The Eocene ( /ˈəsn, ˈ-/ EE-ə-seen, EE-oh-[5][6]) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name Eocene comes from the Ancient Greek ἠώς (ēṓs, "dawn") and καινός (kainós, "new") and refers to the "dawn" of modern ('new') fauna that appeared during the epoch.[7][8]

56.0 – 33.9 Ma
Map of the Earth 50 mya
Name formalityFormal
Usage information
Celestial bodyEarth
Regional usageGlobal (ICS)
Time scale(s) usedICS Time Scale
Chronological unitEpoch
Stratigraphic unitSeries
Time span formalityFormal
Lower boundary definitionStrong negative anomaly in δ13C values at the PETM[3]
Lower boundary GSSPDababiya section, Luxor, Egypt[3]
25.5000°N 32.5311°E / 25.5000; 32.5311
GSSP ratified2003[3]
Upper boundary definitionLAD of Planktonic Foraminifers Hantkenina and Cribrohantkenina
Upper boundary GSSPMassignano quarry section, Massignano, Ancona, Italy
43.5328°N 13.6011°E / 43.5328; 13.6011
GSSP ratified1992[4]

The Eocene spans the time from the end of the Paleocene Epoch to the beginning of the Oligocene Epoch. The start of the Eocene is marked by a brief period in which the concentration of the carbon isotope 13C in the atmosphere was exceptionally low in comparison with the more common isotope 12C. The end is set at a major extinction event called the Grande Coupure (the "Great Break" in continuity) or the Eocene–Oligocene extinction event, which may be related to the impact of one or more large bolides in Siberia and in what is now Chesapeake Bay. As with other geologic periods, the strata that define the start and end of the epoch are well identified,[9] though their exact dates are slightly uncertain.

Share this article:

This article uses material from the Wikipedia article Eocene, and is written by contributors. Text is available under a CC BY-SA 4.0 International License; additional terms may apply. Images, videos and audio are available under their respective licenses.