Scientists flying drones over the Amazon rainforest in Brazil have found more than 450 "geoglyphs" that are similar in size, structure, and possibly purpose to Stonehenge in England. The earthworks were likely used for public gatherings and rituals, researchers report in the Proceedings of the National Academy of Sciences. They've been hidden beneath a thick canopy of trees for about 2,000 years, but modern deforestation has made them easier to spot from above. The earthworks are surrounded by ditches and causeways in a way that history buffs will find familiar. "The earliest phases at Stonehenge consisted of a similarly laid-out enclosure," lead researcher Jennifer Watling, of the University of Sao Paulo, tells the Telegraph.
Researchers say the discovery adds another new wrinkle about the Amazon, refuting the notion that it has been largely untouched by humans until modern times. "The fact that these sites lay hidden for centuries beneath mature rainforest really challenges the idea that Amazonian forests are 'pristine ecosystems,'" Watling says in a news release. But scientists say the indigenous people of the time appeared to manage the land carefully, clearing small tracts of bamboo forest to create the earthworks and encouraging the growth of species they could use and trade, reports UPI. Because few artifacts have been found at the sites, researchers think they were used only for special occasions. (Even earlier ditches may have predated the forest itself.)