This underground route was suggested by the geologist Ramond de Carbonnières in 1787, but there was no confirmation until 1931, when caver Norbert Casteret poured fluorescein dye into the flow and noted its emergence a few hours later 4 kilometers away at Uelhs deth Joèu ("Jove's eyes" Coord) in the Artiga de Lin on the other side of the mountain.