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 The lithosphere is the outermost mechanical layer and is the most rigid layer of the Earth. 2  The lithosphere consists of the crust, and some of the uppermost mantle. 3  The lithosphere averages about 100 km thick. The crust: low density silicate rock, 5-70 km thick. 2  There are two distinct types of crust. 3  Continental crust is variable in thickness and composition. 4  Thickness ranges from 5-70 km.