Geologic Time Scale

Geologic Time Scale Table

Some Important Dates in the History of the Earth

Years Ago Event
4,600,000,000 Origin of the Earth
3,900,000,000 Oldest Dated Crustal Rocks
3,800,000,000 Oldest Evidence for Life
2,000,000,000 First Oxygen Atmosphere/Ozone Layer Forms
900,000,000 Oldest Metazoan Fossils
510,000,000 Oldest Fossil Fish
458,000,000 First Land Plants
375,000,000 That important first step:Amphibians Evolve
245,000,000 Huge Mass Extinction at End of Permian Period / Close of the Paleozoic Era
200,000,000 First Mammals
160,000,000 First Birds
145,000,000 Atlantic Ocean first opens
130,000,000 Angiosperms (Flowering Plants) on the Scene
65,000,000 Adaptive Radiation of Mammals
Dinosaurs Go Extinct
Close of the Mesozoic Era/ Beginning of the Cenozoic Era
3,400,000 New discoveries of Australopithecus afarensis (Lucy) fossils from Ethiopia
2,000,000 Pleistocene Ice Age begins
Light from the Andromeda galaxy seen today left Andromeda
600,000 Age of Homo erectus fossils from Ethiopia
125,000 Oldest rocks in the Bahamas
100,000 Homo sapiens appears in the fossil record
15,000 Last ice sheet retreats from northern United States
7,000 Grahams Harbor, San Salvador, Bahamas floods due to rising sea level after ice sheets are reduced to modern day volume
506 Columbus lands in New World
? You were born

Source: Ritger, S.D. and R.H. Cummins. 1991. Using student-created metaphors to comprehend geologic time. Journal of Geological Education. 9:9-11.