Structured Lists Directory

INI

Geological Time Periods - INI

Geological time periods systematically classify Earth's approximately 4.6 billion year history according to the International Chronostratigraphic Chart established by the International Commission on Stratigraphy (ICS). It is divided into four major divisions: the Precambrian (Hadean, Archean, Proterozoic) and the Phanerozoic (Paleozoic, Mesozoic, Cenozoic). Each geological period is distinguished based on geological evidence including biological evolution, continental drift, and climate change, forming the foundation for scientific research and education.

geology geological time chronostratigraphy Earth history paleontology Precambrian Phanerozoic Paleozoic Mesozoic Cenozoic 
[item.precambrian]
code=EON-1
slug=precambrian
name=Precambrian
description=The period from Earth's formation to approximately 541 million years ago, comprising about 88% of Earth's history.
category=Supereon
durationMa=4059
endMa=541
startMa=4600

[item.hadean]
code=EON-1-1
slug=hadean
name=Hadean
description=From Earth's formation to approximately 4.0 billion years ago. No evidence of life.
category=Eon
durationMa=600
endMa=4000
startMa=4600

[item.archean]
code=EON-1-2
slug=archean
name=Archean
description=Approximately 4.0 to 2.5 billion years ago. Evidence of the oldest life appears.
category=Eon
durationMa=1500
endMa=2500
startMa=4000

[item.proterozoic]
code=EON-1-3
slug=proterozoic
name=Proterozoic
description=Approximately 2.5 billion to 541 million years ago. Appearance of eukaryotes and oxygen increase.
category=Eon
durationMa=1959
endMa=541
startMa=2500

[item.phanerozoic]
code=EON-2
slug=phanerozoic
name=Phanerozoic
description=From approximately 541 million years ago to present. Era of multicellular life proliferation.
category=Eon
durationMa=541
endMa=0
startMa=541

[item.paleozoic]
code=ERA-1
slug=paleozoic
name=Paleozoic
description=Approximately 541 to 252 million years ago. 'Ancient life era.'
category=Era
durationMa=289
endMa=252
startMa=541

[item.cambrian]
code=PER-1-1
slug=cambrian
name=Cambrian
description=Approximately 541 to 485 million years ago. The Cambrian explosion occurred.
category=Period
durationMa=56
endMa=485
startMa=541

[item.ordovician]
code=PER-1-2
slug=ordovician
name=Ordovician
description=Approximately 485 to 444 million years ago. Marine invertebrates flourished.
category=Period
durationMa=41
endMa=444
startMa=485

[item.silurian]
code=PER-1-3
slug=silurian
name=Silurian
description=Approximately 444 to 419 million years ago. Life began colonizing land.
category=Period
durationMa=25
endMa=419
startMa=444

[item.devonian]
code=PER-1-4
slug=devonian
name=Devonian
description=Approximately 419 to 359 million years ago. 'Age of Fishes.'
category=Period
durationMa=60
endMa=359
startMa=419

[item.carboniferous]
code=PER-1-5
slug=carboniferous
name=Carboniferous
description=Approximately 359 to 299 million years ago. Large forests and coal deposits formed.
category=Period
durationMa=60
endMa=299
startMa=359

[item.permian]
code=PER-1-6
slug=permian
name=Permian
description=Approximately 299 to 252 million years ago. Continents united and a great extinction occurred.
category=Period
durationMa=47
endMa=252
startMa=299

[item.mesozoic]
code=ERA-2
slug=mesozoic
name=Mesozoic
description=Approximately 252 to 66 million years ago. 'Age of Reptiles.'
category=Era
durationMa=186
endMa=66
startMa=252

[item.triassic]
code=PER-2-1
slug=triassic
name=Triassic
description=Approximately 252 to 201 million years ago. Dinosaurs and mammals appeared.
category=Period
durationMa=51
endMa=201
startMa=252

[item.jurassic]
code=PER-2-2
slug=jurassic
name=Jurassic
description=Approximately 201 to 145 million years ago. The golden age of dinosaurs.
category=Period
durationMa=56
endMa=145
startMa=201

[item.cretaceous]
code=PER-2-3
slug=cretaceous
name=Cretaceous
description=Approximately 145 to 66 million years ago. Flowering plants and dinosaur extinction.
category=Period
durationMa=79
endMa=66
startMa=145

[item.cenozoic]
code=ERA-3
slug=cenozoic
name=Cenozoic
description=Approximately 66 million years ago to present. 'Age of Mammals.'
category=Era
durationMa=66
endMa=0
startMa=66

[item.paleogene]
code=PER-3-1
slug=paleogene
name=Paleogene
description=Approximately 66 to 23 million years ago. Adaptive radiation of mammals.
category=Period
durationMa=43
endMa=23
startMa=66

[item.neogene]
code=PER-3-2
slug=neogene
name=Neogene
description=Approximately 23 to 2.58 million years ago. Expansion of grasslands and ape evolution.
category=Period
durationMa=20.42
endMa=2.58
startMa=23

[item.quaternary]
code=PER-3-3
slug=quaternary
name=Quaternary
description=Approximately 2.58 million years ago to present. Ice ages and human evolution.
category=Period
durationMa=2.58
endMa=0
startMa=2.58