> Burgundy
The karst areas of Burgundy are the plateaux, dating from the middle and upper Jurassic, situated in the north-east of the Massif Central around the Morvan: Nivernais, Maconais, Chatillonais and Auxerrois. Few caves here have been adapted for visitors. .
> The Alps et the Jura
The French Alps are bordered on the west by a series of limestone uplands of the secondary era (Jurassic and Cretaceous) that form the Pre-alps.
From north to south separated by the valleys of the major Alpine rivers are the Bornes, the Bauges, the Chartreuse, the Vercors, the Dévoluy and the southern Pre-alps (of Digne, Castellane, Grasse and Nice). These formations are formed of very hard reef limestone of a form known as Urgonian. Heavily folded and very fractured, they present more or less tabular surfaces divided by broad valleys (Isère, Arve) or deep gorges (Bourne, Verdon).
These heavily karstified limestone formations boast a multitude of gorges and very extensive underground systems. They include some of the deepest caves in the world: Gouffre Berger (-1278m) in the Vercors, Mirola (-1610m) and Jean Bernard (-1602m) in the Bornes. Although exploring these record-breaking caves remains the privilege of the dedicated caver, many caves are suited to visitors, and display the full variety and decorative riches of the underground world.
The Jura is composed of plateaux of Jurassic limestone and cretaceous chalk. The great waves of folded rock, deeply gashed by transverse valleys and canyons, have encouraged the development of many cave systems and major underground rivers.
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