As we've discussed, Earth's crust is made up of large plates that rest on a mantle of molten rock.

正如我们讨论过的，地壳由位于熔融岩石的地幔上的大型板块构成。

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Reservoirs of this hot rock collect in the base of the mantle.

这些热岩石的储层聚集在地幔的底部。

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The descending rock is substantially cooler than the surrounding mantle and hence is less ductile and much more liable to fracture.

下降的岩石比周围的地幔的温度低很多，因此延展性较小，更容易断裂。

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Unlike any other asteroid known today, Vesta has an iron core surrounded by layers of mantle rock and crust, similar to Earth and Mars, preliminary gravity and density measurements suggest.

WSJ: Asteroid Vesta Gets a Close Study

When the ocean plates sink deep enough, portions are melted by the intense heat generated within the mantle, turning the solid rock into molten magma.

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The origin of this effect may lie at the boundary between the mantle, made up of viscous rock that extends 2, 900 km (1, 800 miles) below the crust, and the outer core, which is thought to be liquid iron with the consistency of water.

BBC: Earth's wobbles reveal deep secrets