The later is controled by melting degree of the upper mantle rock.

后者直接受上地漫岩熔融程度所制约。

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Because of its proximity to Earth's core, the rock at the base of the mantle is much hotter than rock in the upper mantle.

由于靠近地核，地幔底部的岩石比上地幔岩石的温度高得多。

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When a reservoir is sufficiently large, a sphere of this hot rock forces its way up through the upper mantle to Earth's surface, creating a broad bulge in the topography.

当储层足够大时，这种炽热岩石的一个球体强行通过上地幔上升到地球表面，在地形上形成一个宽阔的隆起。

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The rock is peridotite, which is one of the main rocks in the upper mantle, an area that provides a girth below the Earth's crust.

ECONOMIST: Greenhouse gases