At several locations on the northwest coast of North Americ

Question

At several locations on the northwest coast of North America are formations known as chevrons—wedge-shaped formations of mounded sediment—pointing toward the ocean. Most geologists take them to have been formed by erosion, but recently other scientists have proposed that they were thrown up from the ocean by massive waves triggered by meteor impacts in the Pacific Ocean.

Which of the following, if discovered, would most help in deciding which hypothesis is correct?

A) Chevron-like structures which are not currently near glaciers, large rivers, or other bodies of water

B) The presence, in chevrons, of deposits of ocean microfossils containing metals typically formed by meteor impacts

C) Oral-history evidence for flooding that could have been caused by ocean waves

D) The fact that exact data about the location and depth of any meteor impact craters on the Pacific seabed is lacking

E) The fact that certain changes in the shape and location of maritime sand dunes have been produced by the action of wind and waves

ID: 500329
CR59590.02

KarishmaB · Accepted Answer

Phenomenon - Wedge shaped structures on the coast.

Hypothesis 1 - Erosion formed these (perhaps the impact of the waves on rocks)
Hypothesis 2 - Thrown up from oceans by meteor impact

The presence of what will help in deciding which hypothesis is correct (strong support for one and weaken the other)

A) Chevron-like structures which are not currently near glaciers, large rivers, or other bodies of water

If we find similar structures away from water bodies, it doesn't support either hypothesis. Both hypotheses are based on impact of water or water bodies. Since such structures would have been found far from water bodies, they would support neither hypothesis. 
Since hypothesis 1 doesn't specifically say 'erosion by water,' we could imagine erosion being wind erosion but then "wedge-shaped formations of mounded sediment—pointing toward the ocean" doesn't make sense. It ought to have something to do with ocean. So not convincing at all.

B) The presence, in chevrons, of deposits of ocean microfossils containing metals typically formed by meteor impacts
 
Chevrons have ocean microfossils (so likely they came out of the ocean) and they contain metals formed by meteor impact then it seems that meteor impact caused them to come out of the ocean. This strongly supports hypothesis 2 and also weaken hypothesis 1. If they were rocks on the coast and were formed by erosion by waves, how would they contain ocean microfossils? Hence, it helps us in deciding which hypothesis is correct.

C) Oral-history evidence for flooding that could have been caused by ocean waves
 
The moment we read 'oral history,' this option should be frowned upon. Oral history is narrated history by a person as per his/her impressions. This becomes more like 'opinion' than a 'fact.' So will it provide evidence? I am already doubtful.

D) The fact that exact data about the location and depth of any meteor impact craters on the Pacific seabed is lacking
 
A lack of data is not evidence. Perhaps it is there but has not been found yet. Perhaps there is none but it actually did happen.

E) The fact that certain changes in the shape and location of maritime sand dunes have been produced by the action of wind and waves
 
No comparison is given between chevrons and sand dunes. We don't know whether they are similar in any way so any data about sand dunes doesn't help us.

Answer (B)

arvind910619 · Answer

Imo B.

Hypothesis 1 - formed by erosion
Hypothesis 2 - they were thrown up from the ocean by massive waves triggered by meteor impacts in the Pacific Ocean.

Now we have find the necessary information from the answer choices that can help in deciding which hypothesis is correct.

A - Chevron-like structures does not necessarily mean that Chevron actually formed in distant places. It may also be the case that lake or river once existed and in time disappeared. Any how we can not decide so just drop it.

B- Correct If presence of deposits of ocean microfossils containing metals typically formed by meteor impacts then it certainly points out that Hypothesis 2 is correct.

C - Oral history can not the basis for scientific discover. There can be many interpretations.

D - While it does negate hypothesis 2, but that does not mean that hypothesis 1 is correct.

Negation of one hypothesis does not mean that the other hypothesis is correct. This is not a casual relationship.

E - This option suggests that Chevron formation was the result of both wind and waves. It certainly does not help our case.

I think my reasoning for dropping A is somewhat limited. 
I would like some expert to validate my reasoning.

CrackverbalGMAT · Answer

Pre-thinking:

We have two hypotheses here:

Hypothesis 1: Chevrons were formed by erosion
Hypothesis 2: Chevrons were thrown up from the ocean by massive waves triggered by meteor impacts in the Pacific Ocean.

