© Jennie AndersonAn artist's impression of Flagstones in use, thousands of years ago.
Radiocarbon dating of some of the artifacts and remains buried beneath the monument reveals that Flagstones was erected around 3,200 BCE - at least 200 years earlier than previously thought.
This discovery is a small eureka moment, a temporal context that neatly explains the puzzling hybrid features of the monument, and suggests that Flagstones was a precursor to the stone circles that were to follow - including Stonehenge, erected 5,000 years ago.
"Flagstones is an unusual monument; a perfectly circular ditched enclosure, with burials and cremations associated with it," says archaeologist Susan Greaney of the University of Exeter in the UK.
"In some respects, it looks like monuments that come earlier, which we call causewayed enclosures, and in others, it looks a bit like things that come later that we call henges. But we didn't know where it sat between these types of monuments - and the revised chronology places it in an earlier period than we expected."
Flagstones lay hidden beneath the ground in Dorchester for thousands of years. Hints of its presence emerged in the 1890s, when a single "sarsen" - a large block of sandstone - was excavated from the garden of author Thomas Hardy, with bones and ashes buried in a pit beneath it.
The true extent of the monument, however, wasn't revealed until the 1980s, when workers digging up the ground in preparation for a road found more subterranean pits and sarsens, concealed by Earth and time, arranged in a large circle 100 meters (328 feet) in diameter.
Some of the walls of the pits were engraved, and several of the pits also included human remains, some cremated, some buried children. Archaeologists have compared it to similar circular sites, all with pits and cremations, and a marked absence of other artifacts, suggesting at least a partial funerary purpose.
