Did Geologists Find Source of Stonehenge's Boulders?

The source of the rocks forming the inner circle of Stonehenge has been a long debated mystery, but geologists think they have found the source of at least some of the stone.

The Daily Mail reports that Robert Ixer from the University of Leicester and Richard Bevins of the National Museum of Wales think the rocks may have come from Craig Rhos-y-Felin in Pembrokeshire, a county in southwest Wales. They found almost 99 percent of the rhyolite rock samples from Stonehenge's inner circle matched rock from this area.

According to the museum press release, the story deepens:

Along the Rhos-y-felin crags, the rhyolites are distinctly different on a scale of metres or tens of metres. This has enabled Bevins and Ixer to match some Stonehenge debitage samples to an even more precise locality at the extreme northeastern end of the area.

What this means is that the area is now small enough for archaeologists to excavate to try and uncover evidence for associated human activity so providing another strand of the story of how the stones from Pembrokeshire reached Stonehenge.

“Many have asked the question over the years, how the stones got from Pembrokeshire to Stonehenge," Bevins said in the press release. "Was it human transport? Was it due to ice transport? Thanks to geological research, we now have a specific source for the rhyolite stones from which to work and an opportunity for archaeologists to answer the question that has been widely debated. It is important now that the research continues.”

BBC reports that theories surrounding transport of the stone include using a raft, which could be unlikely due to the terrain making it difficult to move the rocks up the coast. Other theories include that the force of nature, such as glaciers, could have moved the stone to the area. BBC notes that in 2000 an effort was undertook to try and move similar stones 240 miles from Wales to the site using land and sea technology that would have been present around 3000 BC. The effort failed.

Wired reports that that the rocky outcrop these geologists believe could be the source of some stone is located  about 160 miles away.