(a) Current geological timescale (after Strachan et al. 2020). (b) Timescale proposal of Van Kranendonk et al. (2012) retaining original colour scheme. Golden spike symbols represent ratified (yellow) and potential (pale) GSSP levels. Clock symbols represent ratified Proterozoic and recommended Archean GSSAs. (c) Proposed chronostratigraphic subdivision of the geological timescale (this paper). (a–c) depict subdivisions of decreasing duration from left to right: eons, eras and periods. Note that era and period boundary ages are only approximate ages and would inevitably change in any internationally agreed chronostratigraphic scheme. Period names in italics represent suggested changes to existing nomenclature. If the first period of the Paleoproterozoic Era were renamed (here as the Skourian Period; cf. Oxygenian Period of Van Kranendonk et al. 2012), we recommend that the term ‘Siderian’ be retained for the final period of the Archean Eon.