That devastating explosion at the Texas fertiliser plant - was it nitrous oxide assisted?

 Update: 11th May 2013:   Criminal probe opened into Texas fertilizer plant explosion
(This Independent article initially invited comments - to which I responded - but the article later appeared stripped of comments, presumably for legal reasons).

This is just a holding post. I'll insert the comments I've been posting on the Guardian and Independent later. They will show an evolution in my thinking, informed (or misinformed|) by the Indy quoting from an US inspector's report that the site DID have ammonium nitrate as well as anhydrous ammonia.

As the search and rescue operation continued, agents from the federal Bureau of Alcohol, Tobacco, Firearms and Explosives scoured the scene for clues to the cause of the blast, which officials said had destroyed about 50 homes. A recent report submitted to the Texas Department of State Health Services suggested the facility contained a stockpile of up to 270 tonnes of ammonium nitrate, and 100,000lb of liquid ammonia.

(ed: normally, when you link to a report in a newspaper, that report stays the same. The UK's Independent is a notable exception.  Articles are not only edited but can be completely rewritten - while still appearing under the same URL. Let the internet surfer - or in this case blogger - beware)

Here's the way my thoughts are going. First, one does not expect liquid ammonia (NH3) to behave like rocket fuel when tanks are ruptured by fire. Escape of ammonia gas yes. Fireball, no. Surely there would be well known precedents if that were the case, with regulations siting the tanks far from population centres. Secondly, one does on the other hand have precedents too numerous to mention of ammonium nitrate producing devastating explosions that have flattened entire communities and killed scores, sometimes hundreds. But there is scarcely any mention of ammonium nitrate as a causative agent in connection with West-comma- Texas near Waco.
(ed: the above sentence was true at the time of writing; we have since learned that some 270 tonnes (yes!) was stored on that site, in breach of National Homeland Security regs).

Here's my hunch. There was BOTH liquid ammonia AND ammonium nitrate on site, and the heat of the initial fire (wooden pallets?) was sufficient to melt the ammonium nitrate and then rupture the ammonia storage tanks.

When molten ammonium nitrate decomposes it produces nitrous oxide, N2O, a gas with similar oxidising properties to oxygen, able to support combustion ( even relights a glowing splint as I recall, the "standard" test for oxygen).

Ammonia gas is reluctant to burn in air, unless introduced into an existing flame, and raised to its air/ammonia ignition temperature of close on 1000 degrees C.

But suppose there had been a mixture of ammonia gas and nitrous oxide, the latter behaving like oxygen. Might that have not been the reason for ammonia behaving like rocket fuel?

NH4NO3 ->  N2O  + 2H2O
ammonium nitrate -> nitrous oxide and steam

2N2O  -> 2N2 + O2
nitrous oxide -> nitrogen + oxygen

4NH3 + 3O2  ->  2N2 + 6H2O
ammonia + oxygen -> nitrogen + steam

Result - in gas phase - BANG! 

Overall word equation:

ammonium nitrate(solid)  + ammonia (gas) -> nitrogen(gas) and steam  (highly exothermic reaction, both products gaseous, to produce a vast fireball and powerful pressure wave)

Further reading: Firefighting and Anhydrous Ammonia

Sample comment from the Guardian:

sciencebod commented on Texas explosion: residents of West shocked by devastation.

19 Apr 2013 5:36pm

@Daveinireland - All we know for certain is that liquified, pressurized anhydrous ammonia was on site.
Theoretically it could have produced the fireball if the ignition temperature of air/ammonia gas mixtures of close on 1000 degrees C had been reached. But if the accident investigators know their explosives chemistry, they will be looking for traces of solid ammonium nitrate and/or for any evidence that the solid was either shipped in, or made on site by reacting ammonia and nitric acid.
Methinks we would have had more precedents in the past for what happened at West, Texas if anhydrous liquid ammonia really were given to behaving like rocket fuel when there's a nearby fire.

Sample comment from the Independent

on Hundreds believed injured in Texas fertiliser plant blast 8 hours ago
 

The short science lesson would have been useful, had it been correct.
Ammonia is a gas at ordinary temperature and pressure. It does not form explosive mixtures with air, but will combust to nitrogen and steam if introduced into an existing flame, the latter being maintained. In other words, ammonia and air alone will not produce a conflagration and certainly not an explosion. Were that the case, there would have been hundreds of explosions from leaking refrigeration plants.
It can be liquified under pressure alone (normal temp and pressure). The only significance of that -33 degrees C is that any leak of liquid ammonia would result in the liquid boiling at the temperature, and quickly changing to highly toxic gas.
As for the fireball, it's hard to see how that could be due to liquid ammonia, even if the tanks ruptured, although the gas might have assisted an existing fire, as mentioned above. What is far more probable is that solid ammonium nitrate was also on site, and that as we know can be a very dangerous and unpredictable substance if exposed to heat alone. Leaving aside specialized detonation to produce instant decomposition with powerful shock wave ("fertilizer bomb") ammonium nitrate produces vast amounts of gas when it thermally decomposes to nitrous oxide and steam, both gaseous, and the only products. One imagines that it was a runaway decomposition that produced the vast fireball that was for all intents and purposes an explosion, even if the chemical purists prefer to describe it as a rapid decomposition rather than explosion.
It's bad enough that liquid ammonia was stored so close to a community - but if reports that ammonium nitrate was also there are correct, then words simply fail one. Have they not read their history books? Many, probably most, of the worst most devastating chemical disasters in history in which hundreds have lost their lives have involved harmless-looking, salt-like ammonium nitrate.
NH4NO3 (solid) -> N2O (gas) + 2H2O (steam)
That is the chemical equation for a potential time bomb - especially if fire breaks out in the vicinity. All that reaction needs is the right (wrong) kind of kick start.

newsjunkie aka sciencebod

Guardian (again)

sciencebod

19 April 2013 9:43pm

"Officials at first suggested the explosion was caused by the anhydrous ammonia igniting, but it was revealed Thursday through Texas state records that the plant also possessed 270 tons of ammonium nitrate, a much more volatile, dry solid, at the end of 2012. Records also suggested that in 2006, the Environmental Protection Agency (EPA) issued a $2,300 fine for deficiencies in the plant's risk management plan."

If there had been even a modest amount of ammonium nitrate as well as anhydrous ammonia on site, and the two were pre-heated close to one another, there is an explanation for that massive fireball.
Ammonium nitrate decomposes to nitrous oxide, N2O, an oxidant that behaves almost like pure oxygen (relights a glowing splint). Ammonia, reluctant to burn in air except at high ignition temperatures (close on a 1000 degrees C) can burn in pure oxygen, so probably in nitrous oxide too, maybe at much lower temperatures than 1000 degrees.

