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
  • 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
  • M. Freudenthal. 2006. Mammal Paleogene zones. personal communication view
  • A. D. Barnosky, M. Holmes, R. Kirchholtes, E. Lindsey, K.C. Maguire, A.W. Poust, M.A. Stegner, J. Sunseri, B. Swartz, J. Swift, N.A. Villavicencio and G. Wogan. 2014. Prelude to the Anthropocene: Two new North American Land Mammal Ages (NALMAs). The Anthropocene Review I(3):225-242 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 127258 collections

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International Chronostratigraphic TimescaleCenozoic SubepochsTen Million Year BinsMammal Paleogene ZonesNorth American Land Mammal Ages
18.5
PaleogeneOligoceneChattianLate OligoceneCenozoic 4MP 30/MP 29/MP 28/MP 27/MP 26MP 25Arikareean23.03
RupelianEarly OligoceneMP 24/MP 23/MP 22/MP 2127.82
Whitneyan29.5
Orellan31.8
EocenePriabonianLate EoceneCenozoic 3MP 20/MP 19/MP 18/MP 17B/MP 17AChadronian33.9
Duchesnean37
BartonianMiddle EoceneMP 1637.71
Uintan39.7
LutetianCenozoic 2MP 15/MP 14/MP 13/MP 12/MP 1141.2
Bridgerian46.2
YpresianEarly EoceneMP 10/MP 8 + 9/MP 747.8
Wasatchian50.5
Clarkforkian54.9
PaleoceneThanetianLate PaleoceneCenozoic 1MP 6MP 1 - 556
Tiffanian56.2
SelandianMiddle Paleocene59.2
Torrejonian60.9
DanianEarly Paleocene61.6
Puercan63.8
66