explain the formation of the present Himalayas and the northern plains
Answers
Explanation:
The plains were formed in the Pleistocene and Holocene during the Quaternary era and are the most recent geological unit of India. The upheaval of Himalayas created a marine depression between the mountains and the Indian peninsula. This marine depression or trough was filled with detrital material. The deposition of alluvium from the Himalayas commenced after the final phase of the Siwaliks and has continued till now. These plains rest upon the older Tertiary sediments of the Himalayan Piedmont.
The plains were formed by layers of different sediments of different sizes in successive deposits.
These successive stages are following:
The Bhabhar belt: This belt has been formed by the boulders and pebbles brought by the energetic action of rivers. It lies at the foothills of the Siwaliks. In this belt mostly the streams floor below the ground because of the high permeability provide by the pebbles and coarse particles.
The Terai belt: It lies next to the Bhabhar. In this belt smaller sized particles are deposited. Here the streams re-emerge onto the surface making the region very moist and marshy.
The Bhangar belt: It has been formed during the middle Pleistocene by the older alluvium brought by the rivers and is very fertile. It is called as the older alluvial belt.
The Khadar belt: It is formed by the newer or fresh deposits and is called younger alluvial belt. It is the renewed belt and lire along the present river channels because it is characterised by the occurrence of fresh deposits