Geological Time scale

The first geological time scales find their source at the 18th century but take a form of precise dating with Arthur Holmes, in the Années 1930. This one publishes a first scale in 1937 and he is recognized today like the father of the geological time scale.

Profiting from the crossing of several scientific disciplines, those relating to the techniques of dating in particular, the science of the Chronostratigraphie does not cease growing rich, and the scales must be periodically updated, with numerical ages given with an increased precision.

Every four years, the International union of geological sciences (UIGS) organizes the international geological Congress whose 32^e edition was held in August 2004 with Florence, in Italy. At the time of the behavior of these congresses, the International commission of stratigraphy, which depends on the UIGS, rules officially on the denomination and the calibration of various divisions and subdivisions of geological times. These congresses are also sponsored by other national organizations, like the Commission of the geological map of the world (CCGM), established with Paris. The last scales published integrate in particular the magnétochrones (inversions of the terrestrial magnetic field) and comprise 5 to 6 standardized levels and under-levels. Old nomenclatures, in particular those of the era S Primary, Secondary, Tertiary and Quaternary, were thus abandoned with the profit of more precise and rigorous subdivisions. The scales presented in this article are based on the publications of the International commission of stratigraphy.

The geological time scale generally begins with the age estimated from the Ground, that is to say more than 4,5 billion years.

Linear synoptic scale of geological times

NB: Each final part of a scale is developed in the scale which follows.

Geological time scale

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