Glaciers in Devon and Cornwall

Above: Dartmoor - low sun and winter frost.

Below:  One of my attempts to show the small thin ice caps of SW England and their incorporation within the glacial limit of the Anglian Glaciation.

Thanks to Pete G for bringing this to my attention.

Am I allowed to say "I told you so"?  As faithful followers of this blog will know, I have mentioned on many occasions that the uplands of SW England (including Exmoor, Dartmoor and Bodmin Moor) must have carried small ice caps during the main glacial episodes.  Now some new research has shown that Dartmoor did carry an ice cap of its own, and that the ice was at various times thick enough and active enough to create streamlined forms.  Apart from Stephan Harrison, most geomorphologists have been wary of getting involved in the "small ice caps" debate, and it's good to see some serious work at last on this topic, published in a peer-reviewed journal.

We should not be surprised -- after all, the glacial models from Aberystwyth University have been showing exactly the same thing as Evans and Harrison are now proposing on the basis of fieldwork on the moor.

The implications are very big indeed, since if there were substantial glaciers on  the uplands of SW England it is entirely reasonable to suggest that the Irish Sea Ice Sheet also pressed far inland into Somerset and maybe even into Wiltshire.

I hope that some of the archaeologists will now sit up and take notice.

I will try to get a copy of the paper, and will report further, but for the moment we will have to make do with the report from the Western Morning News.......


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Dartmoor developed its own Ice Age glaciers – researcher

Wednesday, June 13, 2012
Western Morning News

http://www.thisisdevon.co.uk/Dartmoor-developed-Ice-Age-glaciers-ndash/story-16355689-detail/story.html

In terms of human history the last Ice Age was the biggest thing ever to happen to the West country – but the question always has been just how far south the vast glaciers extending from the Arctic reached.

It's known that mankind lived in the South West before the Ice Age occurred, but for decades geologists believed the massive ice-wall stopped more-or-less along the shores of the Bristol Channel.

Now, however, new research has discovered there were glaciers far to the south.

By using hi-tech new methods of observation, scientists from both Exeter and Durham universities have been able to establish that huge ice-sheets covered the heights of Dartmoor.

They were so big and powerful that the moving ice-sheets were even capable of lopping off some of the mighty granite tors which would, otherwise, still be a feature of the more central parts of the plateau.

The research, which was undertaken by the two universities and Stockton Riverside College, has just been published in the journal Quaternary Science Reviews.

Researchers, who carried out detailed observations on the ground and using aerial photography, say the evidence includes glacial features such as elongated rounded mounds or drumlins and hummocky landforms or moraines.

They believe similar features may also exist on Exmoor and Bodmin Moors, indicating that upland glaciers would have been a feature of the Westcountry's frozen Ice Age landscapes.

The findings are important as they say a good deal about how some of our most high profile landscapes were formed. Researchers believe the glacier ice helped give the highland plateau its distinctive appearance.

On the highest hills the ice cap – which would have been up to 100 metres thick in places – either destroyed and carried away tors, or prevented their formation over thousands of years.

However, the really big tors found around the edges of Dartmoor – such as Yes Tor, Hound Tor and Hay Tor – survived because they were either left untouched by the ice or because the ice layer on them was not substantial enough to destroy and move them.

Dr Stephan Harrison, of Exeter University, told the Western Morning News: "We are saying the broad high plateau areas in the middle of North Dartmoor were able to produce glaciers and these thickened and then flowed downhill into the valleys. The highest ground (such as the area around Yes Tor) was quite narrow and glaciers on these locations could not develop as successfully."

Dr Harrison is adamant the glaciers would have existed on the moors: "Dartmoor was high enough and big enough to develop its own ice cap," he said.

"The evidence is compelling when you look closely at the landscape – and our research techniques may help us to see if other southern upland areas of the UK were also glaciated and shaped by ice."

Professor David Evans, of Durham University, added: "The story is more complicated than we have traditionally believed.

"A landscape that has been regarded as a classic example of cold, non-glacial processes was in fact covered by a glacial ice cap.

"Dartmoor was the location of the southernmost independent ice cap in the British Isles, the evidence for which is so subtle that researchers had missed it for almost 100 years."

The death of the Ruwenzori Glaciers

A new project is mapping the glaciers of Africa -- looking in particular at the Ruwenzori and Kilimanjaro.  There are some spectacular photos on the Guardian web site.

http://www.guardian.co.uk/environment/gallery/2012/jun/02/africa-forgotten-glaciers-in-pictures#/?picture=391043249&index=4

The picture is a universally depressing one.  These two photos are from more or less the same place -- the top one shows the Ruwenzori Glaciers and snowfields as they were in 1925, and the lower photo shows the situation today. Now there is virtually nothing left -- within a decade or so all the ice will probably have melted.  Glaciers have come and gone before, but climatic warming is causing a phenomenally fast shrinkage of glaciers in vulnerable locations at present.....

