The crust is the outermost concentric layer of the earth. It has an average thickness of thirty kilometers and is the thin, rocky veneer that constitutes the continents and the floors of the oceans.

• 地壳是地球的同心圆圈层的最外面一个圈层，它的平均厚度有30公里左右，薄薄的岩石圈层构成了大陆和洋底。