kaolisol

kaolisol, soil that is formed under the heat and heavy rainfall of the tropics, which leaches out the silica and the bases. Thus, the soil is silica-poor; highly weathered, sometimes to a depth of many metres and therefore poor in weatherable minerals; rich in iron, which is released by weathering, is not bound to the clay, and forms concretions that are often large and abundant; and very permeable, because the clay minerals formed do not...