A hiker strolls through a group of large rocks of various shapes forming the chaos of Nîmes-le-Vieux on the Causse Méjean.Hiking in the chaos of Nîmes-le-vieux
©Hiking in the chaos of Nîmes-le-vieux|Rémi Flament

Geology of the Grands Causses

Discover the history, arid plains and exceptional landscapes of the Grands Causses through its geology!

All about

the geology of the Grands Causses

Sandwiched between the Monts d’Aubrac and the Margeride to the north, the Monts du Lévezoux and Lacaune to the west and the Cévennes to the west and southeast, the Grands Causses form arid high plateaus with altitudes ranging from 560 to 1247 meters. They are criss-crossed by rivers that have formed impressive gorges delimiting their borders.

The Causses were formed during the Secondary Era, when the area they now occupy was covered by a vast sea. When the sea retreated 70 million years later, it left behind deposits and sediments, limestone and marl, and numerous shell fossils. In the Tertiary era, the limestone table was lifted by the folding of the Alps, and tectonic plate movements split the plateau with a large number of faults, forming the basis of their present-day relief.

Rock types of the Grands Causses

Limestone is a highly permeable rock that allows water to seep through. So erosion, wind and frost over the millennia have continued to eat away at the plateaus, sculpting the rocks and leading to the formation of sinkholes and caves.

Living conditions

Difficult living conditions prevail here: a mountain climate with harsh winters and permeable soil that exacerbates the summer drought. But nature, in all its harshness, has not forgotten to amaze us: the landscapes here are breathtaking, while the hidden treasures buried underground will never cease to unveil their mysteries.

How to visit

the caves

des Grands Causses?

Would you like to discover the hidden treasures of Lozère? There are two possibilities:

  • Caves: Aven Armand, Grotte de Dargilan and Abîme de Bramabiau.
  • Caving: accompanied by a guide, you can explore the underground world like a real explorer!

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