MYSTERY WIRE (Original story from CBSNews.com) — Stonehenge has perpexed historians and archaeologists for centuries. There’s still no absolute agreement on how it was built and why it was built. But now, there might be an answer to where its sandstone boulders come from.
According to a study published Wednesday in the journal Science Advances, most of the giant stones — known as sarsens — seem to come from the area known as West Woods, also in England about 16 miles from the main structure.
The study lays out the theory the megaliths were brought to Stonehenge all at the same time around 2,500 BC. This would be the second phase of construction.
This study does contradict a previous suggestion that one large sarsen, the Heel Stone, was carved from the same site as Stonehenge and placed before the others.
The study’s lead author David Nash, a professor of physical geography at the University of Brighton, said the technology required to analyze the sarsens, that stand up to nine meters tall (30 feet) and weigh as much as 30 metric tons, did not exist until recently.
He and his team first used portable x-rays to analyze the chemical composition of the rocks, which are 99 percent silica but contain traces of several other elements. “That showed us that most of the stones have a common chemistry, which led us to identify that we’re looking for one main source here,” said Nash.
Next, they examined two core samples from one of the stones that were obtained during restoration work in 1958 but which then went missing until resurfacing over the last three years. They performed mass spectrometry on these samples, which detects a bigger range of elements at a higher precision.
The resulting signature was then compared to 20 possible source sites for these sedimentary rocks, with West Woods being the closest match.