How were the great plains of Northern India formed?
The Northern plain has been formed by the interplay of the Indus, the Ganga and the Brahmaputra rivers along with their tributaries. The formation of the Himalayan mountains left a depression at the foothills of the Himalayas. In due course of time, this depression gradually got filled with deposition of sediments by the rivers flowing from the lofty mountains and the Peninsular plateau.
The depression got filled with alluvium and a flat land of extensive alluvial deposits resulted in the formation of the Northern plains of India. It spreads over an area of 7 lakh sq km. The plain being about 2400 km long and 240 to 320 km broad is a densely populated area.