Result: liquid ammonia becomes effectively rocket fuel if/when there is ammonium nitrate + fire nearby.

Postscript: have just this minute discovered a paper that backs up my hypothesis: nitrous oxide supports the combustion and flame propagation of ammonia, the main product being nitrogen gas.

Here's the title and authors of the 1964 paper:

Combustion of ammonia supported by oxygen, nitrous oxide or nitric oxide: Laminar flame propagation at low pressures in binary mixtures

• D.G.R. Andrews,
• P. Gray

• Department of Physical Chemistry, University of Leeds, Leeds 2 UK

 

Postscript: Virgin Galactic's SS2 uses a solid rubber compound as fuel, which is burned in liquid NITROUS OXIDE.  Never undersestimate the oxidising power of nitrous oxide.

A new unified theory for Stonehenge. Britain’s first community recycling centre – designed for winter survival?

Stonehenge (Brrrr... Neolithic food distribution point - grilled pork a speciality - at least in the dead of winter?)



Summary

 Stonehenge was the focal point of a largely settled agrarian Neolithic culture that devised a novel means of surviving the winter months. It involved communal feasting on spit-roasted pork – but with a difference. The pigs were fed on the flesh of the deceased, who may have died of natural causes, after removal of the heart and other organs, the latter perhaps being buried with due ceremony at a particular spot some 25 miles away that gradually, over the course of some 100 years became Silbury Hill. This winter survival strategy involving what might be called ‘secondary necrophagy’  was a phase in the transition from hunter-gatherer to homesteader lifestyle. Stonehenge lent some ritual and solemnity to this unconventional strategy, helping to legitimise it and overcome inevitable feelings of revulsion. The uprights and pillars, a reprising in durable stone of Woodhenge, may have had a dual purpose – to overawe while serving a utilitarian purpose too, possibly to do with hanging and air- or smoke-curing of carcases and/or comminution to animal feed. The alignment was probably  intended to get a highly visible fix  on the day of the winter solstice – one that the entire community could see with their own eyes, signalling the permitted ‘open-season- when hitherto ‘unclean meat’ would be sanctified as ‘clean’ for the duration of the short  winter days and long nights while awaiting the return of Spring, light and new growth.

INTRODUCTION

 Why was Stonehenge built ? (taken from the current Stonehenge visitor guide)

"This is the most difficult question for archaeology to answer. Stonehenge does not appear to have any obvious practical purposes. It was not lived in and could not have been defended, so it is thought there must have been a spiritual reason why Neolithic and Bronze-Age people put so much effort into building it.

These people were farmers, their survival dependent on the success of their crops and animals, and for them winter would have been a time of fear – dark months when days grew shorter and colder and when food supplies grew low. There would have been a longing for the return of the light and warmth that meant crops would grow and animals would feed and thrive. Light meant life. This may be a reason why Stonehenge was built and aligned so carefully to mark not the longest day of the year but the shortest. This, the winter solstice, was the turning of the year, after which light and life would return to the world."

.....................................................................................................................

The ideas that I, sciencebod, express here, dear reader, are a development of the ones you read above. In proposing the theory that follows (that may require a strong stomach) I freely acknowledge to have been influenced  at least in part by the suggestion that 'winter  survival' was at the top of Neolithic priorities, which may have overridden a lot of other considerations, aesthetic ones included. Our ancestors were first and foremost 'survivors'.

However, there was a separate and earlier departure point for my ideas. That was through thinking through what it might have been like to eke out a living, nay existence, as a Neolithic homesteader on Salisbury Plain some 4500 years ago - see my last but one post). Salisbury Plain may have had several attractions to Neolithic farmers, but by no stretch of the imagination can it be considered as a prime fertile area in Britain with its thin soil overlying a chalk base. Probably the main attraction was so much in what it was, but what it was not : it was not dense woodland with at best a few clearings, with little protection from enemies, human or wild life. But whereas the woods offered a year-round larder for the hunter-gatherer (indigenous UK mammals like deer, wild boar etc do not hibernate)  the safer more open Plain was a challenge for Neolithic farmers in the winter months with dwindling perishable food stores.

Here's a bare bones summary (no pun intended). I'll flesh out later ...

Main points

1     1.  Neolithic farmers on, or in the vicinity of Salisbury Plain and adjacent chalk uplands switched at the winter solstice (approx Dec 21st)  to a religiously-sanctioned diet - one that might be described uncompromisingly as  one based on ‘secondary cannibalism necrophagy'. However, the latter did not involve direct consumption of human flesh, but of domesticated livestock, notably pigs, that had been fed comminuted human flesh, probably well admixed with vegetable matter. Secondary cannibalism  necrophagy (aka anthropophagy) was a compromise between survival and aesthetics. The British are no strangers to the art of compromise...

2.       2. The nearby Durrington Walls site provides some corroborating evidence, with the discovery of “huge quantities of animal bone, mostly young pig, suggesting large scale feasting, particularly in mid-winter” (from Stonehenge visitor guide). See also this link for some disturbing detail on the cruel and wanton manner in which pigs were slaughtered  with arrows (almost as if the aim was to have the animal lose as much blood as possible while still alive, suggesting some dietary concerns re necrophagy), plus the fact that Durrington was used as temporary winter quarters for a sizeable number of folk seemingly engaged in a non-stop pig-fest.

"Animal bones and artifacts from Durrington Walls testify to ceremonial feasting. At Stonehenge such finds are scarce, implying separate ritual areas for the living and dead" (quote from Mike Pitts, Sheffield University)

3.       3. The resort to secondary cannibalism necrophagy was a survival aid that developed during the critical and often fraught transition over 2 or more millennia from hunter-gatherer to settled agrarian existence (fraught because initial crop yields were not sufficient to guarantee survival through the winter months).

      4. The function of Stonehenge,  and before that its predecessor Woodhenge and nearby sites, was to provide a sanctified site at which the recently deceased were given a solemn sending-off ceremony before the practical business of (partial) recycling began- the latter on  a temple-like site that lent dignity to the proceedings, and invested them with an aura of mystery and majesty.

5    5. The purpose of the initial ditch and bank (the latter made from excavated chalk) was to provide screening, with access restricted to one or two ‘causeway’ points.

6    6. The NE-SW alignment of the site entrance and diametrically-opposite opening was designed to pinpoint the winter solstice precisely,  signalling the approved date in the calendar when it became open-season for a winter-mode diet. The closed-season would have resumed perhaps in Spring, or even as late as the summer solstice (longest day, June 21^st) when crops were ripening.

6.    7. For religious and practical reasons, or merely for showing respect to the departed, the recycling of mortal remains was not total.  The internal organs – heart etc- were first removed and given a separate burial marked by ceremony and ritual.

