The ICS International Chronostratigraphic Chart this decade

The International Commission on Stratigraphy (ICS) has been producing and updating its International Chronostratigraphic Chart for several decades. The chart communicates higher-order divisions of geological time and actual knowledge on the numerical ages of their boundaries. Distributed via the ICS website www.stratigraphy.org the chart promotes use in graphic, tabulated and further digital forms in multiple languages. This paper is a status update, eleven years since the last such publication, covering activities between 2012 and 2024. Chart updates during the past decade have echoed the ICS’s primary objective of precisely defining a global standard set of time-correlative units (Systems, Series, Stages) for stratigraphic successions worldwide. These units are, in turn, the basis for the Periods, Epochs, and Ages of the Geological Time Scale. Their standardization is fundamental for expressing geological knowledge, in application and education, outreach and continuing research. The chart offers a framework through which regional-scale higher-resolution divisions can be linked, equated and collated. Likewise it offers a framework for digital representation of the Geological Time Scale. Maintenance and distribution of chart versions on the web has been a manual endeavour, a process that ICS is upgrading to serve an increasingly digital world.