A. Moho barrier The Moho is the boundary between the crust and the mantle in the earth.
B. Oceanic crust
is the uppermost layer of the oceanic portion of a tectonic plate. The crust overlies the solidified and uppermost layer of the mantle. The crust and the solid mantle layer together constitute oceanic
Lower mantle
A large fraction of Earth's interior, from a depth of about 650 km (400 miles) down to 2,900 km (1,800 miles), consists of the lower mantle, which is composed chiefly of magnesium- and iron-bearing silicates, including the high-pressure equivalents of olivine and pyroxene.
upper mantle
The upper mantle begins just beneath the crust and ends at the lower mantle.
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