The Geological Times

The Earth's history is divided into different periods called the Geologic Time Scale that traces the 4.54 billions years of our planet.

The first division of the history was published by A. Holmes in 1913, the founding father of the geologic time scale, even tough the concept dates back to the 19th century. Since then scientific advances have enriched the scale with increasingly accurate ages. Every four years, the International Stratigraphy Commission meets to decide on the name of the divisions and recalibrate the ages according to the latest discoveries.

The Geological Time Scale

This scale is divided into several units. The principle is simple. Imagine a series of boxes like the Russian dolls: a big unit is divived into several sub-units which are themselves sub-divided into smaller ones etc...

The times are divided into five major units:

.: Eons represent the longest periods of time and defined the great events of Earth's history. Four in number (Hadean, Archean, Proterozoic & Phanerozoic), the first three cover 4 billions years.

Looking down at the next subdivision with the .: eras that are defined by palaeontological and geodynamic arguments at Earth's scale.

Next with the .: periods and .: epochs which represent the duration of a geological formation i.e. the duration of a set of sediment layers sharing common characteristics.

And last, the .: ages, based unit of the geology, that refer to an outcrop (called a stratotype). They are used as a reference in the world and last few millions years.

(example: the Kimmeridgian was defined at Kimmeridge - Dorset, UK)

Did you know ?

Which subdivision do we belong to ?

↪︎ Eon: Phanerozoic

↪︎ Era: Cenozoic

↪︎ Period: Quaternary

↪︎ Epoch: Holocene

↪︎ Age: Meghalayan