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Wednesday, 24 August 2016

Children of Nature



This is wildly off-topic, so please forgive me.  I have just discovered that my all-time favourite film, called Children of Nature (1991), is now available on YouTube  for viewing in full.  You will need reasonably fast broadband.  Here is the link:

https://youtu.be/wBv0iBzH4hc

The film has a special resonance for me, since the focal point in the latter part of the film is the Vestfirdir region of NW Iceland, to which I led my first university expedition in 1960.  Then I went back to the area for several summer research trips in the 1970's.  We visited Hesteyri, where the final scene is set -- deserted and indescribably beautiful.

So I am a child of nature myself, as you might have gathered.....

The opening sequence of the film, in which the old man leaves his house, is very slow, but is an exquisite piece of film-making -- poignant, and so full of human dignity. I defy anybody to watch it without getting a lump in the throat or a tear in the eye.  I think the whole film, at 1 hr and 22 mins, is a masterpiece.  Enjoy!

Gelli-fawr menhir


This is a splendid standing stone -- one of the biggest in the area.  It's in a field not far from the Gelli-fawr hotel, looking down into the Gwaun Valley.  It's dolerite,  clearly collected from a huge litter of dolerite boulders in this area, and less than 20m away there is another massive lump of dolerite, this time recumbent and with just a part of it sticking through the turf.  I reckon the weight of this one must be about 6 tonnes......

Gelli-fawr morainic debris

I have been trying to track down the precise location of the "source area" for all those massive stones which have been used in the landscaping of the new visitor centre at Tafarn y Bwlch.   A successful mission.  They have all come from the uncultivated fields above the Gelli-fawr hotel, mostly upslope of a little shale quarry (used for roadstone) at grid ref SN065347.   The altitude is c 240m.  Thousands of tonnes of mostly dolerite boulders have been taken from here, with a double purpose as planned by landowner Llew Rees: he has helped to clear the land of large stones here, while creating some very effective landscaping at Tafarn y Bwlch.

The landscape features in the fields around the quarry are very subtle, but there are traces of elongated morainic ridges that might be associated with an ice edge.  The face of the quarry is interesting:


W can see that the top 3m of the shale bedrock is broken and shattered, and that the strata have been "bent over" by slope processes over a great length if time.  This is one of the most spectacular examples of downslope broken rock transport I have seen in a long time. 

If you look carefully, you can see that there are erratic boulders embedded in the upper layers of these slope deposits.  This is the base of an overlying layer, about 4m thick, of stony and gravelly till packed full of abraded and faceted boulders of all shapes and sizes.  Nearly all of them are made of locally derived dolerite.

Above the quarry Llew has now made a depot of stones which may still be intended for Tafarn y Bwlch.  A very nice collection of glacially shaped boulders -- they could easily have come from Stonehenge!


This is interesting, since the obvious occurrence of glacial deposits here matches with the observations I have made from elsewhere in the vicinity -- for example at Cilgwyn, Gernos Fawr and Tafarn y Bwlch.  It's quite possible that ice lobes pushed into the col occupied by Gernos Fawr smallholding from both the west and the east.  Watch this space for further developments.....



An interesting "fact" from Stonehenge



Looks as if BBC Countryfile will have a report on the latest Durrington dig next Sunday, 28th August.

Still on the BBC web site.  Countryfile from Stonehenge from Sept 2015: This is one of the "seven facts" presented in connection with the advance publicity -- "5. The largest stone, which weighs over 40 tonnes, is thought to have travelled as far as 140 miles from the Preseli Hills in Pembrokeshire, which may have taken place following the melting of a glacier. In 2000, a group of volunteers attempted to test the feat in the modern day, but the bulk fell into the Bristol Channel on the ancient replica boats used to transport it." This is one of the worst pieces of garbled nonsense it has ever been my misfortune to encounter. Almost everything about it is wrong..... who on earth wrote this crap?

http://www.countryfile.com/explore-countryside/history/7-stonehenge-facts-you-probably-didnt-know#.V72299AJkPg.facebook

Bang goes the Carngoedog Neolithic quarryman's row........


 Carn Goedog.  The postulated quarrying settlement is right at the base of the long rocky slope, at the right hand edge of the photo.

