The earth’s mantle is the thick, rocky layer between the earth’s crust and its core. Beneath it is the molten, metal-rich outer core that spins faster than that of the mantle.
- The earth’s mantle occupies about 84% of its mass but only about 20% of its volume. The uppermost section of the mantle—the continental crust—is relatively light because it’s composed largely of silica (SiO2), which has a low density.
- The mantle is about 60 miles thick and made mostly of silicate rock; it takes up 80% of Earth‘s volume; it has no solid outer shell (it does, however, have an inner liquid one); and it’s divided into two sections: the lower part (which includes mantle plumes) which floats on the upper part (the immobile crust).
- Earth‘s Mantle occupies approximately 84% of Earth by mass, but only 20% by volume. The main mineral component of the mantle is silicate rock.
- The outer core carries a current sheet of electrical currents driven by convection in Earth’s outer fluid layer: the upper mantle and lower crust.
- Almost all of Earth’s volcanism occurs at or near boundaries between tectonic plates. These include mid-ocean ridges, subduction zones, hotspots and island arcs. However, some of the most dramatic eruptions occur at more mobile sites such as those associated with the El Centro and Galapagos hotspots.
- Plate tectonics involves the slow, shuffling of the Earth’s crust due to interaction between the outer core, mantle and crust. The plates themselves are made of convection currents that circulate at speeds of up to 1 centimeter per year in the upper mantle and over 50 centimeters per year in the lower mantle.