热点 的意义不只局限于它们所起的参照作用,现在看来,它们好像还对推动板块在地球表面漂移这一地球物理过程产生重要影响。当大陆板块漂移到热点上方并停留时,从地层深处涌出的物质使板块凸出,形成一个大的圆丘。圆丘不断增大,并且出现许多裂纹,至少有若干次,大陆板块沿其中的一些裂纹完全断开,因此.热点引发了新海洋的形成。正如早期理论解释了大陆的移动性,热点理论可以解释它们的可变性(非稳定性)。
测试题
1.We can learn from che first paragraph that_____________.
A. there are no volcanic activities on hoc spots
B. most hoc spots are located in the inner part of a plate
C. hot spots usually lie. at che boundaries of drifting plates;
D. the passage of plates through hot spots will leave dead volcanoes
2.The author believes that_____________.
A) the motion of the plates corresponds to thar of the earths interior
B) the geological theory about drifting plates has been proved to be true
C) the hot spots and the plates move slowly in opposite directions
D) the movement of hot spots proves the continents are moving apart
3.That Africa and South America were once joined can be deduced from the fact that_________.
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