The continental crust consists of a layer of metamorphic, igneous and sedimentary rock. It contains felsic or granitic rock. The oceanic crust, mainly contains mafic or basaltic rock. This dark colored rock is rich in iron and magnesium. The density of the granitic rock of the continental crust is approximately 2.7 gm/cm3. The oceanic crust on the other hand, has a density of 2.9 g/cm3 which makes it more dense than the continental crust. The oceanic crust is a thinner layer than the continental crust--the oceanic crust is 3.3 miles in contrast to the continental which is 18.6 miles thick. There is evidence to support the fact that the continental crust is much older than the oceanic crust.