New discovery throws further light on the origins of famous bluestones of Stonehenge

The ongoing debate surrounding the source of the famous bluestones forming the distinctive inner circle and horseshoe of Stonehenge has taken another turn after new findings emerged from Amgueddfa Cymru – National Museum Wales.

One type of bluestone, the so-called spotted dolerite, was convincingly traced to the Mynydd Preseli area of North Pembrokeshire in the 1920s, but the origins of many of the others have remained a mystery. Now geologists at the museum in Cardiff believe they have identified the source of one of the rhyolite types.

A team led by Keeper of Geology Dr Richard Bevins has been using “standard petrographical techniques” and “laser ablation induction coupled mass spectrometry” on samples from Stonehenge and Pembrokeshire.

Their findings, which involve the application of zircon chemistry as a new tool for “provenancing rhyolitic lithics”, point to a source for the stones in an area north of the Mynydd Preseli range, in the vicinity of Pont Saeson.

The results, which are due to be published in the March 2011 edition of the Journal of Archaeological Science, may also provide some new clues about how and why the stones were transported to the Stonehenge area.

“It has been argued that humans transported the spotted dolerites from the high ground of Mynydd Preseli down to the coast at Milford Haven and then rafted them up the Bristol Channel and up the River Avon to the Stonehenge area,” explained Dr Bevins.

“However, the outcome of our research questions that route, as it is unlikely that they would have transported the Pont Saeson stones up slope and over Mynydd Preseli to Milford Haven.”

Doctor Bevins, who admitted that trying to match stones from the famous henge with rocks in Pembrokeshire was “like looking for a needle in a haystack”, said that an alternative route should now be considered for their transportation from Pembrokeshire to Salisbury Plain.

The findings may also throw some new light on the belief held by some archaeologists that the stones were transported by the actions of glacier sheets during the last glaciation.

Stonehenge scholar Mike Parker Pearson, Professor of Archaeology at Sheffield University, said the findings were “a hugely significant discovery" and would fascinate Stonehenge enthusiasts.

“It forces us to rethink the route taken by the bluestones to Stonehenge and opens up the possibility of finding many of the quarries from which they came. It’s a further step towards revealing why these mysterious stones were so special to the people of the Neolithic.”

Dr Bevins and his team are now looking for the sources of the other Stonehenge volcanic and sandstone rocks.