Britain's tallest surviving prehistoric stone row was built with 25-tonne blocks that were dragged at least 18 kilometers, or 11 miles, from a rugged area of North Yorkshire, according to new research.
The Devil's Arrows stand near Boroughbridge in northern England and rise as high as seven meters, about 23 feet. The stones form an unusual alignment in a lowland landscape, and until now scientists could not say where they came from.
Tracing the stone to its source
A team led by Curtin University in Australia, working with the University of York, matched the stones to Brimham Rocks. Plumpton Rocks, which is closer to the monument, had been identified as the probable source. The new study says the builders passed it over.
"Our research shows these stones weren't simply taken from the nearest available source -- they were deliberately chosen from a challenging landscape 18 kilometers away," said lead author Dr. Anthony Clarke of Curtin's School of Earth and Planetary Sciences.
Each block weighs more than 25 tonnes, or about 55,000 pounds. Moving them would have taken planning, coordination and engineering skill, the researchers said.
Why the distance matters
The choice of a far-off source suggests the landscape around Brimham Rocks carried cultural, symbolic or spiritual meaning for the people who built the monument. The stones were probably moved and raised in the Late Neolithic or Early Bronze Age, possibly around 2000 BC.
Dr. Jim Leary of the University of York, a co-author, said the finding changes how researchers interpret prehistoric monument building, because it shows that convenience was not the only concern. The results add to a growing body of work suggesting that where building stone came from was itself part of what a monument meant.
The study is the first to pinpoint the geological source of the towering stones, which have stood in the same field for roughly four thousand years.