Question

1. why are index fossils useful for determining the age of rock layers? a. they form in all types of rock b. they lived during a short, specific time period c. they are rare and fragile d. they can only be found in one location

Explanation:

To determine why index fossils are useful for dating rock layers, we analyze each option:

• Option A: Index fossils are typically found in sedimentary rocks, not all rock types, so A is incorrect.
• Option B: Index fossils lived during a short, specific geologic time period. This allows geologists to correlate rock layers with that time, making B correct.
• Option C: Index fossils are widespread and abundant (not rare/fragile) to be useful, so C is incorrect.
• Option D: Index fossils are found in many locations (not just one), so D is incorrect.

Answer:

B. They lived during a short, specific time period