marl, the crumbly combination of limestone and clay which is often added to soils lacking limestone (see lime). Many of the finest wines of the côte d’or are from grapes grown on predominantly calcareous marl with some limestone. Whitish marl is found naturally to some extent in the vineyards of beaune and pommard. It assumes more importance in meursault, where it forms the best soil for grapes grown for white wines. There is pebbly marl in the jura region of France, and tavel in the southern rhône has soils which are predominantly Cretaceous marl. In the German region of rheinhessen, the soil is partly derived from marl. See entries prefixed soil.