The great Northern plain extends from west to east, between Himalayas in the north and Great Indian Plateau in the south. The plain extends from the arid and semi-arid areas of Rajasthan in the west to Brahmputra valley in the east.
This plain is made up of the soils brought down and deposited by the rivers flowing from the Himalayas in the North and the Great Indian plateau in the South. The rivers have been depositing their sediments in this plain over millions of years. Therefore, the alluvium in this plain is quite a few hundred metres deep.
The relatively higher part of the plain is called bangar. This area is never covered with flood water of the rivers. Contrary to this, the comparatively lower area is called the khadar. This area is flooded by streams almost every year. Khadar area is know as bet in Punjab.
The great Northern Plain can be divided into four parts:
This region includes the Rajasthan desert and bangar region lying to the west of Aravali ranges. The desert is partly rocky and partly sandy. In the ancient period, the perennial streams - Saraswati and Drishadvati - flowed through this region. This region includes the fertile area of Bikaner.
River Luni flows through this bangar region and falls into the Rann of Kutchchh. The famous salt water lake of Sambhar is situated in this part of the plain.
This plain extends over Punjab, Haryana and Uttar Pradesh. The part of this plain extending into Punjab and Haryana has been formed by the alluvium brought by rivers Satluj, Beas and Ravi. This is a very fertile area. The part of this plain lying in Uttar Pradesh is made up of the deposits laid down, by the rivers like, Ganga, Yamuna, Ramganga, Gomati, Ghagra and Gandak. This part of plain is highly fertile and has been the cradle of Indian civilization and culture.
This part of the great plains covers the middle and the lower Ganga valley lying in the states of Bihar and West Bengal. Ganga flows through the middle of this plain in Bihar. Ghagra, Kosi and Gandak join Ganga from the north while Son joins from south. On entering West Bengal the plain widens further extending from the foot hills of the Himalayas upto the Bay of Bengal.
The southern part of the plain is delta region. Ganga is divided into several distributaries in the delta region. Hooghly is the best example of a distributary of Ganga.
The northeastern part of the Great Indian Plain extends into Assam. This plain has been formed by deposition of alluvium brought down by river Brahmputra and its tributaries.