By looking at the layers beneath our feet, geologists have been able to identify and describe crucial episodes in life's history. These key events frame the chapters in the story of life on earth and the system we use to bind all these chapters together is the Geologic Time Scale.

Originally released by Knowledgemotion, 2018. Streaming video file encoded with permission for digital streaming by Infobase on February 21, 2020.

A Brief History of Geologic Time (12:08); .