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。

youdao

I walked along the outer edge of the track.

我沿着跑道的外缘走。

《牛津词典》

That seems at the outer edge of restrictive, even by the standards of overcontrolling parents.

即使以控制欲过强的父母的标准来衡量，这似乎也有点过分。

youdao

Nash's drive from the outer edge of the right circle was deflected in front by Gaborik, who put the puck back in on Reimer.

WSJ: Gaborik rallies Rangers past Maple Leafs 5-2

Its event horizon, the outer edge inside which not even light can escape from the black hole's gravitational pull, would be only about 7.5 million kilometres.

BBC: By BBC News Online Science Editor Dr David Whitehouse

Goldman has to stay out ahead of its rivals in trying daring and innovative approaches that push the outer edge of the boundary between what is okay and what may not be.

FORBES: Magazine Article