Its due to the continental plate is lighter than the oceanic plate the pale get subducted due to the slab push and slab pull effects. The continental plate further reaching the depth burns due to the pressure and intense temperature also this causing the melting of the rocks and leading to the formation of volcanoes and mountain chains of all sizes.
Mountain forms and is composed of lava and basaltic matter from below. The collision of the plate leads to the formation of faults along the boundaries this led to the formation of the many large mountains on earth.
The Himalayas are thereby known as the young fold mountains.
