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....
To order, click
HERE

Tuesday, 26 April 2011

Teetering tors -- some more scilly than others

In my post of 24 March 2011 I examined the evidence for tors of different shapes and histories and pondered on their relationship to the Devensian ice limit in West Wales.  Info here:

http://brian-mountainman.blogspot.com/2011/03/teetering-tors-damaged-tors-and-denuded.html

Then I came across this map by James Scourse in which he refers to 4 different tor types in the Isles of Scilly and relates them to the glaciation limit (again assumed to be Devensian).  It's interesting and persuasive work (in the Geol Conservation Review volume for SW England, p 265).  James maps the 4 different tor forms and shows that the smoothed and rounded tors are basically within the ice limit and the other types are outside it -- so although this was all very close to the ice edge, the ice still had enough strength to erode away the more fragile elements of the tor morphology.

This isn't an exact science -- and I wouldn't mind betting that there is a degree of subjectivity (and maybe even bias?) in deciding which category any particular tor should fall into.  So the map may or may not be 100% reliable.  No matter --- the broad principles of the exercise are fine, and the map does tell us something quite interesting about the capacity of a glacier to modify the landscape quite dramatically very close to the ice edge, even if the ice was only present there for a few years.

On Pseudoscience


I seem to spend a lot of my time dealing with material that I consider to be pseudo-scientific, so I thought it worthwhile to reproduce a chunk of the Wikipedia entry on Pseudoscience.  This is a very difficult area, and I have touched on it before in this blog -- entries can be found by using the search facility for "Popper" and "Occam's Razor."  Of course, one person's science is another person's pseudoscience, and in the real world the border between the two is difficult to find.  It would be nice if we could all follow faithfully the scientific precepts of Karl Popper, and pursue the ideal of scientific falsification.  But psychology and even sociology -- and even politics -- come into the frame, and sometimes we get so attached to our theories (for reasons of self-esteem and reputation) that we become blind to their deficiencies, and refuse to see what others consider to be blindingly obvious.  And as we all know,  politics and even economics can maintain the "respectability" and the "value" of hypotheses (like the bluestone / human transport theory) which have really become redundant and which are not supported by actual field evidence.  In the territory covered by this blog, all hypotheses are (or should be) based on published field evidence which is verifiable and maybe falsifiable -- but the problem is that some hypotheses are based on just one or two small pieces of field evidence, and are then formulated and even published by authors who simply refuse to accept the great mass of published material that tends to disprove what they claim to be true........

 
PSEUDO-SCIENCE

From Wikipedia

The following are some of the indicators of the possible presence of pseudoscience.

Use of vague, exaggerated or untestable claims

    • Assertion of scientific claims that are vague rather than precise, and that lack specific measurements.[29]
    • Failure to make use of operational definitions (i.e. publicly accessible definitions of the variables, terms, or objects of interest so that persons other than the definer can independently measure or test them).[30] (See also: Reproducibility)
    • Failure to make reasonable use of the principle of parsimony, i.e. failing to seek an explanation that requires the fewest possible additional assumptions when multiple viable explanations are possible (see: Occam's razor)[31]
    • Use of obscurantist language, and use of apparently technical jargon in an effort to give claims the superficial trappings of science.
    • Lack of boundary conditions: Most well-supported scientific theories possess well-articulated limitations under which the predicted phenomena do and do not apply.[32]
    • Lack of effective controls, such as placebo and double-blind, in experimental design.

Over-reliance on confirmation rather than refutation

    • Assertions that do not allow the logical possibility that they can be shown to be false by observation or physical experiment (see also: falsifiability)[33]
    • Assertion of claims that a theory predicts something that it has not been shown to predict.[34] Scientific claims that do not confer any predictive power are considered at best "conjectures", or at worst "pseudoscience" (e.g. Ignoratio elenchi)[35]
    • Assertion that claims which have not been proven false must be true, and vice versa (see: Argument from ignorance)[36]
    • Over-reliance on testimonial, anecdotal evidence, or personal experience. This evidence may be useful for the context of discovery (i.e. hypothesis generation) but should not be used in the context of justification (e.g. Statistical hypothesis testing).[37]
    • Presentation of data that seems to support its claims while suppressing or refusing to consider data that conflict with its claims.[38] This is an example of selection bias, a distortion of evidence or data that arises from the way that the data are collected. It is sometimes referred to as the selection effect.
    • Reversed burden of proof. In science, the burden of proof rests on those making a claim, not on the critic. "Pseudoscientific" arguments may neglect this principle and demand that skeptics demonstrate beyond a reasonable doubt that a claim (e.g. an assertion regarding the efficacy of a novel therapeutic technique) is false. It is essentially impossible to prove a universal negative, so this tactic incorrectly places the burden of proof on the skeptic rather than the claimant.[39]
    • Appeals to holism as opposed to reductionism: Proponents of pseudoscientific claims, especially in organic medicine, alternative medicine, naturopathy and mental health, often resort to the "mantra of holism" to explain negative findings.[40]

Lack of openness to testing by other experts

    • Evasion of peer review before publicizing results (called "science by press conference").[41] Some proponents of theories that contradict accepted scientific theories avoid subjecting their ideas to peer review, sometimes on the grounds that peer review is biased towards established paradigms, and sometimes on the grounds that assertions cannot be evaluated adequately using standard scientific methods. By remaining insulated from the peer review process, these proponents forgo the opportunity of corrective feedback from informed colleagues.[42]
    • Some agencies, institutions, and publications that fund scientific research require authors to share data so that others can evaluate a paper independently. Failure to provide adequate information for other researchers to reproduce the claims contributes to a lack of openness.[43]
    • Appealing to the need for secrecy or proprietary knowledge when an independent review of data or methodology is requested.[43]

Absence of progress

    • Failure to progress towards additional evidence of its claims.[44] Terence Hines has identified astrology as a subject that has changed very little in the past two millennia.[45] (see also: Scientific progress)
    • Lack of self correction: scientific research programmes make mistakes, but they tend to eliminate these errors over time.[46] By contrast, theories may be accused of being pseudoscientific because they have remained unaltered despite contradictory evidence. The work Scientists Confront Velikovsky (1976) Cornell University, also delves into these features in some detail, as does the work of Thomas Kuhn, e.g. The Structure of Scientific Revolutions (1962) which also discusses some of the items on the list of characteristics of pseudoscience.
    • Statistical significance of supporting experimental results does not improve over time and are usually close to the cutoff for statistical significance. Normally, experimental techniques improve or the experiments are repeated and this gives ever stronger evidence. If statistical significance does not improve, this typically shows that the experiments have just been repeated until a success occurs due to chance variations.[citation needed]

Personalization of issues

    • Tight social groups and authoritarian personality, suppression of dissent, and groupthink can enhance the adoption of beliefs that have no rational basis. In attempting to confirm their beliefs, the group tends to identify their critics as enemies.[47]
    • Assertion of claims of a conspiracy on the part of the scientific community to suppress the results.[48]
    • Attacking the motives or character of anyone who questions the claims (see Ad hominem fallacy).[49]

Use of misleading language

    • Creating scientific-sounding terms in order to add weight to claims and persuade non-experts to believe statements that may be false or meaningless. For example, a long-standing hoax refers to water by the rarely used formal name "dihydrogen monoxide" (DHMO) and describes it as the main constituent in most poisonous solutions to show how easily the general public can be misled.
    • Using established terms in idiosyncratic ways, thereby demonstrating unfamiliarity with mainstream work in the discipline.

