Above the core is a layer of silicate rocks.  This mantle is about 1,750 miles (2,800 km) thick.  It makes up about 44 percent of Earth's radius.  Earth's crust is a rocky shell covering the mantle.  It is 5 to 25 miles (8 to 40 km) thick.  The crust makes up less than one percent of Earth's radius.  Surrounding the crust is the oxygen and nitrogen atmosphere.