Answer:
Eras
Step-by-step explanation:
In the geological time scale, eons are divided into various eras and eras are divided into various periods. Periods are further divided into many epochs. Hence, many periods together make an era.
Example: Cretaceous, Jurassic and Triassic periods together make the Mesozoic era. Likewise, the existing period "Quaternary" is the part of Cenozoic era.