Let us consider the options:

A) Chevron-like structures which are not currently near glaciers, large rivers, or other bodies of water  This could indicate that chevrons  need not always be  thrown up by big waves. However, this also could also act against the erosion hypothesis, since there are no water bodies nearby. In the minimum, there is no support for the erosion hypothesis. Eliminate.

B) The presence, in chevrons, of deposits of ocean microfossils containing metals typically formed by meteor impacts  This provides strong support for both aspects of hypothesis 2. Ocean microfossils indicate that the chevrons may have come from the ocean and the metals indicate that they could have been formed of material formed by meteor impacts. Correct answer.

C) Oral-history evidence for flooding that could have been caused by ocean waves  While this could be evidence for large waves, this does not indicate in any way that these waves did bring the chevrons. Additionally there is no support for any meteor impacts in this option. We could consider the large waves as indicating some erosion, but it is weak evidence at best. Eliminate.

D) The fact that exact data about the location and depth of any meteor impact craters on the Pacific seabed is lacking  This does not provide any support for the meteor-wave hypothesis, nor for the erosion hypothesis. Eliminate.

E) The fact that certain changes in the shape and location of maritime sand dunes have been produced by the action of wind and waves  This indicates erosion  as a possible cause  only, but that is a fact already considered (since it was earlier hypothesized). There is no evidence in this option that  these chevrons  were formed by erosion. Eliminate.

Hope this helps.

NiftyNiffler · Answer

At several locations on the northwest coast of North America are formations known as chevrons—wedge-shaped formations of mounded sediment—pointing toward the ocean. Most geologists take them to have been formed by erosion, but recently other scientists have proposed that they were thrown up from the ocean by massive waves triggered by meteor impacts in the Pacific Ocean.

Which of the following, if discovered, would most help in deciding which hypothesis is correct?

Pre-thinking: We have to apply yes/no answers to the options and see if it strengthens and weakens the hypothesis correctly. We have two alternatives here. One set of geologists who think chevrons are formed by erosion and the other set who think meteor impact is the cause.

A) Chevron-like structures which are not currently near glaciers, large rivers, or other bodies of water  -- This has no link to the meteor theory, on which the conclusion of the hypothesis is based.
 
B) The presence, in chevrons, of deposits of ocean microfossils containing metals typically formed by meteor impacts  -- CORRECT, if microfossil deposits are found on chevron, then it strengthens the hypothesis, if not we believe what most geologists believe that erosion is the cause.

C) Oral-history evidence for flooding that could have been caused by ocean waves  -- IRRELEVANT, doesn't have any link to the meteor theory as well
 
D) The fact that exact data about the location and depth of any meteor impact craters on the Pacific seabed is lacking  -- There could be other data that could corroborate the meteor hypothesis or with newer technology, data could be found. Lot of missing info here.

E) The fact that certain changes in the shape and location of maritime sand dunes have been produced by the action of wind and waves  -- This is outside info, neither related to erosion or meteor theory.

Answer is  B

MikeScarn · Answer

Between A and B

Notice (A) says " Chevron-like structures ". So, these structures that were found that are not near bodies of water are only  similar  to chevron structures. They're not necessarily actual chevrons.

Irrelevant!

In (B), we're told that deposits of  ocean microfossils  containing metals that are formed due to  meteor impacts  are found within chevrons.

This strengthens the other scientists' hypothesis! The chevrons have ocean microfossils and remnants of meteors.

Correct

dadele · Answer

Hi, could an expert please elaborate on how did we determine that the given question stem was that of a paradox question. "Which of the following, if discovered, would most help in deciding which hypothesis is correct?" This seems to suggest that we need to find an option that provides us with a conclusive evidence that would help us choose one hypothesis and drop the other.

AndrewN · Answer

Hello,  dadele . I am not sure how the idea came about that the above question is a paradox type. According to the OG, there are nine different types of CR questions. This one comfortably fits into the category  Evaluating hypotheses . In fact, the  skill  that is supposedly taxed in such questions is the  ability to identify a hypothesis that most plausibly explains the occurrence of a phenomenon or event . That sounds a lot like what we are being asked to do, regarding the chevrons and the competing hypotheses. Meanwhile, a paradox question fits into the category  Resolving apparent inconsistency , defined as the  ability to reconcile two apparently conflicting states of affairs . I can see how that might seem confusing, but at the same time, our goal in this question is not to  reconcile  the hypotheses, but to evaluate what would tilt the balance in favor of one over the other. Although labeling a question to fit a certain mold can prove somewhat useful, such a method does not beat a tried-and-true approach in which you read the question and passage carefully and stick to the keywords to make sure that everything is in alignment, whatever the question may look like.

