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The Geological Periods of Earth
The Geological Periods of Earth
Published: 2010/10/16
Channel: PixelHistory
The Geological Timescale
The Geological Timescale
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Geological Time Scale with reference to India - 4 Eras & 10 Periods Explained
Geological Time Scale with reference to India - 4 Eras & 10 Periods Explained
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The History of Life on Earth - Crash Course Ecology #1
The History of Life on Earth - Crash Course Ecology #1
Published: 2012/11/05
Channel: CrashCourse
The Geological History of Earth
The Geological History of Earth
Published: 2015/03/18
Channel: GeoScience Videos
A Brief History of Geologic Time
A Brief History of Geologic Time
Published: 2017/11/06
Channel: PBS Eons
Geologic "Eras", animated
Geologic "Eras", animated
Published: 2009/09/21
Channel: Pell Osborn
What Is A Geological Period?
What Is A Geological Period?
Published: 2017/12/10
Channel: Claribel Pisano Tipz
Period (geology)
Period (geology)
Published: 2016/01/29
Channel: WikiAudio
6th period geology
6th period geology
Published: 2007/11/07
Channel: Brett Gilley
The Geologic Column: Dinosaur & Human Fossils Together - Don Patton
The Geologic Column: Dinosaur & Human Fossils Together - Don Patton
Published: 2017/01/03
Channel: Chris Carlascio
Quick Overview Geologic Time Scale
Quick Overview Geologic Time Scale
Published: 2014/02/25
Channel: Matthew Mabrey
The Paleozoic Era
The Paleozoic Era
Published: 2016/04/29
Channel: LilliVallance
Gold Mining and Geology 101, Ground Support in Mines
Gold Mining and Geology 101, Ground Support in Mines
Published: 2017/07/23
Channel: Period Six Mining and Exploration LLC
Pennsylvanian (geology)
Pennsylvanian (geology)
Published: 2016/08/31
Channel: WikiWikiup
The Evolution of Life on Earth
The Evolution of Life on Earth
Published: 2012/11/28
Channel: AsapSCIENCE
-Geologic Time Music Video-
-Geologic Time Music Video-
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Channel: BlethwynFilms
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Geological time scale trick | eon | age | epoch | geology extinction | timescale tricks evolution
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Channel: Vinay Rajput Tutorial
CENOZOIC PERIOD / GEOLOGY PROYECT
CENOZOIC PERIOD / GEOLOGY PROYECT
Published: 2016/11/02
Channel: Analaudefontenebro
Welcome to the Cambrian
Welcome to the Cambrian
Published: 2013/03/14
Channel: CambrianScience
If Jurassic Park Were In Different Geological Eras
If Jurassic Park Were In Different Geological Eras
Published: 2015/06/26
Channel: CollegeHumor
Gold Mine and Geology 101 Series, Episode 1, Mine Terms
Gold Mine and Geology 101 Series, Episode 1, Mine Terms
Published: 2017/07/06
Channel: Period Six Mining and Exploration LLC
Bored In 8th Period (Geology)
Bored In 8th Period (Geology)
Published: 2007/01/19
Channel: B Mason
Ancient Earth Series 1 1of3 The Permian
Ancient Earth Series 1 1of3 The Permian
Published: 2017/08/21
Channel: Documentaries Only Please
Layers Down Geology Project Video Period 3
Layers Down Geology Project Video Period 3
Published: 2016/11/17
Channel: Katelynn Kuminkoski
Valentines Geology
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Published: 2013/02/14
Channel: Reina Strohmayer
EVOLUTION : Geological Time Scale : EPOCHS ; Memory trick for NEET / AIIMS - 2018
EVOLUTION : Geological Time Scale : EPOCHS ; Memory trick for NEET / AIIMS - 2018
Published: 2017/08/18
Channel: CITY OF BIOLOGY
Group 37 Geology Project - Mississippian Period
Group 37 Geology Project - Mississippian Period
Published: 2014/11/26
Channel: David Freeman
New England Geology: Sea Level and the Last Glacial Maximum
New England Geology: Sea Level and the Last Glacial Maximum
Published: 2012/12/19
Channel: Rick Le Mon
Sphinx: 800,000-7000 Years Old. Geological EVIDENCE
Sphinx: 800,000-7000 Years Old. Geological EVIDENCE
Published: 2016/12/13
Channel: Charles Kos
Geology project- Jurassic period PowerPoint
Geology project- Jurassic period PowerPoint
Published: 2017/02/14
Channel: Hollie Lawler
The History of Earth (HD - 720P)
The History of Earth (HD - 720P)
Published: 2012/06/06
Channel: Science For the Win
Overview of the Hadean Eon
Overview of the Hadean Eon
Published: 2014/04/21
Channel: Timothy Frese
A Brief History of Life: When Life Exploded
A Brief History of Life: When Life Exploded
Published: 2016/07/20
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Published: 2014/09/24
Channel: Mint Hill Middle School - 8th Grade Science
#047 - Cambrian Geology with Fred Bowyer
#047 - Cambrian Geology with Fred Bowyer
Published: 2017/08/25
Channel: Trolling With Logic
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Four ways to understand the Earth's age - Joshua M. Sneideman
Published: 2013/08/29
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Appalachian Geology, Part 3
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The Deadliest Ice Age Ever
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Oligocene Epoch - Florida Fossils: Evolution of Life and Land
Oligocene Epoch - Florida Fossils: Evolution of Life and Land
Published: 2010/02/02
Channel: FloridaMuseum
Field Geology, Frederic H. Lahee, Geologic Time Scale
Field Geology, Frederic H. Lahee, Geologic Time Scale
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The Anthropocene, New Geologic Age Of Humans
The Anthropocene, New Geologic Age Of Humans
Published: 2014/10/06
Channel: GeoBeats News
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Channel: Geology
Earth Ice Age Documentary
Earth Ice Age Documentary
Published: 2014/04/14
Channel: EarthNET
Historical Geology: Devonian Geology
Historical Geology: Devonian Geology
Published: 2015/10/12
Channel: DCC - Geology Online
Inside the Manitoba Museum: Pt 1. Geology and Paleontology
Inside the Manitoba Museum: Pt 1. Geology and Paleontology
Published: 2013/10/28
Channel: Manitoba Museum
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WIKIPEDIA ARTICLE

