British

Archaeology

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Cover of British Archaeology 96

Issue 96

September/October 2007

Contents

news

Ambassador sees peace message in museum

Archaeologist who fought for history's underdogs dies

Roman fort found in Cornwall

Full scale of ancient Welsh stone quarry revealed

In Brief & Phase 2

features

More travels - This is not just a walk, this is an archaeological walk
John Cannon considers places to see in County Durham

Green treasures from the magic mountains
Alison Sheridan describes exciting new French project on Jade Axes

Fading star: Star Carr
Fieldwork at the iconic mesolithic site reveals new fears

opinion

Let Lucy sparkle

on the web

Recommended websites
Who's blogging? And the Society of Antiquaries of London

letters

Views and responses

CBA correspondent

Campaigns, comment and communications from the CBA
Mike Heyworth wonders what lies ahead for archaeology

 

ISSN 1357-4442

Editor Mike Pitts

features

Green treasures from the magic mountains

A few prehistoric jade axeheads were found in Britain over a century ago. The number grew as the years passed: but where they had come from remained a mystery. Alison Sheridan describes new work by Pierre Pétrequin, Michel Errera and Yvan Pailler that looks finally to have cracked the problem.

The recent ban placed on the proposed export of the privately-owned jade axehead from Newton Peverill, Dorset (News, May/Jun) has brought these beautiful neolithic objects into the public eye once more. Well over 100, in various shapes, sizes and shades of green, are known from Britain and Ireland. They have been the subject of speculation and study both here and abroad for over a century. Early suggestions that they came from China were soon replaced by claims that they were made from Alpine rock, and various attempts have been made by geologists over the years to find the sources.

Now, thanks to the pioneering work of Pierre Pétrequin (of the Centre National de la Recherche Scientifique and the University of Besançon) and his wife Anne-Marie Pétrequin over the last 16 years, this has been achieved. Their research, which has morphed into a current three year, million-Euro, international project funded by the French government, is revolutionising our understanding of every aspect of these objects, not just here, but across the whole of Europe. If your museum has a jade axehead, then Projet JADE will be coming its way soon!

The history of research into these objects in Britain and Ireland has been one of listing, mapping and analysing – sometimes by cutting disfiguring slices, a technique that is no longer either acceptable or necessary for these precious artefacts. The first attempt at a British and Irish corpus was made by Lily Chitty in the 1930s. By 1949, when Stuart Piggott and Terrence Powell published an updated list after finding a fragment in an early neolithic tomb at Cairnholy in south-west Scotland, the total had risen to 50. Other surveys followed, and by 1977 the list had more than doubled, to 112. Today, thanks partly to the museum-based sleuthing of Breton scholar Yvan Pailler, it stands at nearly 130... and rising.

To date, however, only two jade axeheads have come from firm British archaeological contexts: the Cairnholy fragment, from a deliberately-broken axehead, found on the paved floor of the tomb's "antechamber"; and a pristine, complete specimen, found in 1973 beside the Sweet Track in Somerset. This wooden trackway is dendro-dated to 3807/3806Bcand the axehead could have been deliberately deposited not long after its construction. As for the Cairnholy fragment, opinions as to when it was placed in the tomb differ but a date of around 3800Bcis quite plausible, given the early Carinated Bowl pot found in a primary deposit in the tomb's forecourt. Other specimens, found in neolithic enclosures in southern England at Hambledon Hill, Dorset and High Peak, Devon were frustratingly unstratified.

The geographical distribution is widespread but uneven. The four definite and provenanced Irish examples are scattered from Donegal to Tipperary. There is one Manx example, and one fragment from the Welsh Marches. Scotland's 35-odd specimens are found from Caithness in the far north down to the Borders; and then there is a gap in northern England, as far as Derbyshire. Further south, there is a marked concentration on and near the Hampshire and Dorset coast, and more diffuse clusters around the Thames, in East Anglia and in the north Midlands.

Mountain discoveries

By 1979 a number of British jade axeheads had been analysed and found mostly to be jadeite, with omphacite also significantly represented; but where they came from remained uncertain (see box). There the matter lay, with little fresh research being done for the next 25 years. But in France the Pétrequins were busy. In the 1990s, with Serge Cassen (CNRS Nantes), they initiated a Europe-wide database of all jade axeheads longer than 140mm, gathering information on mineral composition, shape, colour, finish, context and date. They also undertook challenging fieldwork high in the Italian Alps to look for primary raw material sources and evidence for their exploitation.

