Lidar exposes the remains of an ancient civilization covered in vegetation in the Amazon
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Lidar exposes the remains of an ancient civilization covered in vegetation in the Amazon

It’s Friday and the world is falling apart, so let’s take a quick mental health break with some exciting news from the field of archaeology, where technology is enabling exciting new discoveries. A new lidar-powered analysis of land in the Amazon Basin has provided evidence of a previously unknown urban center of “mind-boggling” complexity. To be clear, that doesn’t mean ancient aliens or long-lost technology, just that it far exceeds the expected levels of organization and population that scholars thought possible for Amazonians 1,500 years ago. “No one expected that kind of society in that region… 20-meter-high pyramids,” Heiko Prümers of the German Archaeological Institute said in a video produced by Nature. “The entire region has been so densely inhabited during pre-Hispanic times that it is unbelievable. There is a new civilization, a new culture, waiting for us to study them.” Until recently, the Amazon was thought to have nothing more than smaller tribes until the arrival of Spanish and Portuguese explorers, a typically Eurocentric view increasingly questioned by new studies. In this case, Prümers was intrigued by the mounds called knolls, hidden under the vegetation but hinting at something larger. Excavations showed that these were not garbage dumps (as some thought), but organized areas for graves, rituals, and other things indicative of a complex and hierarchical society. But finding bumps in the ground under the canopy of a rainforest is no easy feat, so in 2019 they set out to scan the area by helicopter, using lidar to reconstruct the contours of the surface below the trees. This technique has proven very fruitful recently, with entire Mayan cities and even a kilometer-long artificial embankment discovered in this way.Image credits: Prümers et al. Lidar beams pass between leaves and branches, bouncing back to give an amazingly detailed view of the height of the ground below. And more than ever, this data can be quickly collected and analyzed to produce a 3D point cloud that is easily inspected for hidden structures. What the team found was more than a few new mounds: platforms, massive pyramids, defensive structures, reservoirs and canals, and more connecting what appeared to be hundreds of settlements of various sizes. This goes against assumptions that the local peoples were nomadic or foraging cultures, not sedentary and agricultural.Lidar images of features discovered in the city of Casarabe using LIDAR.Lidar images of features discovered in the city of Casarabe using LIDAR. Image credits: Prümers et al. The Casarabe culture, as it has been named after its discovery, remains mostly a mystery. After all, its existence was only recently confirmed, but this provides a starting point for further investigation. “We have to be patient and wait for more excavations at those sites to be able to explain some of what we’re seeing right now,” Prümers said, though it’s work of a scale and duration that may require him to hand it down to his students. . “For me, who have worked these last 20, 25 years in that region, it is like a dream come true! To say at the end of my career that, yes, we have a new culture? That’s good, I admit. As in so many domains, technology is an enabler (Prümers estimated that it might have taken 400 years of digging to unearth all the stuff they found using lidar), but it can never replace the hard work and expertise that humans bring to the equation. You can read the full paper (it’s open access) in Nature.

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