Question

Altitudinal variation is more in west half of himalayas

Answer 1

The Himalayas were formed due to the collision of the Indian plate with the Eurasian plate generally believed to be 5 crore years ago(50 m.y.a.). But some estimates put the formation at 50 crore, stating that the Himalayas were formed even before the Collison.

But regardless of this, the reason for the Eastern side having higher elevation is the same…

The Indian plate was moving from the South-West to the North-East as shown in the below illustration. This is why the Eastern landmass has raised more than the Western one.