Some of the ideas discussed in this blog are published in my book called "The Bluestone Enigma" -- available by post and through good bookshops everywhere. Bad bookshops might not have it....
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Saturday, 23 July 2016

Erratic content of Isles of Scilly glacial deposits

 Modern beach deposit, Gugh Island.  Many of these pebbles have come from old deposits exposed in the nearby cliffs.  There are sandstone and shale erratics in this suite of cobbles -- in spite of the fact that Gugh Island is supposed not to have been glaciated.

Grateful thanks to James Scourse for publishing this information in his 1991 paper:
Scourse, J.D.  (1991) Late Pleistocene Stratigraphy and Palaeobotany of the Isles of Scilly. Phil Trans Roy Soc B, December 1991, Volume: 334 Issue: 1271.
A long time ago, but geological information does not date!  The hand sample identifications were made by JR Hawkes of the BGS Petrology Unit.

Below we reproduce info from the appendices of the paper, relating to the Scilly Till examined at Bread and Cheese Cove on St Martin's Island and to assorted samples collected from the related Hell Bay Gravel.

Above:  features of the Scilly Till

Pebbles identified in hand samples -- Nos 1-56, Hell Bay Gravel

The great range of erratic materials is interesting.  Particularly intriguing are the Lower Palaeozoic sandstones and the red / pink / purple / greenish sandstones and marls  which Dr Hawkes speculates as possibly coming from Devonian outcrops in Pembrokeshire, Devon or Ireland.  Brightly coloured Devonian sandstones are quite widespread, but brightly coloured Cambrian sandstones do not outcrop so frequently, and the most obvious source would be the southern coast of the St David's Peninsula around Porth Clais and Caerfai.  How easy is it to differentiate these from the Devonian sandstones?  As far as I know, nobody subsequently has attempted to work out whether these sandstones have come from Cambrian or Devonian outcrops -- there's an interesting project for somebody.  The samples are apparently still held at the School of Ocean Sciences at Bangor University.

The heavy metal suite from the till is also interesting -- perhaps we could get a view from Myris on that?

Additional information:  Dr Hawkes has also found a 10-tonne erratic block of olivine basalt on Great Crebawethan, one of the western rocks not far from the Bishop Rock Lighthouse, and more than 4 km west of St Agnes. This is reported in Scourse (1991).  Who knows what other large erratics are still to be discovered?

Wednesday, 20 July 2016

More about the Cuckoo Stone

Thanks to Tony for drawing attention to some new work relating to the Cuckoo Stone and its environs.  Some info is here:

It appears that the stone is a large lump of sarsen stone which originally lay in a solution hollow as a recumbent srone.  It was later extracted from its hollow and erected nearby -- and later fell over again, to remain in position where it can be seen today.  In other words, there is no long distance -- or even short distance -- transport involved.

I was interested to read this from the Stonehenge Riverside Project Report for 2007:

The Cuckoo Stone compares well with the Tor Stone at Bulford, about a mile east of the River Avon. In 2005 excavations demonstrated that this stone was similarly associated with an Early Bronze Age cremation burial – in this case a double Food Vessel burial. It too had been raised from its natural recumbent position which was visible as a solution hollow.

There is another mention of the Cuckoo Stone on Dr Nick Snashall's web site here:

Nick mentions that this is the only standing (ie recumbent!) sarsen stone left in the Stonehenge landscape, which of course begs the question "How many might there have been originally, before people started collecting them up and putting them into assorted stone settings or arrangements, at Stonehenge, Avebury and Durrington?  How many solution hollows are there that might once have held sarsens?  We have touched on this now and then, and of course I have expressed the view many times that the builders of Stonehenge collected up their stones (all of them -- bluestones and sarsens) from within striking distance of Stonehenge, and had to give up on the later stages of the project when the supply of stones ran out.  The stones were rearranged many times, but the "grand design" was never completed.

Why was the Cuckoo Stone never collected up and used?  Maybe it was just too much of a shapeless lump, and was rejected as not worth the bother?

