Glossary · Time
Eon, era, period, epoch, age
The ranks of geological time from largest to smallest: the Phanerozoic Eon; the Paleozoic, Mesozoic and Cenozoic eras; periods such as Jurassic; epochs such as Late Jurassic; ages such as Kimmeridgian.
The ranks of geological time from largest to smallest: the Phanerozoic Eon; the Paleozoic, Mesozoic and Cenozoic eras; periods such as Jurassic; epochs such as Late Jurassic; ages such as Kimmeridgian. The rock deposited during each has a matching chronostratigraphic rank (eonothem, erathem, system, series, stage).
Sources
Cite this article
Stratum Study. "Eon, era, period, epoch, age" (Glossary). Stratum Study pack 2026.09, as of 2026-09-16. https://stratum.black/study/glossary/eon-era-period-epoch-age. Accessed 2026-09-20.
@misc{stratum-eon-era-period-epoch-age,
title = {Eon, era, period, epoch, age},
author = {{Stratum Study}},
howpublished = {\url{https://stratum.black/study/glossary/eon-era-period-epoch-age}},
year = {2026},
note = {Glossary article, Stratum Study pack 2026.09, as of 2026-09-16; sources: stratum. Accessed 2026-09-20.}
} Citations carry the pack version and the article's as-of date so they resolve to the same text later. The facts themselves belong to the sources listed below; cite those for the science.