Question

why are mountains formed on the continental crust during convergent movement?

Answer 1

the plates are of broadly equal density, unlike a continental-oceanic convergence, so i suspect that it is the pressure of the magma underneath that forces upwards motion. that's just a thought though, not the researched answer....

Answer 2

Earth's rigid lithosphere floats like a raft on the hot, ductile asthenosphere. Tectonic plates made up of rigid lithosphere are pushed laterally by circulating convection currents acting on the asthenosphere. Just what causes convection currents is not completely understood, but their circular movements are believed to be caused by earth's internal heat engine.