Age And Stage
Age is a geologic time interval (geochronologic unit) corresponding to a ‘stage’. An age is a subdivision of an epoch, which generally has a time interval of three to ten million years. A stage is a basic lithostratigraphic unit below a series in the formal chronostratigraphic terminology hierarchy. A series can be subdivided into several stages. Different biogeographical regions can have different stage names, and a series can consist of different stages in different biogeographical regions. The stage symbols are not consistent in different countries.