Which characteristic is most likely found in fossils that are used to determine the age of rock layers?

• A. Distinctive and widespread features
• B. Ability to fluoresce under UV light
• C. Presence of soft tissue
• D. High levels of radioactivity

Answer: (A)

Verified step by step guidance

1. Understand the concept of index fossils: These are fossils that are used to define and identify geologic periods. They are typically distinctive, widespread, and existed for a relatively short period of time.
2. Consider why distinctive and widespread features are important: Fossils with these characteristics can be found in many locations and are easily recognizable, making them useful for correlating the age of rock layers across different regions.
3. Evaluate the other options: Ability to fluoresce under UV light, presence of soft tissue, and high levels of radioactivity are not typical characteristics of index fossils. These features do not help in correlating rock layers over large areas.
4. Recognize the importance of the time range: Index fossils should have existed during a specific time range, which helps in pinpointing the age of the rock layers they are found in.
5. Conclude that the most likely characteristic of fossils used to determine the age of rock layers is their distinctive and widespread features, as these allow for accurate correlation across different geographic locations.