Q4

[catie0128]

I see how B is correct but, why is E incorrect?

[Nathen.Alan]

E goes too far by saying that lichenometry's usefulness is limited. If you look back at lines 54-58, the passage says that conditions affecting normal lichen growth must be factored in. So we can conclude from this that lichenometry is still useful in these circumstances, & that any shortcomings simply must be accounted for.

[legalrabbithole]

Hm...I also chose E.

I agree with the above poster's reasoning for why (E) is incorrect. At first, I thought (E) was wrong because it didn't account for the 500 year range, but I see now that (E) stretched the facts a bit too far by stating that the lich method could only be used in places where factors didn't affect their growth. When in fact, the researchers simply said that those factors needed to be taken into account.

I think I was fooled by (E) because it was directly quotable from the passage whereas (B) was an unstated inference based on what we know about radiocarbon dating. Need to be more observant next time!

[ltong0529]

I still don't understand why (B) is right and (E) is wrong. The only place I see fault lines mentioned is the first sentence: "To study centuries-old earthquakes...seismologists usually dig trenches along visible fault lines..." It only says that seismologists USUALLY dig trenches on visible fault lines but no where in that sentence does it say that that has to be the case.

On the other hand, the sentence that relates to (E) is that 50-54 where it says "...using lichenometry requires careful site selection..." etc. The word "requires" is what stands out to me. Shouldn't that indicate that any situation that doesn't meet that requirement limits the usefulness of lichenometry?

Thanks in advance.

[ManhattanPrepLSAT1]

I agree that this is not a great question. I think they could have been more clear when writing it.

Nathen.Alan had it correct in his reason for eliminating answer choice (E) - it simply goes too far. We know that those affects listed in the final paragraph have to be factored in, but we cannot say that lichenometry's usefullness would be of limited to areas where those affects do not occur.

The reason why answer choice (B) is supported is that radiocarbon dating works by dating organic matter - which is described in the first paragraph. It simply is a way of dating an event that we know of. But without a known fault line, we would simply be dating organic material located at a place but would not be able to connect that date in any way to an earthquake.

Hope that helps!

[zainrizvi]

(A) is unsupported by the passage, right? Since it never discusses lichenometry being used to predict something in the future.

[ttunden]

(A) is unsupported by the passage, right? Since it never discusses lichenometry being used to predict something in the future.

Yes, prediction was never stated about Lichenometry. The passage only mentioned radiocarbon dating as being able to provide hints about future earthquakes. This is a most strongly supported questions so there has to be some support. A doesn't have any so eliminate.

C too strong. the only viable!? passage doesn't implicate this.
D no support. for Lichenometry we know it is best used for earthquakes that occurred within the last 500 years so 400 years leaves some room for this answer to be wrong. Moreover, We don't know when it is best to use radiocarbon dating. For all we know, it could be best used for earthquakes that occurred 100 years ago. NO support for this so eliminate.

E tricky choice. last sentence refutes this thought because it says you should factor conditions that promote growth(so the accelerate part of answer choice E) and then last sentence also says minimize the influence of disturbances that disturb the growth(slow it down)

so this choice is contradictory to the passage.
we are left with B which can be proven from the 1st paragraph. We know it is usually used for earthquakes along visible fault lines. If they did not occur on a visible fault line its not likely to be of much use. Can safely infer this from the 1st paragraph. If uncertain, you should work wrong to right as that may help.

[mxl392]

Just because visible fault lines are sufficient for radiocarbon dating, we can't assume that they're necessary, right?

Answer choice B states that fault lines are necessary for radiocarbon dating. Where is the support for this? What if there are other ways to determine where fault lines are without eye-sight, can't we still use radiocarbon dating?

[gaheexlee]

Just because visible fault lines are sufficient for radiocarbon dating, we can't assume that they're necessary, right?

Answer choice B states that fault lines are necessary for radiocarbon dating. Where is the support for this? What if there are other ways to determine where fault lines are without eye-sight, can't we still use radiocarbon dating?

B actually does not state anything to that extremity. The relative weakness of answer B's wording allows it to be the correct answer. Notice how it says "radiocarbon dating is unlikely to be helpful," not "will not be helpful" as your description of B implies.

Be careful to not generalize the answer choices! Be intentional with your interpretations as the writers also likely chose the words they did with specific intent.

[mahamkhan0208]

I see how B is correct but, why is E incorrect?

(E) Refer to paragraph 3 regarding outside factors which disturb lichen growth. It suggests that these disturbances must be factored in when dating an earthquake. It does not state that due to these disturbances, past earthquakes can not be dated; as suggested by this answer choice.

So, (E) is wrong because it is an incorrect degree opinion.

[jrnlsn.nelson]

I still don't understand why (B) is right and (E) is wrong. The only place I see fault lines mentioned is the first sentence: "To study centuries-old earthquakes...seismologists usually dig trenches along visible fault lines..." It only says that seismologists USUALLY dig trenches on visible fault lines but no where in that sentence does it say that that has to be the case.

I completely agree ltong0529. I usually end up capitulating to the lsat makers after pondering the answer that they deem correct. Yet, this question is an exception. (B) is never fully supported by the passage, as ltong0529 indicates. Furthermore, (E) seems to be clearly expressed multiple times in the last paragraph:

"They note, however, that using lichenometry REQUIRES careful site selection and accurate calibration of lichen growth rates...Sites MUST be selected to minimize the influence of snow avalanches and other disturbances that would affect normal lichen growth..."

(E) says:

"The usefulness of lichenometry for dating earthquakes is limited to geographic regions where factors that disturb or accelerate lichen growth GENERALLY do not occur."

