One of the central scientific questions of nineteenth-century geology was the origin of mountains. How were they formed? What process squeezed and folded rocks like bread dough? What made Earth's surface move? Most theories invoked terrestrial contraction as a causal force. It was widely believed that Earth had formed as a hot,incandescent body and had been steadily cooling since the beginning of geological time. Because most materials contract as they cool, it seemed logical to assume that Earth had been contracting as it cooled, too. As it did, its surface would have deformed, producing mountains.

In Europe,Austrian geologist Eduard Suess (1831-1914) popularized the image of Earth as a drying apple: as the planet contracted, its surface wrinkled to accommodate the diminished surface area. Suess assumed that Earth’s initial crust was continuous but broke apart as the interior shrank. The collapsed portions formed the ocean basins, the remaining elevated portions formed the continents. With continued cooling,the original continents became unstable and collapsed to form the next generation of ocean floor, and what had formerly been ocean now became dry land. Over the course of geological history,there would be a continual interchange of land and sea, a periodic rearrangement of the landmasses.

The interchangeability of continents and oceans explained a number of other perplexing geological observations, such as the presence of marine fossils on land (which had long before puzzled Leonardo da Vinci) and the extensive interleaving of marine and terrestrial sediments in the stratigraphic record. Suess's theory also explained the striking similarities of fossils in parts of Africa and South America. Indeed, in some cases the fossils seemed to be identical,even though they were found thousands of miles apart. These similarities had been recognized since the mid-nineteenth century, but they had been made newly problematic by Darwin's theory of evolution. If plants and animals had evolved independently in different places within diverse environments, then why did they look so similar? Suess explained this conundrum by attributing these similar species to an early geological age when the continents were contiguous in an ancient supercontinent called Gondwanaland.

Suess’s theory was widely discussed and to varying degrees accepted in Europe, but in North America geologist James Dwight Dana(1813-1895)had developed a different version of contraction theory. Dana suggested that the continents had formed early in Earth history,when low-temperature minerals such as quartz and feldspar had solidified. Then the globe continued to cool and contract, until the high-temperature minerals such as olivine and pyroxene finally solidified—on the Moon, to form the lunar craters, on Earth,to form the ocean basins. As contraction continued after Earth was solid, its surface began to deform. The boundaries between continents and oceans were most affected by the pressure, and so mountains began to form along continental margins. With continued contraction came continued deformation, but with the continents and oceans always in the same relative positions. Although Dana's theory was a version of contraction, it came to be known as permanence theory,because it viewed continents and oceans as globally permanent features.

In North America permanence theory was linked to the theory of subsidence (or sinking) of sedimentary basins along continental margins. This idea was developed primarily by paleontologist James Hall (1811-1898), who noted that beneath the forest cover,the Appalachian Mountains of North America were built up of folded layers of shallow-water sedimentary rocks, thousands of feet thick. How did these sequences of shallow-water deposits form? How were they folded and uplifted into mountains? Hall suggested that materials eroded off the continents accumulated in the adjacent marginal basins, causing the basins to subside. Subsidence allowed more sediment to accumulate,causing more subsidence,until finally the weight of the pile caused the sediments to be heated,converted to rock, and then uplifted into mountains. Dana modified Hall's view by arguing that thick sedimentary piles were not the cause of subsidence but the result of it. Either way, the theory provided a concise explanation of how thick sequences of shallow-water rocks could accumulate, but was vague on the question of how they were transformed into mountain belts.

Questions:
question_stem: According to paragraph 1, most nineteenth-century theories of mountain formation were based on which of the following ideas?
choices: tag: A
text: The heat released at the time of Earth's formation caused rocks to fold.

tag: B
text: Earth's surface expanded and stretched because the planet had become hot.

tag: C
text: Earth's surface shrank and deformed as the planet cooled over time.

tag: D
text: Movements of Earth's surface due to frequent expansion and contraction pushed rocks upward.
answer_key: C
explanation: 题干提问“大多数19世纪的山脉形成理论的依据是什么”。
定位第1段第5-8句，地球形成初期是炽热的天体，后逐渐冷却，期间天体收缩，表面变形，进而形成了山脉。
故选 C。

question_stem: For which of the following purposes did Suess use the image of “a drying apple”?
choices: tag: A
text: To show that Earth's crust had to have been continuous at first

tag: B
text: To show how the processes that led to the formation of ocean basins differed from those that led to the formation of continents

tag: C
text: To prove that Earth's continents and ocean floors were not stable

tag: D
text: To explain how Earth's surface wrinkled over a shrunken interior
answer_key: D
explanation: 题干提问“苏斯使用了干燥的苹果的形象的目的是什么”。
定位第2段第1句，a drying apple 后冒号连接内容 as the planet contracted, its surface wrinkled to accommodate the diminished surface area.
即生动形象地类比说明地球在收缩时表面会出现褶皱的现象。
故选 D。

question_stem: According to paragraph 3, how did Suess explain the occurrence of similar fossils on various continents?
choices: tag: A
text: Continents and oceans exchanged materials,so the fossil record was not unique to a specific region.

