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The lower mantle, historically also known as the mesosphere, represents approximately 56% of Earth's total volume, and is the region from 660 to 2900 km below Earth's surface; between the transition zone and the outer core. [1]
The temperature of the mantle increases rapidly in the thermal boundary layers at the top and bottom of the mantle, and increases gradually through the interior of the mantle. [22] Although the higher temperatures far exceed the melting points of the mantle rocks at the surface (about 1,500 K (1,200 °C; 2,200 °F) for representative peridotite ...
The exact upper and lower boundaries of the mesosphere vary with latitude and with season (higher in winter and at the tropics, lower in summer and at the poles), but the lower boundary is usually located at altitudes from 47 to 51 km (29 to 32 mi; 154,000 to 167,000 ft) above sea level, and the upper boundary (the mesopause) is usually from 85 ...
Earth cross-section showing location of upper (3) and lower (5) mantle Earth's temperature vs depth. Dashed curve: layered mantle convection. Solid curve: whole-mantle convection. [9] A superplume generated by cooling processes in the mantle. [11]
Controversy over the exact nature of mantle convection makes the linked evolution of Earth's heat budget and the dynamics and structure of the mantle difficult to unravel. [21] There is evidence that the processes of plate tectonics were not active in the Earth before 3.2 billion years ago, and that early Earth's internal heat loss could have ...
The pressure at the bottom of the mantle is ≈140 GPa (1.4 Matm). [24] The mantle is composed of silicate rocks richer in iron and magnesium than the overlying crust. [25] Although solid, the mantle's extremely hot silicate material can flow over very long timescales. [26] Convection of the mantle propels the motion of the tectonic plates in the
Scientists Find Surprise Hidden in Earth’s Mantle Krit of Studio OMG - Getty Images "Hearst Magazines and Yahoo may earn commission or revenue on some items through these links."
The transition zone is the part of Earth's mantle that is located between the lower and the upper mantle, most strictly between the seismic-discontinuity depths of about 410 to 660 kilometres (250 to 410 mi), but more broadly defined as the zone encompassing those discontinuities, i.e., between about 300 and 850 kilometres (190 and 530 mi) depth. [1]