In soil classification, an Umbrisol is a soil with a dark topsoil and in which organic matter has accumulated within the mineral surface soil—in most cases with low base saturation—to the extent that it significantly affects the behaviour and utilization of the soil. Umbrisols are the counterpart of comparable soils with a high base saturation (Chernozems, Kastanozems and Phaeozems). Umbrisols develop in weathering material of siliceous rock. They are found in mostly cool humid climates in mountainous regions with little or no moisture deficit, including tropical and subtropical mountains.