你观察过烧开的稀饭吗?米粒从底部翻滚上来,又迅速向四周扩散,并在接近锅边处沉下。这是典型的对流运动的形式。我们脚下广阔大地的板块漂移运动在本质上正是源于厚达两三千千米的地幔的对流运动。把米粒米汤分别类比成地壳地幔,尽管对流运动的实质相同,但在表观上至少存在三大差异:首先,在空间上,两者的规模是不可同日 Have you observed the boiled porridge? The rice rolls up from the bottom, spreads quickly to the periphery, and sinks near the edge of the pan. This is the typical form of convection. The wandering motion of the vast expanse of earth beneath our feet is, in essence, the result of convective movements in the mantle up to two or three kilometers thick. Analogy of the rice grain rice soup to the crust and mantle, respectively, has the same three major differences in appearance although there are essentially the same convective movements: first, in space, the scale of the two is not the same day