International Commission on Stratigraphy

Assembled from 11 blocks · 1 evidence · 7 related

1. Story
2. The body within the International Union of Geological Sciences that defines and maintains the geological time scale, publishes the International Chronostratigraphic Chart, and ratifies GSSPs proposed by its subcommissions. It is the reason deep-time dates are comparable between papers at all: without a single ratified chart, every laboratory would attach its own ages to its own boundaries. The Commission is also a useful corrective to the idea that the time scale is settled. Chart versions are reissued regularly and numerical ages change between them as new high-precision dates arrive — the base of the Cambrian appears as 541.0 ± 1.0 Ma on charts widely cited through the 2010s and as 538.8 ± 0.2 Ma on more recent ones. Nothing about the rocks changed; the measurement improved and the definition stayed where it was.
3. Knowledge
4. International Commission on Stratigraphy
5. Connections
6. Global Boundary Stratotype Section and Point
7. The end-Ordovician mass extinction
8. The Late Devonian crisis
9. The numerical age of the Cambrian base is revised to 538.8 Ma
10. Evidence
11. Supports the stage and period boundary ages used throughout this pack, including the Cambrian base at 538.8 ± 0.2 Ma on recent editions against 541.0 ± 1.0 Ma on earlier ones. V55 verification basis: this session had no network access to any source — WebFetch was egress-blocked and the WebSearch budget was exhausted — so the cited work was not retrieved and its pagination was not re-checked. No chart edition was opened, so the boundary figures are quoted from standing knowledge of the chart rather than read from it, and the edition in which the Cambrian base changed is not identified.