英语阅读理解100篇(中级篇)-35
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Passage Thirty-five (Exploration on the Origin of Continents)

   The origin of continental1 nuclei2 has long been a puzzle. Theories advanced so far have generally failed to explain the first step in continent growth, or have been subject to serious objections. It is the purpose of this article to examine the possible role of the impact of large meteorites4 or asteroids6 in the production of continental nuclei. Unfortunately, the geological evolution of the Earth’s surface has had an obliterating7 effect on the original composition and structure of the continents to such an extent that further terrestrial investigations8 have small chance of arriving at an unambiguous answer to the question of continental origin. Paradoxically, clues to the origin and early history of the surface features of the Earth may be found on the Moon and planets, rather than on the Earth, because some of these bodies appear to have had a much less active geological history. As a result, relatively9 primitive10 surface features are preserved for study and analysis. In the case of both the Moon and Mars, it is generally concluded from the appearance of their heavily cratered12 surfaces that they have been subjected to bombardment by large meteoroids during their geological history. Likewise, it would appear a reasonable hypothesis that the Earth has also been subjected to meteoroid bombardment in the past, and that very large bodies struck the Earth early in its geological history.

   The large crater11 on the Moon listed by Baldwin has a diameter of 285 km. However, if we accept the hypotheses of formation of some of the mare13 basins by impact, the maximum lunar impact crater diameter is probably as large as 650km. Based on a lunar analogy, one might expect several impact craters14 of at least 500km diameter to have been formed on Earth. By applying Baldwin’s equation, the depth of such a crater should be about 20km. Baldwin admits that his equation gives excessive depths for large craters so that the actual depth should be somewhat smaller. Based on the measured depth of smaller lunar crater. Baldwin’s equation gives the depth of the zone of brecciation for such a crater as about 75km. The plasticity of the Earth’s mantle15 at the depth makes it impossible to speak of “bracciation” in the usual sense. However, local stresses may be temporarily sustained at that depth, as shown by the existence of deep-focus earthquakes. Thus, short-term effects might be expected to a depth of more than 50km in the mantle.

Even without knowing the precise effects, there is little doubt that the formation of a 500-km crater would be a major geological event. Numerous authors have considered the geological implications of such an event. Donn et al. have, for example, called on the impact of continent-size bodies of sialic composition to from the original continents. Two major difficulties inherent in this concept are the lack of any known sialic meteorites, and the high probability that the energy of impact would result in a wide dissemination16 of sialic material, rather than its concentration at the point of impact.

Gilvarry, on the other hand, called on meteoroid impact to explain the production of ocean basins. The major difficulties with this model are that the morphology of most of the ocean basins is not consistent with impact, and that the origin and growth of continents is not adequately explained.

We agree with Donn at al. that the impact of large meteorites or asteroids may have caused continent formation, but would rather think in terms of the localized addition of energy to the system, rather than in terms of the addition of actual sialic material.

 

1.        A mare basin is

[A]. a formula for determining the relationship between the depth and width of craters.

[B]. a valley that is filled in when a spatial17 body has impact with the moon or the earth.

[C]. a planetoid (small planet) created when a meteorite3, upon striking the moon, breaks off a part of the moon.

[D]. a dark spot on the moon, once supposed to be a sea, now a plain.

2.        The writer does not believe that

[A]. an asteroid5 is larger than a meteorite.

[B]. material from space, upon hitting the earth, was eventually distributed.

[C]. the earth, at one time, had craters.

[D]. ocean were formerly18 craters.

3.        The article is primarily concerned with

[A]. the origin of continents.

[B]. the relationship between astral phenomena19 and the moon.

[C]. differences of opinion among authoritative20 geologists21.

[D]. the relationship between asteroids and meteorites.

4.        Sialic material refers to

[A]. the broken rock resulting from the impact of a meteorite against the earth.

[B]. material that exists on planets other than the earth.