As it happens, this very day Nick Snashall is giving a guided tour of the Avebury landscape, including West Kennet long barrow.  Hope it's not as unbearably hot as it was yesterday......

More Abermawr revelations

After the winter and spring storms, even more rock exposures can now be seen along the northern edge of Abermawr Bay (on the western flank of the Pen Caer peninsula).  This is one of the most important Quaternary sites in the British Isles, so anything that adds to our knowledge of past events here has considerable significance.  It is now clear that since I started my research work here in 1962 the coastline has retreated between 10m and 20m.  When I was working here in 1962-65 none of the rock faces exposed in this photo were visible.  All were masked by thick pseudo-stratified slope deposits which I referred to as rockfall debris and "lower head" accumulated during a long period of Early and Middle Devensian cold climate.  The erosional features seen in this photo on the rocky cliffs (caves, stacks, smoothed surfaces, wave-cut notches etc) cannot possibly have been formed over a period of just a few months, so they must be pre-Devensian.  They are ancient "fossil features" -- first buried, and now exhumed.  They must also be older than the Ipswichian or Eemian raised beach which sits on fragments of a wave-cut platform on top of the cliffs.

So the assumption must be that we are now seeing the exhumation of a pre-Ipswichian cliff-line formed at a time when sea-level was approximately as it is today.

Next, the exposure of the Aber-mawr Ipswichian raised beach becomes clearer and clearer.   Here is my latest photo, taken as a long shot from the beach below.

We see a jumble of well-rounded boulders and cobbles, with a maximum thickness of about 1 m, overlain by angular rockfall slabs and gravelly debris and then by lower head.  As far as one can see, the raised beach is uncemented.  It looks very similar in appearance and stratigraphic position to some of the raised beaches in the Isles of Scilly.

Here is another photo, showing where the raised beach exposure is located.  The rock platform exposure is fragmentary and it looks irregular, but there is enough of it exposed now to suggest that it extends for maybe 20m along the top edge of the rock cliff, about 6m above current HWMST.   If erosion continues at the present rate, it will soon be possible to scramble up to it and examine it in much greater detail.

The raised beach is exposed at the top of the rock cliff,just above the centre of the photo, in a 
slight gully.

Saturday, 16 July 2016

Exploring Avebury - the essential guide, by Steve Marshall

This is a fabulous new book from Steve Marshall, beautifully organized, filled with stunning images and with enough hard information to keep everybody happy.  Steve's cool and laid-back approach comes through in the text, which is clear and concise -- thankfully there is an emphasis on what we know rather than on what we would like to know.  So fantasy is kept at bay, and what we have in its place is a highly informative portrait of a fascinating place which almost everybody seems to prefer to Stonehenge.

In reading through the text, I was greatly taken by the section on sarsen "drifts" (p 14), and the images of the Valley of Stones on Fyfield Down are both atmospheric and revealing.  Then there is a good section on the mode of formation of sarsen stone.  On p 41 there is a fine section (again illustrated by gorgeous images) on the West Kennet Long Barrow.  This is one of the most interesting long barrows in Britain, not least because it is so old -- it's assumed to have been built almost 6,000 years ago.  This is one intriguing quote:

In today’s restored monument, virtually all the sarsen stone is original. However, the original construction also included sections of dry walling made with small, thin slabs of limestone imported from outside the area, as commonly found in other Cotswold-Severn long barrows. Much of the stone used as dry walling in the WKLB was identified as originating from Calne, 7 miles to the west; some though, came from an area between Frome and Bradford-on-Avon, some 20 miles to the south-west. Well over a ton of this ‘foreign’ stone had been imported to build the barrow.

