(CNN) — From deep in the Amazon rainforest, two dozen previously unknown pre-Columbian earthworks have been brought to light — and more than 10,000 such constructs may still be waiting to be discovered, according to new research.
Across the Amazon basin, rainforests spread their leafy boughs over millions of kilometers. In the ground far below the treetops are ancient, long-hidden remnants of human habitation. They are preserved as ditches, paths and wells, sometimes forming geometric patterns. Known as earthworks, they were shaped by indigenous peoples who lived in the area around 500 to 1,500 years ago.