What is the Earths Mantle?
The Earth’s mantle is the layer in the structure of the Earth that lies directly under the Earth’s crust and above the Earth’s outer core. The term is also applied to the structure of other planets. Earth’s mantle lies roughly between 30 and 2,900 km below the surface. The boundary between the crust and the mantle is the Mohorovicic discontinuity named for its discoverer, and is usually called the Moho. The Moho is a boundary at which there is a sudden change in the speed of seismic waves. At one time some thought that the Moho was the structure at which the earth’s rigid crust moved relative to the mantle. Current research places this zone of movement within the mantle, from 70 km (43 mi) below the ocean crust to 150 km (93 mi) below the continental crust. The mantle just below the crust is composed of cold and therefore rigid mantle fused to the crust but at the same time separated from it by the Moho. This rigid layer of crust and the upper mantle forms the lithosphere. The mantle d
The Earth’s mantle is a ~2,900 km (1,800 mi) thick shell of compressed and heated rock, beginning below the Earth’s crust (lithosphere), which extends 5 km (3.1 mi) below the ocean floor and 30 to 50 km (19 – 31 mi) below the continents. The Earth’s mantle makes up 70% of Earth’s volume, in comparison to the Earth’s crust which makes up less than 1% of the total. In fact, the crust is just a thin layer of frozen rock shielding the mantle from outer space. The crust and mantle are separated by a transition area called the Mohorovičić discontinuity (the “Moho”) where a certain type of seismic wave quickly speeds up when transiting through. Like the crust, the mantle is largely composed of oxide compounds such as olivine, pyroxenes, spinel, garnet, peridotite, and eclogite. The mantle differs in its chemical ratios from the crust, however. It is composed of roughly 45% oxygen, 23% magnesium, 22% silicon, 6% iron, 2% aluminum, 2% calcium, with trace amounts of sodium, potassium, and other
