Gouffre Mirolda

The cave was discovered in 1971 by Marc Degrinis[2], a shepherd .In 1972, the AVEN group in Lyon widened the entrance crack and stopped at −127 m (−417 ft) on an impenetrable meander. In 1976, an upper entrance, the VF3, at 2,324 m (7,625 ft), was discovered by the Villefranche caving club (EESV) with a stop at the bottom of the first 30 m (98 ft) shaft on a narrow slope. The Gouffre Mirolda (CD11) was redesigned in 1980 by SC Lyon. With the help of the GS Cavernicole and the SC du Chablais, the −850 m (−2,790 ft) elevation was reached. In 1981, the river was explored down to −1,100 m (−3,600 ft). Reinforced by the SS Genève and the Thonon Tauping Club, fossil galleries and upstream tunnels enabled the network to reach a height difference of 1,143 m (3,750 ft) in 1988. The unblocking of the Gouffre VF3 gives access to the network named after Lucien Bouclier, a speleologist who died in 1987 on the massif. The junction was made by the Ursus group between the gouffre Mirolda and the réseau Lucien Bouclier in 1992 for a depth of −1,436 m (−4,711 ft) and with the gouffre de la Rondelle Jaune (2,220 m (7,280 ft)). At the bottom of CD11 the elevation rose in 1993 to −1,520 m (−4,990 ft) and −1,610 m (−5,280 ft) in 1998.[3] The Gouffre du Joker (2,332 m (7,651 ft)) joined the network in 1999 and increased the rating to −1,616 m (−5,302 ft). After the dive of the terminal sump in 2003, this chasm has a depth of −1,733 m (−5,686 ft), finally explored. The cave was measured to be −1,733 m (−5,686 ft) deep, making it the deepest natural cave in the world from January 2003 until July 2004,[4][5] when it was passed by the cave Krubera-Voronja in Abkhazia.[6] In September 2022 and 2023 a Collectif Mirolda takes over the topography, modernizes the equipment and examines the possibilities of discovery.[7] It is the deepest cave in France. The cave's name is derived from the forenames of the Rhodanien cavers Michel Schmidt, Roland Chenevier, and Daniel Trouilleux, who were lost in a flood in Gournier Cave in November 1976.[8]

The highest entrance to the cave is at 2332 meters. The lowest point of the cave is at −1,733 m (−5,686 ft) at the grand siphon in the gallery.[9] The bottom of the gallery (after the second siphon) has only been explored once, leaving room for further exploration. Behind the second siphon (approximately −1,620 m (−5,310 ft)) the gallery continues for 22 m (72 ft) horizontally and down 8 meters, leading to an ancient drainage system. Downstream, the gallery descends over a length of 251 meters and a vertical drop of 110 meters before coming up against the first siphon at −1,733 m (−5,686 ft). Past the siphon the gallery splits in two, the left leading up towards the ceiling and the right leading 50 meters to the fossil gallery.[10]

The Gouffre Mirolda is located in the Urgonian Limestone at the contact of the Hauterivian marl following the dip (E-W) then (S-W) towards the Giffre valley. The water flows into the alluvable aquifer and no resurgence is known.[1][3] As at the Gouffre Jean-Bernard, the upstream of the réseau Lucien Bouclier seems older and the bottom of the CD 11 dug following the incision of the Giffre valley.[11]

• Gouffre Jean-Bernard ‎
• List of deepest caves
• List of caves in France
• List of caves