<P> The primary defined divisions of time are eons , in sequence the Hadean , the Archean , the Proterozoic and the Phanerozoic . The first three of these can be referred to collectively as the Precambrian supereon . Eons are divided into eras , which are in turn divided into periods , epochs and ages . </P>
<P> The primary defined divisions of time are eons , in sequence the Hadean , the Archean , the Proterozoic and the Phanerozoic . The first three of these can be referred to collectively as the Precambrian supereon . Eons are divided into eras , which are in turn divided into periods , epochs and ages . </P>
he earth 's geological time scale is divided into four main
he earth 's geological time scale is divided into four main
eons
eons