Eon	Era	Period	Epoch	MYa
Phanerozoic	Cenozoic	Quaternary	Holocene	0.1 (10,000ya)
			Pleistocene	1.8
		Tertiary	Pliocene
			Miocene
			Oligocene
			Eocene
			Paleocene	65
	Mesozoic	Cretaceous
		Jurassic
		Triassic		248
	Paleozoic	Permian
		Pennsylvanian
		Mississippian
		Devonian
		Silurian
		Ordovician
		Cambrian		540
Cryptozoic	Precambrian	Proterozoic		2,500 (2.5 BYa)
		Archean		4,000 (4 BYa)
		Hadean		4,500 (4.5 BYa)

Notes

Please note that the times listed above indicate when the period or epoch immediately to the left began.

Learning this scale is really just an exercise in rote memorization, but it can get confusing at times. To remember the periods of the longest (and most confusing) era - the Paleozoic - I use an acronym: PPMDSOC. I remember that the Permian epoch comes after the Pennsylvanian, because I know that the Pennsylvanian epoch comes immediately after the Mississippian - the only other epoch on this scale to be named after a state. Creating small mnemonic devices like this can be surprisingly helpful.