Reculée de Baume-les-Messieurs, Limestone valley formation in Jura, France.

The Reculée de Baume-les-Messieurs is a branched valley cut into the limestone plateau of Lons-le-Saunier, in the Jura. Its southern branch runs 9.5 km north, 1.1 km wide and about 200 m deep, and splits into four arms where the Longe Bief, the Dard and the Seille flow; the village sits where three arms meet. The upper rims are vertical Middle Jurassic limestone cliffs, the mid-slopes are softer marl carrying vineyards, and the valley floor lies on Quaternary alluvium.

The valley was carved by erosion along north-south fault lines in the limestone of the Lons-le-Saunier plateau, a slow process of dissolution and glacial passage rather than a sudden collapse. Its two main branches, the northern Ladoye-sur-Seille branch and the southern Baume branch, meet about 4 km from where the valley opens onto the Lédonien fault belt near Voiteur and Domblans. The site has been a protected landscape since a decree of 11 March 1998 covering more than 700 hectares.

The valley's name comes from the Latin balma, meaning cave or shelter, and the village grew around a Benedictine abbey founded in the 9th century. The Seille rises from a resurgence at the foot of the valley's cirques, and the slopes between the cliffs and the valley floor carry vineyards on the Lias marls.

Visiting is best done with sturdy footwear since the walking paths vary in difficulty and ground conditions. Access typically starts from the abbey area, where information about different routes and how long they take is available.

The valley is a site classé by decree of 11 March 1998, covering more than 700 hectares for its picturesque character. Geologists consider it the finest example of a reculée, a blind valley cut into the limestone of the Lons-le-Saunier plateau. Its two main branches meet about 4 km from where the valley opens onto the Lédonien fault belt.