Montagne du Laveron

The Montagne du Laveron is a ridge in the Jura , in the French Doubs department , southwest of the city of Pontarlier . It extends over a length of approximately 12 km and is oriented towards the southwest-northeast according to the general fold structure of the Jura in this region. At 1112 m, the highest point in the west of the ridge is reached. Otherwise the ridge reaches an average height of about 1000 m above sea level.

From a structural geological point of view, the Montagne du Laveron forms an anticline of the Jura with a width of around 2.5 km in the north-east and up to 4 km in the south-west . It is bounded in the south by the syncline of the Doubstal and Malpas, in the north by the syncline of the Bassin du Drugeon and thus by the high plateau of Arlier, which averages 820 m. The northeast boundary of the ridge forms a transform fault that can be traced from Montricher to Pontarlier. The valley is traversed by the Doubs and separates the Montagne du Laveron from the Montagne du Larmont . In the southwest, the Montagne du Laveron is separated from the Haute Joux chain by the Klustal des Drugeon. The competent rock layers on the surface of the Montagne du Laveron originate mainly from limestone sediments from the Upper Jurassic ( Malm ). Cretaceous sediments also emerge on the southern limb of the anticline .

At the level of the Montagne du Laveron there are extensive forests and only a few smaller clearing islands, including that of Les Granges Dessus, a hamlet belonging to the municipality of Granges-Narboz . The numerous sinkholes and drainless hollows are typical of karstified areas. At the foot and on the slopes of the ridge there are various springs, especially the karst spring that feeds Lac de l'Entonnoir (also Lac de Bouverans).

Coordinates: 46 ° 51 '  N , 6 ° 15'  E