The gorges of Ardèche (Réserve naturelle des Gorges de l’Ardèche) is a protected area spread over 1575 hectares of forest, with a river flowing through its centre, winding with narrow twists and turns among the spectacular calcareous cliffs. The geologic origin of the territory is an ancient tropical sea, which covered all the south of France around 125 million year ago. The alpine orogenesis of the Tertiary Era (60 million years ago) raised calcareous rock deposits and fractured them deeply. It is precisely in these fractures that the erosion of meteoric waters dug out the gorges. There are numerous spectacular karstic phenomena: grottos, fossil meanders and natural arches. Pont d’Arc is the most renowned and visited; it is not reached by our route, but it can be seen from the carriage way D 290 on the south of the Vallon-Pont-d’Arc.