Impact Craters!!!

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Impact Craters!!!

by dv2020 » Mon May 30, 2011 5:59 am
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 regions must be explained by the lower rates of destructive geophysical processes in those regions.

The conclusion is properly drawn if which one of the following is assumed?

(A) A meteorite that strikes exactly the same spot as an earlier meteorite will obliterate all traces of the earlier impact.
(B) Rates of destructive geophysical processes within any given region vary markedly throughout geological time.
(C) The rate at which the Earth is struck by meteorites has greatly increased in geologically recent times.
(D) Actual meteorite impacts have been scattered fairly evenly over the Earth's surface in the course of Earth's geological history.
(E) The Earth's geologically stable regions have been studied more intensively by geologists than have its less stable regions.
Source: — Critical Reasoning |

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by sivaelectric » Mon May 30, 2011 6:03 am
My choice E
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by newton9 » Mon May 30, 2011 7:02 am
P: X have been found in greater density in geologically stable regions
C: More no of craters can be explained by lower rate of GP processes.

My paraphrase for assumption: X were not scattered highly in these geologically stable regions.

D) Actual meteorite impacts have been scattered fairly evenly over the Earth's surface in the course of Earth's geological history.

This is the required assumption. If we negate this, clearly argument dies.

Negation: meteorite impacts are not scattered evenly. So the argument is weakened, because lower destructive processes cannot explain this.

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by galaxian » Mon May 30, 2011 12:11 pm
IMO D.
Liked Newton9's explanation though I approached the problem by taking it as a Math problem more than CR.Only when we assume that Impacts are scattered fairly over Earth's surface, we can further talk about why some places (or read the Geologically Stable places) have few/more Impacts.

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by sivaelectric » Mon May 30, 2011 8:37 pm
Good explanation Newton9 :)
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