1. The Plains of Rajasthan

They lie to the west of the Aravallis and include the Marusthali and the Bagar of Rajasthan. The Rajasthan plains cover a total area of about 175,000 sq km. This plain has a general slope from north-east to south-west. In the lower reaches of the Luni river (Gujarat), this plain is only 20 metres above sea level. A substantial part of this plain has been formed by the recession of the sea as is evidenced by the presence of saltwater lakes (Sambhar, Degana, Didwana Kuchaman, Lunkaransar-Tai, and Pachpadra). The Sambhar Lake occupying an area of about 300 sq km during the rainy season lies about 65 km to the north- west of Jaipur city.

During the Permo-carboniferous Period, the greater part of the Rajasthan Plain was under the sea. It has several dry beds of rivers, like Saraswati and Drisdavati which indicate that the area earlier was fertile. At present, Luni is the only flowing river which reaches the Arabian Sea through the marshes of the Rann of Kachchh. Its water is sweet in the upper reaches but turns brackish in the lower parts. North of the Luni, there is a large area of inland drainage.

At present, the greater part of the Rajasthan Plains are a desert covered with longitudinal and transverse sand-dunes and barchans (Barkhans). A large number of playa lakes occur in the basins. In the south-western parts of the Rajasthan plain, there are the alluvial tracts known as Rohi (fertile plains). In the north-eastern part they consist of dry beds of the Ghaggar known as the Ghaggar Plains.