Extent. This great plain extends in between the Himalayas and the Peninsular plateau. It is 3200 km long and 150 to 300 km wide. Its average height is 150 metres. It covers an area of 7.5 lakh sq. km.

Formation. It is an alluvium filled trough. It has been formed by the deposition of sediments brought from the Himalayas by the Ganga, Satluj and other rivers.

Main Characteristics :

• It is a dead flat lowland. Its maximum height above sea level is 263 metres.
• It has a gentle gradient.
• It has a huge depth of alluvium.
• A large number of rivers flow in this plain dividing it into Doabs.
• It has fertile alluvial soils namely Khadar and Bangar soils.

Division of Northern Plain :

1. Bhabar and Terai. It is a long, narrow zone along the foothills. It is a pebble-studded zone. Swampy areas occur in Terai.
2. Punjab Plain. This plain has a slope in the South-West direction. It has been formed by the deposition of sediments by Ravi, Beas and Sutlej rivers. Chos (seasonal streams) cause soil erosion in foothills of Shivaliks.
3. Ganga Plain. This plain has been formed by the deposition of sediments brought by the Ganga and its tributaries. It can be divided into three regions: upper Ganga plain, middle Ganga plain and the lower Ganga plain. It occupies an area of about 3.5 lakh sq. km. Sunder Ban Delta is formed in the lower Ganga plain.
4. Brahmaputra Plains. These plains are situated in the Eastern part and are often known as Assam valley. The Brahmaputra river forms a large delta in Bangladesh.

The Great Indian Desert plain of the west. This covers the western part of the Aravali mountains. This region has a sandy land, so it is also known as the Thar desert. This region gets very little rainfall, due to which the agriculture is not developed here. There are many saltwater lakes like the Sambhar, Didwana and Panchpadra, from which salt is extracted.

The formation of Northern Plain.
The northern plain lies in between the Himalayas and the peninsular India. It has been formed by the filling of the depression formed by Tethys sea. The Himalayan rivers after eroding the Himalayas deposited huge amount of silt and deposition in the ever shrinking Tethys sea. This depression has been filled gradually to form northern plain or the Indo-Gangetic plain. The Himalayan rivers have deposited silt to form Ganges delta in Bangladesh. Due to continuous deposition, the delta is still advancing towards sea.