Then,seventy-million years ago, the Earth's surface, or crust,pushed upward.

VOA: special.2010.01.04

And, seawater contains only 3.7% of the total magnesium present 7% in the Earth's crust.

而海水只含有,地表镁总量的,3。

麻省理工公开课 - 固态化学导论课程节选

"It's a horizontal motion of two pieces of the Earth's crust on either side of a vertical crack in the Earth,"

VOA: standard.2010.01.13

Earthquakes generally occur when the tectonic plates that make up the Earth's crust move suddenly.

VOA: standard.2010.01.13