Good luck with your studies.

- Andrew

dadele · Answer

Thanks for your response, Andrew. This question has been tagged as a paradox one on GmatClub.

When I attempted the question, I also tried to look for a response that would tilt the explanation to one of the two hypotheses, and hence chose option A. However, the correct answer is B, which seems to be resolving the contradiction, as against tiling the argument towards a side.

Posted from my mobile device

AndrewN · Answer

Sorry, I cannot see the tags if they are supposed to appear somewhere on this page. I think that if this question has been tagged a paradox, it could be a misattribution. As for (A), my thinking fell in line with that of  MikeScarn  above: the passage says nothing about  chevron- like   structures, so that information cannot tilt the balance one way or the other. It is a well-designed trap, nothing more. A paradox question, in my mind, involves putting two pieces of information together that seem to be mutually exclusive, and the goal is then to explain how that synthesis was achieved. If this were indeed a paradox question, I would expect an answer choice that somehow incorporated both  erosion  and  massive waves triggered by meteor impacts . No such answer is present. It is not a huge issue either way, but again, I would look to follow the reasoning of the passage more than a label to answer whatever question was being asked.

- Andrew

kovid231 · Answer

At several locations on the northwest coast of North America are formations known as chevrons—wedge-shaped formations of mounded sediment—pointing toward the ocean. Most geologists take them to have been formed by erosion, but recently other scientists have proposed that they were thrown up from the ocean by massive waves triggered by meteor impacts in the Pacific Ocean.

Which of the following, if discovered, would most help in deciding which hypothesis is correct?

Evaluate the argument question needs an answer choice which if proven true swings the conclusion in one direction and if proven wrong, swings the conclusion in the opposite direction.

Let's look at the crystallising the sentence above.
There are Chevrons around the NW coast. 
One set of scientists say this was formed by erosion
the other set says these were massive waves because of meteor impacts that threw them.

Let's look the answer options. I like to give them 2 reads, as the first one lets me negate all obviously incorrect answers. and then I can look at the closely related answers. What this allows me to do sometimes, since I go in expecting that I will have 2 really strong answer choices which will be really tough to negate, my mindset becomes of someone who is ruthlessly negating all obviously incorrect answers, it sometimes leaves me with one answer choice too.

A) Chevron-like structures which are not currently near glaciers, large rivers, or other bodies of water

Okay, looks like a good option. Let's keep this and look at more obviously incorrect ones.

B) The presence, in chevrons, of deposits of ocean microfossils containing metals typically formed by meteor impacts

Okay, looks like a good option. Let's keep this and look at more obviously incorrect ones.

C) Oral-history evidence for flooding that could have been caused by ocean waves
- This won't help us evaluate the argument. Imagine there is no oral history of ocean waves, does that mean erosion caused it?

D) The fact that exact data about the location and depth of any meteor impact craters on the Pacific seabed is lacking
- Both are hypothesis that were presented, the presence of evidence can be used more conclusively to prove which is correct more than the absence of evidence. We don't have any information about the other point of view either. 
Again, look at it like this, if we don't have exact data on location and depth of meteor impact craters, does that mean Chevron appeared because of erosion?

E) The fact that certain changes in the shape and location of maritime sand dunes have been produced by the action of wind and waves
-This is out of scope.

Let's look at the 2 shortlisted option now.

A) Chevron-like structures which are not currently near glaciers, large rivers, or other bodies of water

okay, so on closer examination we can see a few flaws in these.
1. Chevron-like structures and actual chevrons are different, finding something resembling Chevron shouldn't be a clue for anything
2. Let's still look if there is any other flaw in this.: What if we don't find Chevron like structures near other water bodies, does that mean the Chevrons appeared because of erosion?

Let's also look at the other option.

B) The presence, in chevrons, of deposits of ocean microfossils containing metals typically formed by meteor impacts
1. Okay, so we checked the chevrons and found microfossils containing metals typically formed by meteor impacts, that would mean there was a meteor impact and would sway the decision in one direction
2. And on exception we find there aren't any microfossils, that will sway the decision in the other direction.

Hence B is the correct answer.

VerbalBot · Answer

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At several locations on the northwest coast of North Americ

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At several locations on the northwest coast of North Americ

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