A couple of years ago there was considerable speculation from Prof MPP and others that the workforce of the fanciful and fantastical Carn Goedog Neolithic bluestone quarry was housed in the "row of huts" located at the foot of the crags, on the north side. It was speculated that because there were clear rectangular patterns visible on the ground the huts were not likely to have been Bronze Age, but maybe Neolithic instead. A quarry plus accommodation for the workers -- a very pleasing scenario.......

Then it went all quiet, and we now know why. I get sent information (including unpublished reports) all the time, and I really don't know where this one came from. It's a draft or unpublished report with the following title:

Carn Goedog medieval house and settlement

By Rhiannon Comeau, Rob Ixer, Mike Parker Pearson, Duncan Schlee and Kate Welham

The fieldwork might be part of an unpublished thesis by Rhiannon Comeau. She and the others examined the settlement site, and the discussion is appended below, with acknowledgement.

The result of the work? The settlement is essentially medieval, and has nothing to do with the Neolithic and nothing to do with quarrying. Some of the traces of older settlements might go back to the Bronze Age, but not earlier.

See also:

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

Discussion

All of the artefacts from the excavation of House C derive from layers immediately outside it and are presumably the remains of refuse discarded from its interior. They point to the house being occupied in the high and/or late medieval period and subsequently abandoned. However, earlier occupation cannot be ruled out given the aceramic character of the local area before the 12th century, and the notoriously poor survival of pre-Conquest material culture. There were no artefacts that could be considered to be either earlier or later in date, and no evidence of multiple periods of occupation, suggesting that House C was built, used and abandoned within the medieval period rather than being reoccupied at different periods in the past. A radiocarbon date from the floor deposit could establish the date of occupation of the building. 

Similarities in the form of the neighbouring buildings suggest that Houses A-B and D-J are likely also to date to the medieval period. The group perhaps represents a havod (a small seasonally occupied dwelling associated with exploitation of the upland pastures). The curvilinear houses I, K, L, M, N (and perhaps O) are undated but the more denuded appearance of their stone walls may well reflect their greater antiquity as pre-medieval structures. Remains of field walls forming a north-south coaxial pattern leading northwards onto the lower ground north of Carn Goedog could be associated with either or both of these settlement clusters.

In summary, then, we have here a group of nine sub-rectangular buildings and ancillary structures. Their lengths, when surveyed before excavation, ranged from 4.4m to 7m externally, with most having unexcavated internal dimensions of around 4m x 2-3m. All have their long axis at right angles to the contours. House C, whose pre-excavation survey measurements were 5m x 4.6m externally and 3.6m x 3m internally, was revealed by excavation to have external measurements (at maximum) of 6.2m x 4.4m and internal measurements of 4.5m x 2.2m. Dating evidence – pottery – suggests occupation in the medieval period, but not later.
 

Similar groups of single-celled habitations (described both as ‘platform houses’ and as ‘long huts’ – definitions vary) are recorded elsewhere in many upland locations in Wales (Roberts 2006: 172–5, 207). Entrances are usually on the long sides and are often – as in House C – opposed, which may be linked with occasional suggestions of internal partitions (Leighton 2012: 120; Locock 2006: 45; Silvester 2006: 34). They are commonly associated with medieval and early post-medieval occupation, although few have been excavated and even fewer are dated (Leighton 2012: 127). A cross-contour placement, at right angles to the slope, is typical of medieval examples (Roberts 2006: 177). Sizes vary considerably: the Carn Goedog long huts fall into the 4m–7m length range noted for many long huts in central Wales, but much larger examples exist, like those at Gelligaer in Glamorgan which are dated to the late 13th or early 14th century (Fox 1939: 173; Silvester 2006: 34). They are generally thought to be linked to the use of seasonal pasturage, although interpretation of evidence for the seasonal or permanent occupation of excavated dwellings is contested (Silvester 2006: 33-4). It is these seasonal pastures that are referred to as the ‘hafod’ in medieval sources; the term transfers to dwellings from the 16th century onwards (Davies 1980: 3–7; Sambrook 2006: 95–9). Thirteenth-century Welsh law uses the term ‘haf ty’ (‘summer house’) for the dwellings on the hafod, and their relatively insubstantial nature can be seen in the low compensation values attached to them (Davies 1980: 7; Jenkins 1990: 190, 353). The same law code indicates that it was expected practice for the bondsmen and animals of farming settlements to relocate to seasonal pastures from the beginning of May until the harvest was in (Jenkins 1990: 40, 236).