 

     'Butter-textured' material? Did anyone think of testing for fat? Fat can be remarkably-resistant to biodegradation (it's those hydrocarbon side chains in the fatty acids, especially the saturated ones without the double bonds)

 I I have suggested that was the purpose of SilburyHill – a place for disposal of those vital organs – which probably were seen as having the soul of the deceased, the remainder being seen as a mere husk -  once the body was stripped of it vital organs and their perceived spiritual significance.

8   8. The initial Stonehenge, and perhaps its Woodhenge predecessor too, had those mysterious bluestones, thought to have come all the way from the Preseli Hills in west Wales, either by human agency(!) or carried and then deposited by ancient glaciers. No practical explanation has been offered for those much-prized bluestones. Practical note: comminution with initial separation of flesh from bone would make heavy demands on pre-Bronze age flints which would quickly chip or lose their sharp edges. Reminder: the major, but not exclusive rock type, bluestone not being a recognized geological term, is dolerite with its feldspar inclusions, which is harder than granite. I suggest that some may have been used for superior “flints” (there being much bluestone debris aka 'debitage' on site, or maybe pillars of dolerite were used to keep a keen edge of the flints used to reduce the deceased to comminuted form.

9   9.   Some means of flesh preservation would have been needed.

     This image  accompanies an article that mentions Neolithic pig husbandry (in Spain) with references to the problem of keeping pigs fed in winter, and an interesting, perhaps relevant mention of "air-cured ham".

     The design of Woodhenge and Stonehenge with uprights and lintels may have been to create shelves and racks for hanging and drying in an age before salting/curing/smoking had been developed (?) Early precursors of the henges may even have been "Towers of Silence" relying on carrion feeding birds, as per Zoroastrian culture to provide what was considered an alternative to burial.

1   10.   Early forms of Stonehenge may have been used for human sacrifice (as per conventional explanations)  or even execution  of captured enemies, based on the finding of cremated remains of some 60 or so young adult males at the base of the Aubrey post holes, the latter being thought  to be an initial Mark 1 henge before the stones arrived. Indeed, the domesticated form of disposal/recycling of human remains may have evolved from an earlier military/punitive version.

      Secondary cannibalism  necrophagy was the 'smart technology' of 2500 BC. (It meant that you and your family did not starve, and you probably didn't catch horrible diseases either)

II

     More to come later. (As I say, a work in progress).

      Addendum 1: We tend to think  - or assume- that the transition from hunter-gather to settled agrarian existence was a smooth one. In fact it was probably anything but. As the first agrarians cleared trees to make a settlement, they made life more difficult for the hunters, and in so doing would have reduced their ability to supplement their agriculture with some hunting on the side. In other words the two life-styles came into conflict since each was encroaching on the territory of the other. So the transition was a difficult and risky one, especially in northern latitudes with winters and short days. So 'secondary necrophagy' may well have been an essential stage in the transition.One likes to think that natural mortality may have sufficed to provide enough of those unconventionally-fed pigs in winter, but there would have been no guarantees. One suspects that during lean periods, there may well have been pretexts created, no doubt backed by ad hoc  justification - to generate more turnover so to speak, which we would tend to pass off, 4500 years later, as religion-inspired "sacrifice" without perhaps appreciating an underlying utilitarian, i.e. survival  motive. Even in the modern world, we read of parts of the world where execution of criminals feeds a growing demand for transplant organs. Spare part surgery is a wonderful innovation, and not difficult to justify, but might the abuses of that innovation not provide a clue to the mindset that may have existed 4500 years ago ... a means can always be found to balance supply and demand...

     Addendum 2: From wiki, under the 'scavenger'  entry: 

I     In humans, necrophagy is taboo in most societies. There have been many instances in history, especially in war times, where necrophagy was a survival behavior.
     In the 1950s Louis Binford suggested that early humans were obtaining meat via scavenging, not hunting.^[2] In 2010, Dennis Bramble and Daniel Lieberman also proposed that early humans were scavengers that used stone tools to harvest meat off carcasses and to open bones. They proposed that humans specialized in long-distance running to compete with other scavengers in reaching carcasses. It has been suggested that such an adaptation ensured a food supply that made large brains possible.
       The eating ating of human meat, a practice known as anthropophagy (and known more commonly as cannibalism), is extremely taboo in almost every culture.

     Addendum 3 : from National Geographic( for kids!) regarding that scary Neolithic Center Parc  aka Durrington Walls:

"    "The village was shown to be about 4,600 years old, the same age as Stonehenge and as old as the pyramids in Egypt. The village is less than 2 miles (3.2 kilometers) from Stonehenge and lies inside a massive manmade circular earthwork, or “henge,” known as Durrington Walls.

Remains found at the site included jewelry, stone arrowheads, tools made of deer antlers, and huge amounts of animal bones and broken pottery. These finds suggest Stone Age people went to the village at special times of the year “to feast and party,” says Mike Parker Pearson from Sheffield University in England.

He said many of the pig bones they found had been thrown away half-eaten. He also said the partygoers appeared to have shot some of the farm pigs with arrows, possibly as a kind of sport before barbecuing them.
 

      An ancient road which led from the village to a river called the Avon was also unearthed. Here, the experts think, people came after their parties to throw dead relatives in the water so the bodies would be washed downstream to Stonehenge."

      I'm starting to regret this project. Maybe I should have stuck with the Shroud of Turin.

    Colin Berry aka sciencebod

     Update: May 27th

      Have just discovered through googling that Silbury has previously been described as a tomb for the "souls" of Neolithic folk.  The link is to a 2007 article in the Mail. No mention of mortal remains though. As I say, I think the internal organs of folk were consigned to Silbury over a longish period (say a century), such that the mound grew like topsy - with no preconceived plan to create so dominant a feature on the landscape.

Final word here: I try not to overload this generalist science site with any one topic. For that reason future postings will now appear on my new site called "Sussing out Stonehenge - and Silbury Hill too".  

    Suggestions for new science-based topics always welcome, especially if topical.

A new theory for Silbury Hill - a communal reliquary for the "souls" (and vital organs) of the recently-departed?

 Silbury Hill, Wiltshire, England (approx 1 mile from Avebury Stone Circle and 25 miles from Stonehenge). Communal organ reliquary?

From the Daily Telegraph, 2007:  "The original purpose and use of the hill, which is south of the village of Avebury, is still a mystery. Theories suggest it was either a burial mound, a solar observatory or a representation of a Neolithic goddess. "It is very unlikely we will ever know why it was built," said Robert Bewley, English Heritage regional director for the South West."

Well, almost 5 years on from that article and its pessimistic soundbite, I’ve been reading a highly factual account of man-made Silbury Hill in Wiltshire, published in 2010.

