Question

How do index fossils assist in dating other fossils?

A. Fossils found in rocks above the index fossils are older.
B. Fossils with similar physical features as the index fossils are the same age.
C. Fossils with the same chemical composition as index fossils are the same age
D. Fossils found in the same rock as the index fossil are considered to be the same age

Answer 1

Certain fossils, called index fossils, help geologists match rock layers. To be useful as an index fossil, a fossil must be widely distributed and represent a type of organism that existed for a brief time period. Index fossils are useful because they tell the relative ages of the rock layers in which they occur.