samirnajeeb wrote:A is in fact the OA. passage indicates that scientists did indeed measure. it states "Geologists' pre-1965 assumptions .. based on calculations".

Mike@Magoosh wrote:Dear Bryan88,

I'm happy to answer your question.

I agree with GmatKiss's answer. Here's my explanation.

The first sentence of the passage says:
Prior to 1965 geologists assumed that the two giant rock plates meeting at the San Andreas Fault generate heat through frictions as they grind past each other, but in 1965 Henyey found that the temperatures in drill holes near the fault were not as elevated as had been expected.

The question:
6) According to the passage, Henyey's findings in 1965 were significant because they
(A) revealed an error in previous measurements of the temperature in the San Andreas Fault zone.
(B) indicated the types of clay present in the rocks that form the San Andreas Fault.
(C) established the superiority of a particular technique for evaluating data concerning friction in the San Andreas Fault.
(D) suggested that geologists had inaccurately assumed that giant rock that meet at the San Andreas Fault general heat through friction.
(E) confirmed geologists' assumptions about the amount of friction generated by the common varieties of rocks, such as limestone and granite.

First of all, look at that first sentence. Before Henyey, there were just assumptions, no measurements of any kind. Then, Henyey comes along, makes what appears to be the first relevant measurement, and the data gathered contradicts the assumptions.

(A) revealed an error in previous measurements of the temperature in the San Andreas Fault zone.
So far as we can tell from the passage, there were no previous measurements. We know scientists had assumptions (not measurements), and then when Henyey finally made a measurement in 1965, they contradicted the assumptions. Presumably, if someone else had made a measurement previous to Henyey, that scientist also would have found data that contradicted the prevailing assumption, so the fact that didn't happen strongly implies Henyey's is the first measurement. [spoiler](A) = wrong[/spoiler]
(B) indicated the types of clay present in the rocks that form the San Andreas Fault.
Problem #1: The whole discussion of rock vs. clay is one that emerges after Henyey's measurements, as a way of explaining what Henyey measured. Problem #2: Clay was an explanation that some scientists floated, but it appears not to have been confirmed. Originally, folks thought clay would explain the lower amount of heat due to friction, but that turned out to be an invalid assumption (that's what the second paragraph shows). By the end of the passage, it's simply not clear that the rock in the San Andreas Fault is clay, so stating "clay present in the rocks that form the San Andreas Fault" as fact is unwarranted. [spoiler](B) = wrong[/spoiler]
(C) established the superiority of a particular technique for evaluating data concerning friction in the San Andreas Fault.
As explained above, it appears that Henyey was the first to make these measurements. It's not that other people tried to measure it and didn't so as good a job, and then Henyey did a better job (if that's the case, there's absolutely zero evidence for it in the passage). The passage seems to suggest that folks simply had guesses, assumptions, and then Henyey performed a measurement. It's true, in science, measuring is superior to assuming, but that doesn't warrant the description "the superiority of a particular technique for evaluating." [spoiler](C) = wrong[/spoiler]
(D) suggested that geologists had inaccurately assumed that giant rock that meet at the San Andreas Fault general heat through friction.
Here, we have that Henyey "suggested" (through his data) that the previous assumptions were inaccurate. That's exactly what the first sentence conveys. [spoiler](D) = correct[/spoiler]
(E) confirmed geologists' assumptions about the amount of friction generated by the common varieties of rocks, such as limestone and granite.
This one says, more or less, the opposite of what Henyey discovered. According to scientists models, when rocks like limestone or granite grind against each other, they produce a certain amount of heat --- this model was the basis of the pre-1965 assumptions. Henyey's 1965 data did not confirm those assumptions --- rather, it contradicted them. Furthermore, after Henyey, the composition of rocks was called into question, and (according to the second paragraph), it seems that friction would be the same regardless of composition, so by the end of the passage, the composition of the rocks is not clear at all. Therefore, according to the passage, any measurement of what's going on at the San Andreas Fault cannot be construed as having implications for rocks of a particular composition. [spoiler](E) = wrong[/spoiler]

Is all that clear? Please let me know if you have any further questions.

