Subduction zones form when an oceanic plate collides with another oceanic plate or continental plate. The continental crust is lighter and less dense than oceanic crust. Continental crust's density is approximately 2.7 grams per cubic centimeter. Oceanic crust is thinner and the average density is about 3.3 cubic centimeters. When the two crustal plates converge the oceanic plate always bends and subducts beneath a continental plate. Consider this image of a typical subduction zone. Where would you expect intrusive igneous rocks to form?