Geological time scale

Geological time scale:-

> Earth’s history is approximately 350 million years old.

> Geologists have used two major units for subdividing the geological history of the earth these are- time and strata.

> On the basis of time the geological history of earth has been divided into five Eras namely Archaeozoic, Proterozoic, Palaeozoic, Mesozoic and Coenozoic.

> Eras have been divided into periods and periods into epochs.

> Similarly on the basis of strata, the geological history of the Earth is divided into system,series, stage and zone.

> The various eras and their age along with plant groups evolved during that period have been described in the given figure.