Explain the relationships among eons, eras, epochs, and periods of the geologic time scale

The largest time span of the geologic time scale is the eon. It is an indefinitely long period of time that contains at least two eras. Geologic time is divided into two eons. The more ancient eon is called the Precambrian, and the more recent is the Phanerozoic. Each eon is subdivided into smaller spans called eras. The Precambrian eon is divided from most ancient into the Hadean era, Archean era, and Proterozoic era.

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