Geologic Time Scale

This Geologic Time Scale provides a directory of links to web pages for each time interval.

The links focus on:

• general information on the time period
• paleogeography for the period
• representative fossils of the period

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Eon	Era	Period	Age at Base* (start)
Phanerozoic	Cenozoic	Quaternary	1.6 Ma
		Tertiary	65 Ma
	Mesozoic	Cretaceous	140 Ma
		Jurassic	205 Ma
		Triassic	250 Ma
	Paleozoic	Permian	290 Ma
		Carboniferous	355 Ma
		Devonian	410 Ma
		Silurian	438 Ma
		Ordovician	510 Ma
		Cambrian	540 Ma
Precambrian	Proterozoic	Vendian	680 Ma
			2500 Ma
	Archean		3960 Ma
Hadean			4550 Ma

* Ma = million years ago

Links to the other Geologic Time Scales on the web:

• Clickable Geologic Time Scale
• Geologic Time Scale: Phanerozoic
• Geologic Time
• Geologic Time Scale (USGS)

Many of the links on the directory pages were found by members of the Spring 1998 "History of Life" course at San Francisco State University.