South Pembrokeshire Standing Stones

 Acknowledgement:  Royal Commission.  Top:  Ty Newydd, Mathry (N Pembs).  Bottom: Harold Stone, Skomer Island (S Pembs)

Have a look at this site:

http://www.rcahmw.gov.uk/HI/ENG/Heritage+of+Wales/Gallery/The+J.C.+Young+Pembrokeshire+Standing+Stones+Paintings/

Fascinating!  Detailed paintings of 53 standing stones in Pembs -- most of them are in the north, but there are some in the south.  Only 21 of the paintings are reproduced on this site -- I wonder where the others are?  Will continue to investigate......

The Caveman Effect

  Pentre Ifan -- a place of special sacredness, or simply one of many, of which most of the 

others have been removed?  In other words, simply a cromlech that nobody had any 

particular reason to get rid of?  A random relic rather than a supreme example of megalithic engineering?

As readers of this blog will know, one of my favourite themes is sampling bias.  I have recently been trying to explain to Geo that there is not necessarily any great "significance" in the fact that a few old geologists found a few erratics from a certain area in another area where there happened to be a few ploughed fields which were easy to examine.  On that basis they described what they found, thereby inviting other geologists to go and have another look in the same place, some 70 years later -- that, in a grotesque sort of way, invested the location with even more "significance" simply because it was mentioned by name...........


But actually, our concentration on this particular site is entirely illogical and artificial........ it may well be that there is a far more significant site one field away, or a kilometre away, or ten kilometres away, which nobody has yet discovered or got round to looking at........


This is a quote from the Wikipedia page on sampling bias:
An example of selection basis is called the "caveman effect." Much of our understanding of prehistoric peoples comes from caves, such as cave paintings made nearly 40,000 years ago. If there had been contemporary paintings on trees, animal skins or hillsides, they would have been washed away long ago. Similarly, evidence of fire pits, middens, burial sites, etc. are most likely to remain intact to the modern era in caves. Prehistoric people are associated with caves because that is where the data still exists, not necessarily because most of them lived in caves for most of their lives.

 One of the Lascaux cave art images.  Were the painters cave dwellers or did they live in the open?  Were they better painters than those who painted things outside the caves?  Were the Lascaux artists uniquely clever?  Lots of questions, and lots of room for sampling bias......

I have previously admitted to sampling bias myself,  when in my D Phil thesis I gave great importance to a site called Ogof Golchfa, thinking it to be unique and hugely important, whereas when I went back many years later I realised that there was an even better (and more important) site just round the corner, which I had entirely missed.  Why had I missed it?  It might have been covered with brambles at the time, or it may have been pouring with rain when I walked past it, or it may only recently have been revealed by a rockfall.

On the same basis I have expressed concerns about the incredibly detailed provenancing by Rob Ixer and Richard Bevins of the "foliated rhyolites" from Craig Rhosyfelin to within a few metres of one particular sampling location.  As I have explained before on this blog, I am not sure that you can do that, unless you have sampled several hundred sampling points on a detailed and very tight grid, across a large area.  And your sampling is in some way biased towards the places where you have rock outcrops at the surface.   In other words, the provenancing conclusion may be down to sampling bias rather than reality.  So although their geology is highly impressive, I retain a degree of doubt and reserve judgment on the conclusions reached. 

In the archaeological field, we see over and over again that a site or group of sites may be interpreted as belonging to some great cultural complex, only for the thesis to be overturned as new discoveries show wider distributions than anticipated, or even larger and more complex associations of features elsewhere.  In Pembrokeshire, for example, we have suspected for many years that the distribution of cromlechs or standing stones (as we see them today) may have no geographical or cultural significance -- it may simply be that those features in the roughest areas have survived better, while features in the lowlands which have been heavily used for agriculture over the past few centuries have been flattened or simply removed because of their "nuisance value."  And those features that have survived in the uplands have not survived because they were venerated in any way, or even because they were erected in "sacred places" -- but because in recent centuries they were not particularly in anybody's way, so that nobody could be bothered to remove them.

The Neolithic Argonauts

Here is an extract from Chapter 5 of "The Bluestone Enigma"  pp 78-80.  It deals with the matter of maritime transport and the likelihood of 80 or so large bluestones being carried by water across the Bristol Channel.  Actually, the stones have many different geological provenances, but let that little matter pass for the moment.....

