A tree's age can be determined by counting the annual growth rings in its trunk. Each ring represents one year, and the ring's thickness reveals the relative amount of rainfall that year. Archaeologists successfully used annual rings to determine the relative ages of ancient tombs at Pazyryk. Each tomb was constructed from freshly cut logs, and the tombs builders were constrained by tradition to use only logs from trees growing in the sacred Pazyryk Valley.
Which one of the following, if true, contributes most to an explanation of the archaeologists' success in using annual rings to establish the relative ages of the tombs at the Pazyryk site?
(A) The Pazyryk tombs were all robbed during ancient times, but breakage of the tombs seals allowed the seepage of water, which soon froze permanently, thereby preserving the tombs' remaining artefacts.
(B) The Pazyryk Valley, surrounded by extremely high mountains, has a distinctive yearly pattern of rainfall, and so trees growing in the Pazyryk Valley have annual rings that are quite distinct from trees growing in nearby valleys.
(C) Each log in the Pazyryk tombs has among its rings a distinctive sequence of twelve annual rings representing six drought years followed by three rainy years and three more drought years.
(D) The archaeologists determined that the youngest tree used in any of the tombs was 90 years old and that the oldest tree was 450 years old.
(E) All of the Pazyryk tombs contained cultural artefacts that can be dated to roughly 2300 years ago.
OA: C
Why not B?
Since trees growing in the Pazyryk Valley have annual rings that are quite distinct from trees growing in nearby valleys, and since the tombs builders used only logs from trees growing in the sacred Pazyryk Valley - this combination helps to determine the relative ages of the tombs of Pazyryk site.
However C discusses only about the logs in the tombs. It is not necessary that these logs came from Pazyryk Valley
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Pazyryk valley
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ceilidh.erickson
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Here's the general chronology of this argument:
--> trees grow to a certain age --->
--> they're chopped down to make tombs --->
--> archeologists find those tombs some unknown number of years later --->
--> they look at the logs to know how old the trees were --->
--> knowing how old the trees were when they were chopped down tells us WHEN they were chopped down, i.e. how old the tombs are.
So what's missing in the argument as it stands? Something that connects the age of the trees to the age of the tombs. They could have used 50-yr-old logs on tombs built 100 years ago, or 50-year-old logs on tombs built 2500 years ago. How would we know?
With each answer choice, we need to ask: does this connect the age of the tree to a particular period in time?
(A) The Pazyryk tombs were all robbed during ancient times, but breakage of the tombs seals allowed the seepage of water, which soon froze permanently, thereby preserving the tombs' remaining artefacts.
This has nothing to do with the age of the trees. Incorrect.
(B) The Pazyryk Valley, surrounded by extremely high mountains, has a distinctive yearly pattern of rainfall, and so trees growing in the Pazyryk Valley have annual rings that are quite distinct from trees growing in nearby valleys.
This would make them distinctive ACROSS TIME. We could look at the trees and determine WHERE they came from, but not WHEN.
(C) Each log in the Pazyryk tombs has among its rings a distinctive sequence of twelve annual rings representing six drought years followed by three rainy years and three more drought years.
These trees exhibit a specific pattern. If historians have records that indicate that this exact pattern - 6 drought + 3 rainy + 6 drought - happened only once in the history of that region, we would know that that must have been the time period just before the tombs were built. Correct!
(D) The archaeologists determined that the youngest tree used in any of the tombs was 90 years old and that the oldest tree was 450 years old.
To my earlier point, this could still be true in 100 yr-old tombs or 2500 yr-old tombs.
(E) All of the Pazyryk tombs contained cultural artefacts that can be dated to roughly 2300 years ago.
This doesn't tell us anything about how the TREES give us info on the tombs' age.
The correct answer is C.
Does that help?
--> trees grow to a certain age --->
--> they're chopped down to make tombs --->
--> archeologists find those tombs some unknown number of years later --->
--> they look at the logs to know how old the trees were --->
--> knowing how old the trees were when they were chopped down tells us WHEN they were chopped down, i.e. how old the tombs are.
So what's missing in the argument as it stands? Something that connects the age of the trees to the age of the tombs. They could have used 50-yr-old logs on tombs built 100 years ago, or 50-year-old logs on tombs built 2500 years ago. How would we know?
With each answer choice, we need to ask: does this connect the age of the tree to a particular period in time?
(A) The Pazyryk tombs were all robbed during ancient times, but breakage of the tombs seals allowed the seepage of water, which soon froze permanently, thereby preserving the tombs' remaining artefacts.
This has nothing to do with the age of the trees. Incorrect.
(B) The Pazyryk Valley, surrounded by extremely high mountains, has a distinctive yearly pattern of rainfall, and so trees growing in the Pazyryk Valley have annual rings that are quite distinct from trees growing in nearby valleys.
This would make them distinctive ACROSS TIME. We could look at the trees and determine WHERE they came from, but not WHEN.
(C) Each log in the Pazyryk tombs has among its rings a distinctive sequence of twelve annual rings representing six drought years followed by three rainy years and three more drought years.
These trees exhibit a specific pattern. If historians have records that indicate that this exact pattern - 6 drought + 3 rainy + 6 drought - happened only once in the history of that region, we would know that that must have been the time period just before the tombs were built. Correct!
(D) The archaeologists determined that the youngest tree used in any of the tombs was 90 years old and that the oldest tree was 450 years old.
To my earlier point, this could still be true in 100 yr-old tombs or 2500 yr-old tombs.
(E) All of the Pazyryk tombs contained cultural artefacts that can be dated to roughly 2300 years ago.
This doesn't tell us anything about how the TREES give us info on the tombs' age.
The correct answer is C.
Does that help?
Ceilidh Erickson
EdM in Mind, Brain, and Education
Harvard Graduate School of Education
EdM in Mind, Brain, and Education
Harvard Graduate School of Education
