The Park’s territory boasts several unique natural sites, which are mostly due to the geographical distinctiveness of its various sectors. Among them are the Tarn and Jonte gorges; the caves (Aven Armand, Dargilan and Bramabiau); the felsenmeer or block fields, such as Nîmes-le-Vieux and Païolive Wood; and Les Bondons with its characteristic puechs (hills).
Towards the end of the Palaeozoic era, the Causses were covered by water. The sea withdrew at the end of the Jurassic. This phenomenon, combined with the raising of the Pyrenees and Alps, caused immense geological faults to appear, which then were deepened further by the various waterways: Tarn, Jonte, Doubie and Lot. Swallow holes, caves and gorges formed. The exceptional Jonte and Tarn gorges are symbolic of these landscapes.
Since the end of the 19th century, three exceptional underground spaces discovered by Edouard-Alfred Martel, the father of French cave exploration, have been counted among the country’s great natural sites. With his second-in-command, Louis Armand, he made it possible to open these spaces to the public as early as the 1890s.
The superb landscape dominating the cham (small causse) of Les Bondons contains two natural eccentricities: the Eschino d’aze (donkey’s spine) ridge and the puechs of Les Bondons, two conical buttes of black marl.
The felsenmeer (block field) of Nîmes-le-Vieux is a ruiniform site located in the north-eastern part of the Causse Méjean, in the central zone of the Cévennes National Park. It was given its name in 1908 by its discoverer Paul Arnal, pastor of Vébron, by analogy with the felsenmeer of Montpellier-le-Vieux, a similar site discovered 25 years earlier by Edouard-Alfred Martel.
Païolive wood is an astonishing forest of petrified rock and white oak that extends over 16 kilometres of Park land near Les Vans (Ardèche).