The oceanic crust is composed of dark igneous rocks called __________; whereas the upper continental crust has an average composition of a __________ rock.
The reason why the continental crust differs from the oceanic crust is much different in its compositions. The continental crust is thin and less dense , is made of sedimentary and metamorphic rocks than the oceanic crust and is made of lighter elements. The tectonic plates move the composition to the rocks.