As at Newgrange, it seems that the big stones were used more or less where they were found, and infilling or facade materials were carried in from a few miles away.   That would not have been a major task -- but one is of course quite justified in wondering whether some of the small stones might be erratic material, carried in by ice from the west........  some of the infill slabs and blocks look quite fresh, and Steve mentions that around a tonne of original (Neolithic) material was so rotten by 1950 that it was replaced by new dry walling stone brought in from Calne.  Some of the small slabs look to me (in the photos) to be very worn -- I wonder whether stone shapes and abrasion features have ever been systematically studied?

On p 64 there is a useful explanation of how the stones in the main Avebury stone settings were emplaced.  Steve cites the geophysical work of Martin Papworth in identifying a hundred or so buried stones and also sockets assumed to have held monoliths at some stage; but since the majority of the standing and recumbent stones appear to have come from the immediate neighbourhood, some of the holes interpreted as "sockets" might of course simply be extraction pits.  These are difficult to tell apart without physical examination -- and even then, the task is not an easy one.

On p 104 there is a chapter called "Where did the stones come from?  Again, this is comprehensive, well illustrated and quite revealing.  Good geology, simply explained.  The ten "primary stones" are assumed to have been used more or less where they were found, but the abundant "henge stones" are thought to have been brought in as batches with certain physical differences (colour, texture etc) from sources not far away.  On p 109 there is a good section on possible extraction pits.  The author is not particularly keen on confrontation, but he does suggest (ever so politely) that there is no evidence to support the widely-cited Atkinson theory that the Avebury sarsen stones were carried to the site by heroic Neolithic stone-hauling squads from the Marlborough Downs......

Silbury Hill and lots of other features in the Avebury landscape are also dealt with in detail -- there is far too much to cover in a short review.  But buy the book!  It's very informative, and Steve deserves our congratulations.  And even if you are not into detailed archaeology, buy it as an essential piece of archaeo photographic porn to share with your dinner guests!  I hope it sells well.


First published 2016
The History Press, The Mill, Brimscombe Port, Stroud, Gloucestershire, Gl5 2QG

isbn 978 0 7509 6766 2
soft cover, 226 x 248mm, 144 pages, full colour,  £14.99

From Steve's site:

"Exploring Avebury is really excellent, being quite clearly the best current introduction and guide to the whole monumental complex: up to date, consistently fair-minded, and superbly illustrated."
Prof. Ronald Hutton, historian

Avebury in Wiltshire is best known as the world’s largest stone circle, but surrounding it is a wealth of ancient monuments. Captivated by its unique atmosphere, many visitors form a personal, often spiritual, connection to Avebury and its ‘sacred landscape’. What was it that first attracted people to the Avebury area more than five thousand years ago?
Beautifully illustrated with over 400 photographs, maps and diagrams, Exploring Avebury invites us on a journey of discovery. For the first time the importance of water, light and sound is revealed, and we begin to see Avebury through the eyes of those who built it.

"Not only is this the most beautiful book to be published on the Avebury landscape, but it offers the reader one of the finest introductions to a region remarkable for its stunning prehistoric heritage and understated natural beauty. Steve Marshall has followed in the footsteps of an earlier generation of great Avebury observers and writers such as William Stukeley and A.C. Smith, to produce an account rich in stunning imagery, detailed personal observation and insightful interpretation. This is the essential guide!"
Dr Joshua Pollard, archaeologist and author 

Whether you are new to Avebury or are a seasoned visitor, this book really is essential. For first-time visitors it is an ideal guide for navigating the Avebury landscape and its monuments; for those who think they already know Avebury, there are surprises in store.  Packed with hundreds of gorgeous photographs, the book shows Avebury not just in the summer, but throughout the seasons. Although Avebury sees few visitors in the winter, it is then that its springs and rivers begin to flow and the place comes truly alive. 
Author Steve Marshall lived close to Avebury for many years whilst researching and taking the photographs for this book. His acclaimed study of Avebury’s springs and rivers resulted from many months of dedicated fieldwork, largely conducted in freezing weather.
Why was Avebury built where it is? Where did the sarsen stones come from? How does Silbury’s ditch fill with water each winter? What was the Avebury landscape like in prehistory? Exploring Avebury: The Essential Guide contains a wealth of new information and examines some of Avebury’s greatest mysteries afresh.
Exploring Avebury includes all the monuments and natural features of the 'sacred landscape' within a five mile radius of the Avebury Henge, including:

  • West Kennet Avenue
  • Silbury Hill
  • West Kennet long barrow
  • The Sanctuary
  • Longstones
  • Windmill Hill
  • Marlborough Mound
  • Beckhampton Avenue
  • West Kennet Palisaded Enclosures
  • Devil's Den
  • Adam's Grave
  • East Kennet long barrow
  • Fyfield Down Valley of Stones
  • Piggledene
  • Lockeridge Dene
  • Alton Yew & Springs
  • Swallowhead Springs
  • and more...

South Downs field systems -- are they really from the Bronze Age?

There has been much coverage in the media in the past week about the LIDAR imagery revealing ancient field systems near Arundel, within the South Downs National Park -- in areas now thickly covered in forest.  The press got very excited and flagged the field systems up as Bronze Age.  They are certainly very extensive and are wonderfully revealed in the LIDAR imagery,  but I cannot see anything in the press release to suggest that they are pre-Roman.  The only info in the press release is this:  "evidence suggests that they (the field systems) go back much further to before the Roman settled here."  What is the evidence?  Does anybody know?  It seems more likely to me that the pattern of field boundaries picked up in the imagery is the Roman pattern as it looked when the Romans left and Britain descended into some sort of chaos -- I would suspect that the pattern inherited by the Romans was much simpler, and on a much smaller scale.


Mysterious prehistoric farmers and missing Roman road revealed

July 12, 2016

Decades of speculation on the route of a Roman road in southern England have ended but the research which confirmed its location has revealed the extent of prehistoric farming on the South Downs before the Romans arrived.

The discoveries were made after airborne laser scanning (LiDAR) technology was used to map part of the South Downs National Park hidden under woodland for hundreds of years. The work is part of Secrets of the High Woods, a three-year community archaeology project, supported by the Heritage Lottery Fund, led by the South Downs National Park Authority in partnership with Chichester District Council and Historic England.

Trevor Beattie, Chief Executive of the South Downs National Park Authority, said:
“The LiDAR survey lets us peel back the woodland cover from National Park to reveal archaeology both hidden, and protected, by the trees. One of our biggest findings is the discovery of a vast area farmed by pre-historic people on an astonishing scale. Archaeologists are going to have to rethink the human story in this part of the country.”

James Kenny, Archaeology Officer at Chichester District Council, said:
“It’s exciting to see such extensive field-systems so well preserved which have probably lain untouched since the Romans left 1,600 years ago. But evidence suggests that they go back much further to before the Roman settled here.

“The find raises so many questions. Who was growing these crops and who was eating all of this food? We haven’t found signs of settlement so where were they living? The scale is so large that it must have been managed, suggesting that this part of the country was being organised as a farming collective on a very large scale.

“The degree of civilisation this implies is completely unexpected in this part of the world at this time – something closer to the Greeks, Romans and Egyptians than current views of pre-historic Britain.”

When Britain was conquered in 43 AD, a great construction project took place across southern England which resulted in a network of roads – many of which survive to this day. For decades archaeologists and historians have speculated that there must have been a Roman road leading eastwards from Chichester towards what is now Brighton. The project has confirmed that Romans heading east would have left Chichester on Stane Street before branching east and following a typically straight course towards Arundel through Binsted Woods.

Helen Winton, Aerial Investigation Manager at Historic England, said:
“The recognition of the ‘missing link’ in the Roman road west of Arundel, by Fiona Small at Historic England, was a highlight in a project full of exciting results.

“The interpretations and mapping from the LiDAR and aerial photographs by the Historic England and Cornwall Council National Mapping Programme (NMP) teams clearly demonstrated what was long suspected – the South Downs National Park has one of the most remarkable archaeological landscapes in England in terms of the range, extent and time depth of the archaeological earthworks preserved in the woodland.