Psychological explanations

Pseudoscientific thinking has been explained in terms of psychology and social psychology. The human proclivity for seeking confirmation rather than refutation (confirmation bias),[55] the tendency to hold comforting beliefs, and the tendency to overgeneralize have been proposed as reasons for the common adherence to pseudoscientific thinking. According to Beyerstein (1991), humans are prone to associations based on resemblances only, and often prone to misattribution in cause-effect thinking.

Lindeman argues that social motives (i.e., "to comprehend self and the world, to have a sense of control over outcomes, to belong, to find the world benevolent and to maintain one’s self-esteem") are often "more easily" fulfilled by pseudoscience than by scientific information.[56] Furthermore, pseudoscientific explanations are generally not analyzed rationally, but instead experientially. Operating within a different set of rules compared to rational thinking, experiential thinking regards an explanation as valid if the explanation is "personally functional, satisfying and sufficient", offering a description of the world that may be more personal than can be provided by science and reducing the amount of potential work involved in understanding complex events and outcomes.

Monday, 25 April 2011

The inundation of Cardigan Bay -- the oldest story in Wales?

Upper Image:  Andrew David (click to enlarge)
Lower Image:  David Thorpe

The story told below (which I published in my book called "Pembrokeshire Folk Tales") is thought to have elements within it which date back to the Iron Age -- and it's certainly older than the better-known version of the story of Cantre'r Gwaelod which is associated with Seithennin the Immortal Drunkard.  Whichever story we go for, the essential feature is a folk memory of a time when Cardigan Bay was dry land -- and according to the legend a place of rich settlements and fertile farmland.  The legend as no doubt kept alive over the centuries by frequent sightings of the submerged forest around the coasts of Cardigan Bay -- these submerged woodlands contained tree stumps, branches, roots and even peat beds and layers of hazel nuts.  Here and there the trees all appear to have been felled as. a result of some catastrophe -- the trunks all lie parallel to one another in the peat.  Another thing contributing to the story is the occurrence of long ridges in the bay which are only exposed at extreme spring low tides.  They are still referred to as "causeways" in the local folklore tradition -- but they are in fact long ridges of lateral moraine, left by the last valley glaciers to flow out of the North Wales valleys into the lowland later to become Cardigan Bay.

This is of course another confirmation that during the Palaeolithic and Mesolithic relative sea-level was substantially lower than it is today, and that it rose gradually towards its present position, as outlined on a number of previous posts on this blog.



 Are you sitting comfortably?  Then I'll begin..........

Mererid, the Guardian of the Sacred Well        

Once upon a time,  very long ago, there was a fine fertile kingdom which later came to be called Cantre'r Gwaelod or the Lowland Hundred, to the north of Dewisland and Cemais. However, the land was known to its people and to neighbouring peoples as Maes Gwyddno.  As one might expect from the name, it belonged to a king called Gwyddno, and there were many fine palaces, and many princes and warriors who lived there in those far-off times.

There were four particularly famous warriors, named Mor, Kynran, Kenedyr, and Seithennin.  The mightiest and wisest of these was Mor, who was nicknamed Mor the Grand because of his feats in battle. Kynran was thought by many to be weak in the head. He was valiant in battle, but he was liable to strange utterances, predicting over and over again that the waters were going to burst forth, that the land would be lost beneath a great flood, and that the people should build boats in order to save themselves. Nobody took his seriously, for the sea was far away, and between Gwyddno's kingdom and the far-off land of Ireland there was a fertile plain with two slow and gentle rivers flowing to the south-western ocean. Kenedyr trusted nobody and was always prepared for war; he built himself a fine fort, called in Welsh Caer Kenedyr, to protect himself and his clan at times of trouble. And Seithennin, the last of the four, was himself a son of a king of Dyfed called Plaws Hen. He was honest and faithful to King Gwyddno, but he was over-fond of wine and mead and was of somewhat feeble mind.

In the kingdom of Gwyddno there was a magic well, whose secrets were entrusted to a damsel called Mererid.  She did not herself know these secrets, for they were tabu to all but the high priests. Mererid knew only that the well contained the mysteries of wisdom, and inspiration, and poetry; and she knew that nobody was allowed to gaze into its depths. Only she was allowed to take the sacred water from the well while averting her eyes, and only she could serve it in golden goblets to the king and his nobles.  It was also her duty to keep the well covered with a flat stone to contain its secrets and to keep it from overflowing. She was a mysterious and very beautiful young woman, well versed in the ways of the spirits. Like the priests of the kingdom, she was given to wierd incantations and strange behaviour which the common people did not understand. Indeed, Mererid was herself a sort of priestess, and even the king, while thinking her very comely, was slightly in awe of her.

Now it happened that the king had been at war with one of the kings of Ireland who had coveted his territory; but he had won a mighty victory and returned to Maes Gwyddno bearing with him the severed head of the Irish king. Flanked by his heroes Mor, Kenedyr, Kynran and Seithennin he rode through the gates of his fortified town to a tumultuous welcome from the people. The king and his people rejoiced. There was singing and dancing in the streets, the priests offered thanks to the gods, and in the king's palace a great feast was prepared.

The feasting and celebrations went on far into the night, with music and entertainments of the most lavish kind. The wine flowed freely, and everybody drank too much. Mererid was invited to the party, and temporarily forgot her sacred duties to join in the jollification.  She became a centre of attention, because she had never before been seen to let her hair down; and she too drank too much wine......

In the early hours Mererid returned to her well, none too steady on her feet and singing to herself in the moonlit velvet darkness. She thought that all was well with the world. Then she had an idea.  No harm would be done, she thought, if she was to remove the stone cover from the sacred well and to take just a little peep inside. Perhaps she could obtain a glimpse of its secrets. Perhaps she  would discover something of its wisdom and inspiration, and maybe write a poem or two to celebrate the king's victory in battle. And, so, feeling a trifle afraid but giggling to herself nonetheless, she moved the heavy stone aside and gazed into the depths of the well.

Immediately a great flood of water burst out of the well and threatened to overwhelm Mererid. She screamed and attempted to replace the stone cover, but the torrent continued, and in her drunken state her struggles with the heavy stone were clumsy and to no avail.  At last she gave up the fight and fled from the well, shouting out warning at the top of her voice.  But nobody heard her, for the common people were all deeply asleep following their celebrations, and the king and his family and nobles were still making merry in the palace. Inexorably the water poured out of the well and followed Mererid in a great tidal wave, flooding the town and the wide fertile plains of the kingdom. She struggled up to the highest rocky crag in the town and there, as she watched the water rising higher and higher, she threw her arms wide open and cried and pleaded and offered prayers to her gods for deliverance and forgiveness.

