Answer:
Geological time scale
The vast expanse of geological time has been separated into eras, periods, and epochs. The numbers included below refer to the beginnings of the division in which the title appears. The numbers are in millions of years. The named divisions of time are for the most part based on fossil evidence and principles for relative dating over the past two hundred years. Only with the application of radiometric dating have numbers been obtained for the divisions observed from field observations.
