Question

volcanic rock has often been found early in the rock record but less frequently in later rock layers. what does this suggest to scientists about early earth?

volcanic rock is more easily preserved than other kinds of rock.

volcanic activity was more common in the past than it is today.

volcanic activity is the same today as it was early in earths history.

volcanic rock is easier to find.

Explanation:

To determine the correct answer, we analyze each option:

• Option 1: The question is about the frequency of volcanic rock in different rock layers over time, not about preservation compared to other rocks. So this is incorrect.
• Option 2: If volcanic rock is more common in early rock layers (past) and less in later ones (today), it suggests that volcanic activity was more frequent in the past. This matches the observation.
• Option 3: The observation shows a difference in the frequency of volcanic rock over time, so volcanic activity can't be the same. This is incorrect.
• Option 4: The question is about the occurrence of volcanic rock in different time periods, not about how easy it is to find. This is incorrect.

Answer:

B. Volcanic activity was more common in the past than it is today.