The document provides information about the geologic time scale. It begins by defining the geologic time scale as a timeline that chronologically relates geological eras, periods and epochs based on stratigraphy and life forms throughout Earth's history.
It then outlines the four main divisions of the geologic time scale - eon, era, period, epoch. The rest of the document describes each of the eons, eras, periods and epochs in detail, providing the time ranges and key events that occurred during each period of Earth's history from the Pre-Cambrian eon to the present Holocene epoch. It also includes two short tests at the end to assess comprehension.