Graham Shields et al. outline rock-based concepts to subdivide pre-Cryogenian time

Two years ago, a working group of the International Commission on Stratigraphy was set up with Graham Shields (Earth Sciences) as chair to see how the first 85% of Earth history can best be subdivided so that the names and ages of periods, eras and eons match known tectonic, environmental and paleobiological events recorded in the rock record. The hope is that this will allow more intuitive appreciation of our planet’s formative years for future scientists, students and the general public. A global debate ensued (mostly during the various lockdowns) that resulted in surprising consensus and earlier this month we published the results as an open access paper in the Journal of the Geological Society (https://doi.org/10.1144/jgs2020-222). The figure below shows the new proposed time scale, which forms the basis of a white paper that we are now submitting formally to the International Commission on Stratigraphy for their consideration and eventual ratification.