[C]. a composite of rock typical of continental areas of the earth.

[D. material that is man-made to simulate materials that existed far back in geological history.

 

Vocabulary

1.       meteorit                          陨石,陨星

2.       asteroid                         (火星和木星轨道间)小行星

3.       obliterate                         除去,消减……痕迹

4.       crater                            火山口,陨石坑

5.       mare                            海,(也指月亮,火星上的)阴暗区

6.       impact                           撞击

7.       impact crater                      陨石坑,撞击火山

8.       brecciate                         合成角砾岩

         the zone of brecciation         角砾岩地带

9.       mantle                           地幔

10.    stress                            应力

        local  stress                 局部(本身)应力

11.    sialic                           硅铝的

12.    probability                        概率,可能性

13.    disseminate                       传播,分散,浸染

14.    morphology                       组织,结构,形态(学)

15.    astral                            星(星状体)的

 

难句译注

1.       Unfortunately, the geological evolution of the Earth’s surface has had an obliterating effect on the original composition and structure of the continents to such an extent that further terrestrial investigations have small chance of arriving at an unambiguous answer to the question of continental origin.

[结构简析] 句中用suchthat 句型。

[参考译文] 遗憾的是,地球表面的地质变化对大陆原始结构和组成起了抹煞的作用。这种消除作用达到了这种程度,使进一步的大陆的研究工作很难对大陆起源问题去得明确的答案。

2.       In the case of both the Moon and Mars. It is generally concluded from the appearance of their heavily cratered surfaces that they have been subjected to bombardment by large meteoroids during their geological history.

[结构简析] in the case of 就……说,至于……,论到。

[参考译文] 拿月亮和火星来说,一般都从它们表面严重的陨石坑得出结论:它们在其地质进化过程中遭到过巨大的陨星的撞击。

3.       Two major difficulties inherent in this concept are the lack of any known sialic meteorites, and the high probability that the energy of impact would result in a wide dissemination of sialic material, rather than its concentration at the point of impact.

[结构简析] that clause high probability 的说明同位语。

[参考译文] 这一概念本身固有的两大难点是缺乏任何已知的硅铝陨石和下列现象的高概率:即撞击的能量会导致硅铝材料广泛分散,而不是集中于撞击点上。

 

写作方法与文章大意

   文章一开始就说明了此文论述“大陆核生成过程中大的陨星的撞击作用。”由于地球表面地质进化抹去了大陆原始结构和组成的痕迹,只好由月亮和火星作为研究对象来说明地球。从三方面来论述:一是鲍德温的方程式,深度和宽度;二是硅铝组成;三是海洋盆地。最后结论。

 

答案祥解

1.        D. 是月球上的一个黑点,一度认识是海,现在知道是平原。Mare basin海盆地。词义本身说明D项对。另一方面,第二段开始提及“鲍德温所列出的月球上最大的陨石坑直径为285公里。可是,如果我们接受了某些由于撞击而形成海盆地的结构假设,那么月球上最大陨石坑的直径可能有650公里大。”这里都说mare basin指的是月球上陨石坑。这就排除了A,B,C三个选项。

A. 是测定陨石坑深度和宽度的公式。       B. 当某一天体或地球撞击时填入的深谷。       C. 当陨星撞击月亮时,撞掉的部分月亮而形成小星体。

2.        D. 海洋是原来的陨石坑。倒数第二段“另一方面,Gilvarry 用陨星撞击来解释海洋盆地的形成。这一模式的最大困难在于大多数海洋盆地结构和撞击情况不符。”

A. 小行星大于陨星。          B. 来自太空的材料,在撞击地球时,均匀分布。        C. 地球一度有过陨石坑。这三项明显不对, 谈不上相信不相信。

3.        A. 大陆起源。这在文章一开始就点明“大陆核起源长期以来一直是个谜。进展到现在的理论一般都不能说明大陆生长的第一步情况,或者遭到严厉的反对。这篇文章的目的就是要研究大陨星或小行星的撞击在地球核生成中可能起的作用。”另见难句译注1

