Two British geologists have linked fragments of rocks — believed to have been used 5,000 years ago to create Stonehenge’s first stone circle — to an outcrop in southwest Wales.

A rock outcrop is the visible exposure of bedrock on the earth’s surface.

Their discovery reignites the age-old controversy about just how the rocks that make up Stonehenge got there.

One theory is that the rocks were randomly moved to a site near Stonehenge during the Ice Age by glaciers.

Another theory maintains that the rocks were excavated from a quarry and were transported there by early man.

This recent discovery makes it possible for archeologists to now see if there are any signs of a quarry or any human activity near the outcrop, Robert Ixer, a geologist and retired professor from the University of Leicester told the Star.

Ixer has been studying Stonehenge’s rocks for the past 20 years.

He began working with Richard Bevins, from the National Museum of Wales, on trying to match some of the stone fragments of Stonehenge in 2009.

The pair looked at about 700 broken stones and fragments from Stonehenge — known as “foliated rhyolite” — by using a Victorian technique of examining thin layers of rock under a microscope.

These broken stones and fragments are believed to come from another circle of bluestones – the types of stones at Stonehenge – that is believed to have been part of the original monument that are now missing and perhaps were destroyed.

“Our assumption is these scattered stones have come off destroyed bluestones,” he explained.

Ixer said he and Bevins were able to match the 700 stones to an outcrop known as Craig Rhos-y-Felin in Pembrokeshire, in southern Wales.

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“It was astounding when we found the same petrography (a detailed description of rocks) could be matched to a single outcrop in South Wales,” he said.

“It’s the first time any bluestone from Stonehenge has been so specifically matched to an outcrop in Wales.”