The Story of Silbury Hill by Jim Leary and David Field (foreword by David Attenborough), English Heritage

 It gives a commendably detailed account of the numerous excavations that have been made – right to the very centre, tracking close to ground level to penetrate the original core. 

  The aim was to find what this enigmatic hill was for, what (if anything) it concealed, and why anyone would go to so much trouble. 

Well, I hope the authors will not mind if I provide a trailer, so to speak, of what lies between the covers of their fascinating book, and quote bits from some key passages (no pun intended).

  What those miners and archaeologists did NOT find was what, for now,  I shall refer to as "X", which I believe was buried at Silbury a little at a time, plus a few baskets-full of soil or chalk to hide the evidence, then more X, then more soil and chalk. Why not? Because X is biodegradable, highly so, and which millennia later would leave scarcely any evidence, if at all, of its existence.

Artist's impression - but based on the excavation evidence

 Silbury Hill began as Silbury Mound, which we learn  was simply  as a heap of “sticky” (hmmm) gravel. Yup, that’s what they found at Ground Zero, sticky gravel.  Bit by bit the cone enlarged to make what a few generations later was the highest man-made mound in Europe, as it remains to this day.

So what was X?

I trust the authors do not mind if I turn this into a tease for the reader by quoting some carefully selected  passages from their book, highlighting certain words and key phrases. I will then state simply what I consider was X, leaving readers to recoil, cringe, feel nauseated whatever, and then proceed to write a follow-up post to this missive, which goes on to suggest the real purpose of one of Silbury’ two sister structures - Stonehenge, leaving Avebury for later.

Yup, despite being some 25 miles apart, I believe the two are related – at least in a utilitarian sense -  even if not operating as a dual unit. Indeed, the idea for one may have evolved from the latter, or they developed as different solutions to the same problem of being a settled Neolithic homesteader. The problem?  Clue – it’s one of everyday life – and what inevitably follows... And curiously it’s centred on aesthetics – even if at first sight what I write here may seem to fly in the face of aesthetics.

Let’s now look at that book.

Page 96  under “The earliest mound”

“Deep inside the tunnel...  it was possible to make out, dull, golden, sticky gravel resting on top of the stripped surface. The gravel had clearly been piled up into a small rounded mound a little less than 1m high and nearly 10m in diameter; hardly a worthy predecessor to the giant mound we see today, but a mound nonetheless.”

Page 97 under “Pieces of Place”

(Around the gravel mound) ... a ring of stakes had been hammered into the ground to define the perimeter of a larger 16 metre area. Individual loads of mud and dark soils, probably carried in baskets or hides, had been tipped into this space to create a mound that was about waist high...”

Facing page: an artist’s reconstruction with an interesting caption: “The organic mound surrounded by stakes”.  (what do you suppose the authors meant by “organic”?).

Page 99:  A few metres away to the south and south-east, two smaller mounds were visibly outlined in the section, and others may well exist beyond the confines of the tunnel. Made from dark organic mud, these two small mounds stood less than half a metre high. They were not natural features but deliberately constructed mounds that were added to and modified over time, and one even had a tiny gully dug around it; like a small scale model of the final Silbury. This is an entirely new discovery, and we can now say that the early phases of Silbury do not comprise just one monument, but a number of them that later became subsumed into a single form.”

Further down:

“The soils from all these early mounds preserved organic material astonishingly well...   Insects are ...  staggeringly well preserved... There is an abundance of weevils and some leaf beetles too, as well as a variety of dung beetles, which feed on the droppings of animals such as cow and sheep...”

“seeds and plant remains confirm evidence from the insects that these early mounds were set in mature, well-grazed grassland...”

Page 102 “Mound building stops”

“...  pits were dug into the top and side of the central organic mound... These pits were not large – around 1 metre in diameter and depth... their fill seems to have been little more than the dug-out material pushed back in...”

Page 103   “... and then resumes...” (i.e. mound building)

“Mound assembly continues, and these pits, along with the organic mounds, became sealed under dumps of different materials that had been tipped over the top. This was made up from basket-loads of top soil, chiefly gathered from soil that directly overlay chalk, and therefore from beyond the immediate clay-with-flints area...as well as basket-loads of chalk, clay, gravel and more turf..”

“...turning to (famed Silbury/Stonehenge archaeologist) Richard Atkinson’s evocative description  helps to conjure the image of a cross-section through these multi-coloured and interweaved layers : 

"Seen in section, these upper layers have a stripe pattern, like a polychrome tiger’s skin the white chalk contrasting sharply with the dark-grey soil and the yellows and browns of the gravel and clay. Together these layers formed a mound with an estimated diameter of 35m and which was perhaps as high as 5m or 6m...  a number of ... sarsen boulders were present as well ... deliberately incorporated within the body of the mound as an element of its composition ... like raisins in a cake...  The material for these early mounds had been carefully chosen; this was no random spoil heap, but pieces of other places carefully piled high."

Still on p 104 under “The white mound”

Once this intricate stack had been built up, chalk was then added... sometimes mixed with clay... which would have formed rings round the earlier monument...with the material engulfing the earlier organic mound and forming successively larger white mounds...

Atkinson ... described Silbury Hill as ‘an enormously complicated and highly-coloured layer cake’... and in The Listener the organic mound formed  ‘a kind of enormous biological club sandwich’.

Moving to p 106, and referring now to the encircling Silbury ditch 

“The unweathered sides of this ditch suggest that it had not been open to the elements for long before it was, very deliberately, backfilled and re-cut slightly further out. This happened not just once, but at least three times, moving successively outwards with each cycle of backfill and re-cut; the ditch, like ripples in in water,moving ever further out...  no sooner had one ditch been dug, than it had to be filled and cut slightly further out. Perhaps the bank and ditch enclosure needed to move further outwards to make room for the ever expanding chalk mound within it ... Silbury Hill was constantly being adjusted. There was no fixed plan.”

All this is a far cry from any notion that someone once gave the order – "build me the biggest hill ever". This was no ordinary hill. It was an organic thing, that word again, though whether organic in the present context (meaning to grow progressively) is what the authors mean by their term “organic” for the original mound, I am not sure. In fact, I  have scoured the earlier chapters of the book for that term organic, but while doing so another meaning for the term entered my head. 

I refer to the one used by gardeners and farmers for “organic” compost, i.e. dead and decaying plant and animal material that gradually rots down to leave nothing resembling the original material, at least  in a well aerated heap, except dark, crumbly, wholesome-smelling humus.

By now, dear reader, you should have an idea as to the direction in which my thoughts are going, especially when you see those bolded-up words for soil, dark soil, etc etc.

