verrucano

Century Dictionary and Cyclopedia

1. n. The name given by Alpine geologists to a conglomerate of more or less imperfectly rounded fragments of white or pale-red quartz, varying in size from that of a grain of sand up to that of an egg, held together by a cement of reddish, greenish, or violet-colored silicious or talcose material. It occurs in numerous localities both north and south of the Alps, and in northern Italy, sometimes in masses of great thickness, which often take on a gneissoid or schistose structure. In certain localities the verrucano overlies a slaty rock which contains plants of Carboniferous age: hence some geologists have considered it as belonging to that formation, while others have regarded it as the equivalent of the Rothliegende, the lower division of the Permian.