The mystery of the origin of giant sarsen stones at Stonehenge has been solved. A team of archaeologists succeeded in decoding the decades old mystery by using a missing piece of the site which was returned after 60 years.

Accoridng to archaeologists, the mysterious stones were brought to an area 15 miles (25km) north of the site near Marlborough. Talking to BBC, English Heritage’s Susan Greaney said the discovery was “a real thrill”.

The seven-metre tall sarsens weigh about 20 tonnes. They form all fifteen stones of Stonehenge’s central horseshoe as well as outlying stones. It is to be noted that the smaller bluestones of Stonehedge were traced to the Preseli Hills in Wales, but the mystery of sarsens remained intact until now.

The return of the core, which was taken away from the site during excavations in 1958, enabled archaeologists to analyse its chemical composition. No one was aware of this until 89-year-old Robert Phillips decided to return part of it in 2019. Philips was also involved in excavation works.

Researchers conducted x-ray fluorescence testing of all the remaining sarsens at Stonehenge which showed that most shared a similar chemistry and came from the same area. The researchers then studied sarsen outcrops from Norfolk to Devon and compared the chemical composition of these outcrops with the chemistry of a piece of the returned core.

Prof David Nash from Brighton University, who led the study, said: “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. Each outcrop was found to have a different geochemical signature, but it was the chance to test the returned core that enabled us to determine the source area for the Stonehenge sarsens.”

Greaney said, “To be able to pinpoint the area that Stonehenge’s builders used to source their materials around 2,500 BC is a real thrill. While we had our suspicions that Stonehenge’s sarsens came from the Marlborough Downs, we didn’t know for sure, and with areas of sarsens across Wiltshire, the stones could have come from anywhere. They wanted the biggest, most substantial stones they could find and it made sense to get them from as nearby as possible.”