calcareous rocks come in many forms, including marl, chalk, limestone, marble, and dolomite. (see geology). The presence of calcium minerals in soils increases friability and drainage, especially where such calcareous soils underlie clay. See soil texture and soil and wine quality. In northerly European wine regions such as Burgundy and Champagne, the drainage encouraged by calcium in the soils accounts for some of their suitability for premium viticulture.