It is theorized that the age of the earth is about 4.6 billion years old, formed at about the same time as the rest of our solar system. It was composed of hydrogen and helium produced in the Big Bang, as well as heavier elements ejected by supernovas.
Geologic Time Scale
Eon- largest time division divided into..
Era- which is divided into..
Period-which is divided into
Epoch
Life may have began 3 billions years ago, and the earth is 4.5 billion years old. But an "explosion" of life only began 570 million years ago.
Each of these time divisions are marked with a distinct change in the fossil record >> A Mass Distinction.
Evolution of the earth has indeed been affected by the periodic mass distinctions.