Geological Time Overview

Eon/time	Era	Period
The Precambrian extends through the Hadean, Archean, and Proterozoic Eons. The Phanerozoic commences with the Cambrian. Hadean Eon : 4.6 - 3.8Ga
Archean Eon : 3.8 - 2.5 Ga
3.8-3.6 Ga	Eoarchean
3.6-3.2 Ga	Paleoarchean
3.2-2.8 Ga	Mesoarchean
2.8-2.5 Ga	Neoarchean
Proterozoic Eon : 2.5 Ga ~ 542 Ma
2.5-1.6 Ga	Paleoproterozoic Era	Siderian 2.5-2.3
		Rhyacian 2.3-2.05
		Orosinian 2.05-1.8
		Stratherian 1.8-1.6
1.6-1.0 Ga	Mesoproterozoic Era	Calymmian 1.6-1.4
		Ectasian 1.4-1.2
		Stenian 1.2-1
1.0 Ga-542 Ma	Neoproterozoic Era	Tonian 1.0 Ga -850 Ma
		Cryogenian 850-635 Ma
		Vendian or Ediacaran, 635-542
Phanerozoic Eon : 542 Ma - present
542-251 Ma	Paleozoic Era	Cambrian 542-488.3
		Ordovician 488.3-443.7
		Silurian 443.7-416
		Devonian 416-359.2
		Carboniferous 359.2-299.0 Mississippian and Pennsylvanian
		Permian 299-251
251-65.5	Mesozoic Era	Triassic 251-199.6
		Jurassic 199.6-145.4
		Cretaceous 145.4-65.5

Eon/time	Era	Period	Epoch
65.5-present	Cenozoic Era	Paleogene 65.5-23.03	Paleocene 65.5-55.8
			Eocene 55.8-33.9 : ends with Grande Coupure extinction event
			Oligocene 33.9-23.03 : climate cooling begins by end of epoch
		Neogene 23.03-present	Miocene 23.03-5.332
			Pliocene 5.332-1.806
			Pleistocene 1.506-.005
			.005- present