After Casiano de Prado the infill of Madrid Basin consists of: the "diluvium" or quaternary deposits which surface and thickness was overestimated in his work, and "fresh water tertiary deposits". In the tertiary deposits he distinguished three units: A calcareous upper unit (Colmenar Stone), a gyspsiferous middle unit (Gypsum of Colmenar), and a lower unit that consists of sandstones and conglomerates which outcroppinng in NE and W of the basin, concordant with cretaceous deposits. In his work has been described convoluted and disturbed evaporite deposits, as well as dolostones and siliceous rocks and sepiolite