2. 职称英语
  3. 地球上散落分散着一百多个互不相连且面积不大的火山活动区，被地质学家称为热区。与大多数火山不同的是，它们都不位于形成地球表面的巨大漂移板块的连接处，许多反

地球上散落分散着一百多个互不相连且面积不大的火山活动区，被地质学家称为热区。与大多数火山不同的是，它们都不位于形成地球表面的巨大漂移板块的连接处，许多反

游客2024-01-02  23
问题     地球上散落分散着一百多个互不相连且面积不大的火山活动区，被地质学家称为热区。与大多数火山不同的是，它们都不位于形成地球表面的巨大漂移板块的连接处，许多反倒藏于板块的深处。大多数热区移动极其缓慢，有时，板块滑过这些热区，便留下死火山的痕迹。热区及其火山痕迹是板块移动的标志。
    板块漂移现在已是无可争辩的了。以非洲和南美洲为例，由于有新物质嵌入洋底，两个大陆距离越来越远。虽然远隔大洋，但相互吻合的海岸线和好像跨越过海的地质特征，会使人想到这两个大陆曾是连成一片的。带着两个大陆漂移的板块做相对运动，这已得到详细说明，但不能把一个板块相对于另一板块的运动简单地解释为板块与地球内部之间的运动。人们还不能确定两个大陆是否在朝相反的方向运动，也不能确定是否是一个大陆原地不动，另一个大陆正在离它而去。位于地壳深处的热区提供了解决这一问题的测量仪。从热区的人口情况分析来看，似乎非洲板块是固定的，三千万年过去了也没有移动。
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答案     Scattered around the globe are more than 100 small regions of isolated volcanic activity known to geologists as hot spots. Unlike most of the world’ s volcanoes, they are not always found at the boundaries of the great drifting plates that make up the earth’ s surface. On the contrary, many of them lie deep in the interior of a plate. Most of the hot spots move only slowly, and in some cases the movement of the plates past them has left trails of dead volcanoes. The hot spots and their volcanic trails are milestones that mark the passage of the plates.
    That the plates are moving is not beyond dispute. Africa and South America, for example, are moving away from each other as new material is injected into the sea floor between them. The complementary coastlines and certain geological features that seem to span the ocean are reminders of where the two continents were once joined. The relative motion of the plates carrying these continents has been constructed in detail, but the motion of one plate with respect to another cannot readi-lybe translated into motion with respect to the earth’ s interior. It is not possible to determine whether both continents are moving in opposite directions or whether one continent is stationary and the other is drifting away from it. Hot spots, anchored in the deeper layers of the earth, provide the measuring instruments needed to resolve the question. From an analysis of the hot spot population it appears that the African plate is stationary and that it has not moved during the past 30 million years.
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