International Chronostratigraphic Timescale

The interval definitions in this timescale are derived from the following sources:

  • K. M. Cohen, S.C. Finney, P.L. Gibbard and J.-X. Fan. 2023. The ICS International Chronostratigraphic Chart v2023/09. view
  • F. M. Gradstein, J. G. Ogg, M. D. Schmitz and G. M. Ogg. 2020. Geologic Time Scale 2020 view
  • W. B. Harland, R. L. Armstrong, A. V. Cox, L. E. Craig, A. G. Smith and D. G. Smith. 1990. A Geologic Time Scale 1989. view
  • F. M. Gradstein, J. G. Ogg, and A. G. Smith. 2004. A Geologic Time Scale 2004 1-589 view
  • B. D. Webby. 1998. Steps toward a global standard for Ordovician stratigraphy. Newsletters in Stratigraphy 36:1-33 view

There are 59 timescales which overlap this one. show

Interval boundaries marked with * have been interpolated based on the differences between the ages for international timescale boundaries quoted in the source and the currently accepted ages for those boundaries.

Interval names marked with † are no longer in current use.

This timescale is used in the definition of 126848 collections

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International Chronostratigraphic TimescaleCambrian of North AmericaSilurian of North AmericaOrdovician of China
SilurianPridoliCayugan419.2
Niagaran422.5 *
LudlowLudfordian423
Gorstian425.6
WenlockHomerianLockportian427.4
Sheinwoodian430.5
LlandoveryTelychianOntarian433.4
Aeronian438.5
Alexandrian438.7 *
MedinanClinton440.1 *
440.7 *
Rhuddanian440.8
OrdovicianLate OrdovicianHirnantianHirnantianXiaoxita †/ShikouWufeng †443.8
KatianChientangkiangian445.2
Neichianshanian/Hanjiang449.5
Sandbian453
Middle OrdovicianDarriwilianDarriwilianGuniu †/Hulo458.4
Hunjiang †Dawan †/Daobaowan/Ningkuo466.3 *
DapingianDapingian467.3
Early OrdovicianFloianYiyangian470
TremadocianXinchangian477.7
Lianghekou †477.9 *
CambrianFurongianStage 10Franconian †/Dresbachian/Millardan485.4
Sunwaptan487.5
Jiangshanian489.5
Steptoean493 *
Paibian494
MiaolingianGuzhangianMarjumianAlbertian †497
Drumian500.5
WuliuanTopazan504.5
Delamaran506.5
Series 2Stage 4Waucoban †509
Dyeran511 *
Stage 3514
Montezuman514.8 *
Begadean519.9 *
TerreneuvianStage 2521
Fortunian529
538.8