Thoughts of the imperatives for making a good compost heap were reinforced by the following references to crushed chalk and chalk boulder walls that were built within the mound as it progressed:

“The deposits on the top were made up of dumps of crushed chalk, laid one on top of another, and held in place by large loose pieces of chalk rubble...  the walls were carefully tilted inwards to hold the chalk in place, thus preventing collapse... The rubble walls hold the horizontal chalk layers in place, making it extremely stable. The voids left by the loose-fitting rubble allow rainwater to drain freely through the great mound, thereby limiting erosion. It is the reason the mound is still standing 4,500 years later.

Page 111:  The shape of Silbury

“... the mound is not in fact truly circular, but built in a series of straight lengths, and its outer shape may have been dictated by a series of radial spines, between which are straight construction lines forming something like a spider’s web ... it could have been dictated by a series of buttresses that help tie the structure together... the idea that Silbury Hill was (later) reconstructed as a garden mount... can be discounted. “

Page 112:

“The radiocarbon dates taken from the Hill suggest that its overall construction was rapid, thrown up in the years between 2400 and 2300 BC, and therefore it perhaps took only three of four generations to go from small gravel mound to the massive final chalk mound. Work on it, therefore, must have been frenzied at times...”

Thanks Jim Leary, thanks David Field for that cogent and illuminating exposition. I wish I had your economy and precision with words.

So what is one to make of all that – a hill that began as a mound, around which was constructed radial revetments ('retaining walls'?) of chalk boulders holding back layer upon layer of soil, turf, crushed chalk - but what else (X??)

The only rational answer I can think of (while recognizing that things did not always happen in prehistoric times for rational reasons) is that something (X) was being deposited, covered over, then a new addition of that something etc etc – rather like building a compost heap, but with no intention of later harvesting (thus the chalk etc). What could that something  X have been. Could it have been “organic” but something that has rotted down so completely as to leave nothing except dark soil?

The centre of the 'organic' mound.  Why is the soil so dark , and in layers?

One thing is for sure. It could not have been human corpses, or at any rate intact corpses. That would have left skeletons or traces of bone. 

Could it have been just part of a deceased person (or less likely animal) which was the part our ancestors might have wished to dispose of quickly, allowing them to delay subsequent disposal of the rest of a cadaver. Was it a part that Neolithic man might have wished to dispose of quickly and systematically to avoid attracting wild animals – rats, flies ,foxes,  wolves etc - that would have picked up the scent from afar, and come to investigate, posing a threat to children, livestock, public health etc?

There is a part of the human anatomy that ticks these boxes, and though   

I hesitate to mention it, the internal organs - of the thoracic and abdominal cavities?

Is it possible that there was a passing fashion in Wiltshire, lasting approximately 100 years,such that when there was a death in the family, the first thing to be done was to convey the corpse to specialists at the Mound(initially) and later the Hill, where the internal organs would be removed for immediate interment with due ceremony and ritual.  They would have been quickly harvested, then covered over with soil and chalk, and the remaining cadaver, with better preserving characteristics,   then handed back to the grieving family for disposal at leisure (maybe taking what was left to nearby Avebury or even Stonehenge for second-stage ceremonial disposal)? 

Is it possible that thousands, nay tens of thousands of such additions were made to Silbury Hill in its relatively short life as a disposal site? Has the biodegradation of those organic remains left small cavities that have contributed to the sharp drainage that our two authors claim is the reason why the Hill has survived the downpours of four and a half millennia?

“There is also an unknown degree of iron pan formation”. Hmmm ? Degraded haemoglobin?

Addendum: . Francis Pryor estimates that by 4000 BC the population of Britain was around 100,000 while that of Ireland was some 40,000. For 2000 BC his estimates are 250,000 and 50,000 respectively. Reminder: Silbury Hill was constructed in a relatively short time span between 2400-2300BC, based on radiocarbon dating. That century coincided approximately with Stonehenge's "late stone phase", i.e. 2450BC according to the English Heritage visitor guide, but well before the "final stone phase" about 2000BC.

Probably most of those preferred to live on the chalk uplands, having given up a hunter-gatherer existence in the dense woodland that still covered most of southern England. That would mean an increasingly large number of mortalities per year in a relatively small area, creating  a disposal problem. How many more barrows can be added to the landscape, taking up valuable land for livestock and crops?

Oh, and I see that one of our authors - Jim Leary -  discovered a "sunken floor" in the foundations of the Marden Henge (of which only the bottom 15 cm remain), purpose unknown. Hmmm: was it the equivalent of a mortuary slab?

Finally: for a scientific hypothesis or theory to have value, it must have predictive utility. OK. I predict that the darker soil seams in that hill will be enriched in the chemical elements that are in human tissue. The soluble ones will probably have leached out, but given the alkaline conditions that pertain in chalk, I suspect there may be elevated levels of iron, deposited or precipitated as iron (III) oxide or hydroxides. Note the earlier comment/link re the 'iron pan' formation, which may simply be a consequence of local geology, or there again, maybe not.

It is also possible that there is still "fossil" carbon in the dark-coloured soil if the equivalent of plant humus. Radiocarbon-dating, matched against appropriate controls from non-dark clay and other debris could point to an exceptional contribution from a Neolithic carbon-rich source.


Could it be that ritualistic evisceration("cleansing") of the recently deceased was a de rigeur convention ("fashion statement") for a brief period (a century or thereabouts) in progressive Neolithic society? Or there again, a monument that contained the hearts of the deceased (and much else besides) may in time have come to be seen (from afar)as a powerful symbol of the continuity of life and society. Maybe the heart and soul were perceived as one for that brief period of history.


My theory for Silbury Hill: it served as a communal organ reliquary, or, more picturesquely, as a visceral Valhalla.

Next post - Stonehenge.  Complementary to Silbury - or a separate  facility also centred on novel and evolving means for disposing of the mortal remains of the deceased in response to the pressure of growing population density?

The Great Stupa, Sanchi, India

"Stupas originated as circular mounds encircled by large stones" (wiki)

Some might see parallels with the Buddhist stupa  also described as a giant outdoor reliquary...


 Colin Berry, aka sciencebod  May 17, 2012

Why is Salisbury Plain so steppe-like? A prelude to another look at the Stonehenge mystery

Hello. Sciencebod is back again, after a break of some 4 months (I've been researching the Turin Shroud - see previous posting and link to my specialist site).

My new interest is Stonehenge - like... what was it for, and how did the bluestones get there, all the way from the Preseli hills in west Wales - reckoned to be 135 miles or so as the crow flies?

UPDATE: please try to read my latest thoughts on Stonehenge and Silbury Hill -  but you will need a strong stomach...

Non-colour coded

 Spot those famous  'bluestones' (colour-coded)

I've been getting acquainted with some of the facts and rival theories on Dr. Brian John's splendid and friendly site (and a paperback copy of his book is due to arrive in a day or two).

