Bayons


Bayons 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 Bayonnais or Bayonnaises.

Geography

Bayons is located in the Massif des Monges some 20 km south by south-east of Gap and 15 km north-east of Sisteron. Access to the commune is by the D1 road from Clamensane in the west which passes through the commune and the village before continuing north to Turriers.
Bayons is situated in a vast Cirque surrounded by high mountains, through which the Sasse flows - exiting through a narrow clue. The commune was formed from the merger of four communes in 1973: Astoin, Bayons, Esparron-la-Bâtie and Reynier. Except for Astoin, the communes joined to Bayons in 1973 are located in parallel valleys perpendicular to the Sasse and downstream from Bayons. The commune is located in a region of mountainous relief and has a Mediterranean climate with challenging features as well as a mountain climate. It is traversed by some tumultuous rivers. Agriculture in the area has always been difficult. The population of the four communes peaked in 1836 with 1625 inhabitants but a century and a half later, 90% of this population had been lost due to the rural exodus that began early and had more breadth in these four communes than in the rest of the department. This persuaded the government to propose the merger of the communes which took place on 1 April 1973. Since then the population has almost doubled: farms have been retained sometimes using regional quality labels. The communal economy is based on tourism but the majority of people in the commune work outside.

Geology

The commune is located in the middle of three major geological Alpine formations:
  • the Nappe of Digne to the east at the tip of the Valavoire lobe: there is a thrust sheet - i.e. a slab nearly 5000 m thick which was displaced towards the south-west during the Oligocene at the end of the formation of the Alps. The lobes correspond to the ragged edge 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 from the Miocene and Pliocene composed of detritic sedimentary rocks.
During the last two major glaciations: the Riss glaciation and the Würm glaciation, there were many small glaciers in the commune. A glacier occupied the northern slope of the Tête des Monges. During the Riss glaciation, a diffluence from the Durance glacier crossed the Col des Sagnes and went down to the Sasse valley. The Würm glaciation was less extensive and only reached Les Tourniquets. It was during this glacial period that the Triassic gypsum and moraines were created that make the terrain unstable in this part of the valley. Another Riss glaciation diffluence reached the top of the Trente Pas torrent but this did not recur during the Würm glaciation.

Relief

The relief of the commune is mountainous, low, but very compartmentalized making communication difficult. It has partly been shaped by glaciers. The main structural element is the Sasse valley, which drains several basins separated by Water gaps.
The southernmost of these basins is the former commune of Reynier, semi-circular in shape with the diameter towards the north-east. This diameter is a ridge of mountains rising between 1200 m and 1700 m separating the Reynier basin from the Esparron-la-Bâtie valley. From north to south:
  • the Pategue ;
  • the Charène Ridge;
  • Colle Ridge;
  • the Citadelle ;
  • the Pinée ridge ;
  • the Maladrech Ridge to the south-east.
Several mountains then define a wide semicircle. On the north side they slope gently and form green mountain meadows. On the south and west side they form a line of steeper slopes. From east to west and from south to north they are:
  • the Raus Ridge ;
  • the Serrière des Cabanes;
  • the Clot des Martres Ridge;
  • the Dormeilleuse Ridge which rises to the Croix Saint-Jean when it connects to Jouère mountain;
  • the Jouère mountain whose peak extends towards the Reynier mountain. This mountain forms a basin to the north, along the Sasse. In the middle of this basin is Le Puy : another mountain with a ridge in the south and an inclined slope to the north.
North of Reynier basin, the Bayons gorge provides access to the upper valley of the Sasse and the Bayons basin. This basin is bounded on the north by a small massif dominated by Pointe d'Eyrolle and Grande Gautière which opens to several valleys in the east and south:
  • to the north is the valley where Astoin is located and which communicates with the Turriers basin through a gorge - the Col des Sagnes - and Les Tourniquets;
  • Trente Pas and Sasse valleys are to the north-east limited by the summits of Terre Grosse, Tête de Charbonnier, Tête Grosse, and Chanau.
Facing Bayons, is l'Oratoire summit.Tête Grosse
Finally, wedged between the Bayons basin and that of Reynier, is the long valley of Esparron-la-Bâtie Sasse closed off from the Sasse by the Rochers de la Lause. The ridges north of this valley are led to the top of l'Oratoire and are marked by the Rocher de l'Aigle and the Rocher du Midi. This valley widens and is closed to the east by the Summit of Clot Ginoux , the summit of Laupie , and the summit of Les Monges.

