Stonehenge breakthrough after analysis of sarsens traces megalith to little-known forest | Science | News

Stonehenge is one of Britain’s biggest ancient mysteries. Archaeologists still aren’t entirely sure what it was used for, though have proposed several uses, including a place to bury the elite.

What further confused scientists was where the stones that make up the structure came from.

Experts were certain its blue stones hailed from the Preseli Hills of South Wales, but question marks remained over the origin of the Sarsen stones.

Originally thought to have come from Marlborough Downs, a more recent analysis by a team of archaeologists and geologists claims to have put a lid on the debate once and for all.

On taking extensive samples from the giant sarsens, the team, consisting of experts from around the world, found evidence that pointed towards West Woods, an area just over 15 miles north of the stone circle site, as the original site.

The woods are closer to Stonehenge than Marlborough Downs, which is a considerable 20 miles away.

Co-author of the study, Professor Mike Parker Pearson (UCL Institute of Archaeology), said: “This settles over 300 years of debate on whether the stones came from around Stonehenge itself or from the Marlborough Downs.

“West Woods was the location nearest Stonehenge where the largest, most suitable monoliths could be obtained and brought along a relatively easy route without too many obstacles.

“Even so, this was an amazing achievement because of the stones’ considerable weight. Rather than using rollers, it’s most likely the stones would have been mounted on wooden sledges that were pulled along on logs laid as rails.”

The stones on average weigh between 10 and 30 tonnes, and stand up to 7 metres tall, or 22 feet.

Sarsens form all 15 stones of Stonehenge’s central horseshoe, and the 25 surviving upright and six lintels of the outer circle, in addition to the stones on the outside that include the Heel Stone, the Slaughter Stone, and the Station Stones.

Modern-day techniques have allowed scientists to use macroscopic and microscopic features of rock to match them to the outcropping from which they were taken.

Such techniques have allowed fieldworkers to confirm that Stonehenge’s bluestones came from South Wales.

The problem with employing the same methods for the sarsens is that the stones are all largely the same, each mostly made up of quartz sand grains stuck together with more quartz.

Instead, the team, whose study was published in the journal Science Advances in 2020, turned to x-ray fluorescence spectrometry, a technique that preserves the stone by beaming x-rays at the stone which sends wavelengths of light bouncing back.

These sample wavelengths are then analysed and often reveal the chemical makeup of the subject.

In the case of the sarsens, the technique revealed the presence of trace elements vital to identifying where they had originally come from.

A sample map of all the potential sites was created, with the highest concentration of similar material present in the West Woods.

“It has been really exciting to harness 21st century science to understand the Neolithic past, and finally answer a question that archaeologists have been debating for centuries. We’re incredibly grateful to the Phillips family for returning the core to us,” wrote Professor David Nash, lead author of the study, from the University of Brighton.

The eventual breakthrough came when a core drilled from Stonehenge’s Stone 58 was returned to English Heritage after having been held in the US.

It and the other stones analysed shared a similar chemistry and were found to come from the same area. Just two of the 52 sarsens appear to have come from elsewhere.

Later opportunities to carry out destructive techniques on stone 58 proved decisive, as the results showed that its chemistry matched that of sarsens found at West Woods.


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