Stonehenge, just west of Amesbury, is situated a short way south of the approximate centre of Salisbury Plain, the latter being described as one of the largest tracts of chalk grassland in western Europe.

Straightaway that seems an odd description to this science bod. I thought the climax vegetation in Britain was supposed to be forest. What's holding Salisbury Plain back, so to speak? Or did it used to be forest, and if so, been unable to regenerate?  If the latter, then why not, apart from all those MOD tank tracks?  OK, so this may seem to be peripheral to the enduring mystery of Stonehenge, where I am still developing ideas, some of which agree with Brian John's, some of which do not (at least for now, but we may converge once I have read his book).

For starters, let's take a look at satellite pictures of Salisbury Plain, courtesy of Google Maps. I have started with a picture that includes most if not all the Plain, and then homed in progressively on the bare region in the centre. The fifth and last picture in the series looks for all the world like a green oasis-like area, but I shall resist the temptation to call Salisbury Plain a desert - not most people's idea of SW England. But I do believe the description 'steppe-like' is fitting and will be exploring this curious geology and/or history of previous land use/misuse in future posts. (Relax, MOD, it is not you I have in my sights, but yours and my ancestors, going back thousands of years).

Picture 1 (click to enlarge) : Note the bare butterfly-shaped area, most of which is left of centre - Salisbury Plain

Now zooming in (labels  and more pictures later)...

Picture 2 (above):

Picture 3 (above):

Picture 4 (above):

Picture 5 (above):




Even without Stonehenge, Salisbury Plain would be weird. Is its un-English- looking steppe-like weirdness (not always apparent if passing by on the A303) part of the reason why Stonehenge came to be where its is?  More to come...


Late addition: 11 May 2012. It has been suggested on Brian John's site, indeed by the blogger no less, that it is the military activity on the Plain that prevents regeneration.  Here's a photograph from Google maps that suggests otherwise.

 Notice the way that the tracks avoid the trees, but that the trees themselves look stunted. Those trees are not happy trees. Now why would that be I wonder. Prepare for another "out-of-the-box" hypothesis soon, one that adds a third possibility over and above bluestones being transported by human or glacial means.

Here's a clue: note Stonehenge. Note nearby grove of trees, happily growing in an otherwise unpromising chalky field with no real soil to speak of...

More to come...

And finally, missus and I visited Stonehenge and a bit of the Plain today. I'll write a short post later. In the meantime, it was good to see Brian John's book on display in the visitor centre.

My own copy was waiting for me on the doormat when we got back. I now have some serious reading to do (and may have to retract some or all of my  "out-of-the-box" ideas" re the local geology  - we shall see...)

Update: Sunday May 13 : here's the way my thinking ("hypothesizing") is going.

Look at the labelling in red that I have added to a standard textbook diagram. (Ignore the rest of the diagram re laccoliths etc at least for now).  I'm not suggesting, of course, that any of the Stonehenge monoliths are dikes that sprouted at that precise spot - but there may have been dikes within, say, a 10 mile radius that provided some or all of those 'bluestones' - about as heterogeneous a bunch of dolerites, rhyolites etc as one can imagine, that just happen to match some that are found  130 or so miles away in the Preseli hills. As the diagram makes clear - dikes/dykes (for once I prefer the US spelling) can in principle come up close to the surface (and become exposed with erosion) pretty well anywhere in principle, depending on the size of the underlying pluton and/or batholith.

Why do I think there is a sill under Salisbury Plain? That was not an ab initio hypothesis - quite the opposite in fact. It is/was an attempt to understand the unusual characteristics of the Plain where English landscape is concerned. (The Plain is described in wiki as one of the largest areas of 'chalk grassland' in Europe, aka calcareous grassland). My starting point was that there is something unusual about the drainage characteristics that make the Plain a difficult habitat in which deep-rooted trees can get established. An impermeant sill, maybe at a slant that allows quick run-off of percolated rain water, might provide an answer. More later.

Further afterthought: there's a well-known phenomenon in probability theory - namely that if you have 20 or so people in the same room, the chances of at least two people sharing the same birthday is surprisingly high  (said to be 50% (p =0.5) for 23 people in the same room ). I cannot help but wonder if the same effect is not operating with respect to the so-called cause-and-effect correspondence between the dolerites of Stonehenge and the Preseli Hills of west Wales .If there's a sizeable heterogeneity ("range of types")  within the bluestones at Stonehenge, and a sizeable heterogeneity of the bluestones at Preseli, then there is an enhanced probability of finding at least one close match. But that should not be an occasion for premature celebration unless one has looked at the heterogeneity of bluestones everywhere within a 200 mile radius of Stonehenge...

Update: Monday 14 May:

Here's a picture of Preseli rocks in situ erupting from the ground as tors (showing their origin as intrusive igneous rock that has become exposed by erosion):

Preseli  - Carn Menyn - presumed source of the Stonehenge bluestones

See the interesting objection made to the supposed Preseli/Stonehenge connection made by a commentator on the 'FreeRepublic' site from which I obtained the above picture (merely searching Google image files for ...  preseli bluestone... And it's geological, to do with quartz intrusions and fracture planes....

http://www.freerepublic.com/focus/f-chat/2772069/posts

To save you, dear reader, the trouble of locating the particular comment, here's the key section from a kindred spirit:

..I also observed that where columns or pillars ARE present in the bedrock outcrops, when they are released and fall onto the scree they almost inevitably break across, because of transverse fractures or other weaknesses related to quartz veins etc.
So away with that particular piece of nonsense. I am quite convinced that there would have been NO reason for Neolithic tribesmen to "target" Carn Meini as an ideal quarry site. There was nothing special about the spotted dolerites (they outcrop over a very wide area), or about the stone shapes, or about the ease of access or stone extraction (other sites would have been easier).
For the best part of a century archaeologists have been indulging in special pleading with respect to Carn Meini. Once HH Thomas announced that that was where the spotted dolerites came from, one generation after another has sought to find justifications or reasons for the "choice" of the site. It's all there, in the literature......

To which yours truly would add - those pillar-like blocks from the same or related pluton or batholith could have erupted elsewhere, and have had a similar chemical composition petrology if the conditions at the other place of intrusion and final exposure had been similar. The crucial factor with an intrusive rock that forms when magma crystallised before reaching the surface is the rate of cooling. The slower the cooling, the bigger the crystals of feldspar etc. Who's to say that  dike A from Pluton1 did not crystallize at approximately the same rate as dike B from the same pluton, with 130 or so miles separating the two dikes?

Here's another picture I came across (the High Force waterfall, River Tees) which refers to dolerite sitting on top of limestone (the latter a close relative of chalk needless to say, both being calcium carbonate, CaCO3, albeit of differing chemical and biological source material):

The caption in the source refers to the dolerite being visible as darker rock (though it all looks much the same to me except for that single rectangle immediately above the top of the fall). Irrespective,  there ARE precedents for English dolerite making it through beds of calcium carbonate.... Maybe there are some closer to Wiltshire than NE England...

