Geologic timescale

The geologic timescale is used by geologists and other scientists to describe the timing and relationships between events that have occured during the history of the Earth. The table of geologic periods presented here is in accordance with the dates and nomenclature proposed by the International Commission on Stratigraphy, and uses the standard color codes of the United States Geologic Survey.

The Earth is thought by geologists to be about 4570 million years old. The geologic or "deep" time of Earth's past has been organized into various periods according to events which took place in each period.

Table of geologic time

1. Paleontologists often refer to faunal stages rather than geologic Periods. The stage nomenclature is quite complex. See Harland for an excellent time ordered list of faunal stages.
2. Dates are slightly uncertain with differences of a few percent between various sources being common. This is largely due to uncertainties in radiometric dating and the problem that deposits suitable for radiometric dating seldom occur exactly at the places in the geologic column where they would be most useful. The dates and errors quoted above are according to the International Commission on Stratigraphy 2004 time scale. Dates labeled with a * indicate boundaries where a Global Boundary Stratotype Section and Point has been internationally agreed upon.
3. Historically, the Cenozoic has been divided up into the Quaternary and Tertiary sub-eras, as well as the Neogene and Paleogene periods. However, the International Commission on Stratigraphy has recently decided to stop endorsing the terms Quaternary and Tertiary as part of the formal nomenclature.
4. In North America, the Carboniferous is subdivided into Mississippian and Pennsylvanian Periods.
5. The Proterozoic, Archean and Hadean are often collectively referred to as Precambrian Time, and sometimes also as the Cryptozoic.
6. Defined by absolute age (Global Standard Stratigraphic Age).
7. Though commonly used, the Hadean is not a formal eon and no lower bound for the Eoarchean has been agreed upon. The Hadean has also sometimes been called the Priscoan.

Graphical timeline

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Colors =

 id:epoch  value:rgb(0.7,0.7,1) # light blue
 id:period value:rgb(1,0.7,0.7) # light red
 id:era    value:rgb(1,1,0.7)   # light yellow
 id:eon    value:rgb(1,0.7,1)   # light purple
 id:black  value:black

Period = from:-4567.17 till:0 TimeAxis = orientation:horizontal ScaleMajor = unit:year increment:500 start:-4500 ScaleMinor = unit:year increment:100 start:-4500

Define $markred = text:"*" textcolor:red shift:(0,3) fontsize:10

PlotData=

 align:center textcolor:black fontsize:8 mark:(line,black) width:25 shift:(0,-5)

 bar:eon color:eon

 at:      0   align:right  $markred
 at:   -542   align:left   $markred
 from: -542   till:    0   text:Phanerozoic
 from:-2500   till: -542   text:Proterozoic
 from:-3800   till: -2500  text:Archaean
 from: start  till: -3800  text:Hadean

 bar:era color:era

 from:  -65.5 till:    0   text:C~z shift:(0,1.5)
 from: -251 till:  -65.5 text:Meso~zoic shift:(0,1.5)
 from: -542   till: -251 text:Paleo~zoic shift:(0,1.5)
 from: -1000  till:  -542  text:Neoprote-~rozoic shift:(0,1.8)
 from:-1600   till:  -1000  text:Mesoproterozoic
 from:-2500   till: -1600  text:Paleoproterozoic
 from:-2800   till: -2500  text:Neo-~archean shift:(0,1.5)
 from:-3200   till: -2800  text:Meso-~archean shift:(0,1.5)
 from:-3600   till: -3200  text:Paleo-~archean shift:(0,1.5)
 fontsize:7
 from:-3800   till: -3600  text:Eo-~arch-~ean shift:(0,2)
 from:start   till: -3800  

 bar:period color:period

 fontsize:6
 from:   -23.03 till:    0
 from:  -65.5 till:   -23.03
 from: -145.5   till:  -65.5
 from: -199.6   till: -145.5
 from: -251   till: -199.6
 from: -299   till: -251
 from: -359.2   till: -299
 from: -416 till: -359.2
 from: -443.7 till: -416
 from: -488.3   till: -443.7
 from: -542   till: -488.3

 from: -630   till:  -542  text:Ed. 
 from: -850   till:  -630  text:Cryo-~genian
 from: -1000  till:  -850  text:Ton-~ian
 from: -1200  till:  -1000 text:Sten-~nian
 from: -1400  till:  -1200 text:Ect-~asian
 from: -1600  till:  -1400 text:Calym-~mian
 from: -1800  till:  -1600 text:Stath-~erian
 from: -2050  till:  -1800 text:Oro-~sirian
 from: -2300  till:  -2050 text:Rhy-~acian
 from: -2500  till:  -2300 text:Sid-~erian
 from: start  till:  -2500

