This repository contains the authoritative data of the Chronostratigraphic Chart produced by the International Commission on Stratigraphy, distributed online at https://stratigraphy.org/chart.
This data is in the form of a Knowledge Graph formulated according to Semantic Web principles, which means it’s serialized in RDF and, after loading, can be queried using the SPARQL query language.
The Chart is formulated as a SKOS Vocabulary with many additional properties relevant to timescales and geology.
This data form of the Chart will soon be used to produce all PDF and other visual forms of the Chart.
To publish a release, go to the GitHub releases page and create a new release. This release should be set to create a new tag using SemVer preceded by v, but the major and minor versions should reflect the stratigraphic versions, for example v2023.09.1.
Creating this tag will trigger a workflow that generates the PDFs and publishes them to the release.
This data is copyrighted as follows:
© International Commission on Stratigraphy, 2026
This data is licensed for use with the Creative Commons Attribution 4.0 license:
A local copy of the license deed is stored in the file LICENSE in this repository.
Please contact the executive of the International Commission on Stratigraphy with all questions via https://stratigraphy.org/executive
You may also log any issues with the data at https://github.com/i-c-stratigraphy/chart/issues.
Make UI changes in chart-ui/.
Install dependencies and run the UI locally from that directory:
cd chart-ui
pnpm install
pnpm run devThe development server runs at http://localhost:3000.
Visual changes affect the generated PDFs, so any layout, typography, spacing, or other presentation change should be tested locally by running:
task test-pdfsThis runs the local PDF generation workflow and prints the path to the generated chart-pdf.zip artifact so it can be inspected before opening a PR or cutting a release.