Structure and composition of the Earth's mantle
The Earth's mantle is found in the crust and core. It is the thickest layer, extending from about 33 km deep (about 8 km in the oceans) to 2900 km, where the earth's core would begin. It makes up 84% of the planet's volume.
- Upper mantle: It begins at the Mohorovičić discontinuity (the one that separates the crust and the mantle), and reaches a depth of 670 km. The upper part of the mantle, together with the crust, forms the lithosphere.
- Lower mantle: It begins at a depth of 670 km and ends at a depth of 2,900 km, at the Gutenberg discontinuity, which separates the mantle from the earth's core.
The terrestrial mantle is a geologically active layer, since the convection movements are produced by which hot materials rise from its lower part (Level D") until reaching the earth's surface, causing the displacement of the tectonic plates (and the continents), which leads to the appearance of earthquakes and volcanoes, mountain ranges, etc. In the same way, the cold materials of the lithosphere descend towards the interior.