New Zealand Geological Timescale 2025

New Zealand Geological Timescale 2025 (NZGT 2025) is the first comprehensive update and revision of the New Zealand Geological Timescale in a decade. The criteria used to establish age ranges of New Zealand Stages within the NZGT have been reviewed, calibrated, and revised where required against the 2023/04 International Chronostratigraphic Chart and the Geological Timescale GTS2020. No new bespoke research was undertaken, although some previously unpublished biostratigraphic and isotopic data have been incorporated. Changes have been made to basal ages of 45 stages and substages since the previous timescale revision (NZGT 2015/1). A stratotype section and point (SSP) is defined for the Upper Oligocene Duntroonian Stage and the definition of the Upper Ururoan Substage is emended. Absolute changes to age ranges since the previous revision (NZGT 2015/1) are mostly ≤2% but a few, particularly in the Middle to Late Jurassic, are more significant.