news/wandering-stones-of-death-valley-explained-1.15773

Nature | News

'Wandering stones' of Death Valley explained
Scientists spot ice shoving rocks on Racetrack Playa in California, resolving a longstanding geological enigma.

Alexandra Witze
27 August 2014

Richard Norris & Jim Norris

Ending a half-century of geological speculation, scientists have finally seen the process that causes rocks to move atop Racetrack Playa, a desert lake bed in the mountains above Death Valley, California. Researchers watched a pond freeze atop the playa, then break apart into sheets of ice that — blown by wind — shoved rocks across the lake bed.

Until now, no one has been able to explain why hundreds of rocks scoot unseen across the playa surface, creating trails behind them like children dragging sticks through the mud.

“It’s a delight to be involved in sorting out this kind of public mystery,” says Richard Norris, an oceanographer at the Scripps Institution of Oceanography in La Jolla, California, who led the research with his cousin James Norris, an engineer at Interwoof in Santa Barbara, California. The work was published on 27 August in PLoS ONE1.

Geologists previously speculated that some combination of wind, rain and ice would have a role. But few expected that the answer would involve ice as thin as windowpanes, pushed by light breezes rather than strong gales.

Visitors to Death Valley have to go out of their way to visit Racetrack Playa, which sits 1,130 metres above sea level and is a bumpy three-hour drive from the nearest town. The researchers began studying the region in 2011, setting up a weather station and time-lapse cameras and dropping off rocks loaded with Global Positioning System (GPS) trackers. The rocks were designed to start recording their position and speed as soon as something made them move.

What was not clear was how long the Norrises would have to wait. Ralph Lorenz, a planetary scientist at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, has been studying the playa since 2007 as an analogy to lake beds on other planets. He had little faith that the GPS-equipped rocks would move in a time frame that anyone would capture. “I thought it was going to be the most boring experiment in the history of science,” he says.

But when the researchers travelled to the playa in December 2013 to check instruments and change batteries, they found a huge ice-encrusted pond covering about one-third of the 4.5-kilometre-long playa. After several days of camping, they decided to sit above the southern end of the playa on the morning of 20 December. “It was a beautiful sunny day, and there began to be rippled melt pools in front of us,” Richard Norris says. “At 11:37 a.m., very abruptly, there was a pop-pop-crackle all over the place in front of us — and I said to my cousin, ‘This is it.’ ”

They watched as the ice began moving past the rocks, mostly breaking apart but also shoving them gently. The rocks began to inch along, but their pace was too slow to spot by eye. “A baby can get going a lot faster than your average rock,” Richard Norris says.

But when the ice melted away that afternoon, they saw freshly formed trails left behind by more than 60 moving rocks. And on 9 January, James Norris returned to the playa with Lorenz and was able to record video of the roving rocks. “This is transformative,” says Lorenz. “It’s not just an anecdotal report, but we have before and after pictures, and meteorological information simultaneous with the event.” By the end of the winter, the farthest-moving rock had travelled 224 metres.

Racetrack Playa rocks move rarely — “maybe a few minutes out of a million,” Lorenz says. And the two events the scientists saw, with thin ice panes shoving the stones across a wet playa, do not necessarily explain every instance of rocks moving there. “But this breaks the back of the problem scientifically,” Lorenz says. “It is ice shove.”

Solving the Racetrack Playa mystery is not exactly a major scientific breakthrough, Lorenz says, but the work does show the rare combination of conditions that allow rocks to move seemingly on their own. And ice shove can have notable effects — in 1952, it uprooted enough telephone poles at a lake in Nevada to break a transcontinental telephone line.

One person who is happy to see the latest results is Dwight Carey. As a university student in the 1970s, he helped with an experiment in which two rocks were placed in a corral on the playa. Over the course of a winter, one stone moved out of the corral, unobserved, and the other did not 2.

The new explanation “makes sense to me”, says Carey, who is now an environmental regulatory consultant in Brea, California. “Eventually you’re going to get enough force on the pile of ice behind the rocks to be able to move them.”

References

Norris, R. D., Norris, J. M., Lorenz, R. D., Ray, J. & Jackson, B. PLoS ONE 9, e105948 (2014).
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0105948

Sharp, R. P. & Carey, D. L. Geol. Soc. Am. Bull. 87, 1704–1717 (1976).




