THE BOOK
Some of the ideas discussed in this blog are published in my new book called "The Stonehenge Bluestones" -- due for publication on June 1st 2018. After that, it will be available by post and through good bookshops everywhere. Bad bookshops might not have it....
To order, click
HERE

Thursday, 26 April 2018

Very smart marketing.....

 Spotted on Twitter, last year.  Brilliant marketing -- now why didn't I think of that myself?  It would have been even more brilliant if the edible MPP had been made of Caerphilly Cheese -- but maybe it's too crumbly?

Craig Rhosyfelin is NOT a Neolithic quarry.....



I discovered that some people are not able to get at things on Researchgate, and have received some advice that it is possible to link to PDFs through the normal posts on Blogger.  So let's do an experiment.  I'm trying to get that short paper (which ANTIQUITY refused to publish) linked onto this page............

https://drive.google.com/file/d/1gN0lDTN1u8nNrFVs29XHko9ZUogcsDIM/view?usp=sharing

I'm trying first with Google Drive.  If anybody would like to try and access this, please let me know how you get on......

Wednesday, 25 April 2018

Burl on boulders



I was idly thumbing through Aubrey Burl's "The Stonehenge People" yesterday and came across this interesting statement on page 21:

Referring to the bedrock stone at Chilmark, to the SW of Stonehenge  "..........it is without grain and is simple to cut into blocks, but it was not extracted by Neolithic people who, if they wanted stone, took what there was to hand, glacial erratics or outcrops, neither of which was plentiful on the plain."

Here he is saying that while glacial erratics and convenient rock outcrops were not "plentiful", he did not consider them to be completely absent.  His more interesting point was that  Neolithic people did not appear interested in quarrying for large stones;  so if they were not interested in quarrying close to home, why would they resort to quarrying for monoliths way off to the west, in Pembrokeshire?  That would not make any sense at all, as I have frequently pointed out on this blog..........

Burl also mentions the famous "Welsh bluestone" found in Boles Barrow, and other big stones as welkl, found in Neolithic contexts.  At Boyton 1, a substantial barrow SE of Heytesbury a large boulder "that took the strength of three men to lift out" was found on top of a pile of flints.  We have no ide what rock type it was.  At Arn Hill (Warminster 1) a 1.5 m high standing sarsen was found inside the mound.   There were four big stones forming a chamber in the interior of the Luckington Barrow in Wiltshire.  At Amesbury 4 (now completely destroyed) there was talk of another chamber made of big stones.  The long barrow called Tidcombe and Fosbury 1, in the NE part of Salisbury Plain, had in its interior "three prodigious big stones" standing vertically, with two other smaller stones "of like sort" resting on top of them.  These stones clearly made a burial chamber inside the mound.  Something similar was found at Adam's Grave (Alton 1) on the Marlborough Downs.

Geoffrey Kellaway and Olwen Williams-Thorpe also made the point that while the great majority of the 69 long barrows on Salisbury Plain were simply made of chalk rubble, there are enough examples of features containing big stones to suggest that where big stones were handy, the Neolithic tribesmen on the plain were not averse to using them.  The idea that the Boles Barrow bluestone was an aberration -- carried in from Stonehenge -- just does not hold up.  The most parsimonious explanation as to why it was used is this:  it was used simply because it was there, a good 500 years before Stonehenge was built.

Tuesday, 24 April 2018

The Warminster boulders


Thanks to Dave M for alerting us to the presence of three (at least!) rather fine boulders at the Warminster Travelodge.  The pic above is from the web and the two below are from Dave.  The boulder shown below looks as if it might be limestone, but the others are something of a mystery.  Are they local, or are they erratic?

Does anybody know anything about them?  Would somebody like to pop over and take a look?



Monday, 23 April 2018

Even more South Pembrokeshire Till



Over the course of three long walks on the South Pembrokeshire coast, I have been finding till all over the place.   At the risk of boring readers, here are some more exposures.  I want them to be recorded for posterity, because South Pembrokeshire is bound to become a focus of activity in the future, as people renew their efforts to define the West Wales Devensian ice edge.  Here we go:


Reddish till made up mostly of shattered limestone fragments with some rounded and faceted erratic pebbles, on the clifftop near Huntsman's Leap.


Rounded erratic cobble in fresh till near Mewsford Point


Till exposure on the clifftop near Bullslaughter Bay


Fine-grained till with mostly small erratic pebbles -- clifftop near Bullslaughter Bay


Till exposed on the clifftop on the western flank of Flimston Fort.  Here again the till is packed with pebbles of quartz -- from ancient Pliocene river gravels or beach deposits?


Another exposure of till near the western edge of Flimston Fort -- on the clifftop.


