When archaeologists in Georgia conducted test excavations at a 3,000-year-old fortress, they worked in tall summer grass. When they returned in the fall, however, they discovered that the flora had previously concealed something shocking.
Using drone technology, researchers in the U.K., Georgia, and the U.S. mapped the sprawl of Dmanisis Gora, a Bronze Age “mega-fortress” in the Caucasus mountains, and discovered that the complex is 40 times larger than previously suggested. Their research, detailed in a January 8 study published in the journal Antiquity, could provide insight into the growth and urbanization patterns of ancient settlements worldwide.
“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,” said Nathaniel Erb-Satullo of the Cranfield Forensic Institute, who participated in the study, in a Cranfield University statement. “Dmanisis Gora isn’t just a significant find for the Southern Caucasus region, but has a broader significance for the diversity in the structure of large scale settlements and their formation processes.”
The Caucasus is a geographical region encompassing parts of Russia, Georgia, Azerbaijan, and Armenia, and an ancient crossroads of many different cultures, including local populations. Large fortress settlements began to develop in the Southern Caucasus region between 1500 and 500 BCE, according to the study.
Erb-Satullo and his co-director, Dimitri Jachvliani from the Georgian National Museum and a participant in the study, began investigating Dmanisis Gora in 2018. After initial test excavations, the team returned to discover that the autumnal landscape had revealed additional fortification walls and stone structures far beyond the inner fortress they’d previously detected. The complex was evidently much larger than they’d thought—but they found it impossible to document just how big from the ground.
“That was what sparked the idea of using a drone to assess the site from the air,” Erb-Satullo said. The researchers used a drone to take almost 11,000 pictures of the site, which they then pieced together to create digital elevation models and orthophotos: aerial photographs corrected to account for elements such as the angle from which the photo was taken.
“These datasets enabled us to identify subtle topographic features and create accurate maps of all the fortification walls, graves, field systems, and other stone structures within the outer settlement,” Erb-Satullo added. “The results of this survey showed that the site was more than 40 times larger than originally thought, including a large outer settlement defended by a 1km long fortification wall.” One kilometer is approximately 0.62 miles.
Erb-Satullo and his colleagues then compared the orthophotos to Cold War-era spy satellite imagery declassified in 2013 to analyze how the site had evolved in the last five decades, highlighting the encroachment of modern agriculture.
Though modern expansion threatens the site, the researchers hypothesize that thousands of years ago, Dmanisis Gora itself underwent impressive urban growth “because of its interactions with mobile pastoral groups,” Erb-Satullo explained. “Its large outer settlement may have expanded and contracted seasonally,” he added.
Now, the team hopes to use the newly collected data to further investigate elements such as population density and intensity, livestock movements, and agricultural practices.
Ultimately, the drone mapping of Dmanisis Gora sheds light on the mega-fortress, as well as on broader patterns of Late Bronze Age and Early Iron Age societies as a whole. It’s also another example of declassified spy satellite imagery lending archaeologists a hand decades after the photographs were taken.
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