How was the northern plains formed?
Northern Plains were formed by the sediments brought in by three major Himalayan rivers (Ganga, Indus and Brahamaputra) and their tributaries. When these rivers flowed through the Himalayas, they eroded rocks, transported and deposited the smaller fragments of rocks in the foothills of the Himalayas. After million of years, the accumulation of sediments led to the formation of the Indian Northern Plains.