Weathering features within the Argile à Meulières profile. (a) Macromorphological organisation of the Argile à Meulières profiles. The meulières develop from the silicified limestone by dissolution of the residual limestone domains to form the highly porous ‘cellular’ facies. Modified from Thiry (1999). (b) Lower massive meulière with secondary silica coating (vitreous-waxy quartzose lustre) on a fracture through micronodules of silicified limestone parent; Bouchy-St-Genest (Marne). (c) Upper cellular meulière facies showing: (1) primary concretionary silica lining voids of silicified limestone to form (2) thin contoured walls, and (3) porous and powdery infilling of hollows resulting from the dissolution of discontinuously silicified limestone matrix; Brie Plateau, St-Cyr-sur-Morin (Seine-et-Marne).