It was in 2010 that Amilcar Adamy first investigated rumors of an impressive cave in southern Brazil.
A geologist with the Brazilian Geological Survey (known by its Portuguese acronym, CPRM) Adamy was at the time working on a general survey of the Amazonian state of Rondonia. After asking around, he eventually found his way to a gaping hole on a wooded slope a few miles north of the Bolivian border.
Unable to contact the landowner, Adamy couldn’t study the cave in detail during that first encounter. But a preliminary inspection revealed it wasn’t the work of any natural geological process. He’d been in other caves nearby, formed by water within the same geology underlying this particular hillside. Those caves looked nothing like this large, round passage with a smooth floor.
“I’d never seen anything like it before,” said Adamy, who resolved to return for a closer look some day. “It really grabbed my attention. It didn’t look natural.
