• Aridisols: mineral soils that have an aridic moisture regime. They are the
soils that prevail in desert regions.
• Entisols: mineral soils with no distinctive horizons within 1 m of the soil
surface. They are found on alluvial deposits as well as in sandy and rocky
deserts.
While the Aridisols usually have a topsoil (A-horizon) consisting partly of
crusts of carbonates and of soluble salts and clay, the Entisols are raw mineral
soils with weakly developed profiles, since they were either formed by young
accumulations or have already been capped. Often they are strongly saline,
as, for example, in the northern parts of the Nile delta and in the Qattara
Depression.