Measuring luminescence helps to date a remarkable new discovery at Stonehenge

FOR MORE than 4,000 years Stonehenge has stood on Salisbury Plain in southern Britain. The landscape surrounding the Neolithic monument contains many secrets, with features dating back to much earlier times. Having surveyed more than 18 square kilometres in the vicinity, archaeologists continue to make surprising discoveries. The latest, a series of deep pits forming a vast circle more than two kilometres in diameter, shows how technology makes it possible to peer even further back into time.Along with their shovels, trowels and brushes, archaeologists have put together a toolbox of new technologies. Using magnetometers, which can detect how different materials in the ground cause slight changes in Earth’s magnetic field, they found a series of anomalies forming circular disturbances in the ground on a broad arch around Durrington Walls, the remains of another large henge three kilometres north-east of Stonehenge. These were thought to be old filled-in ponds.