The chemical, physical and mineralogical characteristics of five soil profiles developed on volcanic material on the Anatolian plateau of Turkey have been studied. The soils, which are mainly Entisols, have high pH values in the range 7·5 to 8·0, low amounts of organic matter (usually <1·0%), low available water capacities and a low to medium ability to sorb phosphate. The soil parent materials are basalts and tuffs which often contain large proportions of volcanic glass. Weathering of this material in the prevailing semi-arid climate results in the development of a smectite-dominated clay fraction with small amounts of kaolinite. The smectite usually yields anomalously high X-ray spacings, probably due to interstratification and absorption of interlamellar material. The characteristics of the Anatolian soils are in marked contrast to those of Andepts which have formed on similar parent materials in humid, temperate climates.