But those were hard times, and the gods would not be denied their retribution. As the waters rose many hundreds of townspeople, and many hundreds more in the countryside of Maes Gwyddno, were drowned. The floods swept through the palace, carrying away King Gwyddno, his wife and his nobles.  And Mererid, on the summit crag, was the last to drown, weeping bitterly as the flood waters closed over her.

Only three men survived the drowning of the Lowland Hundred. One of them was called Kynran, who had prophesied that one day this disaster would happen.  And he it was that had prepared a boat for which others had ridiculed him, and in which he floated away to the higher lands of Cemais. Another survivor was a bard who later composed a lament for the lost land and for the drowned king and his heroic warriors.The lament was remembered and repeated thousands of times by generation after generation of bards. And at last it was written down and included as one of the ancient manuscripts which came to be known collectively as the Black Book of Carmarthen. Mererid is still remembered as the bringer of catastrophe, through trying to know that which should remain unknown; and the well still holds its secret to this day, deep down beneath the grey silty waters of Cardigan Bay.


Date: c 200 BC?                                   Source: Rhys, p. 383

Sunday, 24 April 2011

The Soils of the Stonehenge Area -- no trace of Noah's Flood

 This is from the excellent Wessex Archaeology volume 2008 -- lots of interesting detail, but no trace of a flood either in the Mesolithic or Neolithic.....

Archaeology on the A303 Stonehenge Improvement
By Matt Leivers and Chris Moore
With contributions from
Michael J. Allen, Catherine Barnett, Philippa Bradley, Nicholas Cooke,
John Crowther, Michael Grant, Jessica M. Grimm, Phil Harding,
Richard I. Macphail, Jacqueline I. McKinley, David Norcott, Sylvia Peglar,
Chris J. Stevens, and Sarah F. Wyles
and illustrations by
Rob Goller, S. E. James and Elaine Wakefield

Wessex Archaeology 2008
This volume is available from Wessex Archaeology www.wessexarch.co.uk

Appendix 1: Soil

Richard I. Macphail and John Crowther
(Editorial note: this report was prepared before the analysis of the lithics from the site had been
completed. Interpretative differences between this report and the main text are due to the finer
dating that resulted from the lithic analysis)

Soil micromorphology, chemistry, particle size and magnetic susceptibility

Summary
Six thin sections and four bulk samples were analysed from two sites near Stonehenge. Remarkably,
the investigated soil sequences record rare examples of a prehistoric decalcified soil cover, in a now
generally rendzina-dominated landscape which reportedly has been extant since the Neolithic. At
Site 54379 in the valley of the Avon, Early Neolithic phosphate-enriched animal trampled soils
developed over river alluvium. Ensuing probable local cultivation (alongside likely continuing stock
management) led to colluviation, and evidence of in situ ard-cultivation in the accreting soils is
recorded. At site 48067, a bisequal soil profile had formed in reddish clay (of weathered chalk
origin) and silt (loess), by the early Holocene. This soil was buried by a prehistoric humic
colluvium of probable arable origin. These two soils give rare insights into an environment that is
generally believed to have been an open pastoral rendzina landscape by the Neolithic, and where
any cultivation impact has not been evident. These are also unique examples of in situ animal
herding and cultivation, and demonstrate how any remaining post-glacial decalcified brown soils
could have been eroded under human impact from Neolithic times onwards.

Introduction
Three soil monoliths from the A303 Stonehenge Improvement, Wiltshire were received from
Wessex Archaeology. Monoliths 30 and 31 came from a 0.46 m thick soil sequence containing a
Late Mesolithic/Early Neolithic flint scatter at Site 54379 (NW of Amesbury), which overlies
alluvium and is sealed by some 0.70 m of later soil/colluvium. Monolith 15000 at Site 48067 (300
m south of Stonehenge)sampled the soil in a solution hollow in chalk, and up through the palaeosol
into stony colluvium(?). This soil, which contains less well dated prehistoric flints, occurs below
some 0.35 m of later soil/colluvium and topsoil.


OVERVIEW

There are models of land-use for the topographic variations present in the chalklands of southern
England (Barker 1985, fig 74; Whittle 1997), and a variety of soil types have been investigated
from Neolithic and Beaker sites, which include valley silty gleys (Silbury Hill), rendzinas, and
calcareous brown earths, and occupation sites (Belle Tout, Easton Down, Maiden Castle, Windmill
Hill; eg, Evans 1972; Macphail and Linderholm 2004; Cranborne Chase and Durrington Walls;
French and Lewis 2005; French et al. 2007; French pers. comm. 2008). At the two A303
Stonehenge sites, there are unusual examples of non-calcareous soil accumulations in a landscape
that is generally rendzina-dominated (Icknield soil association; Jarvis et al. 1983), and one that is
thought to have produced very little colluvium (Allen 1992), presumably because it only had a thin
decalcified drift cover. The rendzinas of the region have a silt content that is believed to have a
loessic origin (Catt 1978). This is also an area where a stable, rendzina-dominated pastoral
landscape was often formed by the Neolithic, as based upon numerous soil studies in the area (see
above; French pers. comm.). These two A303 prehistoric locations, including the Late
Mesolithic/Early Neolithic site, thus provide some unique insights into the use, and impact upon,
decalcified brown soils prior to the almost universal development of shallow calcareous rendzinas
and brown calcareous soils. Moreover, these two decalcified brown soils have effectively recorded
ancient land use.

Catt (1978; 1979; 1986) has suggested that much of the loess cover of southern England had
been eroded into valleys by the early Holocene, and clearly Neolithic Silbury Hill buries a valley
gley formed in loessic silt (review of Ian Cornwall’s thin section in Macphail 1986, and
unpublished report to Cardiff University). South of Stonehenge, Site 48067 records both the
presence and character of the bisequel (clayey ß/Bt and silty Eb&Bw) late glacial/early Holocene
argillic brown earth, with the overlying prehistoric humic hillwash apparently recording the erosion
of this decalcified soil cover. Traces of such loessic brown soils occur as decalcified turf fragments
in ditch fills at Neolithic Millbarrow, Wiltshire (Macphail 1994), while Neolithic clearance and
cultivation(?)-induced erosion of loess was reported at Pegwell Bay, Kent. Unfortunately, the
assumed cultivation and associated hillwash at site 48067 can only be broadly dated to prehistory
(Barnett and Norcott, pers. comm.).
At site 54379, however, soil accumulation which can be dated from the flint scatter to the
Late Mesolithic/Early Neolithic seems to be associated with a primary land-use of stock
management and their passage effects at this location, presumably associated with grazing and
drinking along the valley of the Avon. This is both consistent with models of Neolithic valley land
use on chalklands (Barker 1985, fig. 74; Whittle 1997) and on floodplains in general (cf. Neolithic
Raunds, Northamptonshire; Macphail and Linderholm 2004). Ensuing local (upslope) cultivation is
presumed to have triggered additional colluviation that deposited flints, and which produced a
colluvial soil that was ard-ploughed in situ. The 302, 303, and 304 sequence thus records: stock
concentrations (304), presumed cultivation-induced colluviation (303) and in situ cultivation of this
accreting colluvium (302), with the likely continuing presence of stock throughout (303 and 302). It
has been suggested that after clearance of the Mesolithic woodland, soils of this chalkland region
were primarily stable rendzinas used for pastoralism (French and Lewis 2005), and there are plenty
of other buried soil records to support this view (Evans 1972; Macphail 1987; Macphail and
Linderholm 2004). Nevertheless, some Neolithic cultivation of ‘upland’ chalk soils was inferred at
Easton Down, Wiltshire (Macphail 1993), and here near Amesbury, there are clear indications that
cultivation was taking place in the Early Neolithic which was causing active erosion of a locally
present decalcified brown soil cover in the Avon valley.

