The BGS Geological Timechart provides colourful reference material, for use in schools, colleges and the home, setting out the geological timescale and geochronological terms we use at the British Geological Survey.
Several geological timescales exist, reflecting the use of differing datasets and methods of interpretation.
The BGS Geological Timechart is based on 'The Geologic Time Scale 2012' by F M Gradstein, J G Ogg, M Schmitz & G Ogg (2012), with additions.
The result is a composite geological timechart that will be updated as improved timescales become available.
The principal chart shows the Phanerozoic (Cambrian to Quaternary) timescale. The names of the individual periods are links: each one leads to a more detailed chart showing the epochs and ages for that period.
The charts for the individual periods are all drawn to the same scale.
Where there is insufficient or contradictory data on the dating of age boundaries, the ages are given an average duration within the limits of the appropriate epoch boundaries.
These age boundaries appear as dashed lines on the charts. Generally there is one period per chart except for the Palaeogene/Neogene/Quaternary, Permian/Triassic and Ordovician/Silurian.
A chart for the Archaean and Proterozoic (Precambrian) is also included.
There is more detailed stratigraphical information from the BGS Holostrat or Stratigraphical Framework Committee reports.