From Wikipedia, the free encyclopedia
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A geologic period is one of several subdivisions of geologic time enabling cross-referencing of rocks and geologic events from place to place.

These periods form elements of a hierarchy of divisions into which geologists have split the Earth's history.

Eons and eras are larger subdivisions than periods while periods themselves may be divided into epochs and ages.

The rocks formed during a period belong to a stratigraphic unit called a system.

Structure[edit]

The twelve currently recognised periods of the present eon – the Phanerozoic – are defined by the International Commission on Stratigraphy (ICS) by reference to the stratigraphy at particular locations around the world.

In 2004 the Ediacaran Period of the latest Precambrian was defined in similar fashion, and was the first such newly designated period in 130 years; but earlier periods are simply defined by age.

A consequence of this approach to the Phanerozoic periods is that the ages of their beginnings and ends can change from time to time as the absolute age of the chosen rock sequences, which define them, is more precisely determined.

The set of rocks (sedimentary, igneous or metamorphic) that formed during a geologic period is known as a system, so for example the 'Jurassic System' of rocks was formed during the 'Jurassic Period' (between 201 and 145 million years ago).

The following table includes all currently recognized periods. The table omits the time before 2500 million years ago, which is not divided into periods.

Eon Era Period Extent, Million
Years Ago
Duration, Millions
of Years
Phanerozoic Cenozoic Quaternary (Pleistocene/Holocene) 2.588–0 2.588+
Neogene (Miocene/Pliocene) 23.03–2.588 20.4
Paleogene (Paleocene/Eocene/Oligocene) 66.0–23.03 42.9
Mesozoic Cretaceous 145.5–66.0 79.5
Jurassic 201.3–145.0 56.3
Triassic 252.17–201.3 50.9
Paleozoic Permian 298.9–252.17 46.7
Carboniferous (Mississippian/Pennsylvanian) 358.9–298.9 60
Devonian 419.2–358.9 60.3
Silurian 443.4–419.2 24.2
Ordovician 485.4–443.4 42
Cambrian 541.0–485.4 55.6
Proterozoic Neoproterozoic Ediacaran 635.0–541.0 94
Cryogenian 850–635 215
Tonian 1000–850 150
Mesoproterozoic Stenian 1200–1000 200
Ectasian 1400–1200 200
Calymmian 1600–1400 200
Paleoproterozoic Statherian 1800–1600 200
Orosirian 2050–1800 250
Rhyacian 2300–2050 250
Siderian 2500–2300 200

See Geologic time scale#Proposed Precambrian timeline for another set of periods 4600–541 MYA.

Units in geochronology and stratigraphy[1]
Segments of rock (strata) in chronostratigraphy Time spans in geochronology Notes to
geochronological units
Eonothem Eon 4 total, half a billion years or more
Erathem Era 10 defined, several hundred million years
System Period 22 defined, tens to ~one hundred million years
Series Epoch 34 defined, tens of millions of years
Stage Age 99 defined, millions of years
Chronozone Chron subdivision of an age, not used by the ICS timescale

Correlation issues[edit]

In a steady effort ongoing since 1974, the International Commission on Stratigraphy has been working to correlate the world's local stratigraphic record into one uniform planet-wide benchmarked system.

American geologists have long considered the Mississippian and Pennsylvanian to be periods in their own right though the ICS now recognises them both as 'subperiods' of the Carboniferous Period recognised by European geologists. Cases like this in China, Russia and even New Zealand with other geological eras has slowed down the uniform organization of the stratigraphic record.

Notable changes

  • Changes in recent years have included the abandonment of the former Tertiary Period in favour of the Paleogene and succeeding Neogene periods.
  • The abandonment of the Quaternary period was also considered but it has been retained for continuity reasons.
  • Even earlier in the history of the science, the Tertiary was considered to be an 'era' and its subdivisions (Paleocene, Eocene, Oligocene, Miocene and Pliocene) were themselves referred to as 'periods' but they now enjoy the status of 'epochs' within the more recently delineated Paleogene and Neogene periods.

See also[edit]

References[edit]

  1. ^ Cohen, K.M.; Finney, S.; Gibbard, P.L. (2015), International Chronostratigraphic Chart (PDF), International Commission on Stratigraphy .

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