... 0- 40 Crust 40- 400 Upper mantle 400- 650 Transition region 650-2700 Lower mantle 2700-2890 D'' layer 2890-5150 Outer core 5150-6378 Inner core The crust varies considerably in thickness, it is thinner under the oceans, thicker under the continents. ... Taken as a whole, the Earth's chemical composition (by mass) is: . ... U nlike the other terrestrial planets, Earth's crust is divided into several separate solid plates which float around independently on top of the hot mantle below. ... Moon .. ...