Saturday, 23 April 2011

A History of Holocene Sea-level change in SW Britain

 I have posted this before, but here it is again....

This is the overall pattern of eustatic sea-level rise at the end of the Devensian Glaciation, as agreed by most experts from a wide range of disciplines:

Around 14,500  years ago, sea-level stood around -100 m, but a rapid rise of 40 m occurred up to 13,000 BP at a rate of 3.7 m per century.  A second major melting phase at 11,000 BP raised eustatic sea-level to around – 40 m by the beginning of the Holocene (10,000 BP) at a rate of 2.5 m per century, by which time global ice volumes had been reduced by over 50%.
  

Holocene sea-level then rose in the Bristol Channel area from -35 m OD at 9,500 BP to 2-5 m OD at 5,000 BP.  The rate of sea incursion gradually declined.  Around 7,000 years BP sea-level was around 8 - 10 m lower than it is today, depending on whose curve you are using (there is generally assumed to be a margin of error of + or - 1m)


After around 6,000 BP the marine incursion into coastal areas of northwest Europe took place more slowly.  In Neolithic times, the sea was at c -6m OD, and in Bronze Age times about -4m OD.  About 2,000 years ago (the time of the Romans in the UK) sea-level was probably about 2m below that of today -- but it may have been higher.  


The configuration of the British coastline around the time of Christ was similar to that of the present day, except that it was more indented due to the drowning of wetlands and estuaries which have subsequently silted up.  As mentioned in earlier posts, the evidence is difficult to interpret in some estuarine and fenland environments because of the effects of storm surges, changes of coastal configuration resulting from the breaching of dune barriers or pebble beaches, and from the compaction of sediments.

The Great Mesolithic Inundation (2)

 www.the-stonehenge-enigma.info

Robert Langdon has taken me to task for calling his Great Mesolithic Inundation an inundation.  Well, here's some free publicity for his book, together with a link.  Above is one of Robert's crucial maps, purporting to show how the Stonehenge bluestones were transported by sea, from one Mesolithic harbour to another.  The flooded area, purportedly around 7,500 BC (9,500 BP), is shown in blue.  Looks pretty inundated to me..........

Robert appears to have taken the 100m contour and used that as his reconstructed shoreline.  The only problem is that there is no evidence to support it, and indeed the theory is directly contradicted by the fact that all around the shores of South Wales and SW England there are submerged forests, showing that woodlands were extensive beyond the positions of the present shoreline after 10,000 BP and confirming that relative sea-level was substantially LOWER, not higher, than the shoreline of today.  After 10,000 BP it gradually rose to more or less its present position.

Until Robert manages to explain away the accumulated evidence of the submerged forests and the gradual rise of the Flandrian sea-level, shall we just quietly put his theory to one side, and forget about it?  And while he's about it, perhaps he will also explain away the evidence of Mesolithic settlement sites close to our present shoreline, in places which were at the time, according to him, under 100m of sea water?

What were we saying about pseudo-science?

The Superficial deposits of the Salisbury Area

 This is a crucial publication -- well worth a look.  It was published in 2006.  It's BIG -- 256 pp of detail, with large sections on solid geology and a good section (including lots of borehole data) dealing with Clay-with-flints and Quaternary deposits.  Sadly, Stonehenge is right on the northern edge of the map, and it would be good to have similar detail for the areas to the west and north, where crucial evidence may be lurking.......

Geology of the Salisbury sheet area - NERC Open Research Archivenerc.ac.uk
File Format: PDF/Adobe Acrobat
Report on the Geology of Sheet 298 Salisbury and its adjacent area. ...... margins of the Salisbury Plain Training Area in the north to the ridge south of ...
http://nora.nerc.ac.uk/7175/1/IR06011.pdf

Friday, 22 April 2011

What's in a name?

These are the two alternative views of what the glacier situation might have been in the SW approaches to the British Isles at the peak of the Devensian glacial episode.  The big lobe shown in the top illustration is traditionally referred to as the Irish Sea Glacier or as the Irish Sea Glacial Lobe or even as the Irish Sea Ice Stream.......  I have often used these names myself.

However, I'm increasingly convinced that during the Devensian the Irish Sea Glacier did not have the energy to push through St George's Channel in to the Celtic Sea, and that the ice that affected this southern area came from Southern Ireland.  Can I suggest, therefore, that interested parties should henceforth refer to the Celtic Sea Piedmont Glacier instead?  The word "piedmont" is not perfect, since it implies that the glacier we are talking about occupies a plain at the foot of a mountain range -- and some would have doubts about whether the scale of the Southern Irish uplands is adequate.  However, they look pretty much like mountains to me..... and if you take away the sea (and the ice), the area between Southern Ireland and Cornwall would have looked, around 20,000 years ago, like a very extensive lowland plain with rolling uplands on the northern horizon.

An unrecorded sub-magalithic burial site on Carningli?

This may be a new site, which I found yesterday.  More info on my other blog, for those who are interested:

 http://brian-angelmountain.blogspot.com/2011/04/another-burial-site-on-carningli.html

Those Fishguard Volcanics

In case anybody wonders what those Fishguard Volcanics (now appearing as important in the debitage or debris at Stonehenge) actually look like, you need look no further than the wall of our house.  We live in Cilgwyn, just beneath the lower slopes of Carningli and on the area of Fishguard Volcanics outcrops.  Some of the rocks are exposed along the stream that crosses our land, but for the most part the land surface is covered in till and sands and gravels dumped during the last glacial episode.

But when we built our house extension in 1978 we obtained our facing stone from a small private quarry at Sychpant, about a mile away, where small tors outcrop at the surface.  In the wall we can see blocks of rhyolite, volcanic ash, quartz, and dolerite.  Some of the stones have got abundant vesicles (gas bubble holes) in them.  Some have foliations or stripes, some are rather crumbly, and some are very hard indeed.  What makes many of these stones attractive as facings for buildings is their tendency to split along very flat cleavage planes, which are also iron-stained -- this gives the foxy red colour.  But when you look at the fresh stone the predominant colours are blues and greens.

