1. Radiometric Dating: This is the most precise method. It relies on the predictable decay of radioactive isotopes within rocks and fossils. By comparing the ratio of parent isotopes to daughter isotopes, scientists can determine the time elapsed since the rock or fossil formed.
2. Fossil Succession: Fossils appear in a specific, predictable order in rock layers. This is because life evolved over time, and certain species existed during specific geologic periods. By identifying fossils, scientists can estimate the relative age of rock layers.
3. Stratigraphy: This involves studying the layering of rocks (strata). Younger layers typically overlie older layers. By analyzing the rock types, fossils, and other geological features within these layers, scientists can determine the relative sequence of events in Earth's history.
