Question

The diagram below represents a series of rock layers. Each different type of shape shown in the layers represents a fossil of a different species. For example, the yellow triangles represent one species while the green squares represent another. The thin, reddish-brown layer is a layer of volcanic ash that contains no fossils. Examine the diagram, and then answer the question that follows.


Which of the following best explains what happened 110 million years ago?
A.
A minor amount of volcanic ash erupted and had very little impact on the local ecosystem.
B.
A new species evolved that had no impact on the existing species.
C.
No environmental or biological changes occurred 110 million years ago.
D.
A volcanic eruption caused a sudden change in the local ecosystem.

Answer 1

Based on the information provided, the presence of a thin, reddish-brown layer of volcanic ash in the rock layers suggests that a volcanic eruption occurred, which is likely to have had a significant impact on the local ecosystem. Therefore, the best explanation for what happened 110 million years ago would be:

**D. A volcanic eruption caused a sudden change in the local ecosystem.**