Friday, 29 August 2014

Man dances at Stonehenge


A video is doing the rounds from those who are horrified that somebody did some dancing on top of the sarsens....  Shock!! Horror!!  Sacrilege!!

I wonder what happened to him?  Maybe he just fell off...... but it was pretty clever of him to get up there in the first place. (This was during the Summer Solstice celebrations this year, when almost anything goes.)

Thursday, 28 August 2014

Rhosyfelin radiocarbon rumours

It's all perfectly simple.  If organic material from beneath the "proto-orthostat" has a radiocarbon age in excess of 5,000 yrs BP -- making the sediments Mesolithic or Palaeolithic in age -- that would support both those who believe in the "quarry hypothesis" and those who don't.  On the other hand, if the sediments on the flanks of the big stone, or on top of it, prove to be considerably older than 5,000 yrs BP, the quarrying hypothesis falls.

 In 2013 the diggers went down at least a metre beneath the base of the "proto-orthostat", exposing local till (probably Devensian in age) and hitting bedrock -- a large mass of while quartz.  They have clearly taken samples from these basal sediment layers -- and we would all dearly love to know what the radiocarbon ages of any organic materials might have been.....
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Myris asks for more info on the radiocarbon dates.  It's interesting that he says he has heard nothing about them at all, except from this blog.  Even more interesting that a good friend of his is actually a partner in this project, and if he knew anything, he would certainly have passed it on......

From my report of the 2013 MPP lecture in Moylgrove:  Then Mike moved on to talk about the latest discoveries associated with C14 dating.  He gave no actual dates, did not tell us where they had come from, and gave us no idea how many dates there are from the past and present excavations. Secrecy prevails.  So we were forced to take everything on trust.  Anyway, he claimed to have a sequence of dates ranging from the Neolithic to the Iron Age, some of which were associated with a series of hearths near the position of the Iron Age hearth discovered last year.  I assume that they have found charcoal or other organic materials that have been dated.  It looked as if the hearths were in more or less the same place, in a nice sheltered position beneath the crag, just above the grassy floor of the valley.  Perfect camping places for hunting groups, or for quarrymen, or for jolly family barbeques on a summers evening, depending on your preferences........  That was all quite interesting.  There was no mention of the big pit or stone hole which got so much attention last year.  Wonder why?

As far as I can recall, this sort of statement has been repeated several times, in other contexts -- presumably referring to radiocarbon dates from the 2011 and 2012 digging seasons.  So it's on the record that there are Neolithic and Iron Age dates which presumably support the MPP hypothesis in some way.  So to the rumours, which I have picked up on from two different directions.  Where there is an obsession with secrecy, rumours proliferate......

One rumour is that certain samples collected last year, which were assumed to be of Neolithic date, have actually given radiocarbon dates which place them in the Mesolithic or early part of the Holocene.  The other rumour is that this has caused some internal difficulty regarding the "Neolithic Quarry" hypothesis, and for that reason the dates have been withheld pending further investigations.  I assume somebody has gone back to the lab and said "Surely these dates can't be right?  Might there be some mistake?" and that the lab has said "We stand by the results.  No contamination, as far as we can see."  (It happens all the time.  I have been involved in this process myself, when the radiocarbon date from a rhinoceros scapula from Caldey Island proved to be very "inconvenient" to certain people....... and when C14 shell dates I obtained from fluvio-glacial deposits in Pembrokeshire were similarly disbelieved by people who should have known better.)

As I have said many times before on this blog, if the sediments beneath the famous "proto-orthostat" at Rhosyfelin contain charcoal or other organic materials which can be dated to the Neolithic, c 5,000 BP, that would support the MPP thesis of a Neolithic "quarrying floor" or surface on which the heroic quarrymen went about their business.  As for the sediments in contact with the flanks of the big stone, or overlying it, these would of course have to be later Neolithic, Bronze Age or later for the quarrying hypothesis to stand up to scrutiny.  My own guess is that there may have been quite young deposits on top of the stone, because its upper flattish surface was not buried very deeply beneath the present ground surface.

