Why does ocenaic crust sink beneath the continental crust at a subduction boundary?

Answer 1

The oceanic crust is denser than the continental crust.

Answer 2

Oceanic crust is denser than continental crust due to its composition of basaltic rock and higher iron content. This density difference causes oceanic crust to sink beneath the lighter continental crust at subduction zones, creating a convergent boundary. The descending oceanic plate creates deep oceanic trenches and can trigger volcanic activity when it melts and rises to the surface.