International Commission on Stratigraphy (ICS) updated the International Chronostratigraphic Chart (version dated 2024/12)

The geochronological dating of 49 Phanerozoic stage boundaries has been changed compared to the previous version of the ICC (version dated 2024/03). Some of it was aligned with the ICC published in the monograph Geological Time Scale (2020), but many of the dates were submitted and agreed upon by the Subcommissions on Systems and the Subcommission on Timescale Calibration of the International Commission on Stratigraphy. The change in the geochronological age of the Praghian and Emsian stage boundaries of the Lower Devonian reached 3 Ma and more; the boundary of the Cretaceous system was rejuvenated by almost 2 Ma.

The new geochronological dating is included in the draft General Stratigraphic Scale (GSS) 2025 where it is marked in red.

We would like to recall that the Interdepartmental Stratigraphical Committee (ISC) in 2022 decided to use for the stage boundaries of the GSS units coinciding with the ICC, the geochronological dates of the corresponding ICC boundaries, which were approved by the Subcommission on Systems of the International Commission on Stratigraphy and posted on the website of the Commission in the regularly updated International Chronostratigraphic Chart. In order to maintain the stability of the stratigraphic basis of geological mapping, the Bureau of the ISC annually monitors changes in the geochronological age of the stage boundaries of the ICC and, if there are changes, enters them into the GSS. The updated GSS is annually reapproved by the Scientific and Editorial Board of Rosnedra for use in geological mapping.