Understanding the Structure of the Earth


Lower Mantle

The lower mantle has a solid state, and it boosts a temperature of 3,000°C, and its composition includes aluminum, silicon, oxygen, magnesium and iron.

The lower mantle is present between 670 km and 2,890km beneath the surface of the Earth, and it comprises of solid rock. However, the rock is sufficiently heated to make it melt, but remains solid due to the pressure exerted to keep it down.

Upper Mantle

The upper mantle layer is present 670 km beneath the surface of the Earth and it boosts a temperature of 1,400°C – 3,000°C. This layer is a composition of aluminum, magnesium, silicon oxygen and iron.

While the lower part of the upper mantle comprises of both, melted rock in liquid form and solid rocks, the upper part is rocky and much stiffer since it has a cooler temperature.


The crust is the thinnest layer that covers the surface of the Earth, and it boosts a temperature of around 22°C. Land is made up of continental crust, which comprises of granite, sedimentary rocks and metamorphic rocks, and is 6k to 70km thick.

The Earth's Crust
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Image Credit: National Geographic

The layer that resides underneath the ocean bed comprises of the oceanic crust, which is made up of iron, silicon, oxygen, aluminum, magnesium, and largely, a rock known as basalt, and it is nearly 8km thick.