(i) The internal heat of the earth makes the molten rocks to rush towards the surface of the earth and drive the crust into large fragments known as “Tectonic Plates”. These plates are drifting oven the mantle of the earth. As a result when the two or more plates are pushed towards each other they are called ‘Converging Plates’. On the other hand if they are moving away from each other, they are called ‘Diverging Plates’.
(ii) According to the age of the soils of the Northern Plain they have been differentiated by two names: (a) Bhangar and (b) Khadar. The difference between these two are mentioned below:
(a) Bhangar - These are the older alluvium or old soil and form the largest part of the Northern Plains. They lie above the flood plains of the rivers and present a terrace like structure. It often contains Kankar nodules made of calcareous deposits.
(b) Khadar - The newer and younger deposits of the flood plains are known as ‘Khadar’. So, these are the new alluvium or new soil and are very fertile. Thus, Khadar is ideal for intensive agriculture.
