Earth's lower mantle is made up of mantle-crust that consists of aluminum, silicon, magnesium, calcium, oxygen and iron. These elements in the lower mantle account for 72.9 percent of the entire mass of the Earth's mantle and about 50 percent of the planets entire mass. The lower mantle is directly underneath Earth's upper mantle and stretches from 416.319 to 1809.976 miles below the surface.
Earth's mantle is the thickest part of the planet and consists of very hot and plastic like solid rock. The mantle is divided into the lower and upper mantle, with the upper mantle making up 15.3 percent of the mantle crust mass and 10.3 percent of Earth's total mass.