Spelunking along the Spanish border early this summer, Scientist Georges Lépineux watched a black mountain crow fly into a yawning pit and disappear. Since crows love dark recesses almost as much as speleologists do, Amateur Geologist Lépineux rushed to investigate. A small cave led off the pit floor, and a few feet inside the cave mouth a limestone chimney dropped away into darkness. Cautiously, Lépineux heaved a rock into the opening, waited for the faint, faraway sounds of its fall. Then he rushed to report his discovery.
Last month a twelve-man Belgian-French cave-exploring team went back to Basses-Pyrénées, made the long, hard...