The explanation may be in Earth's mantle, the layer of rock underlying the tectonic plates and extending down over 1,800 miles to the outer edge of Earth's iron core.
解释可能是在地球的地幔中，这是在构造板块下面的岩石层，向下延伸超过1800英里到地球铁芯的外边缘。
2
There one plate dives under the edge of another and is reincorporated into the mantle.