Lost Civilizations, Found by Drones

Equipped with high-tech sensors, unmanned aerial vehicles can help archaeologists discover remnants of ancient societies.

This drone will search for ancient artwork hidden in the Amazon rainforest. (XMOBOTS)

Beneath the barren New Mexican desert, there are remnants of an ancient Pueblo society that thrived some 1,000 years ago. John Kantner, an archaeologist from the University of North Florida, has surveyed the red sands for 20 years in search of ancient religious structures called kivas. Similar to small family chapels, kivas were circular rooms where members of the Chaco group went to perform ceremonies and rituals. Located under the household, the small spaces were buried and filled with soil as centuries passed.

Kantner had uncovered some kivas during his two decades in the desert, but searching for the subterranean structures on foot was difficult and time consuming. He, like many other archaeologists, decided to use technology that is revolutionizing his field: drones.

A buried archaeological feature retains heat differently than the surrounding soil. So Katner used drone surveillance along with thermal imaging to key in on subtle temperature differences while the structure heats and cools. He teamed up with Jesse Casana, an archaeologist from the University of Arkansas who had previously equipped aerial machines with thermal imaging technology for archeological research in Cyprus and Iraq. (Although thermal imaging has been around for decades, pairing it with drone technology is new.)

Researchers uncovered ancient Pueblo structures hidden beneath the New Mexico desert. (John Kantner)

The team flew its eight-rotor drone multiple times before dawn when the desert was at its coolest. It took snapshots of the heat patterns every second. Each frame extracted from the thermal camera provided just a footprint of the ground, but combined together, it created a mosaic of what was beneath the entire area. The team was able to detect heat signals beneath the sand which revealed several kivas. “In the end it was two hours of work to find something that I’ve spent years trying to find,” said Kantner. “That’s pretty remarkable.” They published their findings last year in the Journal of Archaeological Sciences.

Thermal imaging from drones reveals the locations of kivas and other Pueblo structures. (John Kantner)

Drones may also offer new research opportunities when coupled with laser imaging systems like LiDAR, which creates high-resolution maps and can reveal hidden structures that are otherwise impossible to detect. “What we’ll see in the next year or so that will blow the doors off in archaeology will be drone based LiDAR,” Casana said. But LiDAR equipment is expensive, and Casana notes that some researchers might be reluctant to mount the device onto drones, which crash often. “If you can get people to get a drone to carry LiDAR reliably that would be great for archaeology,” he said. “People are salivating to get this to work.”

A team of archaeologists at the University of Exeter is planning to do just that with drones in the Amazon. Jose Iriarte, the team’s leader, will set out with his colleagues to the rainforests later this year to uncover signs of ancient civilizations that once inhabited the thick forests. There is debate within the archaeological community over whether civilizations ever took root in the forest. Some argue that the Amazon is a pristine environment that has always been devoid of large human settlements; while others believe that different cultures have thrived and transformed the rain forest for thousands of years.

Ancient human civilizations may have lived in what is now dense Amazon rainforest. (Projecto Geolifos)

One clue as to which theory is correct lies within massive artworks called geoglyphs which may hide beneath the jungle floor’s vegetation. Getting through the thickets of the Amazon is no easy task, so finding these ancient artworks is a challenge. That’s where drones can help. Equipped with LiDAR, a drone can fly above the tree tops and use its sensors to pierce through the heavy canopies and leaves to reveal any potential geoglyphs hidden below. “No one really knows what they are,” Salman Khan, the team’s remote-sensing specialist, said of the unique designs. “But they are a signature of past human presence in Amazonia.”

So far, archeologists have uncovered about 450 geoglyphs near the jungle using tools such as Google Earth. Khan thinks these findings suggest that there are more geoglyphs hidden within the Amazon forest. Although the circular and square-shaped designs can be as large as 300 meters—equivalent to the size of three football fields—they are hard to spot from the ground. Khan is responsible for the developing the drone and its sensors. “You cannot see them very well if you are on top of them, especially if they are hidden under the forest,” said Khan. “So the only way to actually see them is from a high vantage point.”

A famous example of a geoglyph in Peru that resembles a hummingbird (Dennis Jarvis/Flickr)

He and his colleagues plan to fly a drone, which looks like a miniature single-passenger plane, over parts of the forest. The team will also search for mounds, ditches, and dark soil patches that may also be indicators of ancient human dwellings. They plan to travel to the Amazon to launch their drone during the dry months of September and October.

“We’re hoping to find all these artworks,” said Khan. “The discovery of new archeological features would stimulate the community a lot.”