Years before theadvent of plate tectonics―the widely accepted theory, developed in themid-1960’s, the holds that the major features of Earth’s surface are created bythe horizontal motions of Earth’s outer shell, or lithosphere ―a similar theorywas rejected by the geological community. In 1912, Alfred Wegener proposed, in a widely debated theory that cameto be called continental drift, that Earth’s continents were mobile. To most geologists today, Wegener’s The origin of Continents and Oceans appearsan impressive and prescient document, containing several of the essentialpresumptions underlying plate tectonics theory: the horizontal mobility ofpieces of Earth’s crust; the essential difference between oceanic and continentalcrust; and a causal connection between horizontal displacements and theformation of mountain chains. Yet despitethe considerable overlap between Wegener’s concepts and the later widelyembraced plate tectonics theory, and despite the fact that continental drifttheory presented a possible solution to the problem of the origin of mountainsat a time when existing explanations were seriously in doubt, in its dayWegener’s theory was rejected by the vast majority of geologists.
Mostgeologists and many historians today believe that Wegener’s theory was rejectedbecause of its lack of an adequate mechanical basis. Stephen Jay Gould, for example, argues that continentaldrift theory was rejected because it did not explain how continents could movethrough an apparently solid oceanic floor. However, as Anthony Hallam has pointed out, many scientific phenomena,such as the ice ages, have been accepted before they could be fully explained. The most likely cause for the rejectionof continental drift ―a cause that has been largely ignored because we considerWegener’s theory to have been validated by the theory of plate tectonics―is thenature of the evidence that was put forward to support it. Most of Wegener’s evidence consisted ofhomologies—similarities of patterns and forms based on direct observations of rocksin the field, supported by the use of hammers, hand lenses, and field notebooks. In contrast, the data supporting platetectonics were impressively geophysical—instrumental determinations of the physicalproperties of Earth garnered through the use of seismographs, magnetometers,and computers.
Q25:
Theauthor of the passage refers to the “considerable overlap” (line 23) betweencontinental drift theory and plate tectonics theory most probably in order to
A. suggestthat plate tectonics theory is derived from Wegener’s work
B. introducea discussion comparing the elements of the two theories
C. examinethe question of whether continental drift theory was innovative in its time
D. providea reason why it might seem surprising that continental drift theory was notmore widely embraced by geologists
E. cite anexplanation that has been frequently offered for Wegener’s high standing amonggeologists today
OA is D, BUT I still think of A. Can someone tell me the reason of D?作者: avenue5th 时间: 2012-5-18 06:56
despite overlap很大..........in its day Wegener’s theory was rejected by the vast majority of geologists.
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