Earth's mantle is a layer of silicate rock between the crust and the outer core.
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16 Facts About Earth's mantle
2.
Earth's mantle is divided into two major rheological layers: the rigid lithosphere comprising the uppermost mantle, and the more ductile asthenosphere, separated by the lithosphere-asthenosphere boundary.
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3.
Earth's mantle is divided into three major layers defined by sudden changes in seismic velocity:.
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4.
Top of the Earth's mantle is defined by a sudden increase in seismic velocity, which was first noted by Andrija Mohorovicic in 1909; this boundary is referred to as the Mohorovicic discontinuity or "Moho".
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5.
Upper Earth's mantle is dominantly peridotite, composed primarily of variable proportions of the minerals olivine, clinopyroxene, orthopyroxene, and an aluminous phase.
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6.
Gradually through the upper Earth's mantle, pyroxenes become less stable and transform into majoritic garnet.
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7.
Lower Earth's mantle is composed primarily of bridgmanite and ferropericlase, with minor amounts of calcium perovskite, calcium-ferrite structured oxide, and stishovite.
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8.
Chemical composition of the Earth's mantle is difficult to determine with a high degree of certainty because it is largely inaccessible.
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9.
Rare exposures of Earth's mantle rocks occur in ophiolites, where sections of oceanic lithosphere have been obducted onto a continent.
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10.
The enormous lithostatic pressure exerted on the Earth's mantle prevents melting, because the temperature at which melting begins increases with pressure.
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11.
The volcanism often attributed to deep Earth's mantle plumes is alternatively explained by passive extension of the crust, permitting magma to leak to the surface: the plate hypothesis.
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12.
Convection of the Earth's mantle is a chaotic process, which is thought to be an integral part of the motion of plates.
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13.
The movements of the lithosphere and the underlying Earth's mantle are coupled since descending lithosphere is an essential component of convection in the Earth's mantle.
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14.
The Earth's mantle is considered to be viscous and incapable of brittle faulting.
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15.
Exploration of the Earth's mantle is generally conducted at the seabed rather than on land because of the relative thinness of the oceanic crust as compared to the significantly thicker continental crust.
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16.
On 5 March 2007, a team of scientists on board the RRS James Cook embarked on a voyage to an area of the Atlantic seafloor where the Earth's mantle lies exposed without any crust covering, midway between the Cape Verde Islands and the Caribbean Sea.
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