Around 200 million years ago (in Trias) shallow sea covered Europe (and Switzerland) which had tropical climate. On evaporating, the sea left behind deposits of salt and gypsum. Sometime later, when the Alps thrust their way upwards, waves of stone swamped the salt deposits and the numerous layers of marl and limestone that covered them. Under the double effects of high pressure and bending forces that prevailed in the depths of the Earth, this salt became intimately mixed with the surrounding rock. There it lay dormant for millions of years until the water springs arrived to leach it out. The history of the Saltworks and Mines at Bex is linked directly to the important discovery of salt springs in the Canton of Vaud in the XVth century. At that time salt was a rare commodity, difficult to transport. It permitted the mighty of this world to gain immense profit and power. And the Swiss having no salt of their own were therefore dependent on foreign suppliers. History: 1684 – 1823, Excavation The first steps for the recuperation of salt were limited to tapping it at the spring. It then became necessary to proceed by digging deeper in order to reach the water at a lower level by means of stairs. Between 1684 and 1691, an important excavation was carried out: the Coulat Gallery. A main gallery called 'Principale du Coulat' was begun on the left bank of the Gryonne. A tunnel 700 meters long had to be dug in order to reach the 'Cylindre'. In 1725, the project was to dig a gallery leading out of 'Bouillet'. A distance of two kilometers separated the starting point from the famous 'Cylindre'. There also a second attempt was made from a stairwell of 735 steps. In 1836 large deposits of almost pure salt were discovered at Basel; they were much easier to exploit than those at Bex. And in 1865 the 'Vaudois' once again considered closing down the mines which they judged to be unprofitable. 1867 – 1924: Desalination on a large scale The citizens of Bex united to save their industry. Four of them, it vas created the Compagnie des Mines et Salines de Bex, and instituted a new mode of exploitation. They conceived the idea of flooding the existing caverns and galleries. The water which infiltrates everywhere transforms into brine. It then suffices to pump it out. Towards 1877, the wood-burning stoves were abandoned and replaced by a new technique: salination by thermo-compression with the Piccard apparatus. This system, steadily improved with time, is today still in use worldwide. From 1867 - 1913, the two caverns 'Coulat' and 'Bouillet' furnished 164'486 tons of salt. 1924: Drilling The appearance of boring machines will make it possible to save the mines. First used for prospecting only, the drillings will later, around 1960, allow the desalination of saliferous rock by direct injection, a technique still used today. The commercialization of salt was at first handled by the Canton of Vaud. Only in 1997 the latter entrusted this task and the control of the salt monopoly (salt tax) to the Société Vaudoise des Mines and Salines de Bex. more literature: H.Badoux
Questions to answer: only the information on the spot are valid
1. The salt is extracted with the spring water of two glaciers. What are the names of these glaciers?
2. When did the digging at the gallery le Bouillet begin?
3. How much salt is produced in Bex each year?
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Zusammenfassung in Deutsch:
Salzminen von Bex Vor rund 200 Millionen Jahren (in der Trias) bedeckte das Meer Europa (und die Schweiz), das ein tropisches Klima aufwies. Durch die langsame Verdampfung bildeten sich Evaporite von Salz und Gips. Bei der darauffolgenden Faltung der Alpen wurden diese Evaporite teilweise von Kalkstein- und Tonmergelschichten bedeckt und es bildete sich unter dem Effekt von hohem Druck eine Mischung von Fels und Salz. Diese während Millionen von Jahren "schlafenden" Einlagerungen können durch Wasserquellen ausgelaugt werden.
Fragen:
1. Das Salz wird mit dem Schmelzwasser von 2 Gletschern herausgelöst. Wie heissen diese 2 Gletscher?
2. Wann wurde die Galerie Bouillet begonnen?
3. Wie hoch ist die Jahresproduktion von Salz in Bex?
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Résumé en français:
Les Mines de sel Bex Il y a environ 200 millions d'années (Trias) la mer recouvrait l'Europe (et la Suisse) qui avait un climat tropicale. Suite à l'évaporation lente se sont crées des Evaporites de sel et de gypse. Pendant le plissement des Alpes ces Evaporites ont été partiellement couvertes de couches calcaires et de marnes-d'argile et sous l'effet d'une énorme pression un mélange de roches et de sel s'est crée. Ces accumulations ont "dormi" pendant des millions d'années et peuvent être lessivées avec de l'eau de source.
Questions:
1. Le sel est extrait avec l'eau de 2 glaciers. Quels sont les noms des glaciers?
2. A quelle date la construction de la galerie Bouillet a-t'elle commencé?
3. Quelle est la production annuelle des salines de Bex?
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Attention: Groundspeak a changé les règles des Earthcache en juin 2019, et dorénavant une photo est obligatoire sur chacun de mes Earthcache !
https://www.geocaching.com/help/index.php?pg=kb.chapter&id=51&pgid=296