</timeline>

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Colors =

 id:epoch  value:rgb(0.7,0.7,1) # light blue
 id:period value:rgb(1,0.7,0.7) # light red
 id:era    value:rgb(1,1,0.7)   # light yellow
 id:eon    value:rgb(1,0.7,1)   # light purple
 id:filler value:gray(0.8)      # background bar
 id:black  value:black

Period = from:-542 till:0 TimeAxis = orientation:horizontal ScaleMajor = unit:year increment:100 start:-500 ScaleMinor = unit:year increment:10 start:-540

Define $markred = text:"*" textcolor:red shift:(0,3) fontsize:10 Define $markgreen = text:"*" textcolor:green shift:(0,3) fontsize:10

PlotData=

 align:center textcolor:black fontsize:8 mark:(line,black) width:25 shift:(0,-5)

 bar:eon color:eon
 at:      0   align:right  $markred
 at:   -542   align:left   $markred
 from: -542   till:    0   text:Phanerozoic
 bar:era color:era
 at:      0   align:right  $markgreen
 at:    -65.5 align:left   $markgreen
 from:  -65.5 till:    0   text:Cenozoic
 from: -251   till:  -65.5 text:Mesozoic
 from: -542   till: -251   text:Paleozoic

 bar:period color:period fontsize:8
 from: -23.03    till:  0     text:Neo-~gene shift:(0,0.5)
 from: -65.5  till:  -23.03   text:Paleo-~gene shift:(0,0.5)
 from: -145.5   till:  -65.5 text:Cretaceous
 from: -199.6   till: -145.5   text:Jurassic
 from: -251   till: -199.6   text:Triassic
 from: -299   till: -251   text:Permian
 from: -359.2   till: -299   text:Carboniferous
 from: -416 till: -359.2   text:Devonian
 from: -443.7 till: -416 text:Sil-~urian shift:(0,0.5);
 from: -488.3   till: -443.7 text:Ordovician
 from: -542   till: -488.3   text:Cambrian

</timeline>

<timeline> ImageSize = width:800 height:100 PlotArea = left:65 right:15 bottom:20 top:5 AlignBars = justify

Colors =

 id:epoch  value:rgb(0.7,0.7,1) # light blue
 id:period value:rgb(1,0.7,0.7) # light red
 id:era    value:rgb(1,1,0.7)   # light yellow
 id:eon    value:rgb(1,0.7,1)   # light purple
 id:black  value:black

Period = from:-65.5 till:0 TimeAxis = orientation:horizontal ScaleMajor = unit:year increment:10 start:-60 ScaleMinor = unit:year increment:1 start:-65

Define $markgreen = text:"*" textcolor:green shift:(0,3) fontsize:10

PlotData=

 align:center textcolor:black fontsize:8 mark:(line,black) width:25 shift:(0,-5)

 bar:era color:era
 at:     0  align:right $markgreen
 at: start  align:left  $markgreen
 from:start  till:  0    text:Cenozoic

 bar:period color:period
 from: -23.03   till:  0   text:Neogene
 from:start  till: -23.03   text:Paleogene

 bar:epoch color:epoch
 from: -0.1  till:  0
 from: -1.806  till: -0.1  text:P
 from: -5.332    till: -1.806  text:Plio-~cene shift:(0,1) fontsize:6
 from:-23.03    till: -5.332    text:Miocene
 from:-33.9    till:-23.03    text:Oligocene
 from:-55.8    till:-33.9    text:Eocene
 from:start  till:-55.8    text:Paleocene

</timeline>

References

• GeoWhen Database
• International Commission on Stratigraphy Time Scale

See also

• Age of the Earth
• Fossils and the geological timescale
• Cosmological timeline
• Lunar geologic timescale
• Martian geologic timescale
• Anthropocene
• Logarithmic timeline

External link

• NASA: Geologic Time