His studies of ice-polished rocks in his Alpine home land, far outside

Hi there,

Thanks for posting your doubt here.

The reason why usage of past perfect tense "had existed" is incorrect in Choice A is that the two events that are mentioned n the sentence, i. e. "led" and "had existed", are not related to each or has no bearing on each other.

Even if Agassiz did not propose his theory, the fact remains that the ice sheets still existed. If in place of Agassiz, somebody else would have proposed the theory at some other point in time, still the fact that the ice sheets existed would remain unchanged. So you see, there is no relationship between these two events that needs to be expressed by using past perfect tense.

We use past perfect tense only for those two past events that have some effect on the occurrence of each other. For example:

My friend had left the theater by the time I reached.

Here use of past perfect tense is needed because the two events are related. Because of my reaching late, I could not meet my friend because the friend had already left. But this is not the case with the official sentence. The ice sheets existed irrespective of anyone proposing any theory.

hope this helps.
Thanks.
SJ
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His studies of ice-polished rocks in his Alpine home land, far outside the range of present-day glaciers, led Louis Agassiz in 1837 to propose the concept of an age in which great ice sheets had existed in now currently temperate areas.

(A) in which great ice sheets had existed in now currently temperate areas
(B) in which great ice sheets existed in what are now temperate areas
(C) when great ice sheets existed where there were areas now temperate
(D) when great ice sheets had existed in current temperate areas - currently should be used
(E) when great ice sheets existed in areas now that are temperate - now is not modifying are temprate

To refer to time long back (ages , centuries , decades) we prefer to use inwhich instead of where. However, both can be used.
Now and currently cant be used together in a single sentence. Both are redundant.
had cant be used because there is no past event before which ice sheet existed. Led to propose is not relevant to ice sheet.

Hence B is the answer

WHEN CLAUSE can work as adverb: I learn gmat when you come
WHEN CLAUSE can work as an adjective, the age when you came is good.

"the age when" is correct

Isn't that existence of great ice sheets occurred prior to his proposal of concept?, Do I need to consider them as two different events occurred in different time scale or is it a single event? I'm bit confused here.. Pls let me know where my logic goes wrong..

yeah you are correct that proposal of a concept and existence of great ice sheets were at two different times..

But the moment you say he proposed the concept of an age after going through some studies of..., it clearly shows that the age was naturally before he proposed about it existing..
There is no ambiguity in the chronological order..

And when there is no ambiguity, we can avoid the past perfect..

some more example,
The scientist proposed in 1976 that the dinosaurs became extinct during ice age..
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Here the 'in which' refers to the word 'age'. And the subject of the 'in which' is 'great ice sheets'.

In general, when you encounter a 'preposition + which' construction, the subject can be found in the clause that follows 'which'.
But, in a 'which' construction, the subject occurs before the 'which'.

For example - 1. the box of toffees, which is on the table, is expensive. Note that the subject of the which clause occurs before the which clause. Also, 'which' modifies that subject (the box).
(the subject is 'the box'; also note that since 'which' is followed by a singular verb, it cannot refer to 'toffees').

2. the box, in which toffees are kept, is made of aluminum. Here, the subject of the 'in which' clause is 'toffees'. But the 'in which' clause modifies 'the box'.

Hope this helps
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First Glance

The underline starts with in which. Glance at the answers to notice that other choices offer when instead. The sentence might contain a Modifier issue.

Issues

(1) Verb: had existed

The original sentence uses the past perfect: Ice sheets had existed. Other answers use the simple past existed. Which is correct?

Past perfect is used to denote the longer-ago of two past actions. In this case, the had existed action is paired with a comment about the climate in those same areas now. It's acceptable, then, to use simple past existed; don't use a more complex tense when a simple tense is acceptable. Eliminate answers (A) and (D).

(2) Meaning

In answer (A), now currently is redundant—both words mean the same thing. Eliminate answer (A), and examine the meaning in the other answers:

(B) existed in what are now temperate areas
(C) existed where there were areas now temperate
(D) existed in current temperate areas
(E) existed in areas now that are temperate

Answer (D) drops now and switches from currently to current. That word is modifying the adjective temperate, so it needs to be in the adverb form (currently). The adjective form current can only be used to modify nouns. Eliminate answer (D).

The other answers drop currently and use only now. Answers (B) and (C) are okay, but answer (E) has a meaning problem. The word now must be tied to a particular action or event: Something happened now. In answer (E), the word now is actually tied to existed: Sheets existed now that are temperate. Something can't be simultaneously in the past (existed) and happening now. Eliminate answer (E).

Answer (C) also mixes two time frames: were and now. They were [not] temperate before; they are temperate now. Eliminate answer (C).

The Correct Answer

Correct answer (B) fixes the initial verb error by switching to the simple past existed. The construction in what are now temperate areas properly indicates that the climate has changed in these areas. they used to be cold; they are now temperate.

