(a) The oldest landmass of India (i.e. Peninsular part) was a part of Gondwana land, which included India, Australia, South Africa and South America as one single landmass.

(b) Convectional currents split the earth’s crust into a number of fragments, thereby leading to the drifting of the Indo – Australian plate towards the north after being separated from Gondwana land.

(c) The northward drift resulted in the collision of this plate with much larger Eurasian plate.

(d) Due to this collision, the sedimentary rocks which were accumulated in the geosyncline called the Tethys, were folded to form the mountain systems of west Asia and Himalayas.

(e) The Himalayas represent a youthful topography with high peaks, deep valleys and fast-flowing rivers.