WORDS TO KNOW
geologic time: the span of Earth’s history marked by major events and changes.
era: a division of geologic time.
period: a division of time within an era.
epoch: a division of time within a period.
The timeline of Earth’s lifespan is shown in a geologic time scale. It is broken up into chunks of time called eras. Each era is made up of different periods. Some of the more recent periods are also divided into epochs.
This geologic time scale includes important events in Earth’s history. Some of these events include the appearance and disappearance of different species, major changes in the earth that have caused mass extinctions, and how the planet has changed.