And finally, here's a geological map of England and Wales:

The red star shows the approximate position of Stonehenge, situated on Cretaceous chalk. But what lies beneath that chalk, shown in green (apart from magma if you go deep enough?)

One final post from this science bod on why he thinks the Shroud of Turin is a medieval fake

(Update: added 10th April 2012:  My continuing research and ideas on the Turin Shroud are now to be found on two specialist sites, the more important of the two being this one.


 This site is somewhat past its sell-by-date now as far as the Shroud is concerned - and needs re-writing anyway. Those who are only here for the Shroud should click on the link above.)

 Let's start with some cut-and-paste from one of Dan Porter's sites.   There is a graphic and an excellent account of what it shows (and, more to the point, does not show):

Computerised representation of the Shroud image with 3D enhancement

Here is the accompanying text:

"Look at a full frontal picture of a man. The tip of his nose approaches white and the depth of the recesses of his eyes are darker. The roundness of his face from his cheeks towards his ears is progressively darker.  At first glance, the face on the Shroud of Turin appears to be such a picture. It isn't.
 

How do we know this? All regular pictures, be they paintings or photographs, represent light coming from some direction and being reflected towards our eyes. The eye of the painter or the camera lens is a proxy for our own eyes. The reason the recesses of a man's eyes are darker than the tip of his nose is because less light gets to into the recess. Image analysis shows us that this is not so with the facial image on the Shroud. There is no direction to what seems like light. Something else is causing the lighter and darker shades. That is looks like light to us is an optical illusion.

... with special computer software we can plot the data, the brighter and darker tones, as an elevation. That is exactly what we can do with the image on the Shroud of Turin: plot it as an elevation. 

Let's be clear: You can not plot a regular photograph this way. Nor can you do so for a painting, even a brown and white painting. You can do so with a precise copy of the Shroud, however. 

Not only does this show that the image on the Shroud is not a photograph or painting, it shows that something extraordinary occurred to form the image".

***********************************************************************************


I shall return later and suggest how the original Shroud image was produced, and why it gave rise to the peculiar pattern of light and dark that we see in the green computer-enhanced image above:
First, let's go to the original introduction to this post:

They say a picture is worth a thousand words. Well, here are two pictures that I consider make it 99% certain that the Shroud of Turin is a medieval fake. You may need to consult some of my previous posts on the subject  - some 20 in all - to appreciate the background - which relate an accumulation of steadily growing evidence from simple kitchen experiments - but I shan't clutter up this final post with a lot of verbiage - the pictures tell all.
The first is a picture of a small metal trinket I brought back from Ghana, which I heated over a cooker ring, then thrust face down into a sheet of linen placed over a tray of sand. It shows the scorch mark left by the artefact.

The second is a picture I took after just 30 minutes of playing with an unfamiliar bit of software, one which anyone can download off the internet - which  converts 2D images to 3D representations.

3D metal object with scorch mark left on linen

 From 2D scorch mark (previous picture) to 3D visualisation

 (This was my very first experiment with the software -  if you feel like further tweaking then I will provide a link to the free software)

NEW ADDITON:  I WAS ASKED ELSEWHERE IF THE SAME 3D EFFECT WAS OBTAINABLE WITH A FAINTER IMAGE. THE ANSWER IS YES!

Hot from the press!

The scorch mark could be said to contain "3D-encoded" information, right? Based on the intensity of the scorched-on image, right? Just like the Shroud of Turin image right (scorched on?) one that has millions of folks the world over mesmerised?

Take your pick from the 20th century photo album of computerised reprocessing of the Shroud image

What a wonderful thing is this modern computer imaging technology  - able to enhance in glorious 3D a supposedly first century AD image of the crucified Christ. What's more, it was captured, would you believe it, on his burial shroud in his tomb, at the very instant of Resurrection, by a mysterious flash of light - or even uv or x-rays - according to some Shroud scientists?

Nuff said methinks. I shall use the Comments sections to add, or clarify, or respond to reasonable criticism. Message to internet trolls: please don't waste your time - or mine - since abuse will neither be tolerated nor published.

sciencebod aka newsjunkie aka ColinB

Colin Berry MSc PhD (Biochemistry)

emails to: sciencebod01@aol.com

Postscript: arising from comments, another test for my model has come to mind, but it's a little involved. Are you sitting comfortable? OK, I shall begin:

Suppose one took a bust of a person and chose, let's say, 50 points at random, and then, with the aid of camera and computer, converted the image to a relief map, showing contour lines linking points at the same height above a reference line.Suppose one then put that data into a 3D image analyser to produce the kind of image obtained for the Man on the Shroud? How closely would they compare?  Is the Shroud image really a relief map based on elevation?  I don't think it is, so here's what I propose. Take the same bust, and at each of the 50 points that were selected for relief mapping attach a sensitive electronic pressure monitor. Then push the bust with attached monitors into linen/sand and get a pressure reading for each of the 50 points. That can then be used to plot "isobars", i.e. lines joining points of equal pressure. Then analyse that image for 3D properties. It's my guess that "pressure" map would give a better match to the Shroud image than one based on supposed elevation.


Here's another perhaps simpler way of looking at it. The most intense scorch mark in my sand bed model is not necessarily from points that are highest, e.g. the nose but from points that present square-on to the sand when one presses in, giving the greatest pressure, the closest contact between linen and hot metal, the greatest intensity of scorching..

Look at the Shroud image again. Am I not right in thinking that it is the flattest parts that give the greatest image density, regardless of elevation? That is why those closed eyes are so prominent, despite being  relatively low. That is why one does not see the sides of the face, not because they are particularly low in elevation terms, but because they offer little or no resistance to the linen/sand.

I believe the Shroud image should be re-scanned to see whether it fits a relief model better or worse than one based on angle of plane surface relative to an applied force. (I'm aware there may be potential cans of worms in making this comparison, but it seems at least worth flagging up the idea now).


Something else to consider:  Others, e.g. the Bad Archaeology site, have pointed out that the image is "anatomically impossible", that for example "neck is too long". There is a simple explanation for that in my sand bed model. When the metal effigy (bronze statue or whatever) is pushed into the linen/sand the cloth is first pressed against the "square on" features of the face, and then turns a right angle at the end of the chin, when it is then pressed lightly against the underside of the chin before it hits the next plane square-on surface, i.e. the neck.

 Note the two crease marks at the chin and just below. One is dark, the other light, suggesting the cloth is folded in opposite directions, as might be expected if forced to change directions twice.