If, on the other hand, the material on the flanks of the stone and on top of the stone proves to be Mesolithic or substantially older than 5,000 BP, the Rhosyfelin diggers have a problem, because the hypothesis collapses.  They might try and argue that the sediments are disturbed, and that older organic materials have been incorporated into younger sediments, but from what I have seen of the sedimentary layers, there doesn't seem to be any sign of disturbance.  To repeat my old mantra -- it all looks perfectly natural to me, and is therefore nothing to get excited about.

I may be totally up the creek on all of this, and dates may shortly be released which support everything the quarrymen have said in public -- in which case I will eat humble pie.  But until then, I will continue to ask for less speculation and more evidence.  And, of course, for the immediate publication of the dates.

Stonehenge Empire


I flagged up this multinational co-production about a year ago, and it looks as if it is now made, and is probably in the final stages of editing.  There will be two 60-minute parts -- probably on BBC2 this autumn.  Not yet in the schedules, as far as I can see.......

Interestingly, this doesn't seem to involve National Geographic -- but Smithsonian is in there, and I think I am right in saying that in the past the Smithsonian has generally sponsored the work by the Darvill / Wainwright tribe rather than the MPP tribe.  So it will be interesting to see which "international team of experts" has been involved in putting this latest extravaganza together.

I see no sign of a new Nat Geog Channel documentary on Stonehenge -- and the last one, a few years back, which based the whole programme on MPP's theories, was heavily panned on the basis that there was virtually no evidence in there, but a great deal of fantasy.  Maybe Nat Geog Channel has had its fingers burned, and is waiting for something more reliable before starting advance publicity for a new documentary?

If there is any gossip from the big wide world about all of this, let us know.....

Wednesday, 27 August 2014

How much do the Rhosyfelin partners know?


Here is a screenshot from the University College London web site, relating to the "Stones of Stonehenge" project. It is otherwise called the "Preseli Stones of Stonehenge" project, and currently has funding from: National Geographic Society, Royal Archaeological Institute, and Society of Antiquaries.  It has grown from the Stonehenge Riverside Project, which is now finished, having had a budget of c £500,000.  The budget of the present project is unknown, although somebody must know........ and we do not know how much public money is involved, apart from the fact that many of the "project partners" are paid for their time from the public purse and probably contribute equipment and laboratory / technical assistance via assorted university departments.  You and I, through our taxes, are the ones who pay for all that.  The three major cash funders are educational / charitable institutions which do not advertise the sizes of their grants disbursed to project leaders like Prof MPP.

In the light of the ongoing mystery regarding the research results from three seasons of digging at Craig Rhosyfelin, and the lack of any public statements relating to the radiocarbon dating results of many samples submitted, one wonders how much the project partners know.  In the old days, when I used to be involved in joint projects, we who were partners circulated our results between ourselves, and had an ongoing process of data reporting and information exchange.  Nowadays that process is easy, thanks to things like Dropbox and Cyberduck.

Mike prides himself on the manner in which he consults and bounces ideas around amongst his colleagues.  That's one of the things that comes out clearly from his latest book.  So I have to assume that all of those on the list above are in possession of the radiocarbon dating results from Rhosyfelin, or have at least had a resume or report from MPP............ so why has NOBODY said ANYTHING?




















Monday, 25 August 2014

Regenerated glaciers

 
    
Regenerated glaciers are unusual in that they are able to survive in anomalously low altitude situations because they are physically separated from their ice and snow sources.  The glacier in the top photo -- an unnamed glacier in the Franz Josef Fjord complex of East Greenland -- exists right down at sea level.  The lower photo shows the Supphelle Glacier in Fjaerland, Sogn, Norway.  The lower part of this glacier is only 60m above sea-level, which makes it the "lowest glacier in southern Norway."  In both cases the glaciers are sustained by broken glacier ice which tumbles down a cliff face before becoming compressed and reconstituted down below.  These glaciers are difficult to research, given the constant torrent of ice fragments coming down from above.......  hard hats are not of much use in places such as these, since some of the ice blocks are enormous.....

In the Greenland glacier there is a huge mass of dead ice covered with moraine down at the base of the fjordside.  There is much rockfall debris as well, and it may be that this feature is partly a rock glacier and partly a normal glacier made of ice.

The ice in the lower part of Supphellebreen is much cleaner.  But it is on its way out -- it's melting very fast, both because of warmer conditions down on the valley floor and also because the supply from the icefall above is gradually being cut off.