desert crust[¦dez·ərt ¦krəst]
a dense, surface soil and ground formation consisting of loose material, such as coarse gravel, sandstone, and loam, cemented by calcium carbonate, gypsum, or silica. A distinction is thus made between calcareous, gypsum, and silica desert crusts.
The thickness of desert crusts ranges from several dozen centimeters to several meters. Desert crust is formed in arid regions as a result of the rise of salts from groundwater, the washing in of salts during soil formation, and the wind transfer of salts. Crusts, as dense formations, were formed either on the surface of soil-ground layers or at deeper levels that emerged on the surface as a result of erosion processes. Some desert crusts were formed in regions now occupied by deserts at a time when the region had a moister steppe climate.