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.
1 Crust-thin outer layer; makes up less than 1% of earth's mass. 2  Mantle-middle layer; composes approximately 64% of earth's mass. 3  Core-dense inner layer. 4  Lithosphere-composed of crust and upper mantle; divided into tectonic plates. Crust-thin outer layer; makes up less than 1% of earth's mass. 2  Mantle-middle layer; composes approximately 64% of earth's mass. 3  Core-dense inner layer. 4  Lithosphere-composed of crust and upper mantle; divided into tectonic plates.