1. The passage suggests that which two geological concepts were crucial to the development of Harry Hess’s formulation of the plate tectonics theory?The geologist Harry Hess published a paper that combined the evidence for continental drift with his own work on seafloor spreading to produce an argument for the theory of plate tectonics. Put simply, plate tectonics is the theory that the surface of the earth is composed of rigid plates that “float” on a liquid layer underneath. Sometimes these plates grind against each other at transform boundaries, sometimes they move away from each other at divergent boundaries (this is the cause of seafloor spreading), and sometimes they press into each other at convergent boundaries, in which case one plate is subducted under the other, generally creating mountains in the process.
A. Seafloor spreading and subductionIncorrect. The geologist Harry Hess produced an argument for the theory of plate tectonics using two geological concepts namely – seafloor spreading and continental drift.
B. Subduction and continental driftOption B is incorrect because the geologist HH used two geological concepts (seafloor spreading and subduction) in his theory of plate tectonics.
C. Seafloor spreading and continental driftOption C is correct because the geologist HH published a paper that combined the evidence for continental drift with his own work on seafloor spreading to propose his theory of plate tectonics.
D. Magnetic resonance and continental driftOption D is incorrect as explained for option B.
E. Mantle theory and seafloor spreadingOption E is incorrect as explained for option B.
2. Which of the following would make the most appropriate title for this passage?The passage is primarily concerned with an explanation for - how the views of the majority of earth science professionals on earth’s dynamics changed from “the earth is essentially static - that is, that the earth has always had essentially the same continents and oceans, in essentially the same places, as we see them today ” to “the earth is not static – that is, the continents are moving around, a concept now termed continental drift ”. And this change in view was made possible essentially by the works of the geologist Harry Hess, who produced an argument for the theory of plate tectonics, which could explain all the geological phenomena given in the second passage. The theory of plate tectonics was too powerful to be denied by the majority of the earth science professionals. Therefore the most appropriate title for this passage is
Option C – “Tectonic Shift: The Plate Tectonics Revolution in the Earth Sciences” A. At the Heart of the Matter: The Quest to Determine the Composition of the Earth’s CoreOption A is incorrect because determining the composition of the Earth’s core has not been discussed in the passage.
B. World’s Turning: The Perplexing Story of the Earth’s Magnetic Field Option B is incorrect because the focus of the passage is not the earth’s magnetic field. It is mentioned as one of the geological phenomena in the second paragraph.
C. Tectonic Shift: The Plate Tectonics Revolution in the Earth Sciences – correct.D. Harry Hess: A Man, a Planet, a Theory Although Harry Hess produced the theory of plate tectonics and provided explanation to all the geological phenomena, he is not the focus of the passage. It is his work that is in focus. Option D is incorrect.
E. The Transformation of Heuristic Models in Geology, Oceanography, and PaleontologyOption E is incorrect because no such heuristic models have been discussed in the passage.
3. The author’s attitude toward the plate tectonics theory can best be characterized asFrom the last two lines of the last paragraph – use of “the plate tectonics theory was too powerful to be denied” and “the majority of earth science professionals came to accept plate tectonics as the fundamental explanation for the state of the continents today” - it is evident that the author strongly supports the theory.
Option E is correct. 4. Geologists believe that the Andes mountain chain along the Pacific coast of South America was created by the collision of the oceanic Nazca plate with the continental South American plate; this type of plate boundary is known as a.From the third paragraph it is evident that the rigid plates sometimes press into each other at convergent boundaries and results in one plate getting subducted under the other, generally creating mountains in the process.
Therefore, the Andes mountain chain was created due to collision of the oceanic plate with the continental plate at the convergent boundary.
Option A is correct.
B. Transform boundary Option B is incorrect because the transform boundary may be a divergent boundary or a convergent boundary depending upon several factors.
C. Subduction boundaryOption C is incorrect because no such boundary is used in the passage.
D. Divergent boundaryOption D is incorrect because at the divergent boundary the plates move away from each other (this is the cause of seafloor spreading).
E. Tectonic boundaryOption E is incorrect because no such boundary is used in the passage.
5. The passage suggests that the plate tectonics theory can help explain all of the following phenomena, EXCEPT.The phenomenon of regular tides in seas and oceans has not been discussed in the paragraph so we are not sure if the theory of plate tectonics could provide an explanation for this phenomena. Thus,
option E is correct. Also, the balance geological phenomena have been mentioned and it is specified in the last paragraph that the theory of plate tectonics provides an explanation to all of them.