Topography
The Park’s topography is not at all homogeneous. The terrain rises in tiers from 200 to 1,700 metres in height. Three main natural regions can be distinguished:
The High Cévennes are organised around massifs with an altitude above 1,250 metres: Mont Lozère and Bougès in the North-East, Aigoual and Lingas in the South-West.
The Cévenol Valleys, where narrow ridges alternate with steep-sided valleys, are situated at 200 to 1,000 metres.
The Causses, a vast limestone plateau ranging from 750 to 1,250 metres in height, are cut through by deep gorges.
Geo-morphology
A fundamental trait of the Cévenol terrain is the all-important role of the geological substrate.
The schist of the Cevenol Valleys only offers limited resistance to waterways, making for narrow and deep valleys.
The granite massifs of the High Cévennes display rounded forms, almost exempt from Quaternary erosion. The contact slopes between granite and schist are always steep.
The limestone of the Causses forms the largest karstic massif in Europe. Waterways have cut impressive gorges (Jonte, Tarn) and systems of swallow holes and resurgences (Bramabiau) into it.
Hydrography and climate
There are two water systems: the Mediterranean and the Atlantic. Of almost equal importance, the two systems are separated by a watershed that runs South-West to North-East through the Park’s highest summits.
The topography of the Cévennes, their proximity to the Mediterranean and the continental influence of the Massif Central make for substantial spatial variations in the Cévenol climate. This climate is dominated by heterogeneous average rainfall, with very irregular precipitation and brutal temperature variations.