Question 6: Read the following passage and choose the best answer. Write your answers in the numbered blanks provided below the passage. (20point)
In addition to the great ridges and volcanic chains, the oceans conceal another form of undersea mountains: the strange guyot, or flat-topped seamount. No marine geologist even suspected the existence of these isolated mountains until they were discovered by geologist Harry H. Hess in 1946. He was serving at the time as naval officer on a ship equipped with a fathometer. Hess named these truncated peaks for the nineteenth-century Swiss-born geologist Arnold Guyot, who had served on the faculty of Princeton University for thirty years. Since then, hundreds of guyots have been discovered in every ocean but the Arctic. Like offshore canyons, guyots present a challenge to oceanographic theory. They are believed to be extinct volcanoes. Their flat tops indicate that they once stood above or just below the surface, where the action of waves leveled off their peaks. Yet today, by definition, their summits are at least 600 feet below the surface, and some are as deep as 8,200 feet. Most lie between 3,200 feet and 6,500 feet. Their tops are not really flat but slope upward to a low pinnacle at the center. Dredging from the tops of guyots has recovered basalt and coral rubble, and that would be expected from the eroded tops of what were once islands. Some of this material is over 80 million years old. Geologists think the drowning of the guyots involved two processes: The great weight of the volcanic mountains depressed the sea floor beneath them, and the level of the sea rose a number of times, especially when the last Ice Age ended, some 8,000 to 11.000 years ago.
51. What is the author's main purpose in writing this passage?
A. To trace the career of Arnold Guyot.
B. To describe feature of the undersea world.
C. To present the results of recent geologic research.
D. To discuss underwater ridges and volcano chains
52. The word “conceal” is closest in meaning to which of the following?
A. Contain B. Erode C. Hide D. Create
53. The passage implies that guyots were first detected by means of________.
A. a fathometer B. computer analysic
C. a deep-sea diving expedition D. research submarines
54. The author indicates that Arnold Guyot________.
A. was Harry Hess's instructor B. invented the fathometer
C. named the guyed after himself D. taught at Princeton University
55. What does the passage say about the Arctic Ocean?
A. The first guyot was discovered there.
B. No guyots have ever been found there.
C. There are more guyots there than in any other ocean.
D. It is impossible that guyots were ever formed there.
56. The author states that offshore canyons and guyots have which of the following characteristics in common?
A. Both are found on the ocean floor near continental shelves.
B. Both present oceanographers with a mystery.
C. Both were formed by volcanic activity.
D. Both were, at one time, above the surface of the sea.
57. According to the passage, most guyots are found at a depth of________.
A. less than 600 feet. B. between 600 and 3,200 feet.
C. between 3,200 and 6,500 feet D. more than 8,200 feet
51. Which of the following is closest in meaning to the word “rubble”?
A. Fragments B. Mixture C. Columns D. Core
51. According to the passage, which of the following two processes were involved in the submersion of guyots?
A. Erosion and volcanic activity.
B. The sinking of the sea floor and the rising of sea level.
C. Mountain building and the action of ocean currents
D. High tides and earthquakes
60. According to the passage, when did sea level significantly rise?
A. In 1946 B. In the nineteenth century
C. From 8,000 to 11,000 years D. 80 million years ago
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