*Dates (in millions of years before present) follow Cowie and Bassett, 1989.
The 'Precambrian' is not used here, although it is often in use informally.
Geochronologically the Archaean and Proterozoic are more useful.
Based on 'A Geologic Time Scale 2004' by F M Gradstein, J G Ogg, A G Smith, el al. (2004), and the International Stratigraphic Chart, 2006 (ICS) with additions.