This might come in handy, given the renewed interest in recreating the "bluestone voyages" for a TV documentary to be filmed in August.


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Reference has been made above to the nature of the craft which might have been used by the Early Neolithic adventurers on their crossings of the Bristol Channel or the Severn Estuary.  It is also assumed that the seafarers had reasonable “mental maps” of the seaways they were using, and also considerable maritime skills.  Aubrey Burl, a seafarer himself, was not convinced:

There has been little serious consideration of the logistics involved in the hypothetical journey from Wales to Wiltshire. The most meticulous was by Richard Atkinson. In his scheme, the stones were brought by land and river to Milford Haven, floated along the shores of South Wales and up the Severn, and then taken by rivers and land-portage up to Stonehenge. He suggested the use of a pine raft with a crew of twelve. A modification of his description would envisage a tree-trunk platform about 6m square, constructed for buoyancy in three layers, each of 20 logs 6m long and 0.3m thick. With a dry weight of 35lb per 0.03m3 the logs would have weighed about 20 tons and the entire cargo of wood, stone and men over 30 tons. Whether this unwieldy craft was seaworthy and capable of being manoeuvred during the day and beached night after night by a small crew is doubtful.

On a floating platform without sails, with propulsion dependent on paddles and poles, with little control over steering, affected by every capricious current of the Atlantic Ocean and Bristol Channel, the kamikaze crews faced daunting challenges. Once out of the shelter of Milford Haven, almost immediately the voyagers would have encountered strong tides and under-tows across the dangerous waters surging southwards near Freshwater West. Tidal flows of three to five knots streamed on the east side of Carmarthen Bay, and beyond them were treacherous sandbanks at Cefn Sidan Sands. Between Carmarthen and Swansea Bays heavy currents swirled at every headland. A mile from the coast off Ogmore-by-Sea lay the reef of Tusker Rock on which many mechanically powered ships later foundered.

Even when the mouth of the Severn was reached the struggle was not done. The river could pour seawards at up to ten knots, there were submerged mudbanks, the highest rise and fall of tides anywhere in the British Isles, all this before the Bristol Avon was reached at Portishead. At that point the stone would have to be transferred to something more suitable for travel along narrow and winding rivers. Further miles against the current took the vessel to Frome where everything again had to be disembarked for a portage that required a work-gang to drag the stone some eight or nine miles over land rising persistently to Warminster. There the cargo was replaced in the reassembled craft for another up-river crawl to West Amesbury, and once again unloaded and hauled up the chalk slopes to Stonehenge. This unprecedented undertaking had to be repeated almost 80 times.

What Burl was saying, in quite forthright terms, was that there was not a scrap of evidence to support the theory and that from a logistical point of view it would have been virtually impossible for any “bluestone” voyages to have been completed successfully.  His view is of course underpinned by the shambles known as the Millennium Stone Project, as described in Chapter 3.  The technology required to transport a large group of stones from the Eastern Cleddau to the mouth of Milford Haven, and thence across Carmarthen Bay and up the Bristol Channel, in the face of powerful tidal streams and unstable weather, was just not available to Neolithic tribes.  Besides, the tribes of Middle England were farmers and herders, and not seafarers; and it stretches credibility even further to suggest that they co-operated in their mighty enterprise with friendly coastal tribes who made their vessels and their manpower available -- in exchange for some hypothetical benefits.

It is pointed out -- quite reasonably -- that the sea has never been seen as a barrier but as a highway, presenting opportunities for the movement of goods and for new cultural links and settlement opportunities.  It is also pointed out that  the technology for making substantial cargo boats -- and sailing them across wide stretches of open water -- was available in Bronze Age times and maybe earlier.  However, we are talking here about the EARLY Neolithic, when there was not much trading activity going on in the British Isles, on land let alone at sea.  We know about the trading of a few hand axes and “special treasures” or personal ornaments here and there, and can speculate that animals, crops, skins and furs were exchanged or sold-- but there was no trading of metals or metal ores.