From an old post:


I have been digging around in some of the old records of the Geological Survey -- from about 1905-1938 -- and have found that the old geologists responsible for the fieldwork in west Wales (Strahan, Cantrill, Dixon, Thomas and Jones) knew all about the glacial deposits scattered across South Pembrokeshire. In their publications they describe many locations where thin till and glacial erratics are to be seen -- including Bullum's Bay on Caldey Island. So I'm not the first to describe this till, by any means. In 1905 EL Dixon wrote of Bullum's Bay: "..... the glacial deposit appears to overlie the raised beach, although the exposure is obscure, and the evidence of superposition is not so conclusive as in Gower." (Summary of Progress for 1905, Mem Geol Surv, p 70). He and his colleagues described glacial deposits at Landshipping, in the inner reaches of Milford Haven; till about 7 ft thick at St Florence; glacial sands and gravels at Bubbleton; gravel and sand at Norchard; sandy loam with erratics at Lamphey; and glacial deposits in many pipes and solution hollows at Catshole Quarry, Pembroke, Sandtop Bay on Caldey, and in other places where Carboniferous Limestone is found. Generally the till in such places is coloured red or pink -- with an obvious association with ORS rocks, and striated sandstone pebbles are also recorded in the deposits, as are pebbles and larger stones of greenstone and felsite.

The Geological Survey maps for the Tenby districts show patches of glacial deposits, as do the maps for the Pembroke and Carmarthen areas.

These are the Memoirs on the Geology of the S Wales Coalfield -- Part XI Haverfordwest - 1914; Part XII Milford - 1916; and Part XIII Pembroke and Tenby - 1921. All are out of print long since, but you will find them in libraries.

The only patch of diamicton or till shown on the latest geological map for  in this large coastal tract is just to the east of the eastern arm of the Bosherston Lily Ponds.

In the memoirs the tills or diamictons of South Pembrokeshire are generally referred to by the old geologists as belonging to the "older Drift" glaciation.   They may be right that many of the inland deposits are very weathered and very old -- but I am convinced that the coastal tills are fresh, and that they must be assumed to be of Late Devensian age.

At the moment, I see no reason to make any great alterations to this map:









Erratic boulders on South Pembrokeshire clifftops


Erratic boulder exposed in an inaccessible position on a vertical clifftop near the Huntsman's Leap, west of St Govan's Head.  This one is maybe a metre long -- heavily abraded and polished and bedded in a rough till made up mostly of broken limestone fragments.  The boulder looks to me ro be igneous, but maybe we will never know.  One day, before long, it will go crashing down to the beach below........


This heavily abraded boulder projects from quite a thick layer of reddish till -- again in an inaccessible position -- on the clifftop of Bullslaughter Bay, about 2 km east of the Green Bridge of Wales.  It looks to me as if it might be rhyolite........

Strange till near Stackpole Head


A couple of days ago, on this very beautiful stretch of coast, on the cliffs of Stackpole Warren, between Mowingward and Raming Hole, I encountered several exposures of rather interesting till.  It's something of a miracle that I am still here to tell the tale, because accessible clifftop exposures are few and far between on the top of these vertical limestone cliffs.  Taking samples is very difficult in most cases, and even getting photos requires rather a good head for heights.  It's a good job I don't suffer from vertigo......

Anyway, to the till.  Here are some pics:





All being well, you can click to enlarge each of the above.  The most striking characteristic is the presence of abundant quartz pebbles and cobbles.  Some of them are broken, but many are intact -- having survived glacial transport from not very far away.  But where did the pebbles come from?  At Flimston, a few kms to the west, there are some claypits in which the famous Flimston Oligocene clays are exposed. Organic remains confirm the age.  They are up to 15 m thick, and appear to have been laid down in lacustrine conditions;  that's interesting in itself, given that the bedrock is highly fractured Carboniferous Limestone.  But associated with the clays (probably above them) are deposits of beautifully rounded quartz pebbles and boulders -- assumed by geologists to be Pliocene river or beach deposits laid down in association with the formation of the coastal platform.  Because virtually all the land hereabouts is within the Castlemartin tank firing range, examination of the ground surface is not encouraged;  but rumour has it that deposits of quartz pebbles are quite widespread.  So the pebbles might have come from the existing land surface to the west of the find site, or from a clifftop area which has subsequently been destroyed by marine erosion.

I have no idea how thick or extensive this till layer might be, but it is certainly more than a metre thick in places.  The matrix is sandy and silty, and the deposit is not cemented, suggesting that it is probably Late Devensian in age.  If you look in detail at the photos, you can see pebbles of all shapes and sizes, and the main rock types represented are limestone (as one would expect), shales and mudstones, sandstones and grits (some of them clearly from Old Red Sandstone outcrops either offshore or near the mouth of Milford Haven), and flints.  I did not have time, on a very quick visit, to hunt for igneous pebbles -- but I would not be surprised if they are present in small numbers.

So the conclusion has to be that the ice topped the cliffs in the Stackpole Warren area.  We should not be surprised by this, given that till (apparently of Late Devensian age)  is also to be seen at Swanlake and on Caldey Island.



I'm intrigued by the similarities between the tills at Swanlake and Stackpole and on Caldey Island with the tills exposed in the low cliffs of the Isles of Scilly.  They look very similar, and they must surely be the same age.........