Lower mantle

Region from 660 to 2900 km below Earth's surface

The lower mantle, historically also called the mesosphere, occupies about 56% of the total volume of Earth, and is the region from 660 to 2,890 km (410 to 1,800 mi) below Earth's surface; between the transition zone and the outer core. The preliminary reference Earth model (PREM) separates the lower mantle into three sections, the uppermost (660–770 km (410–480 mi)), mid-lower mantle (770–2,700 km (480–1,680 mi)), and the D layer (2,700–2,890 km (1,680–1,800 mi)). Pressure and temperature in the lower mantle range from 24–127 GPa (3,500,000–18,400,000 psi) and 1,900–2,600 K (1,630–2,330 °C; 2,960–4,220 °F).

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