Gouffre Jean-Bernard or Réseau Jean Bernard, sometimes known simply as Jean Bernard, is the seventh deepest cave in the world, and the third deepest one in Europe. It is in the

Alps The Alps () are some of the highest and most extensive mountain ranges in Europe, stretching approximately across eight Alpine countries (from west to east): Monaco, France, Switzerland, Italy, Liechtenstein, Germany, Austria and Slovenia. ...

Samoëns Samoëns (; Franco-Provençal, Arpitan: ''Samouens'') is an alpine Communes of France, commune on the France–Switzerland border, Swiss border in the Haute-Savoie Departments of France, department in the Auvergne-Rhône-Alpes Regions of France, r ...

France France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...

. The first entrance to the

cave Caves or caverns are natural voids under the Earth's Planetary surface, surface. Caves often form by the weathering of rock and often extend deep underground. Exogene caves are smaller openings that extend a relatively short distance undergrou ...

was found by the French caving group Groupe Vulcain in 1963. More entrances have been found over the years since, and currently at least thirteen are known. The highest entrance, known as C37, is at above

sea level Mean sea level (MSL, often shortened to sea level) is an mean, average surface level of one or more among Earth's coastal Body of water, bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical ...

.. The cave is named after Jean Dupont and Bernard Raffy, two Groupe Vulcain members who died in 1963 in an unrelated expedition in Goule de Foussoubie Cave.

Exploration

The first entrance, known as V4, was discovered in 1963 and exploration in that year took the cave to a depth of . Further explorations in the following year reached the main drain, or master cave, of the system at a depth of . This was further explored downstream in 1965 and 1966, reaching the base of a wet shaft, the Puits des Affreux, at . Explorations in 1968 reached Puits de la Rivière at . A major expedition in 1969, attended by many French cavers, reached a sump at . In the upper part of the Vallon des Chambres, Gouffre B19 at an altitude of , which had been discovered in 1968, was explored down to . In 1975, winter expeditions began. The elevation was exceeded on 4 January and at , the Salle des Crêpes was discovered two days later, marking the end of explorations for that year. The Gouffre B19 was connected to the network on the first of November, giving a system depth of . The

sump Sump may refer to: * An infiltration basin used to manage surface runoff water and recharge underground aquifers * Sump (cave), a permanently flooded section of a cave, where an underground flow of water exits the cave into the earth such that t ...

at was reached on 1 January 1976. In July 1979, exploration of Gouffre B21 at an altitude of allowed the network to become the deepest in the world with a depth of . It remained so until January 1998, when its depth was surpassed by

Gouffre Mirolda Gouffre Mirolda is a karstic cave located in the :fr:Haut-Giffre, Haut-Giffre. mountain range, in the commune of Samoëns, Haute-Savoie, France. It is connected to the Lucien Bouclier cave system, and has a depth of . It is the List of deepest cav ...

. In 1980, 1981, 1982 in February, three sumps were dived increasing the depth to , progress being stopped by a fourth impenetrable sump. In August 1983, Gouffre B22 at was explored and connected to the B21, giving access to the upstream galleries which allowed the system to exceed the difference in height at . At that point, further exploration was blocked by a water-filled passage. More recent explorations have increased the depth to , making it the seventh deepest cave known in the world.

Karst Development

The Gouffre Jean Bernard is located in a synclinal valley (Vallon des Chambres). The various entrances are located on the north-eastern flank of the

syncline In structural geology, a syncline is a fold with younger layers closer to the center of the structure, whereas an anticline is the inverse of a syncline. A synclinorium (plural synclinoriums or synclinoria) is a large syncline with superimposed ...

between and above sea level and are perpendicular to the master cave. The master cave flows close to the

Urgonian Limestone The Urgonian Limestone is a geologic formation in France. It preserves fossils dating back to the Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and f ...

Hauterivian The Hauterivian is, in the geologic timescale, an age in the Early Cretaceous Epoch or a stage in the Lower Cretaceous Series. It spans the time between 132.6 ± 2 Ma and 125.77 (million years ago). The Hauterivian is preceded by the Valangi ...

marl contact in a meander to wide. The resurgence is located at an altitude of in le Clévieux stream. The passages of to in diameter that are found in the upper part of the network are fossil passages developed before the incision of the Giffre valley..

Notes

References

{{Authority control Landforms of Haute-Savoie Jean-Bernard

Exploration

Karst Development

See also

Notes

References