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's crust, which is Earth's outermost layer, is a thin layer. Comprised of two kinds of crusts, continental and oceanic crusts, it is merely 0.473 percent of Earth's mass. The ocean crust's thickness is around 7 km, while the continental crust's thickness is from 10 to 75 km.