Reading ComprehensionDifficulty: Hard

PT132 S3 P2 Q11 Explanation

Late Heavy Bombardment

A free, expert breakdown of this official LSAT Reading Comprehension question.

TopicsNon-Author OpinionScience

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Passage

A vigorous debate in astronomy centers on an epoch in planetary history that was first identified by analysis of rock samples obtained in lunar missions. Scientists discovered that the major craters on the Moon were created by a vigorous bombardment of debris approximately four billion years ago—the so-called late heavy bombardment (LHB). of Earth since, until the LHB ended, life could not have survived here.

Various theoretical approaches have been developed to account for both the evidence gleaned from samples of Moon rock collected during lunar explorations and the size and distribution of craters on the Moon. Since the sizes of LHB craters suggest they were formed by large bodies, some astronomers believe that the LHB was Earth-Moon system, because the debris from such an event would have been swept up relatively quickly.

New support for the hypothesis that a late bombardment extended throughout the inner solar system has been found in evidence from the textural features and chemical makeup of a meteorite that has been found on Earth. It seems to be a rare example of a Mars rock that made its way to more such rocks and perhaps obtain surface samples from other planets in the inner solar system.

What this question is testing

Non-Author Opinion

Anticipate

This asks what all three theorists in P2 would agree on. The trick is to find the common ground hidden under their disagreement.

They argue about whether there was a cataclysm (yes/no), where the debris came from (asteroid breakup, declining bombardment, or local Earth-Moon body), and how broadly it spread. But all three are explaining the same Moon evidence — and all three accept that cratering tapered off after the LHB. (Theory 2 says the LHB just is the tail of a long decline; the cataclysm theories say a burst happened and then ended.)

Goal

Looking for an answer that all three theories accept. Be wary of:

Answers about duration — they disagree

Answers about debris origin or amount — points of explicit disagreement

Answers about the LHB destroying life — the passage only says life couldn't have survived during it, not that it destroyed existing life

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

The question
11.

The author implies that all theoretical approaches to the LHB would agree on which one

Answer choices

  1. Wrong View9% picked this

    the approximate duration of the

    The duration of the LHB is precisely what the three theories disagree about — Theory 2 says the bombardment was a long, declining process, while Theory 3 stresses its brief duration. So duration is not common ground.

  2. Wrong View15% picked this

    the origin of the debris involved in

    The origin of the debris is another point of disagreement. Theory 1 says an asteroid or comet broke apart; Theory 3 says debris came from a body within the Earth-Moon system; Theory 2 says no cataclysm at all. The theories explicitly diverge on origin.

  3. Correct52% picked this

    the idea that cratering decreased significantly after

    Why this is right

    All three theories explain the same Moon evidence and accept that cratering decreased after the LHB. The cataclysm theories say a burst happened and then ended; the no-cataclysm theory says the LHB is itself the tail of a long decline. Either way, cratering goes down after that period — that's common ground.

    Skill tested: Non-Author Opinion · how this choice captures the passage's function is the move to repeat next time.

  4. Unsupported16% picked this

    the idea that the LHB destroyed the life that existed on Earth four

    The passage says only that until the LHB ended, life could not have survived on Earth — not that life existed and was destroyed. There is no claim that life had already started before the LHB.

  5. Wrong View8% picked this

    the approximate amount of debris involved in

    The amount of debris is also a point of disagreement. The asteroid-breakup theory implies a lot of widely scattered debris; the Earth-Moon-only theory implies a smaller, more localized amount; the no-cataclysm theory implies no special burst at all. So debris amount is not common ground.

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