δA² History

Geological eras

The first traces of the region's history date back to the end of the Pre-Cambrian, to the Proterozoic. The following eon saw the explosion of life : it includes the Paleozoic, Mesozoic and Cenozoic eras.

Pre-Cambrian
Hadean	Archean	Proterozoic		Phanerozoic
- 4600	- 4000	- 2500	- 542	Paleozoic	Mesozoic	Cenozoic
(millions of years)				- 542	- 252	- 66	◊
				Permian Carboniferous Devonian Silurian Ordovician Cambrian	Cretaceous Jurassic Trias	Quaternary Neogene Paleogene

The geological eras are divided into four eons:

The Pre-Cambrian is a super eon which brings together the first three eons:
- The Hadean: extreme temperatures and intense bombardment
- The Archean: formation of the earth's crust
- The Proterozoic: appearance of life and plate tectonics
The Phanerozoic is the current eon which includes three eras:
- The Paleozoic: formerly, primary era
- The Mesozoic: formerly, secondary era
- The Cenozoic : formerly Tertiary and Quaternary eras now combined

The Quaternary hosts the prehistory of humanity.