The location itself is also characteristic of ‘hafod’ sites, and is typified elsewhere in south Wales as ‘along a track running diagonally up a slope, in a sheltered position below the summit area’ (Locock 2006: 45). The track next to the Carn Geodog dwellings is shown on a map of Pembrokeshire of 1602 in which it links the farmland of Whitchurch to the north with the parishes of Mynachlogddu and Maenclochog on the southern flanks of the Preseli hills (Owen 1602).

As a building type, House C can thus be seen as typical of many undated upland structures, and its occupation evidence is therefore valuable, both for the unequivocal medieval date of its pottery and for the hints of gendered occupation provided by the spindle whorl. If this is a seasonal structure, this evidence is particularly interesting since the social composition of seasonal occupation could, in principle, range from whole families (the interpretation often surmised from medieval Welsh law) to the teenage boys mentioned locally c.1600 and the hired herdsmen known elsewhere in the post-medieval period (Miles 1994: 44–5; Ward 1997: 104–6; cf Fox 2012: 47ff)

There is, however, little in the site’s excavated evidence that indicates its annual pattern of occupation, whether seasonal or all-year round. The presence of pottery cannot in itself be taken as an indicator, since the site lies on the edge of what appears to have been a well-used medieval track and less than an hour’s walk from areas of permanent settlement. Seasonal land usage is suggested by the nature of the surrounding terrain as well as by its longstanding common land identity and seasonal pasture rights still exercised by farms around the common edge. These rights are thought to derive from a mid-13th century charter, granted to an aristocratic Welsh kin-group who owned much of the arable land to the north in the medieval period (Jones 1979: 28; Owen 1862: 48). Carn Goedog lies within the area defined by the 13th-century charter, and its habitations were presumably occupied by these aristocrats’ bondsmen or tenants. 


The medieval occupation indicated by the pottery is paralleled by documentary indications that any family-based seasonal movements must have ceased by the late 16th century, since they are not mentioned in contemporary descriptions of local agricultural practices (Miles 1994: 62–77, 175). The late 16th-century records of ‘hafod’ place-names for nearby permanently occupied farmsteads at Hafod Wynog (1598) and Hafod Tydfil (1585) – the latter an enclosed island of fields amidst the moors to the northwest of the site – chart accompanying changes in farming practices which see the enclosure of some areas of seasonal pasture for all-year farms (Charles 1992: 105). Other – undated – enclosures can be identified on the moorland to the north and northeast of the site in areas that are now waterlogged and, whilst these may be prehistoric, it is possible that these may also represent intensified exploitation in benign climatic intervals during the medieval period.

Where did the Boles Barrow bluestone come from?


 One of the old photos of the Boles Barrow bluestone in position in the garden of Heytesbury House.  Here we can see the fractured part of the stone, which is most often hidden from view.  It is a reasonable hypothesis that this is a chunk of rock that might have broken off a larger pillar or monolith.


In the light of all the current interest in the Boles Barrow bluestone, let's forget for the moment the arguments about whether it was originally stolen from Stonehenge or was genuinely found within the core of a particular long barrow. (Parker Pearson currently seems to believe that the stone did NOT come from Stonehenge, and that it was put into the long barrow at least 5,500 years ago.)  Let's concentrate instead on what its geological provenance might be.

Parker Pearson et al (2015) refer to it as a "broken but un-dressed bluestone pillar fragment" -- so the assumption is that somewhere or other, the rest of this mysterious pillar remains to be found. 

It is generally assumed that it came -- like most of the other spotted dolerite bluestones -- from the Preseli area of North Pembrokeshire. Ixer and Bevins have stated that it is a "group 3" spotted dolerite, with characteristics different from the Carn Goedog spotted dolerites.  They have speculated that it most closely matches the spotted dolerites outcropping in Carn Breseb, Carn Gyfrwy, Carn Alw and an unnamed outcrop west of Carn Ddafad-las.  These outcrops are associated with doleritic intrusions up to 2km east of Carn Goedog, whose precise details are still not known, although the geologists think that they may all be components of the same elongated dolerite sill.