“The better understanding of the area provided by the project will greatly inform future management of this valuable resource.”

Stuart McLeod, Head of HLF South East, said: “Thanks to National Lottery players, this project has opened up the wonders of archaeology to many more people and it’s fascinating to now see the results of the in-depth work that has been taking place. The research sheds new light on the history of this area and will also help to ensure its protection in the future.”

Find out more in the Secrets of the High Woods exhibition, currently on tour across the South Downs National Park.

Thursday, 14 July 2016

Felin y Gigfran and Castell Mawr LIDAR

Thanks to Dave for drawing our attention to Lle -- a Welsh Government web site on which we can see LIDAR imagery for many parts of Wales.  Above is one composite image extracted by Dave -- showing part of the Afron Nyfer valley.  Click to enlarge.  The letters are inserted by Dave.  His notes:

The meltwater channels show up very well (A), but are there other features more like pre-glacial cut-off valleys at the points I’ve labelled B.  What about what looks like a terrace at C, on the Afon Bannon upstream of Pantyglasier.  It has always looked like it when driving, but not so on the lidar as there are other incised cuttings at D.  How did the flat valley floor develop in places on the Bannon and the Nanhyfer?   Is this some form of glacial meltwater down cutting followed by a period of alluvium buildup?

Yes, the meltwater channels do show up very well, and they are highly complex.  The course of the Nyfer has changed many times as a consequence of glacial diversions and valley blockages by morainic and other materials.  Much work has been done (not by me) on recognising the pre-Devensian course of the Nyfer and comparing it with the post-Devensian course.  The biggest dry valley section is near Nevern itself, where the modern river runs in a great loop to the north of the old valley.  I agree with Dave that the sites lettered A are all glacial meltwater channel sections; and yes, the bits labelled B may be interglacial (not pre-glacial) sections -- but they are more likely to be dry channels used subglacially during the Devensian.  I would need to take a careful look at them to be sure.  The features marked C and D are interesting -- will try to take a look at them some time .......

Unfortunately, there is no LIDAR coverage for Rhosyfelin and Pensarn -- both sites lie just off the bottom of the image shown above.  But take a look at the fantastic detail on the images shown below -- all from the Felin y Gigfran - Castell Mawr area.

The uppermost of these images has OS map data superimposed, including contours and place names.  Note that in this one small area there are three prehistoric features -- Castell Mawr is the big circular earthwork.  Castell Llwyd (the westernmost settlement) is a fortified site on a spur above the river, and we can see another simpler fortified site (called Cwm Pen-y-Benglog Camp) on another spur south of Castell Mawr and close to the Felin y Gigfran nature reserve.  Both of these could be labelled as "promontory forts" and they are most likely to be from the Iron Age.  But who knows?  These days many "Iron Age" forts are being found to have much older origins........

In the Nyfer Valley itself, the big flat terrace to the SW of Castell Mawr must be an old valley floor into which the modern valley has been incised.  There are several features here suggesting subglacial meltwater flow;  in the middle image, look at the elongated rocky spurs inside the main valley.  Do they remind you of anything?  Just think Craig Rhosyfelin...........

Gors Fawr stone circle

Since there is a bit of interest in Pembrokeshire stone circles just now, in the light of the hypothesis that there was a proto-Stonehenge somewhere or other, here is a reminder of the fact that this one -- at Gors Fawr, near Mynachlogddu -- is the only one worthy of the name.

This is one of the best images of it -- taken by my son Martin and used on the cover of a glossy book which I published in the year 2000.  Don't try to get a copy, since it sold well and went out of print very quickly..........

But the Gors Fawr circle is really rather feeble, made of very small stones, and if this is the best we can do in Pembrokeshire I suggest that there was no great tradition of building stone circles here in the Bronze Age, let alone in the Neolithic.

By the way, this stone circle is very well documented.  Plenty in the literature about it.