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a desert and semidesert plain in India and Pakistan, situated along the left bank of the Indus River. The Thar extends from north to south for 850 km and has an area of approximately 300,000 sq km. It is composed of sands of alluvial, marine, or eolian origin overlying ancient sandstones that emerge on the surface in some places. Overgrown sand ridges and parabolic and oar-shaped dunes predominate, and barchans are also encountered. Human activities were responsible, in part, for the further growth of the desert. The climate is tropical, and annual precipitation, most of which falls during the summer monsoon season, varies from 90 mm in the west to 200 mm in the east. Dust storms are frequent.
Small lakes, salt marshes, and takyrs are found in the depressions between sand ridges. There is abundant subterranean water, which is saline in some areas. The sparse vegetation consists of psammophilic shrubs (Leptadenia pirotechnica, Capparis, Calligonum) and occasional acacias and coarse grasses. There is grazing of livestock, and irrigation agriculture is practiced in the oases and in the Indus valley.