The source of the search for the Stonehenge blue Stones has progressed yet another step, with the announcement of a second confirmed quarry site in southwest Wales.
While the monuments sarsens are thought to have been sourced locally from the Marlborough Downs area, about 30km north of Stonehenge it has long been suspected that the smaller bluestones came from further afield with Pembrokeshire posited as a likely source since 1923.
In 20ll Dr Rob Ixer ( UCL) and Dr Richard Bevins (National Museum Wales) identified the first quarry, revealing that the rhyolite bluestones came from a specific outcrop at Craig Rhos y Felin.
Bluestone outcrop Craig Rhos -y- Felin. Photo courtesy National Museum of Wales.
Now Bevins and Ixer, together with Prof, Nick Pearce of Aberystwyth University have located the source of another major type of bluestone- the spotted dolerites- at Carn Goedog in the Preseli Hills. The team used geochemical analysis to re-examine samples taken from upstanding bluestones and debit age drawing on data published by Richard Thorpe at the Open University in l99l.
Cairn Geodog Presili Hills. Another major type of bluestone known as spotted dolerites.
The Open University study looked at what are called ” incompatible elements ” in the rock, which allow you to distinguish samples from different regions, but all these data could prove was that the bluestones were from the Preseli area, ‘said Rob Ixer. However, we decided to look at the ‘compatable elements’ – these tell you about local changes to the molten material as it crystalises at high levels in the crust. Petrochemical analysis showed that all the crags in Presili come from the same batch of magma, but they have recognizable chemical differences, which is very useful. it means you can discriminate between specific outcrops.
These findings which will be published in the Journal of Archaeological Science, could suggest a change of direction in the hunt for the source of the bluestones: traditionally such research has focused on another Preseli outcrop a mile away called Carn Meini.
‘Carn Goedog is a prominent outcrop about l5 m thick and covering some 30 m left to right’, said Richard Bevins ‘ Our next plan is to take samples and create a really detailed geochemical profile for the site-we hope eventually to establish the source of all the ‘Stonehenge bluestones’. It is a search that is likely to continue for some time, Rob Ixer added.
It is believed there are at least ten kinds of bluestones at Stonehenge and most likely from ten separate localities, there is still a long way to go before completion of the second quarry site.
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