GENERAL GEOLOGY

Detailed explanation-1: -If the same index fossil is found within two different layers of rock, then it can be inferred that these two rock layers may have been formed within the same geologic period. Therefore, these two rock layers may have been about the same age.

Detailed explanation-2: -Using the principle of faunal succession, if an unidentified fossil is found in the same rock layer as an index fossil, the two species must have existed during the same period of time (Figure 4). If the same index fossil is found in different areas, the strata in each area were likely deposited at the same time.

Detailed explanation-3: -Index fossils are fossils that are widespread but only existed for a short period of time. Index fossils help scientists to find the relative age of a rock layer and match it up with other rock layers. Living fossils are organisms that haven’t changed much in millions of years and are still alive today.

Detailed explanation-4: -Which best describes the relationship between rock layers and index fossils? Different rock layers can be determined to be the same exact age if they contain the same index fossils.

Detailed explanation-5: -Some strata contain index fossils, or fossils associated with a specific time in Earth’s history. If the same index fossil is found in different strata far apart, the layers likely formed around the same time. By studying strata, geologists have determined the relative order of major events in Earth’s history.