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Solid rock layer between the crust and the core.
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2,885 km thick, the mantle is 82% of Earth’s volume.
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Mantle composition = ultramafic rock called peridotite.
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Below ~100-150 km, the rock is hot enough to flow.
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It convects: hot mantle rises, cold mantle sinks.
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Three subdivisions: upper, transitional, and lower.