A Durisol in the FAO World Reference Base for Soil Resources is a very shallow to moderately deep, free-draining soil of arid and semi-arid environments, that contain cemented secondary silica (SiO2) in the upper metre of soil. Durisols are internationally known as "hardpan soils" (Australia) or "dorbank" (South Africa) or they represent the "duripan phase" of other soils, e.g. of Calcisols (FAO).
Durisols are developed mainly in alluvial and colluvial deposits of all texture classes. They are found on level and slightly sloping alluvial plains, terraces and gently sloping piedmont plains in arid, semi-arid and Mediterranean regions.
Extensive areas of Durisols occur in Australia, in South Africa, Namibia and in the USA (notably in Nevada, California and Arizona); minor occurrences have been reported from Central and South America and from Kuwait. Durisols are a new introduction in international soil classification and have not often been mapped as such. A precise indication of their extent is not (yet) available.