geologic eras
Time measured in millions
Geologic eras are the major divisions of Earth's history, spanning hundreds of millions of years and marked by distinct forms of life.
The current Cenozoic era began with the extinction of dinosaurs.
Earlier eras—Mesozoic, Paleozoic, Precambrian—are defined by fossil records and mass extinction events.
Eras subdivide into periods: The Jurassic period falls within the Mesozoic era.
- eonsImmense spans of time
- PrecambrianEarliest geological eon
- MesozoicAge of Reptiles
- fossilsPreserved ancient organism traces
- JurassicDinosaur-dominated geological period
Archean · sedimentary · fossil record · ice ages · tectonics · radiometric dating · carbon dating · rock layers · extinction events · time periods · supercontinent · dinosaurs · timeline · K-Pg boundary · paleoecology · paleobiology · continental drift · Cenozoic
geologic erasmoments
Short spans of time
instants · seconds · minutes · milliseconds · nanoseconds
geologic erashuman history
Record of civilization's events
recorded history · historical periods · lived experience · dynasties · reigns
geologic, geological, geologically, geology, geologist, eras