A geologist would no doubt give these rocks a whole variety of very complicated names, including welded ash flows, tuffites, ignimbrites etc, but as far as my wife and myself are concerned, they are just very pretty rocks........

Click the photo to enlarge.

Thursday, 21 April 2011

Did the last Irish Sea Glacier have a shallow long profile?

 With reference to this link:
A Glaciological Dilemma
http://brian-mountainman.blogspot.com/2011/02/glaciological-dilemma.html
I have been pondering on ice surface gradients.
When glaciers are in an equilibrium state, for example at the peak of a glacial stage with the ice at its maximum advanced position, they should approximate to the theoretical equilibrium profile described (and calculated) by glaciologists over many years.  The diagram above shows the theoretical profile (solid black line), dependent upon assumptions about basal shear stress, ice movement mechanisms, ice temperatures etc.  The profile approximates to a parabola.  Actual observed profiles on big glaciers, ice sheets and ice caps tend to be very close to the theoretical, showing that the theory is more or less correct.  We can see this on the diagram, with respect to Greenland and Antarctica.  But by definition, the glaciers we are observing today are either high-latitude glaciers, often cold-based and flowing from massive ice sheets; or mountain glaciers, heavily influenced by terrain.  Did glaciers during the main glacial episodes behave in the same way in the lowlands of the mid-latitudes, where there may have been very different thermal regimes in the ice, and where sliding on the glacier bed (for example) might have been very much greater?

Have a look at these long profiles of North American glaciers in mountainous terrain:
We can see that all of them have pretty steep long profiles, conforming quite closely to the theoretical equilibrium profile (ie a steepening towards the snout) but with quite strong regional topographic controls as well.  So, for example, Milne Glacier drops from 1000m to sea level in about 50 km; Henrietta Naismith Glacier drops 1200m in about the same distance; Bent Glacier is very steep, dropping more than 1000m in 30 km; and Gilman Glacier drops 1200m in about 45 km.  Click to enlarge the illustration.

At the time of the maximum (Anglian?)  glaciation of SW Britain, I'm still pretty sure that something as portrayed in the above map happened, with thick ice flowing S, SE and SW from St George's Chennel and with an ice surface around 2,000m between Fishguard and Rosslare.  That still gives a relatively shallow gradient, with a surface drop of 2,000m in c 500 km or 1,000m in about 200 km close to the ice edge.  (As we can see from the theoretical profile above, the ice surface gradient gradually declines with distance from the ice edge.)

But the situation in the Devensian Glaciation, around 20,000 years ago, appears to have been very different.  As noticed in my earlier posts (including the link above) a number of geomorphologists have recently suggested that there was a long shallow lobe of Irish Sea ice (with a gentle surface gradient) that pushed south-westwards from St George's Channel to the Scillies and beyond, at the peak of the Devensian glaciation:

 

I have been a bit sceptical about this, on the basis that ice with such a shallow gradient, with no topographical constraints, cannot have extended southwards as a long narrow lobe over 400 km long without spreading laterally onto the coasts of Somerset, Devon and Cornwall.

I still go for the Celtic Sea Piedmont Glacier idea, as portrayed on this map:


That having been said,  and having looked at some evidence from the Wisconsin glaciation of the Great Lakes area of North America I'm increasingly convinced that the gradient on this piedmont glacier might have been very shallow indeed.  North American geologists and geomorphologists have known for many years that near the southernmost extent of the Laurentide Ice Sheet during the Wisconsin, the ice flowed in a series of semi-independent lobes, reaching their maxima at different times.  Big end moraines and lateral moraines traced on hills and nunataks suggest that the lobes had incredibly shallow profiles, as shown on the top diagram with the green and red lines. (Excuse the fact that the lines are wobbly -- my shaky hand!!)   In Minnesota, South Dakota, Iowa and Montana the long profiles of these lobes was so shallow that the ice surface rose only about 500m over a distance of 500 km.  Now according to classic glaciological theory the ice should not have been capable of moving all that way with such a shallow surface gradient -- UNLESS the ice was moving rapidly in a vast surge, with a highly lubricated bed.  In other words, the shear stress in the glacier ice must have been vastly different from that of the cold-based glaciers used in the classic glaciology studies.  there must have been huge volumes of meltwater moving on the glacier bed......

So if the ice that crossed the Celtic Sea, moving broadly towards the SE from Ireland, was terminating close to present-day sea-level all the way from North Pembrokeshire to the Scilly Isles, what was the ice surface altitude on the coast of Southern Ireland?  I will hazard a guess and suggest that it was around 300m, but that's based on nothing but intuition and geomorphological instinct!

All contributions on this one gratefully received -- especially from geomorphologists.

Wednesday, 20 April 2011

Navigating to Stonehenge -- lessons from Ancient Woolworths stores


On the subject of ancient triangles and Neolithic navigation, this wonderful "press release" appeared in January 2010. Many thanks to Matt Parker.... and it's interesting to think that like the tribal societies of the Neolithic, Woolworths is (was) a lost civilisation, which we will be increasingly at a loss to understand, as the years roll by. Maybe their demise was partly down to the fact they their chieftains were not sufficiently attuned to Earth Energies, and that their triangles were in the wrong places, or were of the wrong size and shape?



Locations of Ancient Woolworths Stores follow Precise Geometrical Pattern
Matt Parker

http://bengoldacre.posterous.com/did-aliens-play-a-role-in-woolworths

5 January 2010

Matt Parker, based in the School of Mathematical Sciences at Queen Mary, University of London, has analysed the locations of the 800 Woolworths stores to reveal precise geometric patterns. This was based on the work of Mr Tom Brooks (a retired marketing executive of Honiton, Devon) who found similar patterns in prehistoric monuments across the UK.

Mr Brooks looked at 1500 sites and found that some of them follow geometric patterns and he concluded that they must have been part of a sophisticated navigational system. This was reported in the UK national press on 5 January 2010, with the Daily Mail reporting that the patterns were so “sophisticated and accurate” that “he does not rule out extraterrestrial help.”

Matt Parker then decided to apply this technique to another ancient and mysterious civilisation: that of the Woolworths stores.

“We know so little about the ancient Woolworth stores, but we do still know their locations” explains Matt Parker, “so I thought that if we analysed the sites we could learn more about what life was like in 2008 and how these people went about buying cheap kitchen accessories and discount CDs.”

The results revealed an exact and precise geometric placement of the Woolworths locations. Three stores around Birmingham formed an exact equilateral triangle (Wolverhampton, Lichfield and Birmingham stores) and if the base of the triangle is extended, it forms a 173.8 mile line linking the Conwy and Luton stores. Despite the 173.8 mile distance involved, the Conway Woolworths store is only 40 feet off the exact line and the Luton site is within 30 feet.  All four stores align with an accuracy of 0.05%.

The bisector of this same triangle then passes through the Monmouth, West Bromwich and Alfreton store locations with an accuracy of 0.5%. There are also grids of isosceles triangles – those with two sides of equal length – on each side of the Birmingham Woolworths Triangle. One such isosceles triangle made with Stafford only has an error of 3% and it points directly at the Northwich Woolworths store that is itself only 0.6% off being exactly isosceles.

