Describe what happens when a plate carrying oceanic crust collides with a plate carrying continental crust.

Subduction occurs and a trench is formed.

Explanation:

When a tectonic plate carrying an oceanic crust collides with a tectonic plate carrying a continental crust then the oceanic plate will slide beneath the continental one, forming a trench. This is possible because the oceanic crust is less dense than the continental crust.

Subduction is a geological phenomenon in which the tectonic plates of one crustal plate descends below the edge of the other. The region where this happens is called a subduction zone.