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- Fri Jun 23, 2017 2:31 pm
#36255
Complete Question Explanation
(See the complete passage discussion here: lsat/viewtopic.php?t=14432)
The correct answer choice is (D)
This question asks us to identify a reason why radiocarbon dating may be unreliable. Passage
organization is once again key. Since the author compared radiocarbon dating to lichenometry in the
third paragraph, any potential downsides to the use of either method can be found there.
Answer choice (A): Although radiocarbon dating does involve measuring the quantity of radioactive
isotopes present in a variety of organic material (line 6), this was never presented as a downside to its
use.
Answer choice (B): The author never discussed the variable quantity of organic material caught in
shifted sediments. Rather, the problem with radiocarbon dating was determining the variable quantity
of carbon 14 isotope contained in such material.
Answer choice (C): If fault lines related to past earthquakes are not always visible, this would
certainly be an obstacle to using radiocarbon dating of fault-line sediments to date such earthquakes.
However, this issue was never raised in the passage, which makes answer choice (C) incorrect.
Answer choice (D): This is the correct answer. The amount of carbon 14 isotope depends on the
intensity of the radiation striking Earth’s upper atmosphere, which has fluctuated greatly during the
past 300 years. This causes many radiocarbon datings to be of little value (lines 45-48).
Answer choice (E): The possibility that radiation has not always struck the upper atmosphere was
never mentioned in the passage, which makes this answer choice incorrect.
(See the complete passage discussion here: lsat/viewtopic.php?t=14432)
The correct answer choice is (D)
This question asks us to identify a reason why radiocarbon dating may be unreliable. Passage
organization is once again key. Since the author compared radiocarbon dating to lichenometry in the
third paragraph, any potential downsides to the use of either method can be found there.
Answer choice (A): Although radiocarbon dating does involve measuring the quantity of radioactive
isotopes present in a variety of organic material (line 6), this was never presented as a downside to its
use.
Answer choice (B): The author never discussed the variable quantity of organic material caught in
shifted sediments. Rather, the problem with radiocarbon dating was determining the variable quantity
of carbon 14 isotope contained in such material.
Answer choice (C): If fault lines related to past earthquakes are not always visible, this would
certainly be an obstacle to using radiocarbon dating of fault-line sediments to date such earthquakes.
However, this issue was never raised in the passage, which makes answer choice (C) incorrect.
Answer choice (D): This is the correct answer. The amount of carbon 14 isotope depends on the
intensity of the radiation striking Earth’s upper atmosphere, which has fluctuated greatly during the
past 300 years. This causes many radiocarbon datings to be of little value (lines 45-48).
Answer choice (E): The possibility that radiation has not always struck the upper atmosphere was
never mentioned in the passage, which makes this answer choice incorrect.