tpo27閱讀原文

　　【3】How can volcanic activity occur so far from a plate boundary? The Hawaiian Islands provide a very instructive answer. Like many other island groups, they form a chain. The Hawaiian Islands Chain extends northwest from the island of Hawaii. In the 1840s American geologist James Daly observed that the different Hawaii islands seem to share a similar geologic evolution but are progressively more eroded, and therefore probable older, toward the northwest.Then in 1963, in the early days of the development of the theory of plate tectonics. Canadian geophysicist Tuzo Wilson realized that this age progression could result if the islands were formed on a surface plate moving over a fixed volcanic source in the interior. Wilson suggested that the long chain of volcanoes stretching northwest from Hawaii is simply the surface expression of a long-lived volcanic source located beneath the tectonic plate in the mantle. Today’s most northwest island would have been the first to form. They as the plate moved slowly northwest, new volcanic islands would have forms as the plate moved over the volcanic source. The most recent island, Hawaii, would be at the end of the chain and is now over the volcanic source.

　　【4】Although this idea was not immediately accepted, the dating of lavas in the Hawaii (and other) chains showed that their ages increase away from the presently active volcano, just as Daly had suggested. Wilson’s analysis of these data is now a central part of plate tectonics. Most volcanoes that occur in the interiors of plates are believed to be produced by mantle plumes, columns of molten rock that rise from deep within the mantle. A volcano remains an active “hot spot” as long as it is over the plume. The plumes apparently originate at great depths, perhaps as deep as the boundary between the core and the mantle, and many have been active for a very long time. The oldest volcanoes in the Hawaii hot-spot trail have ages close to 80 million years. Other islands, including Tahiti and Easter Islands in the pacific, Reunion and Mauritius in the India Ocean, and indeed most of the large islands in the world’s oceans, owe their existence to mantle plumes.

　　【5】The oceanic volcanic islands and their hot-spot trails are thus especially useful for geologist because they record the past locations of the plate over a fixed source. They therefore permit the reconstruction of the process of seafloor spreading, and consequently of the geography of continents and of ocean basins in the past. For example, given the current position of the Pacific Plate, Hawaii is above the Pacific Ocean hot spot. So the position of The Pacific Plate 50 million years ago can be determined by moving it such that a 50-million-year-oil volcano in the hot-spot trail sits at the location of Hawaii today. However because the ocean basins really are short-lived features on geologic times scale, reconstruction the world’s geography by backtracking along the hotspot trail works only for the last 5 percent or so of geologic time.

　　tpo27閱讀實試題

　　1.The author mentions “spreading ridges”, “subduction zones”, and“transform faults” in order to

　　A.illustrate that the boundaries of tectonic plates are neat, thin lines.

　　B.explain why some tectonic plates carry islands or continents while others form the seafloor.

　　C.explain the complex nature of the edges of tectonic plates.

　　D.provide examples of areas of tectonic plates where little geologic action occurs.

　　2.The word “converge” in the passage is closest in meaning to

　　A.expand.

　　B.form.

　　C.rise.

　　D.move closer.

　　3.Which of the sentences below best expresses the essential information in the highlighted sentence in the passage paragraph 2 ? Incorrect choices change the meaning in important ways or leave out essential information

　　A.Volcanic activity is responsible for the formation of the Pacific seafloor in the interior of the Pacific Plate.

　　B.Many volcanoes in the Pacific Ocean are no longer active and have become islands that support coral.

　　C.There are many islands in the Pacific Ocean that originated as volcanoes in the interior of the Pacific Plate.

　　D.The map of the Pacific Ocean reveals fewer volcanic islands than there truly are because many are no longer active and some are completely overgrown with coral.

　　4.The word “instructive” in the passage(paragraph 3)is closest in meaning to

　　A.clear.

　　B.detailed.

　　C.informative.

　　D.familiar.

　　5.The word “eroded” in the passage(paragraph 3)is closest in meaning to

　　A.worm down.

　　B.scattered.

　　C.developed.

　　D.deserted.

