Towards 1680, the springs dried up and the first two galleries were dug at the exact time that a new spring was found. For centuries, kilometres of galleries were dug, in the hope of finding a large collection of salt. As the first traces of salty water were found at an altitude of 1000m, miners dug stairs, creating new galleries deeper. The vast
maze of wells, staircases and tunnels today enable air to circulate in the galleries (through a system using a chimney flue).
Later, a large well was dug from the Fondement, the remains of which can still be seen today. The salt rock from the Triassic Period was then discovered which held large quantities of salt. (The Triassic Period: the era in which the oceans evaporated 180 to 220 million years ago). It is the presence of gypsum in the salt that has kept these
quantities of salt intact.
The Bernese who exploited the mines up to around 1780 wanted to stop working the mines, considering it too complicated. The Revolution in 1798 convinced the people of Vaud to continue working the mines. They decided to wash the rock in situ instead of extracting the salt filled rock and washing it outside. Jean de Charpentier then dug a huge hall, into which the salt rock was piled up to the roof. The hall was then hermetically sealed and the rock literally drowned in the desalination room. From this time forth, it was no longer salt rock which came out of the mine but salt water which was recovered at the bottom of the mine.
In 1840, the people of Vaud abandoned the mines because it was considered too complicated to work them. At this point people from the region, subsequently nicknamed “the founders” refused to abandon them and invested their own money to find concessions, absolutely against losing the years of work and abandoning the many existing galleries. They thus continued to “drown” the halls, the water dissolved the salt stuck in the rock, and given the impermeable nature of the rock, the saline water was recuperated and pumped. This method of exploitation was used until about 1920. At this point rock drilling began with the aim of piercing the rock as deep as possible to find a spring. The core sampling on the other hand began in about 1960, when a French oil engineer moved to Bex and experimented with various drilling techniques.