Geologic Time

Scientists estimate the Earth to be 4.6 billion years old.  It is through the remains of fossilized organisms that paleontologists get clues about ancient times. Fossils helped paleontologists to develop a time scale that organizes Earth’s history into different divisions. On the geologic time scale, the longest unit of geologic time is the eon.  The most recent eon, the Phanerozoic, is further classified into era, periods, and epochs.