Geological Timeline

Era/Period/Epoch/Division							Time (Millions of Years Ago)
Hadean Time Hadean time is not a geological period. No rocks on the Earth are this old - except for meteorites. During Hadean time, the Solar System was forming, probably within a large cloud of gas and dust around the sun, called an accretion disc.							6000-5000
Archaeozoic Era 700 Million year span of heavy asteroid and comet bombardment; Earth's Crust Forms							5000-1500
Pre-Cambrain Era		Pre-Cambrain Period	Archaen Epoch Single-celled organisms		Early Archean		1500-900
					Middle Archean
					Late Archean
			Proterozoic Epoch Earliest fossil animals and plants		Paleo-Proterozoic		900-545
					Meso-Proterozoic
					Neo-Proterozoic	Vendian algae; lichens
Lower Paleozoic Era	Cambrian Period First traces of vascular plants; first chordates evolve (gives rise to vertebrates); first animals with hard skeletons (mollusks, coral) develop; extinction of first great expansion of marine life						545-505
	Ordovician Period Jawless fish appear; second great expansion and diversity of marine life; first land-based plants						505-438
	Silurian Period Widespread distribution of plants on land; first land animals (arthorpods); jawed fishes appear						438-410
Upper Paleozoic Era	Devonian Period Advanced plants evolve; first forests; insects appear; fish groups develop; amphibians appear						410-355
	Carboniferous Period Gymnosperms (seed-bearing plants) first appear; club mosses, horsetails, ferns; trees dominate; amphibians evolve; first reptiles develop and colonize land; mammal-like reptiles dominate land			Mississippian (US Only)			355-290
				Pennsylvanian (US Only)
	Permian Period Mammal-like reptiles and archosaurs dominate land; trilobites and other types of marine life disappear						290-250
Mesozoic Era	Triassic Period Gymnosperms (seed-bearing plants) evolve; reptiles diversify and dominate; dinosaurs appear; mammal-like reptiles disappear; primitive true mammals evolve						250-205
	Jurassic Period Cycads, conifers; dinosaurs reach gigantic forms and are dominate animals; first birds evolve						205-135
	Cretaceous Period Bird groups continue to evolve; dinosaurs continue to diversify; modern mammals begin to evolve; angiosperms (flowering plants) evolve; modern plant types begin to appear; mass extinction of dinosaurs and marine reptiles						135-65
Cenozoic Era	Tertiary Period Mammal groups evolve and become the dominate life on Earth; bird groups continue to evolve; first apes appear; upright hominids appear		Paleocene Epoch				65-55
			Eocene Epoch				55-38
			Oligocene Epoch				38-26
			Miocene Epoch				26-6
			Pliocene Epoch				6-1.8
	Quarternary Period Modern man; early civilization; growth of civilization and rise of technology		Pleistocene Epoch Ice-age mammals; mammoths prominent; Neanderthal man; Cro-magnon man; formation of agriculture and permanent communities				1.8-0.01
			(Lower Paleolithic)				0.50-0.25
			(Middle Paleolithic)				0.25-0.06
			(Upper Paleolithic)				0.06-0.01
			Holocene Epoch				0.01-0