Roche Franche

South of the Reculet ridge, which reaches 1718 m in altitude, the High-Jura mountain range is cut through by a large depression that opens onto the valley of the Valserine. This type of erosion that affects a mountain’s summit or side is called a “combe”. The mountain’s structure shows a superposition of different limestone and marlstone layers, built up over tens of millions of years during the Jurassic period (-175 Mya to -145 Mya). At the foot of the cliffs, screes and landslides fill the heart of the combe, where erosion is still taking place.