Location map. A: the solid black line indicates the cliff line bordering the south Vercors plateau; dashed black line, main roads; B: heavy black lines, location of the transects T1 to T3 studied; dashed light blue lines, southernmost occurrence of coral-rudistid facies atop of calcarenite units (a, for Bi5; b for Bi6-1 units); T1, western Archiane transect; T2, eastern Archiane transect; T3, Montagnette-Combau transect.