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North-facing slopes above sea level in the Judean Desert are covered with a nearly continuous carpet of the meadow grass Poa eigii. The grass functions as a trap for aeolian dust and protects the soil from erosion. The microbiotic crust, composed of mosses, liverworts, lichens, cyanobacteria and fungi, which occur among the tufts of Poa eigii, also contributes to trapping and protection. The presence of allochtonous quartz and clays throughout the 60-cm deep soil profile suggests an aeolian origin of the soil. Stones > 2 mm in diameter contribute to only 13-33% of the soil weight. South-facing slopes have a thinner soil mantle, with 67-92% stones, quartz and clays occurring only at the surface layers and are devoid of the meadow grass. Microbiotic crust composed mainly of cyanobacteria protects the crust from erosion and assists trapping of aeolian material in this layer. (C) 1997 Academic Press Limited