Question

What happens when layers of rock with different densities collide?​

Answer 1

When plates of differing densities collide, the plate that is more dense goes under the less dense plate. Trenches and volcanic mountains form.

Answer 2

Formation convergent boundaries

A tectonic plate boundary always forms when two continental plates collide. Neither plate subducts because the crust have approximately the same density. Instead, the rocks are smashed together causing them to recrystallize due to the intense heat and pressure from the colliding plates