GEOLOGY

Detailed explanation-1: -Such fossils are known as ‘index fossils’ or ‘guide fossils’. Thus, index fossil is an abundant and easily identifiable fossil with a wide geographic distribution and a short geologic range.

Detailed explanation-2: -Scientists specifically use index fossils to correlate strata found in different geographic locations. Index fossils are the preserved remains of plants and animals (primarily animals) that have existed in a limited geologic period, making them highly effective in determining the relative age of a rock layer.

Detailed explanation-3: -Certain fossils, called Index Fossils help geologist match rock layers.

Detailed explanation-4: -Rock layers containing trilobite fossils must be that age. Different species of trilobite fossils can be used to narrow the age even more. Trilobites are good index fossils.

Detailed explanation-5: -Ammonites, for example, make excellent guide fossils for stratigraphy; they can be used to determine the relative age of two or more layers of rock, or strata, that are in different places within the same country or somewhere else in the world.