Fossils help determine what in Earth's history?

• A. The relative timing of events in Earth's history.
• B. The exact age in years of rock layers.
• C. The chemical composition of minerals.
• D. The current climate conditions.

Answer: (A)

Fossils primarily reveal the relative timing of events in Earth's history. By analyzing which organisms are preserved in different rock layers, we can determine the order in which those layers were deposited and when certain life forms existed. The idea that younger layers lie above older ones, along with the use of index fossils—species that lived for a short, well-defined time across wide areas—lets scientists correlate rocks from different places and build a consistent timeline without knowing exact ages. Fossils don’t give precise numerical ages; dating rocks with radiometric methods provides absolute ages, but the fossils themselves primarily establish the sequence of events. They also don’t directly determine the chemical makeup of minerals or current climate, though they can offer clues about past environments.