Authon (; ) is a commune in the Alpes-de-Haute-Provence department in the Provence-Alpes-Côte d'Azur region of south-eastern France.
The inhabitants of the commune are known as Authoniers or Authonières.
Geography
Authon is located in the northern part of the Digne foothills, some 15 km north-east of Sisteron and 22 km north by north-west of Digne-les-Bains.
Geology
The commune is located on the eastern boundary of the Baronnies Orientales on Provençal limestone formations of the Upper Jurassic and Lower Cretaceous periods (sedimentary rocks from a former Alpine Ocean) between three main geological formations of the Alps:
the Digne Nappe at the level of the Valavoire lobe: there is a thrust sheet or Nappe - i.e. a slab about 5000 m thick which was moved to the south-west during the Oligocene and at the end of the formation of the Alps. The lobes (or scales) correspond to the exposed edges to the west of the Nappe; the Durance fault to the south-west in the valley; the Plateau of Valensole to the south-east: a molassic basin of the Miocene and Pliocene periods composed of detritic sedimentary rocks (deposited from the erosion of the mountains which appeared in the Oligocene).
Topography
The village is located at an altitude of 1,137 metres above sea level in the Massif des Monges. The altitude varies from 881 metres (in the downstream gorges of the Vanson and the narrow valley in the west of the commune) to 2,114 metres at the top of Coste Belle along the Conaples ridge in the east. Mount Jouere is located in the north with the ridge of Clot des Martres being the northern boundary of the commune. The Planchettes ravine lies between this mountain and the Lieuron - the mountain overlooking the village.
In the south, the Col de Font-Belle, towards Le Castellard-Melan, lies between the Melan mountain and the escarpment of Géruen. Beyond this to the east are the Ravine des Barres and then the Col Saint-Antoine.
Relief
The commune consists of mountainous topography belonging to the Massif des Monges. The mountains and their ridges alternate with ravines and mountain passes.
Hydrography
Several rivers flow through the commune. Authon is traversed by the river Vançon which rises at Feissal, in the north of the commune at 1900 m altitude. Several streams flow into the Vançon: the Riou d'Authon, the Ravin de la Bastié, and the Verdachon. There is also an enclosed spring north-west of the village.
Land use
The town has 800 hectares of woods and forests.
Human occupation is dispersed across the commune in tiny hamlets, mostly in the western part: Les Fabres, le Vivier, Briançon, Bonnet, Lèbre, Théous, Champdolent. Feissal (location of the village in a former commune) and Bastide Blanche are located in the east. There is also a jas in this part, at a little over 1,800 metres: the jas Monges.
The Vanson Forest is found in the north, south, and east.
Transport
The A51 autoroute passes to the west more than 10 kilometres from the commune in the Durance valley. It goes north towards Gap and south to Aix-en-Provence. Access to the commune is by road D3 from Sisteron in the west via a tortuous route to the south of the commune and the village then continues south to Barras. Hiking is available on the GR 6 hiking trail which passes through the commune.
The nearest railway station is located in Sisteron and is served by TER (Marseille-Briancon). There is also a bus station in Sisteron.
The Sisteron-Theze Aeredrome is located 15 kilometres north-west of the commune at Vaumeilh.
Natural and technological hazards
None of the 200 communes of the department is in a no seismic risk zone. The canton of Sisteron to which Authon belongs is zone 1b (low risk) according to the deterministic classification of 1991 based on the historical seismicity, and zone 4 (medium risk) according to the probabilistic classification EC8 in 2011. Authon also faces three other natural hazards:
forest fire, flood (the Vanson and tributaries) landslide: the town has an average to high hazard on some slopes.
Authon is not exposed to any risk of technological origin identified by the prefecture.
There is no risk prevention plan for foreseeable natural risks (PPR) nor is one planned for the commune and there is no DICRIM.
Climate
The nearest weather stations to Authon are located at Thoard, Beaujeu, Sisteron, and Turriers.