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The Geological Periods of Earth
The Geological Periods of Earth
Published: 2010/10/16
Channel: PixelHistory
Geological Time Scale
Geological Time Scale
Published: 2013/04/28
Channel: Rebecca Yu
A Brief History of Geologic Time
A Brief History of Geologic Time
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Channel: PBS Eons
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The History of Life on Earth - Crash Course Ecology #1
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Channel: CrashCourse
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Channel: Examrace
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Period (geology)
Published: 2016/01/29
Channel: WikiAudio
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What caused the Cambrian explosion? | The Economist
Published: 2015/08/27
Channel: The Economist
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How The Sahara Desert Was Made - It Used To Be Green - Full Documentary
Published: 2017/07/20
Channel: Wise Wanderer
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Published: 2016/12/13
Channel: Charles Kos
Ancient Earth "The Triassic Period"
Ancient Earth "The Triassic Period"
Published: 2017/03/07
Channel: CuriosityStream
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The 6 Craziest Extinctions Ever
Published: 2015/04/22
Channel: AsapSCIENCE
CENOZOIC PERIOD / GEOLOGY PROYECT
CENOZOIC PERIOD / GEOLOGY PROYECT
Published: 2016/11/02
Channel: Analaudefontenebro
4 Billion Years in Under 10 Minutes
4 Billion Years in Under 10 Minutes
Published: 2016/12/07
Channel: SciShow
Episode 1 - Archean Earth
Episode 1 - Archean Earth
Published: 2015/02/09
Channel: Early Earth
Quick Overview Geologic Time Scale
Quick Overview Geologic Time Scale
Published: 2014/02/25
Channel: Matthew Mabrey
The Geological History of Earth
The Geological History of Earth
Published: 2015/03/18
Channel: GeoScience Videos
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Channel: Vinay Rajput Tutorial
Welcome to the Cambrian
Welcome to the Cambrian
Published: 2013/03/14
Channel: CambrianScience
Oligocene Epoch - Florida Fossils: Evolution of Life and Land
Oligocene Epoch - Florida Fossils: Evolution of Life and Land
Published: 2010/02/02
Channel: FloridaMuseum
18 Photos Of The STRANGEST Geological Formations
18 Photos Of The STRANGEST Geological Formations
Published: 2017/02/26
Channel: American Eye
Bored In 8th Period (Geology)
Bored In 8th Period (Geology)
Published: 2007/01/19
Channel: B Mason
Geology project- Jurassic period PowerPoint
Geology project- Jurassic period PowerPoint
Published: 2017/02/14
Channel: Hollie Lawler
Group 37 Geology Project - Mississippian Period
Group 37 Geology Project - Mississippian Period
Published: 2014/11/26
Channel: David Freeman
Appalachian Geology, Part 3
Appalachian Geology, Part 3
Published: 2011/02/06
Channel: WildwoodClaire1
Science Group 15 Geological Timeline for the Quaternary Time Period
Science Group 15 Geological Timeline for the Quaternary Time Period
Published: 2018/02/21
Channel: 22jaskan
Geology Presentation 3
Geology Presentation 3
Published: 2016/02/26
Channel: Merrik Sanders
The Evolution of Life on Earth
The Evolution of Life on Earth
Published: 2012/11/28
Channel: AsapSCIENCE
A Brief History of Life: When Life Exploded
A Brief History of Life: When Life Exploded
Published: 2016/07/20
Channel: SciShow
Geology presentation period 4-5A
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Published: 2015/05/26
Channel: Olivia Sankiewicz
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Published: 2016/11/17
Channel: Katelynn Kuminkoski
Geologic History of the Earth: Part 1
Geologic History of the Earth: Part 1
Published: 2010/07/13
Channel: LindnerFilms07
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What is an Ice Age?
Published: 2013/02/28
Channel: red Orbit
GONDWANA AND TERTIARY COAL GEOLOGY IFOS, UPSC, SSC CGL, CIVIL ENGINEERING, GATE, IIT JAM, BSC
GONDWANA AND TERTIARY COAL GEOLOGY IFOS, UPSC, SSC CGL, CIVIL ENGINEERING, GATE, IIT JAM, BSC
Published: 2017/11/24
Channel: SOURAV SIR'S CLASSES
#047 - Cambrian Geology with Fred Bowyer
#047 - Cambrian Geology with Fred Bowyer
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Channel: MinuteEarth
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Channel: Science For the Win
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National Geographic The Story of Earth HD
Published: 2014/02/07
Channel: Beauty Geography
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Inside the Manitoba Museum: Pt 1. Geology and Paleontology
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Channel: Manitoba Museum
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Channel: Period Six Mining and Exploration LLC
The Ordovician Age - HD Geology Documentary
The Ordovician Age - HD Geology Documentary
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Channel: Mita Dofin
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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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