B. 星际现象和月球的关系。       C. 权威地质学家意见分歧。       D. 小行星和陨星之间的关系。

4.        C. 地球大陆地区特有的岩石构成。第三段第三句:“举例说,Donn et al.提出大陆区域大小的,硅铝结构的天体撞击形成最初的大陆块的设想。”其它见难句译注3

A. 由于陨星撞击地球形成破碎的岩石。        B. 存在于地球之外其它星球的材料。        C. 人造材料模拟存在于遥远地质史上的材料。三项文内都没有提到。



点击收听单词发音收听单词发音  

1 continental Zazyk     
adj.大陆的,大陆性的,欧洲大陆的
参考例句:
  • A continental climate is different from an insular one.大陆性气候不同于岛屿气候。
  • The most ancient parts of the continental crust are 4000 million years old.大陆地壳最古老的部分有40亿年历史。
2 nuclei tHCxF     
n.核
参考例句:
  • To free electrons, something has to make them whirl fast enough to break away from their nuclei. 为了释放电子,必须使电子高速旋转而足以摆脱原子核的束缚。
  • Energy is released by the fission of atomic nuclei. 能量是由原子核分裂释放出来的。
3 meteorite 2wNy1     
n.陨石;流星
参考例句:
  • The meteorite in Jilin Exhibition Hall is believed to be the largest in the world.吉林展览馆的陨石被认为是世界上最大的。
  • The famous Murchison meteorite smashed into the Australian ground in 1969.1969年著名的默奇森陨石轰然坠落在澳大利亚。
4 meteorites 12efd1ed528a28fe1f7cb667a7fbc1e0     
n.陨星( meteorite的名词复数 )
参考例句:
  • Small meteorites have left impact craters all over the planet's surface. 这个行星的表面布满了小块陨石留下的撞击坑。 来自《简明英汉词典》
  • One theory about the existence of extraterrestrial life rests on the presence of carbon compounds in meteorites. 地球外存在生命的理论是基于陨星上存在碳化合物质这一事实的。 来自《简明英汉词典》
5 asteroid uo1yD     
n.小行星;海盘车(动物)
参考例句:
  • Astronomers have yet to witness an asteroid impact with another planet.天文学家还没有目击过小行星撞击其它行星。
  • It's very unlikely that an asteroid will crash into Earth but the danger exists.小行星撞地球的可能性很小,但这样的危险还是存在的。
6 asteroids d02ebba086eb60b6155b94e12649ff84     
n.小行星( asteroid的名词复数 );海盘车,海星
参考例句:
  • Asteroids,also known as "minor planets",are numerous in the outer space. 小行星,亦称为“小型行星”,在外太空中不计其数。
  • Most stars probably have their quota of planets, meteorids, comets, and asteroids. 多数恒星也许还拥有若干行星、流星、彗星和小行星。
7 obliterating ccbd87387f18865c6ec59c3e2975ee4d     
v.除去( obliterate的现在分词 );涂去;擦掉;彻底破坏或毁灭
参考例句:
  • Michael smoked the competition, obliterating field in most of his events. 迈克尔让比赛放光,几乎淹没了他所参加的大多数项目。 来自互联网
  • He heard Pam screaming.The noise became obliterating.Then solid darkness descended. 在一片混乱中,他听到了帕姆的尖叫。接下来,噪音消失了,黑暗降临了。 来自互联网
8 investigations 02de25420938593f7db7bd4052010b32     
(正式的)调查( investigation的名词复数 ); 侦查; 科学研究; 学术研究
参考例句:
  • His investigations were intensive and thorough but revealed nothing. 他进行了深入彻底的调查,但没有发现什么。
  • He often sent them out to make investigations. 他常常派他们出去作调查。
9 relatively bkqzS3     
adv.比较...地,相对地
参考例句:
  • The rabbit is a relatively recent introduction in Australia.兔子是相对较新引入澳大利亚的物种。
  • The operation was relatively painless.手术相对来说不痛。
