Drone photographs taken of a 3,000-year-old “mega fortress” nestled deep in the Caucasus Mountains reveal the settlement is actually 40 times larger than archaeologists once thought. New aerial images of the Dmanisis Gora settlement, located in present-day Georgia, show a large land area well guarded by steep gorges and plastered with various stone structures and field systems. Though the structure’s inner fortress has been well-documented for several years, new mapping made possible thanks to a simple hobbyist drone helped redraw the Bronze Age monument’s boundaries. Researchers shared their findings this week in the journal Antiquity.
The Dmanisis Gora is one of several documented fortresses that popped between the Middle East and the Eurasian Steppe sometime between 1,500 and 500 BCE. Until now, most of the archaeological research on this particular fortress focused on its more well preserved inner areas. The fortress is made up of two distinct areas: a core inner fortress that researchers say show signs of year-round residential use and a more sprawling outer area that may have been used more occasionally by roaming pastoral groups. When researchers from Cranfield University began excavating that area in 2018, they quickly saw evidence of outer walls and other structures that suggested the actual border of the fortress could be much larger. But they couldn’t accurately tell just how much larger it was without an aerial view.
“That was what sparked the idea of using a drone to assess the site from the air,” Cranfield Forensic Institute Senior Lecturer in Architectural Science Erb-Satullo said in a statement.
Erb-Satullo and his colleague acquired a DJI Phantom 4 RTK drone, equipped it with a high-quality camera, and flew it over the area. The drone snapped roughly 11,000 images which were combined together and run through software to create a digital map of the areas filled with elevation models and topographical detail. The new map showed a much larger outer that circled around the inner fortress. Aerial views from the drone revealed a roughly 1-kilometer-long fortification wall snaking around the fortress that wasn’t immediately visible to the naked eye. Previously unobserved graves, field systems, and other structures were also illuminated thanks to the drone.
“The use of drones has allowed us to understand the significance of the site and document it in a way that simply wouldn’t be possible on the ground,” Erb-Satullo added.
Researchers then compared their new drone-based map to other aerial photographs of the area captured by a Cold War-era spy plane nearly 50 years ago. Those images had been classified until 2013. Looking at those two images side by side helped the team better understand how the landscape has changed and to what extent parts of it might have eroded as a byproduct of modern agricultural practices.
[Related: Archaeologists find the 4,000-year-old tomb of an overachieving Egyptian magician]
Drones are helping archeologists redraw maps and uncover lost settlements
Drones have become incredibly useful tools in archeologists’ arsenal thanks to their ability to quickly obtain aerial views of areas that might otherwise be obstructed. Falling prices in consumer hobbyist drones, many originating from China, have made the technology far more accessible to a wider swath of researchers. They’ve already yielded spectacular findings. In 2015, a team of researchers from Colorado State University used a drone equipped with LiDAR to help map out a pair of hidden medieval cities in the mountainous area of Uzbekistan. Another drone LiDAR was used several years later to reveal the remains of an ancient island settlement hidden off of the Florida Gulf coast possibly dating back to 1200 CE. Archaeologists similarly used a drone to uncover the eroded remains of a large pre-Columbian earthworks buried beneath a field in southeastern Kansas.
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