Saint-Léonard underground lake

Lac Souterrain in Saint- Léonard

The Lac souterrain de Saint- Léonard ( German: underground lake of St Leonard ) is this 6,000 m2 area of ​​the lake is the largest natural underground lake in Europe. The entrance to the cave is located at the foot of the vineyards in the parish of St. Leonard, between Sion and Sierre in the canton of Valais, Switzerland. The cave is visited by an average of 100,000 visitors per year.

With an area of ​​6,200 m2, the Subterranean Lake in Lower Austria Hinterbrühl is slightly larger. This, however, was artificially created by mining gypsum mining.

History

The cave was known to the inhabitants of St. Leonard for a long time. For the first time the cave in 1943, explored by the Swiss cave explorer Jean -Jacques Pittard, who was accompanied by Jacques Della Santa.

With the discovery of the cave, the water level was higher than today by a few meters and reached up almost to the ceiling. On 25 January 1946, an earthquake occurred at Sierre with the thickness of 5.5-6 on the Richter scale. The earthquake changed the hydrological conditions of the cave and its surroundings, resulting in the lowering of the lake level.

Already in 1949 the cave was open by two locals to visitors. Since then, boat trips on the lake.

In 2000, sparked a two -ton boulder from the ceiling and crashed on a visitor boat. As the safety of the visitors was no longer guaranteed, the cave was closed by the authorities. In extensive renovation work, the cave ceiling was secured by the introduction of several thousands of large and small rock anchors. The renovation work cost about CHF 2.5 million. 2003, the cave for visitors could be reopened.

Structure of the cave

The length of the lake is 300 m, at the widest part of the lake is 29 m wide. It covers an area of 6,000 m2. The water temperature is a constant 11 degrees. At the end of the navigable cave the further way is blocked by fallen boulders down for the most part. Behind them are other small rooms, all of which are above the water level in the dry rock. This 1956 discovered caves are not accessible to visitors.

The rock of the cave consists of gypsum, slate and marble. The cave, was created in due to the penetrating water dissolution of gypsum masses. The residue of the dissolution process consists of ferruginous clay, which seals the lake bottom. The clay prevents the rapid percolation of water through the column.

Animal finds

Bats are the only large animals that occur naturally in the cave. Only trout, which were settled by the operators of shipping and are fed regularly, live in the lake.