Hadean Era 4.6 to 4 bya

Precambrian Eon

Geologists divide the history of the Earth into Eons, Eras and Periods.

The earliest eon was the Precambrian (meaning "before the Cambrian Period") and the first part of this is called the Hadean Era.

This was the time before life appeared on Earth. Its name comes from the Greek word hades, meaning hellish because of the hot conditions on the young Earth.

Notice this period was relatively short.