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GMATPrep Reading Comp: Tackling a Science Passage - Part 3
In the first installment of this series, I gave you a Science RC passage and three problems from the GMATPrep free exams. If youre just starting here, go through parts 1 and 2 first, then come back to this one!
Here are the passage and the third problem.
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.
According to the passage, Henyey's findings in 1965 were significant because they
(A) revealed an error in previous measurements of 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 plates that meet at the San Andreas Fault generate heat through friction
(E) confirmed geologists' assumptions about the amount of friction generated by common varieties of rocks, such as limestone and granite
First, what kind of question is this one?
The according to the passage language almost always signals a specific detail question; theyre asking you to find something that the passage directly said. Check the wording of the rest of the question to confirm that this really is what they want yep, the passage gave some reason why Hs 1965 findings were significant and we have to find that reason.
Where to look? Let me glance at my Map:
(P1) Pre-65, G: RPs heat via friction
65, H: not so hot
Why? Type of rock? Less L and G, more C? C = less friction
(P2) 92, B test: C same friction w/pressure. > press > heat
water reduce friction?
Right, H was in the first paragraph. Okay, lets dive back into that text.
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.
Put that in your own words. There was this theory that the rock plates generated heat through friction, but Hs experiment showed that the temperatures werent actually as high as they should have been if the theory were true. In other words, Hs results showed that the theory didnt match reality.
Which answer choice matches that idea?
(A) revealed an error in previous measurements of temperature in the San Andreas Fault zone
The passage doesnt mention any prior measurements or experiments of any kind. Hs experiment is the earliest one discussed. Eliminate (A).
(B) indicated the types of clay present in the rocks that form the San Andreas Fault
Hs experiment showed only that the first theory wasnt a good one. The geologists then came up with a new hypothesis to try to explain Hs results. But Hs results didnt prove anything for that new hypothesisrather, Hs results just disproved the old one. Eliminate (B).
(C) established the superiority of a particular technique for evaluating data concerning friction in the San Andreas Fault
Superiority implies a comparison, but the passage doesnt mention multiple technique[s] for evaluating data concerning friction. It mentions only Hs experiment. Theyre not saying Hs way was better than another way; theyre saying that Hs experiment showed that the first theory wasnt right. Eliminate (C).
(D) suggested that geologists had inaccurately assumed that giant rock plates that meet at the San Andreas Fault generate heat through friction
This is it! If the theory (that the plates generated heat through friction) were true, then H should have found higher temperatures. He didnt, so the theory wasnt accurate.
(E) confirmed geologists' assumptions about the amount of friction generated by common varieties of rocks, such as limestone and granite
This is a trap! The passage says the exact opposite: Hs results disproved the geologists first assumption; that's why they had to change their original hypothesis. Eliminate (E).
The correct answer is (D).
Phew. Thats it. Lets summarize the entire process for RC.
Read the passage, jotting down a Passage Map as you go. Dont get into all of the detail; the goal of your Map is to tell you what the high level ideas are. The GMAT is an open book testyou can go back into the passage at any time to look up any detail you might need.
When youre done reading and jotting, articulate the basic story to yourself.
Next, look at the question. Your first task is to identify the question type. That will help you to know what kind of analysis you need to do in order to answer the question.
Second, find the proof. Figure out what you need to re-read in the passage in order to answer the question. (Do NOT skip this step. Do NOT rely on your memory. Be systematic: Re-read the needed material.)
Third, read that text and, if possible, use it to formulate your own answer to the question. Your wording almost certainly wont match the wording of the correct answer, but thats fine. Youre just trying to make clear to yourself the general message you want to see in the correct answer.
Fourth, eliminate wrong answers and find a match!
Look at how much work comes before you get to look at the answers. Figure out whats going on with the question first and youll have an easier time processing the answers.
Key Takeaways for RC
(1) Follow the process. Dont skip steps!
(2) On your read-through, go for the big ideas and the main contrasts or twists. Dont get sucked into annoying detail. Jot down an abbreviated Map to help you navigate the passage later, when youre answering questions. By the time youre done, you will (hopefully!) be able to articulate the Simple Story of the passage.
(3) Know what kind of question type you have, as each type is asking you to perform a different kind of analysis. Find the proof text in the passage (or in your Map) and try to articulate what you want the correct answer to say before you look at the answer choices. Finally, work from wrong to right: cross off the wrong answers until you (hopefully!) have just one left.
* GMATPrep questions courtesy of the Graduate Management Admissions Council. Usage of this question does not imply endorsement by GMAC.
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