Geologic Time

Scale The Geologic Time Scale is a framework for understanding the evolution of life and Earth's physical structure over millions and billions of years. The time scale is divided into eons, eras, periods, and epochs and is a fundamental tool used by geologists and other Earth scientists to measure the age of rocks and fossils. The scale is also used to describe the evolution and history of life on Earth, including the rise and fall of species. Understanding the geologic time scale helps us to understand the current state of the Earth and how it has changed over time.