Mike

Mike@Magoosh wrote:Dear Bryan88,

I'm happy to answer your question.

I agree with GmatKiss's answer. Here's my explanation.

The first sentence of the passage says:
Prior to 1965 geologists assumed that the two giant rock plates meeting at the San Andreas Fault generate heat through frictions as they grind past each other, but in 1965 Henyey found that the temperatures in drill holes near the fault were not as elevated as had been expected.

The question:
6) According to the passage, Henyey's findings in 1965 were significant because they
(A) revealed an error in previous measurements of the temperature in the San Andreas Fault zone.
(B) indicated the types of clay present in the rocks that form the San Andreas Fault.
(C) established the superiority of a particular technique for evaluating data concerning friction in the San Andreas Fault.
(D) suggested that geologists had inaccurately assumed that giant rock that meet at the San Andreas Fault general heat through friction.
(E) confirmed geologists' assumptions about the amount of friction generated by the common varieties of rocks, such as limestone and granite.

First of all, look at that first sentence. Before Henyey, there were just assumptions, no measurements of any kind. Then, Henyey comes along, makes what appears to be the first relevant measurement, and the data gathered contradicts the assumptions.

(A) revealed an error in previous measurements of the temperature in the San Andreas Fault zone.
So far as we can tell from the passage, there were no previous measurements. We know scientists had assumptions (not measurements), and then when Henyey finally made a measurement in 1965, they contradicted the assumptions. Presumably, if someone else had made a measurement previous to Henyey, that scientist also would have found data that contradicted the prevailing assumption, so the fact that didn't happen strongly implies Henyey's is the first measurement. [spoiler](A) = wrong[/spoiler]
(B) indicated the types of clay present in the rocks that form the San Andreas Fault.
Problem #1: The whole discussion of rock vs. clay is one that emerges after Henyey's measurements, as a way of explaining what Henyey measured. Problem #2: Clay was an explanation that some scientists floated, but it appears not to have been confirmed. Originally, folks thought clay would explain the lower amount of heat due to friction, but that turned out to be an invalid assumption (that's what the second paragraph shows). By the end of the passage, it's simply not clear that the rock in the San Andreas Fault is clay, so stating "clay present in the rocks that form the San Andreas Fault" as fact is unwarranted. [spoiler](B) = wrong[/spoiler]
(C) established the superiority of a particular technique for evaluating data concerning friction in the San Andreas Fault.
As explained above, it appears that Henyey was the first to make these measurements. It's not that other people tried to measure it and didn't so as good a job, and then Henyey did a better job (if that's the case, there's absolutely zero evidence for it in the passage). The passage seems to suggest that folks simply had guesses, assumptions, and then Henyey performed a measurement. It's true, in science, measuring is superior to assuming, but that doesn't warrant the description "the superiority of a particular technique for evaluating." [spoiler](C) = wrong[/spoiler]
(D) suggested that geologists had inaccurately assumed that giant rock that meet at the San Andreas Fault general heat through friction.
Here, we have that Henyey "suggested" (through his data) that the previous assumptions were inaccurate. That's exactly what the first sentence conveys. [spoiler](D) = correct[/spoiler]
(E) confirmed geologists' assumptions about the amount of friction generated by the common varieties of rocks, such as limestone and granite.
This one says, more or less, the opposite of what Henyey discovered. According to scientists models, when rocks like limestone or granite grind against each other, they produce a certain amount of heat --- this model was the basis of the pre-1965 assumptions. Henyey's 1965 data did not confirm those assumptions --- rather, it contradicted them. Furthermore, after Henyey, the composition of rocks was called into question, and (according to the second paragraph), it seems that friction would be the same regardless of composition, so by the end of the passage, the composition of the rocks is not clear at all. Therefore, according to the passage, any measurement of what's going on at the San Andreas Fault cannot be construed as having implications for rocks of a particular composition. [spoiler](E) = wrong[/spoiler]

Is all that clear? Please let me know if you have any further questions.

Mike