I have examined the evidence here:

http://brian-mountainman.blogspot.co.uk/2013/11/carn-goedog-and-stonehenge-new-work.html

Then it gets a bit confusing, because the geologists suggest in their paper that although the "group 3" spotted dolerite samples are different from those at Carn Goedog, they might have come from there after all, because the dolerites contain a lot of lateral internal variation.  Confused?  So am I............. and that is probably because the density of sampling points on the Preseli outcrops is far from adequate for really sound conclusions to be drawn.

So might the supposed "Boles Barrow pillar" which has fallen into bits have come from Carn Goedog after all?  That seems to be where the opinion (but not necessarily the evidence) is taking certain people who have a quarrying hypothesis to uphold.......

We can shortly expect a new paper on the Boles Barrow bluestone.  Various little birds have tweeted that it was taken from its perch in Salisbury Museum out into the fresh air in May, so that a detailed laser scan could be completed.  So it has by now been subjected to the full 3D treatment, which will be revealed in all its glory.  That's great -- I look forward to seeing the results.  While they were about it, did the investigators take some samples from the surface for cosmogenic dating?  Is the "old" part of the boulder (or pillar fragment, if you want to call it that) demonstrably older and more weathered than the "broken" or fractured face?  If so, what are the dates?

One of the little tweeting birds tells me that the close examination of the underside of the stone supposedly provides evidence of how it was extracted from its bedrock position.  So the latest hypothesis is that the Boles Barrow stone is not just a piece of a lost pillar, but that the pillar itself can be shown to have been taken from a particular location on a particular outcrop.  Rumour has it that Prof MPP is on the trail, and that he is excavating a specific quarry site.   That has to be Carn Goedog, since he cannot possibly have hunted across several square kilometres of terrain looking for a space from which an imaginary spotted dolerite pillar of unknown dimensions might have come from!  He has already laid out the trail by referring (in his CA article) to precise spots on the Carn Goedog tumbledown tor from which monoliths have been extracted.  I couldn't see them, and I'm not sure anybody else could either, but he has the eye of faith.......

The last question is this.  If the Boles Barrow boulder (or pillar remnant) belongs to spotted dolerite group 3, could one of the other known group 3 stones at Stonehenge actually be the larger part of the same stone?  The candidates are bluestones 34, 42, 43 and 61.  All of these are spotted dolerite, and all are sampled.

34 -- well rounded small boulder or squat pillar, placed on end.  Spotted dolerite with pinkish spots -- in the bluestone circle.
42 -- recumbent wedge-shaped stone with heavy wear on edges.  Densely spotted dolerite?  Projecting through the turf, in the bluestone circle.
43 -- recumbent slightly flattened boulder with heavy wear on edges.  Densely spotted dolerite? Projecting through the turf, in the bluestone circle.
61 -- a slab-like small pillar in the bluestone horseshoe.

The only one of these that looks remotely like a pillar is SH61.  Could that be the rest of the Boles Barrow stone?  Watch this space........


Bluestone SH61 -- courtesy the Stones of Stonehenge web site

Postscript:  I have checked the details for whole-rock analysis in table 1a of the Carngoedog paper by Bevins,  Ixer and Pearce.  The geochemical makeup of SH 61 is NOT the same as that of the Boles Barrow boulder.  In fact the sample from the boulder does not match up precisely with any of the other samples -- if anything, the closest match appears to be with stone SH42. But I can see why the Group 3 spotted dolerites are grouped together, and that the assumption is that they have all come from roughly the same area.  But spot provenancing on the basis of the current evidence?  Frankly, impossible.   Maybe Myris will give us an opinion on this?

Carn Goedog is the likely major source of Stonehenge doleritic bluestones: evidence based on compatible element geochemistry and Principal Component Analysis (2013),
Richard E. Bevins, Rob A. Ixer, Nick J.G. Pearce


Monday, 22 August 2016

Cwm Gwaun subglacial meltwater channel



I came across this excellent photo on a local B+B site.  Many thanks to Deirdre Edwards.  It's one of the best photos I have seen of the subglacial meltwater channel which runs for over 10 kms from Cilgwyn to the sea at Fishguard --  as featured in many textbooks.

The alignment of the channel is still something of a mystery, since it appears to have been cut by meltwater flowing westwards or north-westwards -- against the gradient of the Irish Sea Glacier.  That's why I have suggested on a number of occasions that it might have been cut originally by meltwater flowing beneath an expanded Welsh ice cap, and then modified under the influence of ice flowing in other directions.