Fig. 12

a Location map of the Rocher des Hirondelles Formation at the Rocher des Hirondelles type-sections (Ain, France) and field-photographies. b General view of the Fort de l’Écluse limestone cliff. c Boundary between the Cul du Nozon Bed (GDO Fm) and the “Oolithe caviar” (Fort de l’Écluse Member) showing a progressive transition from marls to oolitic carbonates, northern exit of the Rocher des Hirondelles tunnel. d View of the Fort de l’Écluse Member at the type section with the 3 carbonated sedimentary units with from bottom to top, the “Oolithe caviar”, the coral-rich unit, and the main limestone mass. e Focus on the bored and bioencrusted discontinuity surface D.Ba1 between the “Oolithe caviar”, the coral-rich unit. f Thin section in the oolitic grainstone of the “Oolithe caviar” representing hydraulic-dune environments. g Boundary between the main mass (Fort de l’Écluse Member) and the Rivière Member separated by the bored et bioencrusted discontinuity surface D.Ba3 at the southern exit of the Rocher des Hirondelles tunnel. h Thin section in the Orbitolina-rich, micritic, open-sea, limestone of the Rivière Member. i View of the orange limestone of the Poet Bed below the southern exit of the Rocher des Hirondelles tunnel