Primary Source

History of the Earth in a Cycle

Geologic clock with events and time periods noting the formation of earth and development of life.


Our sense of time has been extended into the deep past in the last two centuries or so, and particularly since the 1950s, when Willard Libby showed that you could use the breakdown of radioactive molecules such as Carbon-14 to date events thousands of years before there were any written documents. Since then, geologists and biologists and astronomers have developed a whole battery of techniques for dating events in the remote past. This graphic uses these techniques to construct a modern timeline for the earth’s history. It’s a remarkable timeline and a foundational document for modern geology. Without such timelines it would be impossible to teach big history. This source is part of David Christian's essay on Big History

This source is a part of the Primer: Big History methods module.


For more on this, see: David Christian, “History and Science after the Chronometric Revolution”, in Steven J. Dick and Mark L. Lupisella, eds., Cosmos & Culture: Cultural Evolution in a Cosmic Context, NASA, 2009, pp. 441-462.

How to Cite This Source

"History of the Earth in a Cycle," in World History Commons, [accessed June 12, 2024]