The time scale has been developed through the study of rock layers and the observation of their relationships and identifying features such as lithologies, paleomagnetic properties, and fossils.

At GSA you'll find the resources, confidence, and connections you need to reach fulfilling new heights in your geoscience career.

Feb 13, 2023 · The answer is the geologic time scale, a system that divides Earth’s history into eons, eras, periods, and epochs. It’s the timeline that connects rocks to time — and time to life.

Dec 1, 2025 · The geologic time scale is the “calendar” for events in Earth history. It subdivides all time into named units of abstract time called—in descending order of duration— eons, eras, …

Jan 11, 2025 · Learn about the geologic time scale or GTS. Discover what it is, how it is divided, and the characteristics of each time period.

The geologic time scale is the “calendar” for events in earth history. It subdivides all time into named units of abstract time called—in descending order of duration—eons, eras, periods, …

The Geologic Time Scale, as shown above, documents intervals of geologic time relative to one another, and has been continuously developed and updated over the last two centuries.

The Geologic Time Scale above is a helpful reference to use along with the information provided below. The left half shows a timeline of Earth’s geologic history which is split into Eons, Eras, …

Geologists have many different ways to tell time. Some determine the order of events and others identify specific times in the past when geologic events took place. Geologists report the age …

May 13, 2025 · Scientists use the geologic time scale to organize Earth's long history into eons, eras, and periods. The Phanerozoic eon is known for the appearance and dominance of …