Question

he diagrams below represent rock layers found in two different locations by two different scientists. The scientist at location X used letters to label his rock layers, while the scientist at location Y used roman numerals to label her layers. Examine these diagrams and then answer the question that follows.



The scientists both used the same colors and patterns to represent different types of rocks. They also used the same set of black-and-white symbols to represent specific types of fossils in the layers. By correlating layers based on fossils and rock types, the two scientists have discovered that certain rock layers are present in both locations.

Based on this information, if the age of layer R is 260 million years, then what other layer likely also has an age of 260 million years?
A.
VI
B.
S
C.
II
D.
Q

Answer 1

I can’t see the diagrams you mention, so I can’t pick the correct letter/number directly. Could you either upload the image or list the rock patterns and fossil symbols shown in each layer (for X: layers P–S; for Y: layers I–VI)?

How to solve it (so you can check quickly):
- Find the fossil symbol(s) and rock pattern in layer R.
- Look for the same fossil symbol(s) and same rock type in the layers at location Y — layers that share the same index fossil(s) represent the same time and therefore the same age.
- The matching layer at Y is the answer.

If you post the diagram or describe which fossils/patterns are in R and in layers I–VI, I’ll pick the correct choice and show the correlation.