The cave Sous-les-Sangles develops in compact limestones of Kimmeridgian ages in the Hôpitaux cluse in the side of Bas-Bugey. Its present morphology, essentially due to flowing water, is influenced however by collapse features. The principal passage is a pressure pipe following the bedding plane. In this gallery, morainic deposits containing alpin clasts are overlain by varved deposits 5-6 m thick; these deposits are unique at present in the Ain, by their volume.La grotte Sous-les-Sangles se développe dans les calcaires compacts à grains fins du Kimméridgien dans la cluse des Hôpitaux, côté Bas-Bugey. Sa morphologie actuelle, essentiellement due à l'eau courante, est cependant influencée par endroits par des effondrements de plafond. La gal...