If this were not the case,the Earth would be covered by a single spherical plate,and no relative plate motion could occur. 如果不是这种情况，地球就会被一个单独的球状板块所覆盖，并且不会有相对的板块运动发生。
Geologists describe the motion of the plates and the consequences of such motion as plate tectonics. 地质学家把板块运动及这种运动所造成的后果看作是板块构造运动。