Their own ethnoarchaeological fieldwork on axehead manufacture in West Papua had convinced them that the production of special, "socially valorised" axeheads could have been bound up with beliefs about the supernatural power of certain rock sources. By making the dangerous ascent to high, near-inaccessible and socially-restricted parts of mountains – liminal places between this world and that of the gods and spirits – the axehead makers could get stone that was imbued with the power of the magic mountain.

Most continental geologists and archaeologists believed Alpine jades had been gathered only from secondary sources in downslope river valleys and screes. The Pétrequins rejected this, and in 2003, after 12 hard seasons of exploration in the Italian Alps and northern Apennines, they were proved right when they found high-altitude quarries – 1800–2450m od – at the south-east foot of Monte Viso, 60km south-west of Turin.

Then in November that year, they struck green gold again, in the vicinity of Monte Beigua, part of the Voltri massif, immediately to the north-west of Genoa. But this was to be a bittersweet discovery. In the summer of 2004 mineral collectors smashed three massive boulders that had been worked during the neolithic, and removed around 1500kg of the rock. To date, nothing appears to have been done to prevent this happening again.

The Pétrequins' fieldwork around Monte Viso in 2004 and 2005 – just published in English in the European Journal of Archaeology – revealed good evidence for rock extraction and working in several areas. Reliablyassociated charcoal samples have produced dates demonstrating that these sources were exploited from as early as 5200BC. The exploitation must have been seasonal.

Not content with these ground-breaking discoveries, the Pétrequins made another major contribution to axehead study. They teamed up with geologist Michel Errera in Brussels and applied the well-established, wholly non-destructive analytical technique of reflectance spectroradiometry to the sourcing of individual axeheads. Initially developed for astronomical and Earth-orientated remote sensing, this measures the electromagnetic radiation reflected by any type of surface. With jades, this type of analysis is little affected by surface patination. It allows the direct comparison of the mineralogical composition of a neolithic axehead with raw material collected from working sites on Monte Viso and Monte Beigua, which often have characteristic signatures.

Since 1999, thanks to international collaboration by a number of archaeologists (including CNRS's Serge Cassen and Lutz Klassen of Århus Museum), Michel Errera has analysed over 700 large axeheads from across Europe, and thousands of raw material samples collected by the Pétrequins from the source areas. Comparison of their results with those previously obtained by specific gravity, thinsectioning and X-Ray diffraction analyses has produced over 95% agreement. The results of each spectroradiometric analysis can be examined against those for every other analysed specimen. This means that any axehead now has around a 70% chance of being reliably matched with one of the two principal Alpine sources, and sometimes with a specific boulder. Thanks to Projet JADE, this analysis can currently be done for free.

The results have been spectacular. The Pétrequins have pieced together a pattern of axehead production and use that links specific types to particular source areas, and of individual variants of green Alpine rocks, at specific periods. To cut a long story short, the earliest exploitation focused on the dark green Monte Viso eclogites, and the products were workaday axeheads for local use in north Italy. But from the beginning of the fifth millennium BC, these were being exported as prestigious exotic novelties up to 700km away, into eastern France and the Paris Basin, and were being copied in local materials.

By around 4500Bcif not slightly before, blocks of the exceptionally rare, pale green jadeites from Monte Viso and Monte Beigua were being transferred over 200km to the northwest fringe of the Alps, to be made into fine long axeheads. These then found their way – via southern France or the Paris Basin – to Brittany, where they were reground and repolished into a thinner, regionally-distinctive shape for burial in the famous massive Carnactumuli, alongside copies made from local fibrolite and imported Spanish beads of variscite (callais). These are the axeheads shown on the Breton menhirs and on the famous passage tomb at Gavrinis. The Alpine sources continued to be exploited into the first half of the third millennium, but the main period of production for very long-distance movement seems to have ended by 4000BC.

Where do the British and Irish axeheads fit in? The first results of spectroradiometric analysis, undertaken in September 2005 in France on around 30 British specimens gathered by project collaborator Alison Sheridan, have confirmed that they were indeed made from jadeite and eclogite from Viso and the Voltri massif. The examples from Caithness had travelled some 1800km as the crow flies from their source area.