tag: B
text: Initially the landmasses that make up today's continents were one continuous landmass.

tag: C
text: The species associated with these fossils gradually spread across the world's continents.

tag: D
text: Coastal terrestrial sediments contained similar fossils across continents.
answer_key: B
explanation: 题干提问“苏斯如何解释在大陆不同地区出现了类似的化石的现象”。
定位第3段第2句 Suess's theory also explained the striking similarities of fossils in parts of Africa and South America.
即苏斯的理论解释了该现象，苏斯的理论出现在第2段第2句 Suess assumed that Earth’s initial crust was continuous but broke apart as the interior shrank.
即起初的大陆板块是连续的，后由于收缩分开。
故选 B。

question_stem: Why does the author mention “Darwin's theory of evolution” in the passage?
choices: tag: A
text: To explain why fossils in the stratigraphic record seemed to be identical

tag: B
text: To indicate that other scientists did not accept Suess's theory of interchangeability

tag: C
text: To point out a complication that Suess had to resolve for his theory to be valid

tag: D
text: To prove that similar species had existed on different continents at an early geological age
answer_key: C
explanation: 题干提问“作者为什么提及 Darwin's theory of evolution”。
定位第3段高亮句（第4句），but they had been made newly problematic by Darwin's theory of evolution. 但达尔文的进化论使这些相似之处成为新问题。结合上下文，第3-6句，理解为：按照达尔文的进化论，这些彼此距离遥远的化石具备高相似度，则它们不是在不同地区独立进化的，而是起初在同一块大陆（an ancient supercontinent called Gondwanaland）。也就证实了苏斯理论的有效性。
故选 C。

question_stem: The word “adjacent” in the passage is closest in meaning to
choices: tag: A
text: open

tag: B
text: extra

tag: C
text: deep

tag: D
text: nearby
answer_key: D
explanation: adjacent adj. 临近的，毗连的。
与 D 选项 nearby 同义。
故选 D。

question_stem: Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.
choices: tag: A
text: The presence of marine fossils on land as well as the distribution of marine and terrestrial sediments had long been a mystery to Leonardo da Vinci.

tag: B
text: The interchangeability of the continents and oceans as well as other geological observations had long been a source of confusion.

tag: C
text: The continual rearrangement of land and sea provided an explanation for some other mysterious geological observations.

tag: D
text: The interchangeability of continents and oceans explained the absence of fossils or sediments in oceans.
answer_key: C
explanation: 第3段高亮句主干信息：The interchangeability of continents and oceans explained a number of other perplexing geological observations.
A 选项主干 the fossils and sediments had long been a mystery to Leonardo da Vinci，并非原文讨论主干内容，错误；
B 选项 had long been a source of confusion，与原文不符，原文是 explained，错误；
C 选项，the continual rearrangement of land and sea = the interchangeability of continents and oceans，provided an explanation for = explained，some other mysterious geological observations = a number of other perplexing geological observations，正确；
D 选项 explained the absence of fossils or sediments in oceans，与原文不符，错误。
故选 C。

question_stem: According to paragraph 5, which of the following led James Hall to propose a theory of subsidence?
choices: tag: A
text: The gradual sinking of the Appalachian Mountains resulting from the forests covering them

tag: B
text: The existence of sedimentary basins along continental margins

tag: C
text: The apparent subsidence of mountains due to erosion

tag: D
text: The notion that the Appalachian Mountains are formed of thick folded layers of sedimentary rock
answer_key: D
explanation: 题干提问“以下哪个原因使得詹姆斯·霍尔提出了沉降理论”。
定位第5段第2句，This idea was developed primarily by paleontologist James Hall (1811-1898), who noted that beneath the forest cover, the Appalachian Mountains of North America were built up of folded layers of shallow-water sedimentary rocks, thousands of feet thick. 
即霍尔发现在森林覆盖之下，北美的阿巴拉契亚山脉是由数千英尺厚的浅水沉积岩褶皱层构成的，进而提出了沉降理论。
故选 D。