Miscellaneous

Note: The in which versus when split turned out be a red herring! Both versions are acceptable.
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I agree with the explanations provided. However, I have one query about the usage of plural tense in a clause starting with 'What'

My understanding is that 'What' needs a singular verb when 'What' acts as the subject of a clause. In this sentence, the clause staring with 'What' is a noun clause. Doesn't this mean that the verb after 'What' would be singular? Please help me solve my confusion.

Thanks in advance

The biggest thing here was the choice between which and when.

Though "when" looks tempting, one has to clearly understand the ambiguity it may create. "when" may refer to 1837 or the age (whose concept has been proposed in sentence). Due to this ambiguity, we should get rid of C,D E.

Of A and B, b is a clear winner, because of redundant use of "now currently"

Hence, B

Hi, can we use "that" here for plural "areas"?

Thanks.

Hi GMATNinja
In one of the post you mentioned that when "what" is used as a preposition, we can substitute "what" with "the thing that" and check whether the sentence still makes sense.
I followed the above and now the sentence is:
(B) in which great ice sheets existed in the thing(or place) that are now temperate areas

The above sentence makes sense to me when I replaced "thing" with "place", thinking its of safe to do that, since instead of a "thing" the sentence is talking about a "place".
Please let me know if my understanding is correct?

That sounds perfect!!

I'm very happy that you didn't take my previous advice TOO literally and simply swap "what" with "the thing that" without using your brain.

Instead, you recognized that this sentence is talking about a "place", not a "thing", so you were flexible in your approach. Nicely done.
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Yes Hital, we can use that to address "areas" here. That is because that is being used to begin a relative clause here and not as a demonstrative pronoun. It would have been incorrect to say that places. You would say Those places. However, when you are kicking of a relative clause, I would say that is number-agnostic.

Hope this helps.

Cheers!

I initially eliminated C,D and E based on the "when" split considering it to be ambiguous. It could refer to either the year 1837 (if we ignore prepositional phrases) or the age.
However, I see some conflicting posts here on whether the usage of "when" is acceptable.

Expert Daagh's post seems to agree with my analysis
While, egmat expert suggests that usage of "when" here is acceptable.

GMATNinja, could you please be the tie breaker and help clarify whether my approach was valid?
Thanks in advance!

In Ex 2 here, isn't "in which" introducing an ambiguity ? As you said, "in which" can be used to replace both "when" and "where". In this sentence, with use of "in which" makes it difficult to identify if you are referring to the old period or kerala. Please clarify

azhr
Where is the the phrase 'old period' or the word 'Kerala' in example 2? There is only 'olden Kerala".
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I am still confused with the past perfect explanation. The reason of why past perfect is required is because isn't the sentence saying that ice ages existed in areas that are now temperate? Meaning, the ice ages existed first (use of had) and now you have areas that are temperate?

Sorry, I'm really late to the party! But in case it isn't too late to be helpful: I think Daagh and Krishna both have a point!

Generally, if you see "when" you'd ask yourself if it's referring to a time period. Here it does. This is Krishna's point.

But, of course, any sentence with an illogical meaning will be incorrect, even if "when" is technically referring to a time. This is Daagh's point, not that "when" is inherently wrong here. It might help to clarify why (C), (D), and (E) are illogical.


This construction is illogical. The ice sheets existed where there were areas, but not in the areas themselves? And the phrase, "were areas now" makes no sense - "were" suggests past tense and "now" suggests present. (C) is out.


There's another logical problem here involving tense. "When" indicates two actions happening at the same time. For example:

"Tim took a shower when his children were fighting over the dog bone."

Here, the actions "took a shower" and "were fighting" happened at the same time. But "had" suggests that one action happened before another in the past. If we wrote, "Tim took a shower when his children had been fighting over the dog bone..." the sentence conveys that Tim showered at the same time that his children were no longer fighting. This is confusing.

In (D), the phrase, "when great ice sheets had existed" is muddled in the same way: "when" seems to tell us that the sheets existed during the age, but "had" seems to tell us that the sheets were already gone. It makes far more sense to write that the sheets existed during the age, so we don't want "had" here. (D) is out.


This is a mess. The phrase "ice sheets existed in areas now," again, gives us contradictory time frames: "existed" suggests past and "now" suggests present. Notice that in the OA, "existed" and "now" are in different clauses, logically conveying that the sheets existed in the past, and that the areas are temperate now.

I hope that helps!
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A) "now" and "currently" are redundant, "had existed" is not necesary given the ice sheets still "existed" in the past, speaking from today
B) correct
C) "where" and "there" are redundant
D) "had existed" is not necessary, and "in current temperate areas" illogically indicate the ice sheets exist today.
E) "in areas now" indicate the ice sheet exist today. The asnwer could be better to be changed to "in areas that are now temperate"