　　6.In paragraph 3, what is the relationship between the scientific contribution of James Daly and Tuzo Wilson?

　　A.Wilson provided an explanation for the observations made by Daly.

　　B.Wilson challenged the theory proposed by Daly.

　　C.Wilson found numerous examples of island chains that supported Daly’s theory.

　　D.Wilson popularized the explanation of volcanic island formation formulated by Daly.

　　7.Why does the author provide the information that “the dating of lavas in the Hawaii (and other) chains showedthat their ages increase away from the presently active volcano”?

　　A.To point out differences between the Hawaii island chain and other volcanic island chains.

　　B.To question the idea that all the islands in an island chain have been formed by volcanic activity.

　　C.To explain why Wilson hypothesis was initially difficult to accept.

　　D.To provide evidence in support of Daly’s and Wilson’s ideas about how the Hawaii islands were formed.

　　8.According to paragraph 4, which of the following is true of mantleplumes?

　　A.They exist close to the surface of tectonic plates.

　　B.They cause most of the volcanic activity that occurs in the interiors of plates.

　　C.They are rarely active for long period of time.

　　D.They get increasingly older away from the present hot spots.

　　9.According to paragraph 5, volcanic islands help geologists to

　　A.reconstruct past geography.

　　B.detect changes in mantle plumes.

　　C.measure the rigidity of tectonic plates.

　　D.explain why the seafloor spreads.

　　10.What can be inferred about the Pacific Plate from paragraph 5?

　　A.The hot spots on the Pacific Plate are much older than the ones located on the other tectonic plates.

　　B.Most of the volcanic sources beneath the Pacific Plate have become extinct.

　　C.The Pacific Plate has moved a distance equal to the length of the Hawaiian Island chain in the past 80 million years.

　　D.The Pacific Plate is located above fewer mantle plumes than other plates are.

　　11.The word “current” in the passage(paragraph 5)is closest in meaning to

　　A.original.

　　B.ideal.

　　C.relative.

　　D.present.

　　12.According to paragraph 5, why are geologists unable to trace back theentire geologic of continents from hot-spot trails?

　　A.Hot spots have existed for only about 5 percent of geologic time.

　　B.Hawaii did not exist 50 millions years ago.

　　C.Oceanic basins that contained old hot-spot trails disappeared a long time ago.

　　D.Hot-spot trails can be reconstructed only for island chains.

　　13. Look at the four squares [■] that indicate where the following sentence could be added to the passage. Where would the sentence best fit? This pattern remained unexplained for a long time.

　　How can volcanic activity occur so far from a plate boundary? The Hawaiian islands provide a very instructive answer. ■【A】Like many other island groups, they form a chain. ■【B】The Hawaiian Islands Chain extends northwest from the island of Hawaii. ■【C】In the 1840s American geologist James Daly observed that the different Hawaii islands seem to share a similar geologic evolution but are progressively more eroded, and therefore probable older,toward the northwest. ■【D】Then in 1963, in the early days of the development of the theory of plate tectonics. Canadian geophysicist Tuzo Wilson realized that this age progression could result if the islands were formed on a surface plate moving over a fixed volcanic source in the interior. Wilson suggested that the long chain of volcanoes stretching northwest from Hawaii is simply the surface expression of a long-lived volcanic source located beneath the tectonic plate in the mantle. Today’s most northwest island would have been the first to form. They as the plate moved slowly northwest, new volcanic islands would have forms as the plate moved over the volcanic source. The most recent island, Hawaii, would be at the end of the chain and is now over the volcanic source.

　　14. Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.

　　Although volcanic activity is concentrated on the edge of tectonicplates, such activity can occur in the interiors of plates as well.

　　A.Our understanding of islands comes from Daly’s and Wilson’s observations of the Hawaiian Islands, which was later confirmed by plate-tectonic theory.

　　B.The hot-spot trails formed by volcanic island chains indicate the positions of tectonic plates as for back as the present ocean basins have existed.

