Open market revealed in studies of Stone Age axes

The popular image of the caveman is never complete without bearskin clothing and a stone axe bound with thong to a wooden handle. But these tools were more likely used for chopping wood than chopping enemies, according to researchers at UCD who are studying these ancient implements.

"They are the most common artefact we have," said Dr Stephen Mandal of the department of archaeology at University College Dublin. "There are about 20,000 of them, mostly held in the Ulster Museum and the National Museum of Ireland."

Dr Mandal is working with Dr Gabriel Cooney to understand better where these axes came from, how they got to where they were eventually found and who might have used them. The work requires the application of advanced technologies which can determine the kind of stone used and its source, sometimes down to the specific quarry. Their work has shown that there was a highly developed trade in stone axes throughout these islands and beyond. Some of the best ceremonial axes found here are made of jadeite stone and came all the way from Piedmont in the French Alps. "They were beautifully crafted but were no use to anyone," Dr Mandal stated.

There are shale axes originating in the southwest and many made of a stone called gabbros, most of it imported from Britain. Another highly-prized axe stone was porcellanite and there are only two locations in these islands where it was and still is available. There is a quarry on Rathlin Island and another at Tievebulliagh near Cushendall, in north Co Antrim.

Porcellanite is a metamorphosed lava, changed under heat rather than pressure. It is a fine-grained blue rock that fractures like flint if you know how to work it, Dr Mandal explained. "We have been doing some experimental work on it and it is bloody difficult to do it," he admitted. "It is a fabulous stone for making stone axes.

"It is clear [axes] weren't just a tool, they meant more to the people that used them. They are often found in ceremonial situations," Dr Mandal said. Stone axes have been recovered from the Hill of Tara and Newgrange.

Stone axes are linked with the Mesolithic and Neolithic periods ranging from 7000 BC to about 2500 BC, he said. Their use continued well into the Bronze age however. "They were pretty much a wood-working tool," he said.

Stone makes a characteristic impression on wood items so it could be established how a wooden item was cut and shaped.

The research at UCD, with laboratory assistance from Trinity College and Queens University, Belfast, relies heavily on chemical analysis and X-ray fluorescence of the rock to determine its source and its mineral composition.

The research teams are also working on gabbros which can be quarried in Tyrone, near Newry and Mayo. Sources in Britain must also be examined because many gabbros axes were imported. The X-ray fluorescence requires bombardment of the sample with high energy X-rays which reveals the different minerals in the stone.

These techniques usually require samples of up to 7 grammes but new techniques using much smaller sample sizes were developed as part of the project in order to reduce damage to the artefacts. The study gives useful information about Neolithic society, Dr Mandal said. The stone used was probably a function of "what they could get" for tools.

While porcellanite is the predominant stone in axes found in the northeast, the other axe types were also found there. "It demonstrates that by the Neolithic period in Ireland there was control over [axe] sources and there was trade and exchange with Britain and Europe. This directly tells you how far people got and their type gives you trade and settlement patterns."