基础提升考研真题阅读每日一篇(5)(2013.3.11).doc

1、1998 Passage 5 Scattered around the globe are more than 100 small regions of isolated volcanic activity known to geologists as hot spots. Unlike most of the worlds volcanoes, they are not always found at the boundaries of the great drifting plates that make up the earths surface; on the contrary, ma

2、ny 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 n

3、ow 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.

4、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 readily be translated into motion with respect to the earths interior. It is not possible to determine whether both continents are moving in opposite

5、 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 station

6、ary and that it has not moved during the past 30 million years.The significance of hot spots is not confined to their role as a frame of reference. It now appears that they also have an important influence on the geophysical processes that propel the plates across the globe. When a continental plate

7、 come to rest over a hot spot, the material rising from deeper layer creates a broad dome. As the dome grows, it develops deep fissures(cracks): in at least a few cases the continent may break entirely along some of these fissures, so that the hot spot initiates the formation of a new ocean. Thus ju

8、st as earlier theories have explained the mobility of the continents, so hot spots may explain their mutability (inconstancy).67. The author believes that _.A the motion of the plates corresponds to that of the earths interiorB the geological theory about drifting plates has been proved to be trueC

9、the hot spots and the plates move slowly in opposite directionsD the movement of hot spots proves the continents are moving apart68. That Africa and South America were once joined can be deduced from the fact that _.A the two continents are still moving in opposite directionsB they have been found t

10、o share certain geological featuresC the African plates has been stable for 30 million yearsD over 100 hot spots are scattered all around the globe69. The hot-spot theory may prove useful in explaining _.A the structure of the African platesB the revival of dead volcanoesC the mobility of the contin

11、entsD the formation of new oceans70. The passage is mainly about _.A the features of volcanic activitiesB the importance of the theory about drifting platesC the significance of hot spots in geophysical studiesD the process of the formation of volcanoes试题解析：67. B 意为：地质学上的板块漂移说证明是正确的。第二段第一句指出，对于板块漂移说

12、目前已不存异议(beyond dispute)。例如，非洲和南美洲正在漂离，新物质不断注入二者之间的海底裂痕。A意为：板块的移动与地球内部的移动是相对应的。第一段指出，地球有100多个地质学家称之为热点的互不相邻的(isolated)火山活跃区。与地球上多数火山不同的是：它们并非都处在构成地球表面的巨大漂游板块的连接处，相反，它们多深埋在板块之下(lie deep in the interior of a plate)。这些热点移动缓慢，有时，当板块从它们上面移动过去时，就会留下死火山痕迹(trails of dead volcanoes)。热点及其火山痕迹标志着板块漂移而过。可见，二者的移动

13、并没有相应处。C意为：热点和板块缓慢作反方向移动。根据第一段，二者的移动并没有相应处。参阅上文题解。D意为；热点的移动证明：大陆板块正在漂离。根据第一段最后一句，热点及其火山痕迹证明板块是移动的。68. B 意为：它们有某些共同的地质特征。第二段指出，对于板块漂移说目前已不存异议。例如，非洲和南美洲正在漂离，新物质不断注入二者之间的海底裂痕；虽然有大洋（大西洋）相隔，二者的海岸线（形状）是互补的(complementary)，共有某些地质特征，说明它们曾经是联在一起的。A意为：这两个大陆还在向相反方向移动。根据第二段最后一句，通过对热点区域的研究发现，非洲板块似乎是静止的(stationary

14、)，至少3000万年未移动了。C意为：非洲板块至少3000万年未移动了。这也许是事实，但不是非洲和南美洲曾经是一个板块的证据。D意为：地球有100多个热点。这也许是事实，但这也不是非洲和南美洲曾经是一个板块的证据。69. D 意为：新的海洋的形成。最后一段指出，热点说的意义不限于提供了一个参照点，它看来对推动板块移动的地质物理学过程也提供了解释。当板块处于热点之上时，底层物质会将板块顶起，形成(develop)巨大的弧线(a broad dome)，弧线变高时，板块出现深深的裂痕。当有些地方裂痕迸裂后，就形成新的海洋。A意为：非洲板块的结构。B意为；死火山的复活。C意为：大陆板块的移动性。热点

15、只能说明板块是移动的，但板块为什么是漂移的，本文却并没有解释。70. C 意为：地质物理学中热点说的意义。本文提到了这种学说的几方面的意义。见上文题解。A意为：火山活动的特点。B意为：板块漂移说的重要性。D意为：火山的形成过程。全文翻译：地球上散落分布着100多个互不相连的小火山活动区，被地质学家称为热点。和世界上大多数火山不同的是，它们并不总是在构成地球表面的巨大漂流板块之间的边界上出现；相反，许多热点处于板块较深的内部。大多数热点移动非常缓慢，有时，板块滑过这些热点便留下了死火山的痕迹。热点及其火山痕迹是板块移动的标志。板块漂移这一理论现在是毋庸置疑的。例如，以非洲和南美洲为例，由于有新的物质注入二者之间的海底，两大洲距离越来越远。但互相吻合的海岸线和某些似乎跨越海洋的地质特征会使人想到这两个大陆曾经是连在一起的。携带这些大陆的板块的相对运动已经能够被详细地阐述出来，但一个板块相对另一板块的运动还不能轻易地解释为它们相对于地球内部的运动。人们不能确定两个大陆是在朝相反的方向运动，还是一个大陆停止不动而另一个从它身边漂移开去。位于地球更深层的热点提供了解决该问题的测量仪器。从热点地区的人口情况分析来看，非洲板块似乎是固定的，在过去3000万年