What is geologic time scale?
geologic time scale meaning a chronological sequence of geologic events usually represented in the form of a chart showing names of various rock layers and indicating the estimated duration of each geologic unit.
- Geologic Time (Fact Sheet 2007-3015)
- Divisions of Geologic Time?Major Chronostratigraphic and Geochronologic Units
reference: USGS – Earthquake Glossary