East-West Extent 2,400 km (3,200 km if the Indus plains are included) Average width:150-300km
1.Largest alluvial tract of the world, extending from the mouth of Indus to the mouth of Ganga between Peninsular plateau and the northern are of the mountains.
2. Alluvial in nature, and are composed of Bhangar (old alluvium), Khadar (new alluvium) in river bed. Bhabar (porous gravel ridden plains at the foot of Himalaya) and Terai (damp thickly forest area, where bhabar stream reappears)
SUBDIVISION OF GREAT PLAINS
THE RAJASTHAN PLAIN
Extent:650km long. Average width:250-300 km wide Thar or Great Indian Desert is the westernmost region of Great Indian Plains in the western Rajasthan. A semi arid plain, lying to the east of Thar desert is known as Rajasthan Bagar. The Luni is the only southwest flowing rivers of this region. The Sambhar(largest), the Kuchaman, and the Didwana are important lakes situated to the north of Luni Basin.
THE PUNJAB HARYANA PLAINS:
Extent:640km in northwest to southeast and 300km in east west direction. Extends from Punjab in the west to Yamuna River(Haryana)in the east. Land of five rivers-is primary made up of ‘doabs’-the land between two rivers. They are composed by Bet(Khadar plains)and Dhaya(Heavily gullied bluffs).
THE GANGA PLAINS:
The largest Great Plain stretching from Delhi to Calcutta across the states of Uttar Pradesh, Bihar and West Bengal. The Ganga and its tributaries like Yamuna, Ghagra,Gomti, Kosi, and Son deposit large amount of alluvium and make this extensive plain more fertile. They comprise of Gango-Yamuna Doab in the west, to the east of this Doab are the Rohilkhand plains which merges which merges with Avadh plain in the east
THE BRAHMAPUTRA PLAIN
The low level plain formed by the Brahmaputra river system is situated between Eastern Himalaya (Arunachal Pradesh) in the North, Patkai and Naga hills in the east, Garo-Khasi-Haintia and Mikir Hills and lower Ganga Plain and Indo Bangladesh border in the west.