the full time from 15 billion to 5 billion years back whenever earths crust had been formed the time whenever just unicellular organisms plus the very first types of life can be found identical to Archaeozoic
- identical to archaeozoic
- of or owned by early in the day of two divisions for the Precambrian period
- the time from 3,800 million years to 2,500 million years back; planet's crust formed; unicellular organisms tend to be very first kinds of life
In some places this is because the regions where they occur have net been carefully studied since the subdivision into Archeozoic and Proterozoic was made, and in others because of the inherent difficulty of separation, as where the Proterozoic rocks are highly metamorphosed.