The Devès is bordered to the west by the upperAllier valley and theMargeride mountains, to the north by theLivradois mountains, to the northeast by theMeygal massif, and to the east by the upperLoire valley and theVivarais mountains.[2]
The Devès massif, which is more of a high plateau, is one of the three volcanic massifs ofVelay, the other two being theMézenc massif and the Meygal.
It is the largest basalt plateau in the Massif Central. The firsteruptions are dated to 6 million years ago, but most of the volcanic activity occurred between 3.5 and 0.6 million years ago, with two peaks at 1 and 2 million years ago.[3]
The surface of the plateau is covered withscoria cones ofStrombolian origin.[4] Some of these cones still retain their craters, similar to somemaar craters, which aredepressions occupied by spontaneous vegetation adapted to wet environments. The most emblematic of the plateau areLac du Bouchet, the narces of La Sauvetat,[5] and the Limagne marsh.[6] The others are called "gardes." There are about 150 of them, forming either a chain of small forest-covered hills along a north–south axis or appearing as features in the middle of fields. Most have been cultivated at their base, leaving a forest cover (pines) at their summit or rocky outcrops.[7]
The climate is cold but relatively dry; theMounts of Cantal andMargeride provide a sheltered position leading to reduced precipitation (about 850 mm/year on average). In winter, snow remains on the ground for several months, and the forests and pastures are swept by the "burle," the local name for theblizzard.[8][9]
The Devès massif is characterized by a balanced landscape of grassland and cultivated systems.[10] Its forest cover rate of 22% is lower than the average for the Massif Central due to the clearing of ancient forests over the past 150 years. The area has the highest number of plant species in the department, with particularly rich flora and the presence of rare plants such asNeslia paniculata subsp.thracica,Camelina microcarpa, andRanunculus lingua, which are critically endangered in Auvergne.[11]
