The Northern Great Plains
The great plains lie between the mountains of the north and the peninsular plateau of the south. It extends over a length of 2400 km. It has a width of 2400 km in Bihar to 500 km in Punjab.
The Great Plains is a flat low lying land made up of Alluvium – the fine silt brought down by the rivers. The plain in the past was a huge depression where the rivers have deposited layers of alluvial sediments. The three big rivers draining this region are Indus, Ganga and Brahmaputra. They collect their water from Himalayan glaciers. The rivers cross the lofty Himalayan range through narrow deep gorges or deep canyons and enter the plains. Geologists consider that these three rivers were older than the Himalayas that as the Himalayas lifted themselves up, the rivers have eroded their valleys. The northern plains are the youngest as they are made up of sediments laid down by the denudation of the Himalayas. The surface relief of Great Plains are classified into four types based on the structure of soil.
- The Bhabar lies all along the foot hills of siwalik. It is a pebble – studded zone of porous beds. It is a narrow belt with 8 to 16 kms.
- The Terai belt is marked by excessive dampness with the growth of thick forest and a variety of wild life.
- The Bhangar is the older alluvium of the plain.
- The Khadar is the new alluvium of the plain. They form a continuous belt of alluvium. These plains may be subdivided into the following basins. i) The Indus basin ii) The Ganga basin iii) The Brahmaputra basin iv) The Ganga – Brahmaputra Delta.