10 primitive vSwz0     
adj.原始的;简单的;n.原(始)人,原始事物
参考例句:
  • It is a primitive instinct to flee a place of danger.逃离危险的地方是一种原始本能。
  • His book describes the march of the civilization of a primitive society.他的著作描述了一个原始社会的开化过程。
11 crater WofzH     
n.火山口,弹坑
参考例句:
  • With a telescope you can see the huge crater of Ve-suvius.用望远镜你能看到巨大的维苏威火山口。
  • They came to the lip of a dead crater.他们来到了一个死火山口。
12 cratered f3774327dd107353b75750c68f1e81c7     
adj.有坑洞的,多坑的v.火山口( crater的过去分词 );弹坑等
参考例句:
  • The surface cratered with the constant dropping of water. 表面因经常滴水而成坑。 来自《现代英汉综合大词典》
  • Artillery cratered the roads. 炮击后大路布满了弹坑。 来自《现代英汉综合大词典》
13 mare Y24y3     
n.母马,母驴
参考例句:
  • The mare has just thrown a foal in the stable.那匹母马刚刚在马厩里产下了一只小马驹。
  • The mare foundered under the heavy load and collapsed in the road.那母马因负载过重而倒在路上。
14 craters 1f8461e3895b38f51c992255a1c86823     
n.火山口( crater的名词复数 );弹坑等
参考例句:
  • Small meteorites have left impact craters all over the planet's surface. 这个行星的表面布满了小块陨石留下的撞击坑。 来自《简明英汉词典》
  • The battlefield was full of craters made by exploding shells. 战场上布满弹坑。 来自《现代英汉综合大词典》
15 mantle Y7tzs     
n.斗篷,覆罩之物,罩子;v.罩住,覆盖,脸红
参考例句:
  • The earth had donned her mantle of brightest green.大地披上了苍翠欲滴的绿色斗篷。
  • The mountain was covered with a mantle of snow.山上覆盖着一层雪。
16 dissemination dissemination     
传播,宣传,传染(病毒)
参考例句:
  • The dissemination of error does people great harm. 谬种流传,误人不浅。
  • He was fully bent upon the dissemination of Chinese culture all over the world. 他一心致力于向全世界传播中国文化。
17 spatial gvcww     
adj.空间的,占据空间的
参考例句:
  • This part of brain judges the spatial relationship between objects.大脑的这部分判断物体间的空间关系。
  • They said that time is the feeling of spatial displacement.他们说时间是空间位移的感觉。
18 formerly ni3x9     
adv.从前,以前
参考例句:
  • We now enjoy these comforts of which formerly we had only heard.我们现在享受到了过去只是听说过的那些舒适条件。
  • This boat was formerly used on the rivers of China.这船从前航行在中国内河里。
19 phenomena 8N9xp     
n.现象
参考例句:
  • Ade couldn't relate the phenomena with any theory he knew.艾德无法用他所知道的任何理论来解释这种现象。
  • The object of these experiments was to find the connection,if any,between the two phenomena.这些实验的目的就是探索这两种现象之间的联系,如果存在着任何联系的话。
20 authoritative 6O3yU     
adj.有权威的,可相信的;命令式的;官方的
参考例句:
  • David speaks in an authoritative tone.大卫以命令的口吻说话。
  • Her smile was warm but authoritative.她的笑容很和蔼,同时又透着威严。
21 geologists 1261592151f6aa40819f7687883760a2     
地质学家,地质学者( geologist的名词复数 )
参考例句:
  • Geologists uncovered the hidden riches. 地质学家发现了地下的宝藏。
  • Geologists study the structure of the rocks. 地质学家研究岩石结构。
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