The Geologic Time Scale

EONS

• PHANEROZOIC (VISIBLE LIFE) EON (0.544 BILLION YEARS [B.Y. OR GA {GIGA ANNUM}]->THE PRESENT)
• PROTEROZOIC (EARLIER LIFE) EON (2.5->0.544 B.Y.)
• ARCHEAN (ANCIENT LIFE) EON (3.96->2.5 B.Y.)
• HADEAN EON (4.6->3.96 B.Y.) [NOTE: this time interval is part of the Archean in your text]
  • Proterozoic + Archean + Hadean = Precambrian or Cryptozoic(4.6-> 0.544 b.y.)
  • Precambrian represents about 90% of Earth history

EONS		AGE
Phanerozoic		0.000 by
Cryptozoic or Precambrian	Proterozoic	0.544 by 2.500 by
	Archean	3.960 by
	Hadean	4.600 by

PHANEROZOIC ERAS

• CENOZOIC (RECENT LIFE)(66 M.Y. ->THE PRESENT)
• MESOZOIC (MIDDLE LIFE)(250->66 M.Y.)
• PALEOZOIC (OLD LIFE)(544->250 MILLION YEARS [M.Y. OR MA {MEGA ANNUM}])

PHANEROZOIC PERIODS

• CENOZOIC -
  • NEOGENE (23 M.Y. ->THE PRESENT)
  • PALEOGENE (66->23 M.Y.)

OR

• QUATERNARY (1.65 M.Y. ->THE PRESENT)
• TERTIARY (66->1.65 M.Y.)

• MESOZOIC -
  • CRETACEOUS (145->66 M.Y.)
  • JURASSIC (208->145 M.Y.)
  • TRIASSIC (250->208 M.Y.)

• PALEOZOIC -
  • PERMIAN (290->250 M.Y.)
  • CARBONIFEROUS (360->290 M.Y.)[IN EUROPE]
    • MISSISSIPPIAN (360->323 M.Y.) & PENNSYLVANIAN (323-> 290 M.Y.)[IN U. S.]
  • DEVONIAN (410->360 M.Y.)
  • SILURIAN (440->410 M.Y.)
  • ORDOVICIAN (510->440 M.Y.)
  • CAMBRIAN (544->510 M.Y.) [NOTE: the Cambrian start is 550 m.y. in your text]

CENOZOIC EPOCHS

• NEOGENE -
  • Holocene/Recent, Pleistocene, Pliocene, & Miocene
• PALEOGENE -
  • Oligocene, Eocene, Paleocene

OR

• QUATERNARY -
  • Holocene (entirely recent)/Recent (10 k.y. ->the present)
  • Pleistocene (most recent)(1.65 m.y. ->10 thousand years [k.y. {kiloyears}])
• TERTIARY -
  • Pliocene (more recent) (5->1.65 m.y.)
  • Miocene (less recent) (23->5 m.y.)
  • Oligocene (little recent) (34->23 m.y.)
  • Eocene (early recent) (55-> 34 m.y.)
  • Paleocene (old recent) (66->55 m.y.)
    

PHANEROZOIC ERAS	PHANEROZOIC PERIODS		AGE
Cenozoic	Quaternary	Neogene	0 my 66 my
	Tertiary
		Paleogene
Mesozoic	Cretaceous		250 my
	Jurassic
	Triassic
Paleozoic	Permian		544 my
	Pennsylvanian	Carboniferous
	Mississippian
	Devonian
	Silurian
	Ordovician
	Cambrian

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