Prior to 1965 geologists assumed that the two giant : GMAT Reading Comprehension (RC)
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# Prior to 1965 geologists assumed that the two giant

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Prior to 1965 geologists assumed that the two giant [#permalink]

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10 Dec 2013, 02:32
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Prior to 1965 geologists assumed that the two giant rock plates meeting at the San Andreas Fault generate heat through friction as they grind past each other, but in 1965 Henyey found that temperatures in drill holes near the fault were not as elevated as had been expected. Some geologists wondered whether the absence of friction-generated heat could be explained by the kinds of rock composing the fault. Geologists’ pre-1965 assumptions concerning heat generated in the fault were based on calculations about common varieties of rocks, such as limestone and granite; but “weaker” materials, such as clays, had already been identified in samples retrieved from the fault zone. Under normal conditions, rocks composed of clay produce far less friction than do other rock types.

In 1992 Byerlee tested whether these materials would produce friction 10 to 15 kilometers below the Earth’s surface. Byerlee found that when clay samples were subjected to the thousands of atmospheres of pressure they would encounter deep inside the Earth, they produced as much friction as was produced by other rock types. The harder rocks push against each other, the hotter they become; in other words, pressure itself, not only the rocks’ properties, affects frictional heating. Geologists therefore wondered whether the friction between the plates was being reduced by pockets of pressurized water within the fault that push the plates away from each other.

The passage suggests which of the following regarding Henyey’s findings about temperature in the San Andreas Fault?

A.Scientists have yet to formulate a definitive explanation for Henyey’s findings.
B.Recent research suggests that Henyey’s explanation for the findings should be modified.
C.Henyey’s findings had to be recalculated in light of Byerlee’s 1992 experiment.
D.Henyey’s findings provided support for an assumption long held by geologists.
E.Scientists have been unable to duplicate Henyey’s findings using more recent experimental methods.

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[Reveal] Spoiler:
A

Can anybody help me explain this question with proper reasoning?
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Re: Prior to 1965 geologists assumed that the two giant [#permalink]

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10 Dec 2013, 10:04
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sahilchaudhary wrote:
Prior to 1965 geologists assumed that the two giant rock plates meeting at the San Andreas Fault generate heat through friction as they grind past each other, but in 1965 Henyey found that temperatures in drill holes near the fault were not as elevated as had been expected. Some geologists wondered whether the absence of friction-generated heat could be explained by the kinds of rock composing the fault. Geologists’ pre-1965 assumptions concerning heat generated in the fault were based on calculations about common varieties of rocks, such as limestone and granite; but “weaker” materials, such as clays, had already been identified in samples retrieved from the fault zone. Under normal conditions, rocks composed of clay produce far less friction than do other rock types.

In 1992 Byerlee tested whether these materials would produce friction 10 to 15 kilometers below the Earth’s surface. Byerlee found that when clay samples were subjected to the thousands of atmospheres of pressure they would encounter deep inside the Earth, they produced as much friction as was produced by other rock types. The harder rocks push against each other, the hotter they become; in other words, pressure itself, not only the rocks’ properties, affects frictional heating. Geologists therefore wondered whether the friction between the plates was being reduced by pockets of pressurized water within the fault that push the plates away from each other.

The passage suggests which of the following regarding Henyey’s findings about temperature in the San Andreas Fault?

A.Scientists have yet to formulate a definitive explanation for Henyey’s findings.
B.Recent research suggests that Henyey’s explanation for the findings should be modified.
C.Henyey’s findings had to be recalculated in light of Byerlee’s 1992 experiment.
D.Henyey’s findings provided support for an assumption long held by geologists.
E.Scientists have been unable to duplicate Henyey’s findings using more recent experimental methods.

Source - GMAT Prep
OA -
[Reveal] Spoiler:
A

Can anybody help me explain this question with proper reasoning?

Dissect the argument and boile it down to a simple scheme

Now the first sentence says: basically the scientists think that the heat among the earth's plates is caused by the friction of the rocks.

BUT in 1965 Henyey found that temperatures in drill holes near the fault were not as elevated as had been expected.. So after this something is weird: could not be this the real reason behind the friction and the consequent heat. Maybe is the type or quality of the rocks or clay or whatever else.

Byerlee's experiment instead says just this: no matter what is the type of rock, they genarate heat.

BUT pressure itself, not only the rocks’ properties, affects frictional heating. Geologists therefore wondered whether the friction between the plates was being reduced by pockets of pressurized water within the fault that push the plates away from each other.

Basically this is the skeleton of the argument that you have to keep in mind to answer the question. (indeed quite tricky) just because pressure + rock's properties could be the cause of all this but we are still wondering why Is this or there is something else that we do not know ??'

A fits the bill

hope this helps
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Re: Prior to 1965 geologists assumed that the two giant [#permalink]

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15 May 2014, 18:43
A is supported by the passage via last sentence.
B is not supported by the passage.
C is not supported by the passage.
D (did not have enough time to look at this one.)
E is not supported by the passage.
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Re: Prior to 1965 geologists assumed that the two giant [#permalink]

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12 May 2015, 01:59
Answer would be A.

Reasoning:

2nd line: but in 1965 Henyey found that temperatures in drill holes near the fault were not as elevated as had been expected.

Last line:Geologists therefore wonderedwhether the friction between the plates was being reduced by pockets of pressurized water within the fault that push the plates away from each other.
Re: Prior to 1965 geologists assumed that the two giant   [#permalink] 12 May 2015, 01:59
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# Prior to 1965 geologists assumed that the two giant

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