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shuibanqing · 发表于 2009-10-24 00:54:00

With the onset of the Industrial Revolution, knowing the age of rocks became a necessary prerequisite to finding industrial minerals, such as coal, iron, and the other materials that fueled and sustained the great Western industrialization of the eighteenth    and nineteenth centuries. It was in the mining regions where engineers, who needed a better system for organizing the various types of rock scattered across Earth's surface, first grappled with scientific approaches to understanding the age of various rocks—and the age of Earth. They realized that if the various rock units could he dated by their relative ages, correlations among even widely separated rocks could be established and from this, some order recognized.

The pioneering European geologists first believed that identifying a rock's type would  give them a strong clue to the age of the rock formation and that one of the most powerful clues came from the hardness of a given rock. Specific rock types were thus assumed to
have formed at characteristically different rimes, the softest rocks having formed the most recently. This crude type of dating was first used to understand the way mountains were formed, In the mid-1700's it was thought thai there were three distinct types of mountains
in Europe, each formed by a different type of rock and each created at a different time. According to this theory, the oldest were the Alps, which had interior cores composed of very hard, crystalline rocks (such as granite, schist, or basalt). These mountains were   called Primitive. Sitting on the flanks of the Primitive mountains were younger, smaller, Secondary mountains composed of layered sedimentary rocks such as limestone. They were often rich with fossils and intermediate in hardness.

4. According to the passage, mining engineers were the first to realize that
(A) various types of rock were scattered across Earth's surface
(B) rocks in different locations could be related by their age
(C) there were wide differences in the appearance of different types of rocks
(D) older rocks were better suited for industrial use
请问这题为何选B呢

8. According to the passage, early geologists believed which of the following about Primitive mountains?
(A) They had interior cores of sandstone and mudstone,
(B) They contained a large number of fossils.
(C) They had been formed during the same limited period in Earth's history.
(D)They were smaller than the Tertiary mountains.
这题又为何选C

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问2个阅读

问2个阅读

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