1. Soils that exist in semiarid environments which have a substantial layer of silica within one meter (39 inches) of the land surface.

The silica occurs either as weakly cemented nodules or as hardpan and accumulates as a result of downward translocation (migration) when solubilized during weathering of the soil.

Durisols are found in the southwestern United States, Chile, South Africa, and especially in Australia, where rainfall is low.

They usually exist in association with Arenosols, Calcisols, Cambisols, Gypsisols, or Vertisols.

Soils in the Aridisol and Vertisol orders of the U.S. Soil Taxonomy that exhibit hardened layers of silica accumulation are closely related to the Durisols.

2. From the classification system of the Food and Agriculture Organization, FAO.
3. Etymology: from Latin durum, "hard".