Matt Parker concludes that “these incredibly precise geometric patterns mean that the people who founded the Woolworths Empire must have used these store locations as a form of ‘landmark satnav’ to help hunters find their  nearest source of cheap sweets that can be purchased in whatever mix they chose to pick. Well, that or the fact that in any sufficiently large set of random data it is possible to find meaningless patterns of any required accuracy.”

These patterns were found from the 800 random ex-Woolworth locations by simply skipping over the vast majority of the sites and only choosing the few that happen to line-up. Matt Parker claims he could find many more such patterns, but he had some actual real work to do. He does envy Mr Tom Brooks though, who with 1500 locations, had almost twice as much data to pull meaningless patterns from.

 “It is extremely important to look at how much data people are using to support an argument” Matt Parker warned. “For example, the case for global warming covers vast amounts of comprehensive evidence, but it is still possible for people to search through the data and find a few isolated examples that appear to show otherwise.”

Triangles everywhere

This is an interesting article, based on a 2009 book claiming that Neolithic man navigated his way round Britain by using the spatial relationships between key points, based on a form of triangulation.  Tom Brooks clearly sees triangles everywhere -- and this all reminds me of the geometry / numerology of Robin Heath, which all sounds very scientific and impressive until you start looking into it.  Need to read up on this a bit more, before reporting back.....

 


Sat-nav: Prehistoric man 'used crude sat nav'

http://www.telegraph.co.uk/news/uknews/8461290/Sat-nav-Prehistoric-man-used-crude-sat-nav.html

 Prehistoric man navigated his way across England using a crude version of sat nav based on stone circle markers, historians have claimed.

They were able to travel between settlements with pinpoint accuracy thanks to a complex network of hilltop monuments.

These covered much of southern England and Wales and included now famous landmarks such as Stonehenge and The Mount.

New research suggests that they were built on a connecting grid of isosceles  triangles that 'point' to the next site.

Many are 100 miles or more away, but GPS co-ordinates show all are accurate to within 100 metres.

This provided a simple way for ancient Britons to navigate successfully from A to B without the need for maps.

According to historian and writer Tom Brooks, the findings show that Britain's    Stone Age ancestors were ''sophisticated engineers'' and far from a barbaric    race.

Mr Brooks, from Honiton, Devon, studied all known prehistoric sites as part of    his research.

He said: ''To create these triangles with such accuracy would have required a    complex understanding of geometry.

''The sides of some of the triangles are over 100 miles across on each side and yet the distances are accurate to within 100 metres. You cannot do that by chance.

''So advanced, sophisticated and accurate is the geometrical surveying now discovered, that we must review fundamentally the perception of our Stone Age forebears as primitive, or conclude that they received some form of external guidance.

''Is sat-nav as recent as we believe; did they discover it first?''

Mr Brooks analysed 1,500 sites stretching from Norfolk to north Wales. These included standing stones, hilltop forts, stone circles and hill camps.

Each was built within eyeshot of the next.

Using GPS co-ordinates, he plotted a course between the monuments and noted their positions to each other.

He found that they all lie on a vast geometric grid made up of isosceles 'triangles'. Each triangle has two sides of the same length and 'point' to the next settlement.

Thus, anyone standing on the site of Stonehenge in Wiltshire could have navigated their way to Lanyon Quoit in Cornwall without a map.

Mr Brooks believes many of the Stone Age sites were created 5,000 years ago by an expanding population recovering from the trauma of the Ice Age.

Lower ground and valleys would have been reduced to bog and marshes, and people would have naturally sought higher ground to settle.

He said: ''After the Ice Age, the territory would have been pretty daunting for everyone. There was an expanding population and people were beginning to    explore.

''They would have sought sanctuary on high ground and these positions would also have given clear vantage points across the land with clear visibility    untarnished by pollution.

''The triangle navigation system may have been used for trading routes among the expanding population and also been used by workers to create social paths back to their families while they were working on these new sites.''

Mr Brooks now hopes his findings will inspire further research into the navigation methods of ancient Britons.

He said: ''Created more than 2,000 years before the Greeks were supposed to have discovered such geometry, it remains one of the world's biggest civil engineering projects.

''It was a breathtaking and complex undertaking by a people of profound industry and vision. We must revise our thinking of what's gone before.''

'Prehistoric Geometry in Britain: the Discoveries of Tom Brooks' is now on sale priced £13.90.

Sunday, 17 April 2011

Geological Survey maps ice limit

 Click to enlarge the map.

Been looking at the Geological Survey map of the Fishguard area (Sheet 210) published last year.  Not only does it give fantastic detail for the Fishguard Volcanics and the other rocks currently attracting attention from the geologists -- but it is also a drift map, showing the superficial deposits of Devensian and more recent age in the area.  The red line shows the Geol Survey assessment of where the devensian drift deposits (till and sands and gravels) end.  North of the line, deposits are widespread.  South of the line, Devensian glacial deposits are not supposed to exist.

The map is quite similar to others recently published on this blog.  However, it is inaccurate in many respects, and the field mappers have only included THICK deposits.  For example, on Dinas Mountain and on Carningli there is a thin spread of till south of the line -- difficult to map, and not always visible when the gorse and heather are thick.  Luckily, recent burning has stripped back the vegetation, allowing these deposits to be seen quite clearly.

I persist with my view that most of Carningli WAS covered by the ice of the Irish Sea Glacier during the Devensian.  What happened further east, on the north flank of the Preseli ridge, is a matter for further research.

Friday, 15 April 2011

Stonehenge erected by Neolithic sex cult



The Asterix Revelation

We are grateful to our correspondent Asterix for the revelation that Stonehenge was erected by a Neolithic sex cult which migrated to Wessex from West Wales.  The cult, which seems to have been obsessed with procreation, placed special emphasis on the bluestones, which were carefully selected for their magical erotic properties.  The hard dolerite stones, which were for the most part tall and slender,  were clearly specially selected as phallic symbols, whereas the softer volcanic ashes and rhyolites, generally more flaky and tending towards disintegration, were symbolic of the fairer sex.  As Rodney Castleden has pointed out, the bluestones were set up in an alternating arrangement of tall thin monoliths (male) and short stumpy ones (female).

It is clear from the evidence on the ground that the placing of each tall bluestone in a sacred socket or pit was in itself an act of profound sexual significance.  There must have been considerable ritual activity connected with the placing of each stone.  Moreover, it has been known for many years that the stone settings were constantly changed, and archaeologists from the Department of Reproductive Archaeology at the University of Salisbury now believe that the ritual stone settings were changed every spring, at the equinox, with new sacred sockets dug and selected auspicious stones inserted into them with due reverence. 

It is now believed that the Altar Stone (which has always puzzled archaeologists) was covered with a bed of daffodils and primroses during such ceremonies, and used for certain ceremonials of a sexual nature.

