The Grands Causses highlands’ geology
Embedded between the Monts Aubrac and Margeride Mountains to the North, the Lévezoux and Lacaune Mountains to the west and the Cévennes to the west and southeast, the whole Grands Causses area form arid highlands of which altitude varies from 560 to 1247 meters. They are crossed by rivers which have formed impressive canyons which delimit their borders.
These Causses highlands formed in the secondary era, a period during which the region they currently occupy was covered by a vast sea. By withdrawing 70 million years later, the sea left deposits and sediments, limestone and marls, and many shell fossils. In the tertiary era, the limestone table was lifted by the folding of the Alps and the movements of the tectonic plates split the plateau with a large number of faults, at the base of their current height.
Limestone is a very permeable rock that lets water infiltrate. As such, erosion, wind and frost over the millennia that followed continued to eat away the plateaus, sculpting the rocks and resulting in the formation of potholes and caves.
Difficult living conditions prevail here: a mountain climate with harsh winters and a permeable soil which worsens the summer’s drought. But nature, in its harshness, has not forgotten to amaze us: the landscapes are breathtaking, while the hidden treasures buried underground will never cease to reveal their mysteries.