For me, the word "generally" softens (E) and thus makes it more appealing. If "generally" was omitted I would have chosen (B), but it's not! (E) definitely seems like its more "strongly supported" than (B).

[mornincounselor]

My issue is between choices A and B.

A. In P1 it is states that RC dating can "provide hints about the likelihood and location of future earthquakes." As it is described in the passage Lichenometry cannot possibly predict the location or likelihood of future quakes as the lichens appear only after the quakes. Then it would seem A is supported by the passage.

For B, the word "usually" can cause some confusion. If we think of that first sentence as "RC dating is usually done by studying visible fault lines" this would lead one to believe the fault lines do not need to be visible for us to RC date. This interpretation would allow us to eliminate B. Of course, the first sentence instead tells us that "Usually scientists use this RC dating, which requires a visible fault line, but this new method . . ."

Overall I think the question is hard because I cannot 100% eliminate A and as I attempt to conclusively eliminate one choice it leads one to misinterpret the key sentence for choice B.

[jasonleb1]

I still don't understand why (B) is right and (E) is wrong. The only place I see fault lines mentioned is the first sentence: "To study centuries-old earthquakes...seismologists usually dig trenches along visible fault lines..." It only says that seismologists USUALLY dig trenches on visible fault lines but no where in that sentence does it say that that has to be the case.

I completely agree ltong0529. I usually end up capitulating to the lsat makers after pondering the answer that they deem correct. Yet, this question is an exception. (B) is never fully supported by the passage, as ltong0529 indicates. Furthermore, (E) seems to be clearly expressed multiple times in the last paragraph:

"They note, however, that using lichenometry REQUIRES careful site selection and accurate calibration of lichen growth rates...Sites MUST be selected to minimize the influence of snow avalanches and other disturbances that would affect normal lichen growth..."

(E) says:

"The usefulness of lichenometry for dating earthquakes is limited to geographic regions where factors that disturb or accelerate lichen growth GENERALLY do not occur."

For me, the word "generally" softens (E) and thus makes it more appealing. If "generally" was omitted I would have chosen (B), but it's not! (E) definitely seems like its more "strongly supported" than (B).

I agree with all of this. I am just not seeing how B is supported in the least. The passage says these visible fault lines are sufficient for the production of shifted sediments which can then be analyzed by radiocarbon dating. Nowhere does it say visible fault lines are necessary nor does it exclude the possibility that radiocarbon dating can be used to study other shifted sediments or be otherwise useful in dating past earthquakes.

I chose E for the same reasons jrnlsn.nelson did. Can someone go into more detail to clear this up please?

[maryadkins]

Ick.

Well, I don't love (B) either.

I, would however, offer that (E) is still more of a stretch than (B). According to lines 54-58, factors that change lichen growth rates can be adjusted (minimizing/addressing factors that affect lichen growth). This portion of the passage would seem to contradict (E)'s assertion that the usefulness of lichenometry is limited to areas without these factors, because otherwise it wouldn't make sense for the passage to discuss how the factors can be addressed such that lichenometry can still be used.

[abrenza123]

I am confused as to how we can assume that radiocarbon dating is unlikely to be useful w/o fault lines - it just seems to be an assumption/stretch that it is unlikely to be helpful. Why can't it be useful when applied to other methods/features of the earthquake?

also, I understand that "usefulness" is strong but I thought that the last sentence was saying sites must be selected to minimize snow/disturbances that affect growth AND other factors promoting growth should also be factored in to site selection. I was confused as to what the dangling preposition was in reference to - the site selection or the accurate calibration? If those things shoudl be factored into site selection, wouldn't they impact the usefulness of lichenometry at a given site?

[ohthatpatrick]

I agree that the support for (B) is pretty weak. The question stem isn't saying "what MUST BE TRUE", so the standard of being right is simply that it's MORE supportable than any other answer.

The softness of "unlikely to be helpful" is important. It's just doing a little bit of speculating. Given that what we heard about radiocarbon dating involved figuring out how old things were that caught in the shifting sediments of visible fault lines, we have SOME grounds for thinking that if we didn't have visible fault lines, we wouldn't do any digging, we wouldn't see where the sediments had shifted underground, and so there would be nothing to date.

Lines 15-22 also helps a bit. These guys have developed "a new model for dating past earthquakes", which suggests that the model for dating past earthquakes we learned about in the first paragraph might be are only other option. "Instead of dating fault-line sediments, lichenometry ...."

Your concern was that maybe there are other uses for radiocarbon dating when it comes to dating past earthquakes, but the way lichenometry is being presented, it's suggesting that we really only have these two viable plans so far:
1. date fault-line sediments?
or
2. measure the growth of lichens on rockfalls?

The strong wording of (E) is that "usefulness IS LIMITED TO" certain types of areas.

In other words, (E) is saying
If you're not in a geographic region that is generally free of factors that disturb or accelerate lichen growth, then lichenometry is not useful for dating earthquakes.

In order for lichenometry to be useful for dating earthquakes, you need to be in a geographic region that is generally free of factors that disturb or accelerate lichen growth.

There is NEGATIVE support for this in the final sentence (i.e. text that goes AGAINST this answer).

The passage makes it seem like lichenometry COULD still be useful in a geographic region that had shade and wind (factors that accelerate lichen growth). It seems to be saying that when we're doing lichenometry in these types of settings, we have to factor in the accelerant of shade and wind.

(E) is saying that if you're in a region with shade and wind, lichenometry will not be useful.

You might be hearing (E) saying
"it's usefulness is limited IN these regions" (in these regions, it doesn't have as much usefulness)
vs.
"it's usefulness is limited TO these regions" (if you're not in this regions, then there's no usefulness)

Hope this helps.