Logical ReasoningDifficulty: Hard

PT5 S1 Q12 Explanation

Impact craters caused by meteorites

A free, expert breakdown of this official LSAT Logical Reasoning question.

TopicsSufficient Assumption

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Stimulus

Impact craters caused by meteorites smashing into Earth have been found all around the globe, but they have been found in the greatest density in geologically stable regions. This relatively greater abundance of securely identified craters in geologically stable rates of destructive geophysical processes in those regions.

What this question is testing

Sufficient Assumption

Premise

Most identified meteor craters are found in geologically stable regions.

Conclusion

The author concludes this is because stable regions preserve craters better — there is less destructive geological activity to erase them.

Evaluate

The author is implicitly comparing apples to apples — assuming the same number of meteorites hit everywhere, so the visible difference must be about preservation. But what if meteorites just hit stable regions more often? Then the crater density would have nothing to do with preservation; it would be about where the meteorites land in the first place.

Imagine you found that most surviving Roman coins are in dry climates. You might conclude: "Dry climates preserve coins better." But that only works if the Romans dropped coins evenly everywhere. If they only built cities in dry climates, the conclusion fails — there are more coins because there were more coins to begin with, not because of preservation.

Goal

Find the answer that establishes meteorite impacts have been roughly evenly distributed across Earth's surface — so any concentration in stable regions reflects preservation, not impact frequency.

Reading along? Open the full official question in LawHub — we show a fragment here and keep the reasoning in our own words.

The question
12.

The conclusion is properly drawn if which one of the following

Answer choices

  1. Out of Scope8% picked this

    A meteorite that strikes exactly the same spot as an earlier meteorite will obliterate all traces

    This is about whether one meteorite obliterates an earlier impact at the same spot. That speaks to crater destruction within a single location, not to whether stable regions had similar overall impact rates as unstable regions. It does not address the alternative explanation that meteorites strike unevenly.

  2. Out of Scope17% picked this

    Rates of destructive geophysical processes within any given region vary markedly

    Variation in destructive processes within a single region over time does not bridge the gap. The argument needs us to know that meteorite impacts have been distributed similarly across regions; this answer talks about variation across time within regions, which is a different question.

  3. Out of Scope1% picked this

    The rate at which the Earth is struck by meteorites has greatly increased in

    The recent rate of meteor strikes does not address whether historical impacts were evenly distributed across Earth. The argument is about why crater density differs by region today — what matters is the long-term distribution of impacts, not the current rate.

  4. Correct67% picked this

    Actual meteorite impacts have been scattered fairly evenly over the Earth’s surface in the course

    Why this is right

    This is the bridge. If actual meteorite impacts have been spread fairly evenly across Earth's surface throughout geological history, then the unevenness in identified craters cannot be due to impacts happening more often in stable regions. The only remaining explanation is that something has made craters survive more in those regions — exactly the author's conclusion (lower rates of destructive geophysical processes). Plug this in and the conclusion follows.

    Skill tested: Sufficient Assumption · how this choice captures the argument's function is the move to repeat next time.

  5. Opposite7% picked this

    The Earth’s geologically stable regions have been studied more intensively by geologists than have its

    If anything, this weakens the argument by offering a different explanation for the observed concentration: stable regions might just be more thoroughly studied, so more of their craters are identified. That is an alternative to the author's preservation explanation — not the bridge the argument needs.

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