There are also real difficulties in imagining the "mental maps" that Neolithic people might have had of seaways and coastal configurations, and hazards including reefs and shoals.  What was their capacity for planning long-distance routes?   The fact that we know that long voyages were completed in the Neolithic does not necessarily mean that people were actually planning to get from A to B.    They may have hoped to go to C, because some seafarer told them there were wondrous things there,  fifteen days' sailing towards a particular star in the heavens, and ended up at B instead.  There must have been a huge random element in these ancient voyages.  And of course for every successful voyage that we may be able to reconstruct, there would have been hundreds or thousands that failed, with seafarers lost without trace.  Also, if the landlubber Wessex tribes had wanted to carry stones from Wales to Salisbury Plain, they would have needed the active cooperation not only of the coastal tribes who lived on both sides of the Bristol Channel, but also of their “navigators” who knew (and fiercely protected) the secrets of travelling by the stars, the sun and the moon.   In trying to assess the extent of their knowledge, all we have to go on is historical information about the “Stone Age” Pacific traders who came into contact with the early European explorers of the Pacific and Indian Oceans.  By the 1700’s these “Stone Age” navigator families had a sophisticated knowledge of how to navigate by the stars,  but by then they had hundreds of generations of accumulated knowledge and observations to build on.  It would be dangerous indeed to assume that Early Neolithic navigators around the western coasts of the British Isles had anything like the same degree of knowledge, since they were moving about in newly explored and newly settled territory.  So while the technical side is one problem (relating to inadequate Early Neolithic vessels), it must also be doubted that our seafarers had the organizational capacity, navigational skills, or territorial / map knowledge assumed by certain imaginative archaeologists.

Now's your chance......

OK  -- own up to it.  You have always wanted to be a film star, playing the part of a little hairy man sweating away in a curragh, or on a raft, trying to deliver a lump of bluestone from one side of the Bristol Channel to the other.  Well, this is your lucky day!  A friend has just sent me this.....

Darlow Smithson make big spectacular films for the Discovery Channel  -- and when you are in that business there is, I imagine,  no room for doubt as to the rightness of your theories.  So, having decided that our Neolithic ancestors were a pretty smart bunch, the film makers are now going to find out how it was all done.  No harm in that -- I'm all in favour of experimental archaeology, having done a bit of stone-pulling myself, back in  the year 2000.

Speaking for myself, I would prefer to ask "Was it all done?" and sort that out first, before asking "How was it done?"  But I understand that archaeologists -- and maybe film-makers -- come from a different direction.  None of them wants to spoil a good story.

Start your training regimes now, folks....  a beard and a tan will probably help too.

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

How were stones weighing up to 45 Tons moved to form Stonehenge in a time before the wheel was invented?

How were some of the stones transported 150 miles across water?

In August an ambitious, unique project will take place in the UK to try to find out.

AND WE NEED YOUR HELP

The Discovery Channel is making a documentary to test theories about the construction of Stonehenge. We are looking for experienced rowers to help recreate the journey that some of the stones took – over 150 miles by sea – from Wales to Wiltshire.

We need rowers who can be in the UK in August this year.

You need to be fit, healthy and prepared to face a massive challenge!

To find out more about the project email:

Stonehenge@darlowsmithson.com

Or call 020 7482 9674

www.darlowsmithson.com

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

Here is the info sent out to prospective paddlers: 

Hello,

Thank you very much for your email about our Stonehenge boat project. Please be assured that we have registered your interest and logged your contact details. If you didn’t send us a telephone number in your original email (and are willing to) please send that by return. It is also helpful for us to know what relevant experience you have.

We are attempting to test archaeologists’ theories about how bluestones weighing between 2 and 4 Tonnes might have been transported from the Preseli hills to Stonehenge around 2500BC. The project will be filmed to make a one hour long documentary for the Discovery Channel that will be broadcast towards the end of this year.

At the moment a replica Neolithic boat is being built and we plan to launch it in early August. There will not be a sail on the boat and it will have to be paddled using the tides and currents and steered with a steering oar. Support vessels will accompany the boat throughout its journey.

Ideally we are looking for a minimum commitment of one week from each of the paddlers but there will be some flexibility about this. We will provide food and basic accommodation during the journey but are asking people to volunteer their time.

Previous attempts to recreate the bluestones’ journey have not been successful and there is no doubt that this will be a very tough challenge, physically and mentally. We also hope it will be good fun but please seriously consider if it’s something you want to commit to.

We will be in touch again with full details as soon as we have definite dates for the voyage to see if you’re still interested and available.

Thanks again for your email.

Best wishes
Lynda


Darlow Smithson Productions
Shepherds Building Central | Charecroft Way | London | W14 0EE
T: +44 (0)20 7482 7027 | www.darlowsmithson.com

All the guff about the Kindle freebie

Tried to put this in a comment post for Jon, but I think it disappeared!  Hope this one will work as a hyperlink........

http://brian-angelmountain.blogspot.co.uk/2012/05/angel-mountain-kindle-freebie-promo.html

By the way, if you are romantically inclined (as I am occasionally), that's Carningli on the skyline.  if you look carefully you can see the reclining Earth Mother, or Earth Goddess, or whatever you want to call her.......  head on the left, breast, rib cage and raised knees to the right.  FAR more sacred that that tumbledown old collection of crags called Carn Meini.........