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

Based on the principle of superposition, in which the oldest rock layers are at the bottom and the youngest are at the top, we can infer the following about the ages of the layers:

• Layer T, which is 120 million years old, is above Layer R, which is 100 million years old.
• Layer M is situated between Layer R and Layer T.

Since Layer M is below Layer T (which is older than 120 million years) and above Layer R (which is 100 million years old), it must be older than 100 million years but younger than 120 million years.

Therefore, the correct response regarding the age of Layer M is: between 100 million and 120 million years old.