2) Earth's inner core is made up of IRON.
3) The earth's crust is thickest when it is below the continent. It is about 25 miles thick below the continents.
4) Earth's mantle has 3 layers. Mesosphere, Asthenosphere, and Lithosphere.
5) Tectonic plates make up Earth's outer shell and are made of crust and uppermost part of the mantle.