Montagne d'Albion

The Albion Plateau is a high plain located across the French departments of Vaucluse, Drôme, and Alpes-de-Haute-Provence. It is administratively divided into seven municipalities: Sault and Aurel (Vaucluse), Ferrassières (Drôme), Revest-du-Bion and Simiane-la-Rotonde (Alpes-de-Haute-Provence), and Saint-Trinit and Saint-Christol (Vaucluse). From 1971 to 1996, the Albion Plateau served as the launch base for the French nuclear deterrent force’s ground-to-ground ballistic missiles, with military installations extending into the municipality of Lagarde-d’Apt. In Antiquity, the plateau was inhabited by the Albienses, a people belonging to the Albici federation. In Classical Provençal, it is referred to as Plan d’Aubion, and in Mistralian-norm Provençal as Plan d’Aubioun. Access to the Albion Plateau is via several mountain passes: Col des Abeilles, between Sault and Villes-sur-Auzon, Col de l’Homme Mort, to the north, toward Drôme, Col du Négron, toward Drôme and the Méouge Valley. During the Jurassic period, more than 1,000 meters of alternating layers of limestone, marl, and clay were deposited. The plateau rests on a limestone substratum of Urgonian facies (Cretaceous). This formation features a karstic landscape with limestone pavements, calcarenite, and dolines. It is associated with Aptian sedimentary layers and Barremian calcareous sandstones, overlain by siliceous colluvium, alluvium, and Quaternary decalcification clays. The limestone plateau, characterized by numerous sinkholes, forms a large aquifer extending from the Lure Mountain to Mont Ventoux. Its underground rivers supply the Fontaine de Vaucluse. More than 200 sinkholes or shafts have been identified, often with narrow and difficult-to-access openings. The deepest include the Jean Nouveau shaft, with a 168-meter vertical drop, and the Autran shaft, both exceeding 600 meters in depth. The Souffleur system (Aven des Neiges–Aubert–Trou Souffleur) in Saint-Christol connects to the Albion River at 620 meters, with explorations reaching water-filled chambers at a depth of 921 meters.

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