　　C.Whereas volcanic islands formed by mantle plumes are typically small, most of the world’s largest islands are formed at the edges of tectonic plates.

　　D.It has only recently been discovered that tectonic plates are closely fitting rather than loosely constructed, as geologist previously believed.

　　E.Volcanic island chains such as the Hawaiian Islands form in the interior of a tectonic plate as the plate moves over a fixed volcanic source in the mantle.

　　F.The Pacific Plate has existed for as long as the Hawaiian Islands have existed, namely for more than 80 million years.

　　tpo27閱讀答案及解析

　　1.原文這部分介紹了各種不同的edges的現象，并做了詳細的解釋，前面也說到plate的組成就像是jigsaw puzzle，從兩處可以看出應該是要體現其復雜性。A與原文矛盾，原文并沒有對B做出解釋，D原文給出的是geologic action常發的地方，而不是little ~ occurs。

　　2.這一段描述的前兩種現象，一種是move closer，一種是move apart。對第三種的描寫是neither…nor…既不也不，因此應該是與前兩種都不同，所以應該是既不聚合，也不分開，根據詞根可以判斷diverge是分開，converge是聚合。所以答案為D。

　　3.根據這一段的第一句可以看出后面是在舉例說內陸平靜的exception。A，B，D選項都是句子的細節部分，不能表達出其目的。所以不選。

　　4.instructive是有意義的，教育性的。 A是清楚的，B是細節的，D是熟悉的。只有C是有益的，教育性的，意思吻合。前面是問句，后面說夏威夷群島提供了怎樣的解答，那么應該是這個例子可以回答這個問題。根據這層意思，可以推出答案。

　　5.這句話說不同的島嶼看起來經歷了相似的演變過程，但有些隨著時間推移被更……，所以可能更古老。那么島嶼如果經歷的時間更長應該會被海水“侵蝕”的更厲害。所以答案選A，worn down 磨損。 B是分散的，C是發達的，成熟的;D是被遺棄的。

　　6.根據兩個科學家的名字進行定位。從then in 1963這一句可以了解到兩者關系，說在板塊理論剛開始發展的時期，tuzo Wilson發現……那么肯定是使板塊理論進一步發展了。所以B不對。而C雖然邏輯關系對，但文中只給了夏威夷島一個例子。所以C不選。D說使解釋流行，之前daly只是給了理論，并沒解釋，所以不對。而A既符合邏輯關系，也對wilson的描寫是正確的。

　　7.這個題很簡單啦，往后面再多看一點點就知道答案啦。Just as Daly had suggested。

　　8.根據mantle plumes定位，可定位地第一句(已用紅色標出)就說了它是導致板塊內部火山爆發的原因，往后讀可以看到它首先是起源于很深的地方，其次活動時間很長。因此A，C，D都不對。所以正確答案為B。

　　9.定位到這一段的第二句。D選項雖然也對，但是A可以包括D。

　　10.定位到for example，定位句幾乎就是選項C的原義轉換啦。A，B，D原文都沒提到。

　　11.current是現在的意思。A是原始的，B是理想的，C是相對的，D是現在的。根據原句中也可以判斷，因為后文說，通過大平洋板塊什么的位置，可以判斷其5千萬年前的位置，那么兩者應該是相反的。所以答案為D。

　　12.定位到最后一句。說不能追蹤到整個變化過程是因為海洋盆地的變化相對比較快。

　　13.D的位置前面提到了大陸版塊構造論，但并沒給出解釋，后半部分給出了很多年后另一位科學家給出的解釋。

　　14.A正確 整篇文章都在說這個。。。一直是在說夏威夷島的火山現象證明了大陸板塊構造理論呀。B錯誤，不選。這個老早就發現了吧，當初daly提出的時候就說的是closely fitting的呀。C正確，對應文章最后一段的橘黃色標出部分。D正確，對應文章第二段紅色標出部分。E錯誤，不選。文章沒提到這些火山小。F錯誤。文章最后一段說到ocean basin是相對短暫的存在。并沒有存在超過8千萬年。