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Mike@Magoosh
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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
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
Magoosh GMAT Instructor
https://gmat.magoosh.com/
https://gmat.magoosh.com/
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samirnajeeb
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A is in fact the OA. passage indicates that scientists did indeed measure. it states "Geologists' pre-1965 assumptions .. based on calculations".
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alex.gellatly
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Are you the creator of the question? How can you state that your opinion is the OA? Remember OA = Official Answer. And actually look at the document. The correct answer is D, as stated by GMAC. Therefore D is the OAsamirnajeeb wrote:A is in fact the OA. passage indicates that scientists did indeed measure. it states "Geologists' pre-1965 assumptions .. based on calculations".
A useful website I found that has every quant OG video explanation:
https://www.beatthegmat.com/useful-websi ... tml#475231
https://www.beatthegmat.com/useful-websi ... tml#475231
Hello 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
passage already says that rocks generate heat through friction. only thing is the amount of heat generated is not optimum. then,why D mentions that it was an inaccurate assumption that "plates generate heat through friction"?
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Mike@Magoosh
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Dear Buoyant,buoyant wrote:Hello Mike!
passage already says that rocks generate heat through friction. only thing is the amount of heat generated is not optimum. then,why D mentions that it was an inaccurate assumption that "plates generate heat through friction"?
I'm happy to respond.
The second sentence quite clearly cites "the absence of friction-generated heat" as something compelling that needs to be explained. In other words, Henyey gave evidence for "the absence of friction-generated heat." It's not just that the friction was making some heat, just less than expected. It's that Henyey's data forced them to understand "the absence of friction-generated heat."
Does this make sense?
Mike
Magoosh GMAT Instructor
https://gmat.magoosh.com/
https://gmat.magoosh.com/
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Mike@Magoosh
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My friend, I'm not sure what else to say. If the passage itself says there was zero friction-generated heat, then we have to take that as true. That's why it was deemed inaccurate to assume that "plates generate heat through friction," because there is no heat created by friction at these faults.buoyant wrote:Thank you for the response Mike.
I am still not clear on this
Please help.
I would strongly suggest that you go back to the passage and find this exact line, in the second sentence of the passage.
Does this make sense?
Mike
Magoosh GMAT Instructor
https://gmat.magoosh.com/
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Hi Mike,
i get what you say. I have very much read the sentence you are talking about.
This is exactly what my query is.
Don't you find the following two sentences contradictory?
1)Henyey found that temp was not as elevated as assumed by the geologists prior to 1965
2)Some geologists wondered whether the absence of friction-generated heat could be explained by...
Moreover, rest of the passage discusses the factors that can affect the frictional heating.
Do i have some understanding gap?
i get what you say. I have very much read the sentence you are talking about.
This is exactly what my query is.
Don't you find the following two sentences contradictory?
1)Henyey found that temp was not as elevated as assumed by the geologists prior to 1965
2)Some geologists wondered whether the absence of friction-generated heat could be explained by...
Moreover, rest of the passage discusses the factors that can affect the frictional heating.
Do i have some understanding gap?
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Mike@Magoosh
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Dear buoyantbuoyant wrote:Hi Mike,
i get what you say. I have very much read the sentence you are talking about.
This is exactly what my query is.
Don't you find the following two sentences contradictory?
1)Henyey found that temp was not as elevated as assumed by the geologists prior to 1965
2)Some geologists wondered whether the absence of friction-generated heat could be explained by...
Moreover, rest of the passage discusses the factors that can affect the frictional heating.
Do i have some understanding gap?
First of all, I do not find the sentences directly contradictory. There is something paradoxical, that needs a little thought to resolves --- that's precisely what makes this a good GMAT passage: it doesn't just hand the information to you on a silver platter. You have to engage with it and really think about it.
Suppose, when we drill down into the Earth, there is some other kind of heat present in the background. Maybe we are getting close to the lava of the Mantle. Maybe there's some radioactive kind of heat, who knows? We don't need to know the nature of this other background heat. Scientists would be expected this type of heat already. In addition to this, they also assumed the plates would make friction-based heat, more heat than the typical background heat found everywhere. Then, when Henyey drilled down at the fault line, he found only the typical background heat, not the friction-heat plus the background heat. Thus, it would be perfectly correct to say
1) Henyey found that the temperature was not as elevated as assumed by the geologists prior to 1965
2) Some geologists wondered whether the absence of friction-generated heat could be explained by...
Thus, there actually was heat there, the ordinary background heat, just not the extra friction-based heat they were also expecting. That would reconcile both sentences.
That's one way to resolve the paradox, not necessarily the only way. This is just one example of a possible assumption that would reconcile an apparent contradiction in the text. You have to assume that a GMAT RC passage is not actually contradicting itself, so anything like this demands some kind of assumption that resolves the apparent paradox.
Notice, that the rest of the paragraph is not exactly about frictional heating. It's about resolving a discrepancy --- how can plates move against each other (presumably with rocks rubbing) and yet not create frictional heating. Essentially, since Henyey's work, scientists are trying to answer the question, "Why is there no frictional heat at the fault lines?" That's not the same as being about "frictional heat" itself.
Does all this make sense?
Mike
Magoosh GMAT Instructor
https://gmat.magoosh.com/
https://gmat.magoosh.com/
awesome explanation 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