Professor Tintin Obelix of the DRA department commented:  "These new revelations are very stimulating indeed, and require careful analysis.  We are inclined towards the view that Stonehenge was indeed a "place of the living" rather than a "place of the dead", and that the Neolithic builders of the early monument were preoccupied with having a good time.  Indeed, we know that they had jolly barbeques just up the road at Durrington Walls, and that Welsh party-goers always brought their own beefsteaks.   These people clearly knew how to rave, and it is regrettable that following the "erotic bluestone" phase at Stonehenge, things became much more boring when a new chieftain took over and started putting up all those miserable sarsen stones with lintels........."

Professor Obelix added that the new research confirmed what many people had been thinking for centuries, but had been reluctant to articulate for fear of upsetting Oliver Cromwell and Mary Whitehouse.

It is now believed that the standard guidebooks to Stonehenge will have to be rewritten, with special editions for children and others of a sensitive disposition.

Thursday, 14 April 2011

From another ancient manuscript.....

 A typical Welsh henge, associated with an ancient sport of ritual execution, invented in Wales 
and now played all over the world

Thinking about my latest theory regarding the building of Stonehenge, and the link with Pont Saeson,  it's worth referring our learned readers to the following ancient text, which I have every reason to believe is authentic.  I first posted it in December last year:

Stonehenge was built as a place of execution of invaders by my great great great great grandfather ffred fflyntstwn who found fame and fortune when he paddled his stone coracle across the sea to discover america and potatoes, the latter he imported into his home country selling them at one and six for 20, or 2 shillings if filter tipped. The profits from this enterprise paid for the building of Stonehenge.
The first executions were of Picts and Scots who came down from the north and despoiled the countryside by carving white horses into the chalk hillsides to advertise their native drink; a most serious offence against the hill-fort and ridge & furrow planning regulations.
The invaders were executed in batches of 15 on each Saturday afternoon while the watching britons sang their traditional execution songs.
This practice has continued down to the present day. On the outskirts of Cardiff two wood henges are erected at opposite ends of a green sward and between them, as a Saturday afternoon’s entertainment,
15 foreign invaders are executed, their screams of agony being drowned by the singing of “Calon lan yn llawn daioni ……“sung in a minor key.
The very first execution was of one known to the Britons as Toni ap Robyn whose severed head garlanded with mistletoe was displayed on a pole at the centre of the circle, unfortunately the head refused to hold its tongue and kept heckling the chief druid during the summer solstice executions. This situation could not be tolerated so the head was buried at a secret location , during the internment a dreadful curse placed upon his descendants in perpetuity. The curse compels them to roam the land, digging wherever they go in a vain attempt to recover the head and give it a decent burial. To this day one might encounter Toni ap Robyn’s descendant flanked by his two ceremonial spade bearers, Mick of the flowing hair and Phil of the feathered hat, marching through the land, pausing to dig for the cabbalistic number of three days, then moving on under the guidance of their high priestess the lady Carenza
Love
Boadi

Pentre Ifan and Stonehenge



Now here's an interesting thought, which I contribute without charge to all those who are interested in conspiracies and fairy tales.  Pentre Ifan, the most famous Neolithic site / megalithic monument in Wales, is located slap in the middle of the Fishguard Volcanics area, about 2 km from Pont Saeson.  It is made of locally-derived slabs and pillars of volcanic rock, very similar to that which appears to be represented in the debitage at Stonehenge.  It is normally referred to as a variation on the portal dolmen theme, and as a precursor of the Severn-Cotswold type of tomb found in SE Wales and as far east as Salisbury Plain.  Pentre Ifan is dated to about 3,500 BC or 5,500 BP.

Pentre Ifan is very spectacular structure, built by people who understood how to "lift" very large slabs of rock and to perch them rather precariously onto supporting uprights.

At Stonehenge we have an even more spectacular monument, with the big uprights and lintels made of sarsens but with many stone fragments in the soil layer which MIGHT (still to be proved) come from the Fishguard Volcanics.  According to conventional wisdom, the first stone settings at Stonehenge were made around 2,400 BC or 4,400 BP -- a thousand years or so after Pentre Ifan. 

But I offer this as a suggestion to the makers of future TV programmes:  

Stonehenge was built by a tribal group that migrated eastwards from the Pentre Ifan area in Pembrokeshire.  They were very clever builders, who had inherited skills in working with big stones, and the inhabitants of Salisbury Plain accorded them high status.  They were typically Welsh, very good at starting things but not finishing them.  When they had the monument almost half-finished, and stones became increasingly difficult to find, their enthusiasm started to flag, and to encourage them the Stonehenge chieftain sent emissaries to Pont Saeson (where Uncle Dafydd lived) to bring back some buckets full of magic stones.  These were ritually scattered across the site at Stonehenge, with a view to reinvigorating the workers.  But what happened was unexpected.  The workers all became afflicted with hiraeth, and before you could say "Llanfair PG" they had all downed tools and returned to Wales, singing soulful songs and complaining about lousy working conditions.  So Stonehenge never was finished, and there remains to this day a vague folk memory that Stonehenge has something to do with Wales.

And if you think THAT'S far-fetched, just take a look at the publications of English Heritage and the magazine articles of certain learned professors..........

Fishguard Volcanics terrain

These two maps give a picture of the geomorphology of the area where the Fishguard Volcanics outcrop.  You can use Newport Bay and the coastline as a reference in reading the lower map.  Broadly, the volcanics outcrop on the north-facing slope of the Carningli upland,  in the broad depression which is the catchment area of the Nevern River, and then in the upland area at the eastern end of the Preseli ridge.  These rocks, including rhyolites and ashes, are softer and therefore more easily eroded than the dolerites and other intruded rocks shown as black on the geology map.  So just as the volcanics are referred to as "soft rocks" or "rubbish rocks" at Stonehenge, because they have not persisted as well as the dolerites in the standing stone settings, they are also associated with a softer and gentler type of landscape because fluvial and glacial processes have managed to erode them away -- leaving the dolerite areas as hill masses and ridges. 

Wednesday, 13 April 2011

Precision in provenancing


I've been mulling over the question of the precise provenancing of the standing stones, stumps and fragments found at Stonehenge.  I don't think we sorted this out properly during our previous discussion.

As an amateur geologist who became quite good at the matching up of hand samples but who became completely lost when I sat in on an Oxford University optical mineralogy class, I'm still not sure how close science has brought us to being able to say that fragment A (or thin section A) comes from location B, to an accuracy of maybe 100m.  As I understand it, the two methods we have currently for this provenancing are petrography, giving a physical measure of the minerals and their arrangement or "structure" in a thin section, and geochemistry, giving a chemical and hopefully quite unique representation of the number of minerals present and their abundance.  The two together should give an accurate "fix" -- and should enable one sample to be compared with another in order to find an identical (or maybe just a close) match.

