EON

ERA

PERIOD

EPOCH

Characteristic organisms and major geological events

Duration in millions of years

Began (m.y.a.)

Phanerozoic Eon

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QUARTERNARY PERIOD

Quarternary

HOLOCENE EPOCH

Last 5,000 years

0-10,000 years ago

PLEISTO-
CENE EPOCH

2.5 million years

10,000 to 1.6 million years ago

TERTIARY PERIOD

Late Tertiary
Late Tertiary
Middle Tertiary
Middle Tertiary
Early Tertiary
Early Tertiary
K T Times
KT Times

PLIOCENE EPOCH

4.5 million years

2.5-7 million years ago

MIOCENE EPOCH

19 million years

7-26 million years ago

OLIGOCENE EPOCH

12 million years

26-38 million years ago

EOCENE EPOCH

16 million years duration

38-54 million years ago

PALEOCENE EPOCH

11 million years duration

54-65 million years ago

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CRETACEOUS PERIOD

Later Cretaceous
Later Cretaceous
Early Cretaceous
Early Cretaceous

UPPER
Maastrichtian
Campanian
Santonian
Coniacian
Turonian
Cenomanian

76 million years duration

65-141 million years ago

LOWER
Albian
Aptian
Barremian
Hauterivian
Valanginian
Berriasian

JURASSIC PERIOD

Jurassic

UPPER
Tithonian
Kimmeridgian
Oxfordian

54 million years duration

141-195 million years ago

MIDDLE
Callovian
Bathonian
Bajocian
Aalenian

LOWER
Toarcian
Pliensbachian
Sinemurian
Hettangian

TRIASSIC PERIOD

Triassic

UPPER
Rhaetian
Norian
Carnian

30 million years duration

208-245 million years ago

MIDDLE
Ladinian
Anisian

LOWER (Scythian)
Olenekian
Induan

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PERMIAN PERIOD

Permian

UPPER
Lopingian
- Changhsingian
- Wuchiapingian


MIDDLE
Guadalupian
- Capitanian
- Wordian
- Roadian

55 million years duration

245-280 million years ago

LOWER
Cisuralian
- Kungurian
- Artinskian
- Sakmarian
- Asselian

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PENNSYLVANIAN

UPPER
Kasimovian | Gzhelian

45 million years duration

280-325 million years ago

MIDDLE
Moscovian

LOWER
Bashkirian

MISSISSIPPIAN

Carboniferous
Carboniferous

UPPER
Serpukhovian
MIDDLE
Viséan

20 million years duration

286-360 million years ago

LOWER
Tournaisian

DEVONIAN PERIOD

Devonian

UPPER
Fammenian | Fransnian

50 million years duration

360-408 million years ago

MIDDLE
Givetian | Eifelian

LOWER
Praghian | Lockhovian

SILURIAN PERIOD

Ordovician

UPPER
Pridolian | Ludlovian

40 million years duration

408-438 million years ago

LOWER
Wenlockian | Llandoverian

ORDOVICIAN PERIOD

Ordovician

UPPER
Ashgillian | Caradocian


MIDDLE
Llandeilian | Llanvirnian

65 million years duration

438-505 million years ago

LOWER
Arenigian | Tremadocian

CAMBRIAN PERIOD

Late Cambrian
Late Cambrian
Early Cambrian
Early Cambrian

UPPER
Furongian

70 million years duration

505-540 million years ago

MIDDLE
* table below

LOWER
* table below

Pre Cambrian

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VENDIAN PERIOD

vendian

--

540-650 million years ago

PRE-VENDIAN PERIOD

650-2,500 million years ago

ARCHAEAN
3.8 to 2.5 billion years ago
The atmosphere of Earth was very different from what we breathe today; at that time, it was likely a reducing atmosphere of methane, ammonia, and other toxic gases. During this time, the Earth's crust cooled enough that rocks and continental plates began to form. Early in the Archaean that life first appeared on Earth. Our oldest fossils date to roughly 3.5 billion years ago, and consist of bacteria microfossils. All life during the more than one billion years of the Archaean was bacterial, stromatolites, colonies of photosynthetic bacteria which have been found as fossils in Early Archaean rocks of South Africa and Western Australia. Stromatolites increased in abundance throughout the Archaean, but began to decline during the Proterozoic.

2,500-3800 million years ago

HADEAN
4.5 to 3.8 billion years ago
Hadean time is not a geological period as such. During Hadean time, the Solar System was forming. Sometime during the first 800 million or so years of its history, the surface of the Earth changed from liquid to solid. Once solid rock formed on the Earth, its geological history began. This most likely happened prior to 3.8 billion years, but hard evidence for this is lacking. Erosion and plate tectonics has probably destroyed all of the solid rocks that were older than 3.8 billion years.

3,800-4,600 million years ago

CAMBRIAN SUBDIVISIONS
Cambrian is divided into three epochs — the Early Cambrian (Lower Cambrian, Caerfai or Waucoban), Middle Cambrian (St Davids or Albertian) and Furongian (a.k.a. Late/Upper Cambrian, Merioneth or Croixan). Each of the epochs are divided into two faunal stages. Only one, Paibian has been recognized by the International Commission on Stratigraphy. Others are still unnamed. However, the Cambrian is divided into several regional faunal stages.
Source: Answers.com - Cambrian Subdivisions

  Chinese North American Russian-Kazakhian Australian Regional
Furongian   Ibexian Ayusokkanian Idamean Dolgellian
  Sunwaptan Sakian Mindyallan Festiniogian
  Steptoan Aksayan Payntonian Maentwrogian
  Marjuman Batyrbayan    
Middle Cambrian Maozhangian Mayan Boomerangian  
Zuzhuangian Delamaran Amgan Undillian  
Zhungxian     Florian  
      Templetonian  
  Dyeran   Ordian  
Early Cambrian Longwangmioan Toyonian Lenian
Changlangpuan Montezuman Botomian    
Qungzusian   Atdabanian    
Meishuchuan   Tommotian    
    Nemakit-Daldynian