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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 preliminary reference Earth model (PREM) separates the lower mantle into three sections, the uppermost (660–770 ...
The deep biosphere is the part of the biosphere that resides below the first few meters of the surface. It extends down below 10 kilometers below the continental surface and 21 kilometers below the sea surface, at temperatures that may reach beyond 120 °C (248 °F) [1] which is comparable to the maximum temperature where a metabolically active organism has been found.
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
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]
The cerebral cortex, also known as the cerebral mantle, [1] is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals. It is the largest site of neural integration in the central nervous system , [ 2 ] and plays a key role in attention , perception , awareness , thought , memory , language , and consciousness .
Slabs can either penetrate directly into the lower mantle, or can be retarded due to the phase transition at 660 km depth creating a difference in buoyancy. An increase in retrograde trench migration (slab rollback) (2–4 cm/yr) is a result of flattened slabs at the 660-km discontinuity where the slab does not penetrate into the lower mantle. [38]
The deep water cycle, or geologic water cycle, involves exchange of water with the mantle, with water carried down by subducting oceanic plates and returning through volcanic activity, distinct from the water cycle process that occurs above and on the surface of Earth. [ 1] Some of the water makes it all the way to the lower mantle and may even ...
Earth's mantle is a layer of silicate rock between the crust and the outer core. It has a mass of 4.01 × 10 24 kg (8.84 × 10 24 lb) and makes up 67% of the mass of Earth. [1] It has a thickness of 2,900 kilometers (1,800 mi) [1] making up about 46% of Earth's radius and 84% of Earth's volume. It is predominantly solid but, on geologic time ...