| Gournier cave | |
| Map: | France#France Auvergne-Rhône-Alpes |
| Depth: | + 680m (2,230feet) |
| Length: | 18000m (59,000feet) |
| Elevation: | 572m (1,877feet) |
| Geology: | Limestone |
The Gournier Cave is located near Choranche in the Vercors Massif in south-eastern France. The entrance is at an altitude of at the base of a cliff on the Presles plateau. It is one of the exsurgences (points at which an underground stream reaches the surface if stream has no known surface headwaters)[1] of the Coulmes massif, and the cave is considered by many speleologists to be the most beautiful underground river in the Alps.[2]
In 1899 Decombaz visited the entrance lake by boat. In 1947, a climb over the lake by Jean Deudon gave access to a fossil gallery, which was explored by a team including André Bourgin for nearly 2000m (7,000feet), when two access points were discovered to the underlying river. The same team were stopped by a 12m (39feet) waterfall in 1949. The latter was climbed in 1952 by Pierre Chevalier, and the river was followed to a large chamber. In the 1960s, the Spéléo Club de la Seine found the way on, but were eventually stopped by a sump at a height of +270m (890feet).[3]
March 1973, the Club Spéléo de Lyon passed the obstacle, but were stopped by a second sump. In 1974, this was passed by diving, and in November 1975, 5.3km (03.3miles) from the entrance, the height of 460m (1,510feet) above the entrance was reached at the foot of a 5m (16feet) waterfall. In November 1976, while to pass the obstacle, three speleologists from the Rhone region, Michel Schmidt, Roland Chenevier and Daniel Trouilleux, were swept away by a flood.[4]
The Spéléo Club de Dijon resumed the explorations in May 1981, and above the 5m (16feet) waterfall, a further 2200m (7,200feet) of galleries were discovered reaching a height of +605m (1,985feet). In 1982 the end was reached at + 680m (2,230feet).[5]
In August 1996, a cave diver, Frédéric Poggia, dived the sump l'affluent des Parisiens, discovering 1200m (3,900feet) of passages. He stopped at a fifth sump.[6]
Speleologists have been digging sinkholes above the end of the cave for several years, hoping to reach the underlying passages.[7]
Within the entrance porch is a long lake, above which is the entrance to a long fossil gallery, wide, which has beautiful stalagmite floors in places. In the floor of this passage are four entrances to the underground river. The fine river passage can be followed up waterfalls and through pools to the large Salle Chevalier. After a complex section the river rejoins the cave. The Jerome siphon can now be passed by swimming.[8]
A second sump can be avoided, and then the gallery broadens out, with a section of . The continuing passage, called the Aquagalerie, continues narrow and high, sometimes with deep water. Upstream of a waterfall the river passage continues. After the Salle des Burgondes, the gallery becomes broader, and then the passages become high and narrow, often requiring travsersing, to close down at +.[2]
The cave has developed at the Urgonian-Hauterivian contact. The river has dug down into the Hauterivian, and the entrance fossil gallery lies within the Urgonian. The network developed along a northeast-southwest fault.[9]
The fossil gallery was probably formed in the Pliocene in a subtropical climate, 3–4 million years ago. The active system was formed during the glacial episodes of Riss II and Würm.[10]
In 1997, a catchment to supply the village of Presles was considered, but another solution was found.[11]