Bodmin Moor in north-east Cornwall is one of Britain’s most breathtaking wildernesses, where heather-flowered high moorland is punctuated by granite outcrops in sharp river valleys and lonely woodlands. You wouldn’t associate this place with much human activity: its seemingly most at home inhabitants are the region’s wild horses. Only piles of stone circles and strange rock formations – their mysterious origins and purpose lost in the mists of time – hint at a human presence in the past.
A glimpse of the entire human history of the area
But this year’s archaeological discoveries are changing the perception of Bodmin and the neighboring Valley of the Tamar Ships and its sister wilderness, Dartmoor in Devon. This archaeology, however, does not involve the old-fashioned technique of slowly scraping across the soil to trace back centuries. Today’s history-changing discoveries are being made in a very modern way: by laser scanning.
Over the past few months, archaeologists have scrutinized high-tech LIDAR (light detection and ranging) scans to uncover a whole new timeline of human occupation of the land, from prehistoric burials to hidden Roman roads and, perhaps most interestingly, hundreds of previously unsuspected medieval farmsteads and settlements.
Lidar provides high-resolution scans of the landscape from the air by sending fast, continuous laser pulses from an aircraft, helicopter or drone to the ground and measuring how they reflect back. The difference in return time and wavelength is then used to produce accurate digital 3D maps of the terrain. LIDAR was first developed in the 1960s and one of its earliest uses was to map the surface of the Moon during the Apollo 15 mission in 1971.
In the UK, the main use of LIDAR for decades was to collect information for the Environment Agency in response to coastal erosion and inland river flooding. But the decision to make the data publicly available in 2015 offers British archaeologists an exciting new way to discover previously undiscovered historical features below the surface, such as the linear imprints of ancient Roman roads and ancient Iron Age forts.
“One word is ‘transformative,'” said Dr. Christopher Smart, a landscape archaeologist at the University of Exeter who has been using LiDAR scanning to gain fresh insights into past human activity in western England. “The key to LiDAR is that it can detect subtle topographic changes on the ground that are not visible to the naked eye, or from aircraft using standard photography. They simply wouldn’t have been picked up any other way.”
Examining just one-tenth of the available LiDAR data, Smart’s team this year uncovered some 30 previously unsuspected settlements believed to date back to between 300 B.C. and A.D., as well as hundreds of medieval farms, farm systems and quarries, plus more than 20 miles of previously unknown Roman roads. These discoveries reveal that human activity in the area was far busier 2,000 years ago than any expert had previously believed.
Even sites previously thought to have abandoned all historical data are being re-evaluated. “Almost everywhere LIDAR has been applied, we’ve seen tremendous insights, even in landscapes that have been well studied, such as Stonehenge,” says Rebecca Bennett, whose Pushing the Sensors consulting firm provides LIDAR training. Using LiDAR in combination with other high-tech tools such as magnetometers and ground-penetrating radar (GPR), discoveries around Stonehenge include the remains of a large 6,000-year-old timber-framed building believed to have been associated with burials and rituals, in addition to up to 60 previously unknown massive stone pillars spread over a 1.5-kilometer area, a wider area than today’s iconic single stone circle.
More discoveries are likely to be made once the Environment Agency completes its national LiDAR programme, which aims to scan the whole of England by mid-2021. “Archaeologists will be discovering new sites in all areas,” Smuts said. “I look forward to the data from southern England to explore the possibility of unknown remains associated with westward Roman military operations in the second half of the 40s AD. Another important use of the LiDAR data is to map the medieval landscape: open fields, hedgerowed paddocks and settlements from 1100-1700. We will be able to reconstruct those past landscapes in a way that has never been done before.”