Hydrography

The commune is traversed by the Sasse, a tributary of the Durance, which is formed from many streams and has many tributaries draining the adjacent valleys. On the right bank the Sasse receives:
  • the stream from the Trente Pas ravine;
  • the Eau Amère stream which becomes the Clastre when traversing Les Tourniquets;
  • the Mardaric, which passes at the foot of Bayons;
  • the Rouinon, whose confluence with the Sasse is between Forest-Lacour and Bédoin.
The left bank tributaries of the Sasse are:
  • the Chabert, a stream 5.5 km long flowing through the Bayons basin;
  • the Riou de Pont, which drains the Esparron-la-Bâtie valley and, when crossing the Rochers de la Lause, forms a waterfall and becomes the Ruisseau des Tines, a stream 10 km long;
  • the Reynier, a stream 9.1 km long.
In the upper part of the Esparron-la-Bâtie valley is a small lake, Lake Esparron at 1544m, to the east of the Maladrech ridge.

Environment

The town has 5500 hectares of woods and forests or 44% of its area.
Chamois are endemic in the Massif of Monges but had nearly disappeared from the area in the 1970s as victims of intensive hunting. The National Forests Office has created a game reserve in the Haute Combe which includes the reserves of Monges, Hautes-Graves-Ruinon, and Montsérieux. Since the 1980s the species is still hunted but with quotas.
The Mouflon had been exterminated and its presence is due to its reintroduction in early 1990. Two population nuclei are in the commune: in the hunting reserve of the Hautes-Graves-Ruinon and in the Massif des Monges. Roe Deer had also disappeared since the beginning of the 19th century together with its natural environment the forest. It has returned to the commune from a core reintroduced into the Vançon valley in the 1970s. The presence of the Alpine marmot is also mainly due to reintroductions. The otter, which was once present, has disappeared but has not been reintroduced.

Natural and technological risks

None of the 200 communes in the department is in a no seismic risk zone. Bayons is in area 1b according to the deterministic classification of 1991 and based on its seismic history and in zone 4 according to the probabilistic classification EC8 of 2011. Bayons also faces four other natural hazards:
  • Avalanche
  • Forest fire
  • Flood
  • Landslide
Bayons is not exposed to any risk of technological origin identified by the prefecture.
There is no plan for prevention of foreseeable natural risks for the commune and there is no DICRIM.
The commune has been the subject of orders for natural disasters in 1994 for floods, landslides and mudslides. The worst flooding occurred in 1492 when rains caused the formation of debris flows that destroyed several hamlets and part of the village. This monstrous flood has remained in the annals of the commune. See the History section for details.

Localities and hamlets

In addition to the village, the town includes several hamlets:
  • Astoin ;
  • Haute Combe;
  • Basse Combe;
  • La Rouchaye;
  • Esparron-la-Bâtie ;
  • Le Pont;
  • Baudinard;
  • Le Gayne;
  • Le Sapie;
  • Le Forest-Lacour;
  • Reynier.

    Pictures of roads and bridges in the commune

History

Prehistory and Ancient times

Although Homo heidelbergensis probably inhabited the Monges massif several hundreds of thousands of years ago there is no evidence that they specifically occupied the area of Bayons. The Vitrolles site, 30 km to the west, shows that 11,000 years ago the area was frequented by hunters and gatherers who came in summer then went away to the south.
Most of the Durance valleys and the Massif des Monges experienced the Neolithic Revolution when Mesolithic societies disappeared and were replaced by Cardium pottery and then by the Chasséen culture. The Lithic core found at Thèze was an example of the technical progress in the era: stone tools are no longer cut by impact but by pressure applied on the chosen part.
A treasure of Massaliatic obols dating from the Gallic period was discovered in the commune in 1850. The romanization of Bayons in the following centuries is manifested by constructions at altitude.

Middle Ages

Astoin

The castrum of Astoin was near the mule track connecting Bayons to Turriers.
The Counts of Provence were lords of Astoin during the 14th and 15th century through the Ayroles and Ancelle families. During the crisis caused by the death of Queen Joanna I of Naples, Raoux Ancelle, Lord of Astoin, fought with Charles, Duke of Durazzo, against Louis I of Anjou. The rallying of Sisteron to the Angevin cause in November 1385 brought about his change of commitment and he paid homage to Louis from 30 November 1385.
Astoin had 28 fires in 1315 but only 6 in 1471. It was at that time that the old site, located on a hill 500 m from the current site and named Vière, was abandoned in favour of the current site. By 1765 there were 264 inhabitants.