(v) Desert Soils: A large part of the arid region belonging to western Rajasthan, Haryana, and Punjab lying between the Indus river and the Aravalli range is affected by desert and conditions of geologically recent origin. This part is covered with a mantle of the blown sand which, combined with the arid climate, results in poor soil development. The Rajasthan desert is a vast sandy plain including isolated hills or rock outcrops at places. The soil in Rajasthan improves in fertility from west and north-west to east and north-east.