Welcome to Brainstuff, a production of I Heart Radio. Hey Brainstuff, Lauren Vogelbaum. Here, it's possible that there's a giant, beadly serpent hanging out at the bottom of the Fustillon spring in the Burgundy region of France. It's also possible that there's no serpent. It's a legend concocted by ancient inhabitants of the village of Tonair, where the spring is located, but nobody's ever been able to get to the bottom of it. Because nobody's ever been able to get to
the bottom of it. Fustillon is a karst spring, karst being in a regular limestone region with sinkholes underground streams and caverns. The spring burbles up an average of eighty two gallons that's three hundred and eleven liters of water every second, which is an unusually high discharge rate for this type of spring. About the velocity of the water
varies from season to season. What you would be able to see of the spring if you visited the Fustillon, which translates to divine pit by the way, is a circular stone pool that was built in the eighteenth century, filled with jewel poned water, turquoise, amber and cerulean colored by the minerals, and the limestone caves from which the waters emerge. The opening of one of those caves is
visible from the edge of the basin. Because humans have been using the Fastillon since before anybody was keeping track for drinking, washing, cooking, and bathing, there are stories and legends about the spring, some of which we know and some we don't. In the Middle Ages, it was thought that there was serpent that cruised around deep in the heart of the Fastillon, and some even thought it was
the portal to another world. The spring features prominently in accounts of the miracles performed by the seventh century monk Saint Jean de Ryon, and I hope I said that correctly, I do not know French. He arrived in the area in the year sixty five CE to clean up the spring,
which was at the time an unusable swamp. The monk reportedly dug a basilisk, a monster that's half rooster and half lizard, out of the spring and killed it, allowing people to regain the use of the Falstillon for drinking, washing, et cetera. These days, the Fustillon looks very civilized from the outside, and its stone basin surrounded by a communal washing place that was built in the eighteenth century to protect washer women from the elements as they did their
laundry in the springs water. But below the surface the spring is just as wild as when Saint Jean arrived to tame it. The great mystery of the Falstillon spring is where the water actually comes from. There's certainly a lot of water coursing out of it, and like other Karst springs, the water emerges from a network of subterranean limestone caves. It's thought the Fostillon is fed by both rainwater from the hills around Tornair and at least one
underground river. However, no diver has ever been able to find its source, and many of those who have tried haven't come back alive. No one even attempted to plumb the depths of the Fustillon until nineteen seventy four, when two divers undertook navigating the maze of chambers and narrow tunnels of the spring. Neither of those divers came back to tell us what they had seen. In nineteen ninety six, another diver attempted it, but he lost his life to
the Fustillon as well. Before many years after, divers were prohibited from diving into the spring until twenty nineteen, when a diver undertook exploring about a thousand, two hundred feet that's three hundred and seventy meters of passageways. Luckily, he returned alive, but didn't find the source of the spring, nor did he find another dimension or a monstrous serpent.
But hey, there's still time. Today's episode is based on the article France's Mysterious Fustillon Spring stubbornly keeps its secrets on how stuffworks dot com, written by Joslin Shields. Brain Stuff is production of by Heart Radio in partnership with how stuffworks dot Com and is produced by Tyler Thing. Or more podcasts from my heart Radio, visit the heart Radio app, Apple Podcasts, or wherever you listen to your favorite shows. H