We know from the Sweet Track specimen that they were here by at least 3800BC. Both there and at Cairnholy they are loosely associated with distinctive early neolithic pottery, and they may well have arrived from north-east France as part of a "Carinated Bowl neolithic" package of novelties, associated with a farming way of life. This would certainly account for their wide scattering across Britain and Ireland. We know, from the Pétrequins' Europe-wide study, that the various types of Alpine stone axehead found here had been made several centuries before their date of deposition. They must therefore have been old when they got here. The same thing – featuring the same kinds of axehead – was happening around the same time in central Germany and Denmark.

Treasured posessions

It is tempting to view these beautiful objects as the ancient treasured possessions of incoming communities. The axeheads would have been replete with the mythology and symbolism of the inconceivably-distant magic green mountains whence they had originated: powerful talismans in stories of how the world began. Such was the belief in their innate power and extreme value that, occasionally, individual specimens would be deliberately broken and shared around. And by laying them down in the realms of the spirits and ancestors, their owners were hoping for continued benefit to the living.

As Projet JADE progresses, more revelations are emerging from the associated research. Yvan Pailler's work in British and Irish museum collections has been revealing, for the first time, that copies of some of these distinctively-shaped exotic treasures were made using local rocks. And British and Irish patterns of stone exploitation – not least a fascination with green-coloured stones – are also becoming easier to understand. The exploitation of difficult-of-access mountain rock sources, as at Great Langdale, Cumbria and Tievebulliagh, Antrim for instance, could have been a way of recreating the "magic green mountain" experience according to early neolithic cosmology. And in a nice cross-fertilisation of research projects, the intriguing discovery that one or two early bronze age archery wristguards (c2450–1800BC) may be of Alpine rock is helping John Hunter and Ann Woodward's study of bronze age grave goods.

Elusive Jade

Archaeologists have long used "jade" as a loose term for a group of tough green minerals that work up to an attractive surface sheen: jadeite (and variants), omphacite, eclogite and nephrite. While over 1,600 large axeheads made from these minerals are known from Europe, they form a small minority of all the stone axeheads found. For example, out of over 21,000 stone axeheads recorded by the Irish stone axe project, only four are of jadeite.

The first British analyses of jade axeheads featured microscopic thinsectioning, carried out in the 1940s by the grandly-named sub-committee on the petrological examination of stone axes of the South-Western Group of Museums. During the 1960s William Campbell Smith, of the then British Museum (Natural History), added X-Ray powder photography and measurements of specific gravity and refractive indices to the range of analytical techniques.

The next decade saw advancements in thin-sectioning and the use of the electron probe microanalyser for chemical analysis. A British Museum project by mineralogists Alan Woolley and Clive Bishop, with archaeologists Richard Harrison and Ian Kinnes, applied this technique to 14 axeheads. They found those made of chemicallydistinctive variants of rock types (eg chloromelanite and omphacite) had different shapes and sizes. Most were jadeite, but eight were identified as nephrite. Where they came from was still a problem, and in 1979 the scientists concluded: "we fear that the source of the light green pure jadeite from which many British large, thin axes are fashioned is likely to prove very elusive".

Most recently Pierre and Anne-Marie Pétrequin's Projet JADE has taken a Europe-wide approach, locating axehead sources high in the mountains of northern Italy. First quarried were the dark green eclogites on Monte Viso, by 5200BC. From the first half of the fifth millennium, the exceptionally rare, pale green jadeites from Monte Viso and Monte Beigua were being worked, as well as nephrite from the Swiss Wallis. In Brittany the imported axeheads were copied in local fibrolite, and in Britain and Ireland Yvan Pailler's work has shown that copies were made here in local rocks too.

In 2005 Alison Sheridan took some British specimens to France for analysis. They were made from jadeite and eclogite from Viso and the Voltri massif. AS

An international, Jeux Sans Frontières-style study week takes place every year in late September at Le Frasnois in the Jura mountains. Sheridan is gathering material for this year's "mission": your artefacts can be non-destructively tested for free (a.sheridan@nms.ac.uk). Pétrequin will be giving a keynote lecture at the Implement Petrology Group's international conference, Stone artefacts as material and symbolic markers in cultural landscapes, in York Sep 6–9: see www.york.ac.uk/depts/arch/conferences/ipg.htm. Pierre Pétrequin is Projet JADE coordinator; Alison Sheridan, Michel Errera and Yvan Pailler are project collaborators.

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