Scientists have found the exact source of Stonehenge’s smaller bluestones, new research suggests.
The stones’ rock composition revealed they come from a nearby outcropping, located about 1.8 miles (3 kilometers) away from the site originally proposed as the source of such rocks nearly a century ago. The discovery of the rock’s origin, in turn, could help archaeologists one day unlock the mystery of how the stones got to Stonehenge.
The work “locates the exact sources of the stones, which highlight areas where archaeologists can search for evidence of the human working of the stones,” said geologist and study co-author Richard Bevins of the National Museum of Wales. [In Photos: A Walk Through Stonehenge]
The Wiltshire, England, site harbors evidence of ancient occupation, with traces of pine posts raised about 10,500 years ago. The first megaliths at Stonehenge were erected 5,000 years ago, and long-lost cultures continued to add to the monument for a millennium. The creation consists of massive, 30-ton sarsen stones, as well as smaller bluestones, so named for their hue when wet or cut.
Stonhenge’s purpose has long been a mystery, with some arguing it was a symbol of unity, a memorial to a sacred hunting ground or the source of a sound illusion.
But for decades, researchers agreed upon at least a few things. In 1923, geologist Herbert H. Thomas pinpointed the source of one type of the stones, known as dolerite bluestones, to a rocky outcropping known as Carn Meini on high ground in the Preseli Hills of western Wales. He became convinced the other bluestones (made from other types of igneous, or magmatic, rock) came from the nearby location of Carn Alw. That, in turn, lent credence to the theory that Stonehenge’s builders transported the stones south, downhill, to the Bristol Channel, then floated them by sea to the site.