Iliac crest pain is not that common in the general population, but it is frequent in older individuals, runners (and athletes in general), lower back pain sufferersâ¦ But that doesn`t mean âregularâ people like you and me can`t experience it from time to time!
The mantle is composed of iron-magnesium silicates, and the crust is composed of roughly 5 percent iron. All together, iron makes up an estimated 35 percent of the Earth's mass. Oxygen. Oxygen, the second most abundant element on Earth, is found mainly in the crust.
The earth has four layers: the crust, mantle, inner core, and outer core. The lithosphere is the crust and the upper part of the mantle. The lithosphere is about 5 to 30 miles deep. The mantle is about 1800 miles thick. The outer core is about 1300 miles thick and the inner core is about 800 miles to the center of the earth. The inner core is a solid layer.