GEOLOGY

Detailed explanation-1: -If the same index fossil is found in different areas, the strata in each area were likely deposited at the same time. Thus, the principle of faunal succession makes it possible to determine the relative age of unknown fossils and correlate fossil sites across large discontinuous areas.

Detailed explanation-2: -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.

Detailed explanation-3: -Index fossils are commonly used to match rock layers in different places (Figure below). If two rock layers have the same index fossils, then they’re probably about the same age. Using Index Fossils to Match Rock Layers. Rock layers with the same index fossils must have formed at about the same time.