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Geologists Harris and Gass hypothesized that the Red Sea rift developed along the line of a suture (a splice in the Earth's crust) formed during the late Proterozoic era, and that significant observable differences in the composition of the upper layers of rocks deposited on either side of the suture give clues to the different natures of the underlying igneous rocks.
Other geologists argued that neither the upper rock layer nor the underlying igneous rocks on the one side of the rift differ fundamentally from the corresponding layers on the other side. These geologists believe, therefore, that there is inadequate evidence to conclude that a suture underlies the rift.
In response, Harris and Gass asserted that the upper rock layers on the two sides of the rift had not been shown to be of similar age, structure, or geochemical content. Further- more, they cited new evidence that the underlying igneous rocks on either side of the rift contain significantly different kinds of rare metals.
Part of the Harris and Gass hypothesis about the Red Sea rift would be weakened if it could be demonstrated that the composition of upper rock layers
A.cannot cause a suture to develop
B.has no effect on where a suture will occur
C.cannot provide information about the nature of underlying rocks
D.is similar on the two sides of a rift unless a suture divides the two sides
E.is usually different from the composition of underlying rocks
It can be inferred from the passage that the "Other geologists" (line 8) would be most likely to agree with which of the following statements?
A.Similar geological features along both sides of a possible suture imply the existence of that suture
B.Sutures can be discovered only where they are not obscured by superimposed geological features.
C.The composition of igneous rocks permits pre- diction of the likelihood of a rift developing through them.
D.It is possible to date igneous rocks by carefully studying the different kinds of rare metals contained in them and by observing their simi- larity to the layer of rock that lies above them.
E.he existence of rock layers on one side of a rift that are similar in composition to rock layers on the other side suggests that no suture exists between the two sides.
It can be inferred from the passage that Harris and Gass have done which of the following?
A.Drawn detailed diagrams of the Red Sea rift.
B.Based their conclusions on the way in which sutures develop in the Earth's crust.
C.Rejected other geologists objections to their hypothesis about the Red Sea rift.
D.Suggested that the presence of rare metals in rocks indicates an underlying suture.
E.Asserted that rifts usually occur along the lines of sutures
According to the passage, Harris and Gass have mentioned all of the following properties of rocks along the Red Sea rift EXCEPT
A.age of the upper layers of rock
B.structure of the upper layers of rocks
C.geochemical content of the upper layers of rocks
D.metallic content of the underlying igneous rocks
E.age of the underlying igneous rocks
