Question

The diagram above shows a stack of rock layers. Examine the diagram, and answer the question that follows. Layer T contains a well-known index fossil that is 120 million years old. Layer R contains a different index fossil that is 100 million years old. Based on this information and the principle of superposition, how old is Layer M?

(1 point)
Responses

younger than 100 million years.
younger than 100 million years.

either 20 million years or 220 million years.
either 20 million years or 220 million years.

older than 120 million years.
older than 120 million years.

between 100 million and 120 million years old.

Answer 1

between 100 million and 120 million years old.

Since T (120 Ma) is below and R (100 Ma) is above, M lies between them, so by superposition M must be intermediate in age (between 100 and 120 Ma).