Continental and Oceanic Crusts
		q Some liothspheric plates are composed primarily of oceanic crustal material, whereas others are composed primarily of continental materials. q The continents stand, on average, about 4.5 km above the floor of the ocean basins. q Continental crust is relatively light (density 2.7 g/cm3), whereas oceanic crust is relatively heavy (density close to 3.2 g/cm3).