Critical Reasoning

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

IMO : D

D should be it

Hi Its between B and C
We must look for an answer which explains how Archaeologists successfully used annual rings to determine the relative ages of ancient tombs at Pazyryk
A,D and E elaborate on irrelevant things.
(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.
The tombs are not necessarily located in pazyryk valley
Even if the trees have annual rings that are quite distinct from trees trees growing in nearby valleys , it doesnt explain how Archaeologists successfully used annual rings to determine the relative ages of ancient tombs at Pazyryk

So Answer is C

mundasingh123 wrote:Hi Its between B and C
We must look for an answer which explains how Archaeologists successfully used annual rings to determine the relative ages of ancient tombs at Pazyryk
A,D and E elaborate on irrelevant things.
(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.
The tombs are not necessarily located in pazyryk valley
Even if the trees have annual rings that are quite distinct from trees trees growing in nearby valleys , it doesnt explain how Archaeologists successfully used annual rings to determine the relative ages of ancient tombs at Pazyryk

So Answer is C

I couldn't choose between B & C. If the annual rings are what the archaeologists use to determine the ages, choice B clearly supports that. The comparison with trees growing in the nearby valleys is irrelevant. But nonetheless, the builders used the logs from the Pazyryk valley and if the rings are quite distinct, it should be easy to measure the age of the tombs.

Choice C tells the same thing, but in a different way. It has a sequence of 12 rings (for 6 drought yrs+ 3 rainy + 3 drought yrs). Enables us to calculate the age of the tombs.

The OA is C, but why not B?

(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.
The tombs are not necessarily located in pazyryk valley

I couldn't choose between B & C. If the annual rings are what the archaeologists use to determine the ages, choice B clearly supports that. The comparison with trees growing in the nearby valleys is irrelevant. But nonetheless, the builders used the logs from the Pazyryk valley and if the rings are quite distinct, it should be easy to measure the age of the tombs.

Hi , The Answer choice doesnt say that the rings are distinct.The Choice says that the rings are distinct from trees that grow in nearby valleys.
It means that the trees in the nearby valley might have hexagonal rings while the trees from Pazyryk valley might have Circular rings and vice versa.It still doesnt explain why it makes it easy for the Archaelogists to measure the age of the Tombs .
But C does give us a kind of an Algorithm with which we can measure the Age.

mundasingh123 wrote:(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.
The tombs are not necessarily located in pazyryk valley

I couldn't choose between B & C. If the annual rings are what the archaeologists use to determine the ages, choice B clearly supports that. The comparison with trees growing in the nearby valleys is irrelevant. But nonetheless, the builders used the logs from the Pazyryk valley and if the rings are quite distinct, it should be easy to measure the age of the tombs.

Hi , The Answer choice doesnt say that the rings are distinct.The Choice says that the rings are distinct from trees that grow in nearby valleys.
It means that the trees in the nearby valley might have hexagonal rings while the trees from Pazyryk valley might have Circular rings and vice versa.It still doesnt explain why it makes it easy for the Archaelogists to measure the age of the Tombs .
But C does give us a kind of an Algorithm with which we can measure the Age.

The shape does not matter. Be it hexagonal or octagonal. It is the thickness of the rings that help the archaeologists to measure the age.

You are missing my point altogether.
I am trying to eliminate option B . The Option says the trees in paryzyk valley have rings that are distinct from the trees nearby.I just gave an example that 1 way in which the rings might be distinct could be Shape or size if u insist.

mundasingh123 wrote:You are missing my point altogether.
I am trying to eliminate option B . The Option says the trees in paryzyk valley have rings that are distinct from the trees nearby.I just gave an example that 1 way in which the rings might be distinct could be Shape or size if u insist.

I know what you r saying. But as long as they are distinct, it should be good enough to estimate the age of the log used for building the tomb.

How does the distinction between the rings of trees from the paryzyrik valley from the rings of trees nearby the Tombs affect help to estimate the age of the tombs vis-a-vis the conclusion which is that the archaeologists successfully calculated the relative age of the Tombs. If you say yes , then you would have to back up your answer with more assumptions.
Moreover Option B is not as good as Option C.

mundasingh123 wrote:How does the distinction between the rings of trees from the paryzyrik valley from the rings of trees nearby the Tombs affect help to estimate the age of the tombs vis-a-vis the conclusion which is that the archaeologists successfully calculated the relative age of the Tombs. If you say yes , then you would have to back up your answer with more assumptions.
Moreover Option B is not as good as Option C.

The more I support choice B, the more I feel that choice C makes a stronger statement.

Hello Experts,
Can you please clarify, how can we know the age of the tombs if we know age of the trees.

Agreed if we know rings and other details we can know the age of the logs at the time they were cut, but how we will know the age of the tombs as I assume once the logs are cut no rings are formed?

Please guide!

shekhar2fight wrote:Hello Experts,
Can you please clarify, how can we know the age of the tombs if we know age of the trees.

Agreed if we know rings and other details we can know the age of the logs at the time they were cut, but how we will know the age of the tombs as I assume once the logs are cut no rings are formed?

Please guide!

We don't know the age of the tombs, not from the statements of the fact set anyway.

One of the facts of the fact set: Archaeologists successfully used annual rings to determine the relative ages of ancient tombs at Pazyryk.

The archaeologists were able to find the relative age of tombs using tree rings. Since each tomb was made from a fresh log from a particular region, if we can explain how the archaeologists were able to differentiate between relative ages of the trees, we have our justification.

Option C, correctly talks about each log in the tombs having a distinct pattern of representing 12 years of a particular climate pattern. Consider two logs. By counting the number of rings around that particular pattern for each log, let's call the numbers A and B, the archaeologists can determine the relative age of logs, by finding A minus B. Since they can determine the "relative age" of the logs, they can determine relative age of the tombs made out of the logs.

Therefore C is, undoubtedly, correct.

Let me know if this helps

Thank you!

That makes it pretty clear, I was confused with ages of the logs and tombs earlier