But here's the crucial point: when the linen is then removed and laid flat, the neck will look too long because the top portion represents the underside of the chin, which can be a considerable length (it is about 10 cm on both me and the missus.)

Oops. I said I would  attempt to explain the peculiar 3D image (green) at the top of the page. OK, here we go. Observe closely where there is shade. The shade is under the eyebrows, under the eyelids, under the nose, under the lips etc. It's almost as it there had been a source of light above the face that had cast into shadow any feature that was beneath an "overhang", no matter how small. Well, once could suggest thatthe face is an image in the harsh glare of an overhead light, captured by some kind of photography, but I do not believe photography had any role to play, and (curiously) those who think the image is in some way or another miraculous have failed to comment on the "top-lighting" effect.

Here's my explanation: all the shaded regions represent parts of the face on a 3D replica, e.g. bronze replica of the crucified Christ that would not be able to compress the linen onto the sandbed, due to being in a plane that is vertical to the one that gives compression. Consider the nose: a small part of the bridge of the nose, pressed into linen/sand, would encounter resistance as the sand is compressed, and would leave a branded imprint. But the underside of the nose, with the nostrils would not. The sides of the nose, being slightly angled, would leave a small imprint, but not a major one.

 It is time that the Shroud image was thoroughly re-examined to see if the image density corresponds to my sand bed theory, and is a mapping of contours in relation to compaction pressure, and with it the degree of close contact between hot metal and linen to result in differering degrees of heat-scorching.


So much then for the Turin Shroud where this site is concerned. I have created (Feb 2012) a new WordPress blog that will report any further results and ideas I may have on the subject:

Spotlight on that Shroud of Turin Without All The Hype

Why does the Turin Shroud appear to have scorched-in crease marks? Tell-tale signature for medieval forging?

 The standard model - linen draped loosely over the body contours

I had an idea this morning while out on a stroll. Most of the Shroud literature refers to a cloth that is loosely draped over the supposed body of the crucified  Christ. That is then the starting point (all too often) for some frankly amazing speculation about an image being projected onto a cloth (Quite how that is supposed to happen without an imaging system – converging lens etc – or a source of (non-supernatural) radiation is anyone’s guess). Some even seem to imagine that loosely draped cloth being at least momentarily and miraculously spread out flat immediately prior to capturing the image, or so it would seem when one encounters references to "foreshortening" and other effects borrowed from photography and optics generally.

But my model, or rather John Jackson’s plus a supporting bed of sand (the latter being my finishing touch –  does not have a real person, 1^stcentury AD or otherwise, but a metal replica, e.g. a bronze statue, one that is heated and then thrust DOWNWARDS with a degree of force into the linen with that all-important backing bed of sand. 

Now think about it: a loosely draped-over sheet creates at most gentle folds, without creases, but being forced into a bed of sand where the cloth gets pushed first this way, then another, is likely to create creases. And those creases, or at any rate some of them, might be captured for all time, so to speak, were they to be forced to make contact with hot metal and then scorched along the new apposed edges. Where would such creases be most prominent? Surely over those parts of a bronze where there is the most abrupt change of relief, e.g. at the end of the chin? 

I could not wait to get home and have another look at the Shroud images. Somewhere at the back of my mind was a recollection of having seen just such creases.

Hallelujah – exactly as predicted. There are indications of prominent crease-like marks in the head region alone – one at the base of the chin, and one where the temple turns through almost 90 degrees to become the top of the head (the latter being un-imaged – worthy of a post in itself). 

Negative image (as seen by eye). Note prominent line at chin level, and a fainter one at the top of head

Here's a comparison of negative v positive images. Both lines are now clearly visible.

Obviously I am restricted to available images of the Shroud, but is there any other useful information that might be gained by looking at those crease-like marks at greater magnification?

Here’s a close -up:

 Seems to be a double-track, like a railway line, rather than a single line

Further magnified

(Note the interesting extra kink in the middle that widens the "track")

Notice that the mark is a railway track-like feature with two outer dark lines and a lighter space in-between.(That's "railroad track" in US parlance).  The dark lines are presumably the result of the same scorching process that produced the main image - the one I call thermo-printing. The intermediate light area is presumably a non-scorched intermediate zone.   Already, and possibly prematurely, I found myself wondering about the geometry of creasing, i.e. which is “inside” and which is “outside” on that crease. Having done so, back-of-envelope style (I reserve the right to have second thoughts) and this being a blog that describes a journey, not the final destination, which incidentally I shamelessly edit and re-edit, I decided to go for broke and add a last paragraph.

Here’s a little piccy I’ve just knocked off on MS Paint to indicate how think those two crease (?) marks could have arisen in a sand bed model. The linen has got rucked slightly to form invaginations, i.e. “creases” in common parlance (sorry ladies, but that seems the most apt appropriate terminology) the U-shaped  interiors of which are protected from conducted heat by slight separation from hot metal, so would appear as that white strip between the two parallel tracks when the cloth is flattened out. 

 Modelling the origin of two scorched-in creases in the Turin Shroud: green - head of heated bronze effigy; white- linen shroud; brown - scorch mark (note two interruptions); blue - cold spot in crease; yellow - sand bed

The aim is to illustrate beyond any shadow of doubt that a 3D object pushed into sand-supported linen can produce scorched-in creasing around major and abrupt changes in relief, and importantly ONLY at those regions.

Conclusion: I regard those two crease marks as evidence for the image having been formed by applying force, consistent with my thermo-printing model, especially with a backing bed of sand. The scorched-in creases would seem to me to be inconsistent with any model that has fabric loosely draped over a 3D subject – living, dead or inanimate. Now please refer again to the title of this post.  Are those creases not a signature for the Shroud having been produced as a forgery, using a replica, e.g. bronze statue, of the crucified Christ?

Postscript: some further predictions that could be made from the sand bed model (although the fourth, a late addition, is perhaps more by way of explanation than prediction):

1. The weave would show greater separation, i.e. stretching,  of yarn fibres  - warp and weft - over the prominences of a metal effigy - the bridge of the nose etc.

2. There could be adhering or impressed sand (?) particles on the reverse side of each image region.

3. Image regions could have traces of metal oxides, eg those of copper and tin if a bronze effigy had been used

4.The ventral (frontal) image would have to inconveniently end at the tip of a toe with no surplus sheet beyond the foot  - since an overlong sheet would have risked imprinting both sides of the feet (think how it would respond to pushing into a sand bed)!  It does seem odd that the Shroud ends precisely at a foot in both ventral and dorsal views, which is somewhat unexpected, is it not? Would one not expect a burial cloth to have had sufficient surplus at the two free ends to permit easy sewing up.  The total length (over 14 feet) of linen was surely sufficient to allow that?

I have always felt there was something not quite right about the position of the feet, right at the end of the Shroud).