As I understand it, Rob and Richard have been able to say that the rhyolite at Pont Saeson has a characteristic structure which is altered (by a long process of metamorphism) from the way it looked originally.  So far so good.  But how big is the area over which that precise degree of alteration of that precise mixture of minerals is recognizeable?  Ten metres?  A hundred?  A kilometre?  If the Pont Saeson sample used in the recent work came from the prominent rock outcrop in the valley, and if it was 90% matched with a fragment from Stonehenge, there is obviously a pretty good chance that the fragment came from the outcrop.  But is it not possible that there is another locality, somewhere in the yellow area (Fishuard Volcanics) shown on the map where there is a 100% match?  The ACTUAL provenance of the fragment might not be a prominent outcrop at all -- indeed it may nowadays be covered with sediments, and may therefore be quite invisible without excavation...........

 Three locations where Fishguard Volcanics are exposed -- 
Brithdir Mawr, Pentre Ifan and the coast near Dinas

What I'm getting at is misplaced confidence.  We have all had a good go at Herbert Thomas for his simplified and even simplistic provenancing of the Stonehenge bluestones to Carn Meini and the immediate neighbourhood........ and although huge progress has now been made in both geochemistry and petrography, there is still a margin of error that we must not forget about.  How many locations within the yellow area on the map have been sampled with a view of matching the fragment now assigned to Pont Saeson?  It would be good to see a map of the sampled points.  Maybe that is something that will come in a future publication?

I raise this not because I want to throw any doubt on the excellent and important recent geological work on the bluestones, but because I'm particularly interested in the ENTRAINMENT process.  There is no particular reason why bluestone boulders, pillars or pebbles should be entrained from prominent tors like Carn Meini, or from smallish rock outcrops like that in the valley at Pont Saeson.  The entrainment of big and small lumps of volcanic ash, rhyolite, ignimbrite and other complicated rocks with unpronounceable names could have occurred anywhere within that area marked yellow, and we should expect that material to show up in the Stonehenge "debitage."

I look forward to seeing the next paper on the next batch of fragments....

Tuesday, 5 April 2011

Stonehenge Rocks and the Irish Sea basin



More about Stonehenge rocks in issue 254 of Current Archaeology -- newsy items about the Ixer / Bevins / Pearce work on the bluestones and their provenance, and about the laser scanning project which will target all of the standing stones.  In the writeup based on the Leicester, National Museum and Aberystwyth press releases,  the writer does at least acknowledge the possibility of glacial transport, but then he spoils it all by referring to the Irish Sea Glacier as a "huge ice stream that gouged out the Irish Sea..."  Oh dear, wherever did he get that strange idea from?  Here I am, trying to educate archaeologists (and other human beings) in the fascinating world of geomorphology and glaciology -- and they still get it all wrong.  What can one do?  Swallow hard, and press on.....

For the record, the Irish Sea Basin is immensely old and has a complex origin.  It was the overall form of the basin, and the channel of Cardigan Bay and St George's Channel, that directed the southward flow of the glacier on more than one occasion during the Ice Age.  Sure, the glacier will have achieved substantial erosion in some parts of the basin, bit it was also responsible for a lot of deposition too.  It's doubtful whether the glacier widened or deepened the basin to any great extent.

A geological dilemma or two

Now here's an interesting question or two, that maybe Rob, Olwen or Richard can answer.  The Pont Saeson rocks that have been matched at Stonehenge have come from an innocuous outcrop of volcanics slap in the middle of the area marked yellow on the above map.  The precise location is near the DD in Mynydd Preseli.  That means that outcrops of the same suite of rocks occur to the SE (in the area including Foes Drygarn and Carn Alw at the eastern end of the Preseli ridge), to the N (in the area to the east of Pentre Ifan burial cjamber) and then to the NW (in a belt of country on the north flank of the Carningli upland).  That latter area includes Sychpant, the strip of land incorporating Newport Castle, and then the "inland cliff" above Dinas.

What I want to know is this.  Within this whole area, (yellow on the map) how unique will be the "rock signature" of the samples taken from Pont Saeson?  The general pattern is one of strips of igneous rock, most obvious with the strips of dolerite but also (presumably) occurring within the rhyolites and other rock types within the Fishguard Volcanics).  So could the Pont Saeson samples found at Stonehenge actually have come from the same outcrop, but further north -- for example from Sychpant or the Newport or Dinas area?  I ask that because those would be the areas where I would expect entrainment to occur if a thick glacier was flowing across the landscape from NW towards SE.

Then another question -- what about the Stonehenge rocks identified (by the OU team around 1998) as probably having come from Carn Cwn, Carn Clust-y-ci and Carn Llwyd -- also on the northern flank of Carningli?  Do those identifications still stand?  Has the geochemistry on those samples now been supplemented by other work -- for example on the zircons?

Answers on this blog, rather than on a postcard, please...... thanks!

Nice design -- pity about the content

 The online edition of Wiltshire magazine is now available, and so we can all read the article by Robert Harvey at our leisure.  It's called "New Light on Old Stones" but there is nothing new in it at all -- in fact, it isn't even up-to-date enough to report on the geology reports of the last 12 months or so.  The design is delightful, but one would have thought that the author could have found SOMETHING relatively new to place before his readers.  The Darvill - Wainwright nonsense about sacred stones and healing springs is repeated yet again -- although the author does have the good grace to report on Mike Pitts' scepticism.......

http://edition.pagesuite-professional.co.uk/launch.aspx?referral=other&refresh=B1q4aS7080Yw&PBID=0f3b4ce9-f813-40d4-a5bc-df2b571ee089&skip=

Time for a revamp of the old old story?



Good news for the Wiltshire Heritage Museum in Devizes -- money for a revamp of displays and the development of new Bronze Age galleries.  Congratulations to the museum -- it's difficult to pick up funding in these times of massive competition and financial constraints. 

Wouldn't it be nice if the Museum people were to take this opportunity to reinterpret the Stonehenge story -- and at least to acknowledge that there is a sound alternative to hoary old "bluestone transport" myth?  Just some mention of the glacial transport theory and the recent geological studies would be a nice move in the right direction....... and a move towards a proper respect for science and the balance of probabilities.



Heritage Lottery Fund awards development funding to Wiltshire Heritage Museum
Thursday, 31 March, 2011
http://www.wiltshireheritage.org.uk/news/index.php?Action=8&id=131&page=0

Friday, 1 April 2011

Profs D & W: Repeat something often enough and it becomes true.......

Following the revelations (sorry, meant "repetitions") in Current Archaeology and Salon in recent weeks,  Profs Darvill and Wainwright have apparently been beavering away again.  Tony reports that there is something in the magazine called Wiltshire, written by Robert Harvey and entitled "New light on old stones of Stonehenge."  Is this a nightmare or another April Fools joke?  We shall see.....

It looks as if the author has been thoroughly briefed by our two learned friends, to the point of regurgitating ancient stuff that we hoped had long since been forgotten about.  Haven't seen the article myself -- it doesn't penetrate this far west, but I look forward to seeing it in due course.

As somebody said a long time ago, if you repeat something often enough, it becomes true -- in your mind at least, while the rest of the world looks on in wonderment.