Precambrian



The Precambrian is, according to the defenders of an old age for the Earth, the large span of time in Earth's history before the Paleozoic era and it spans from the formation of Earth about 4,600 million years ago to the beginning of the Cambrian Period, about 530 million years ago.

According to the hypothetical geological time scale, the precambrian is divided into three major eons :


 * Hadean - Between 4,600 million years ago and 3,800 million years ago.
 * Archean - Between 3,800 million years ago and 2,500 million years ago.
 * Proterozoic - Between 2,500 million years ago and 538 million years ago.

Some authors divide the precambrian into two major eras :


 * Archeozoic - Between 4,500 million years ago and 925 million years ago.
 * Proterozoic - Between 925 million years ago and 570 million years ago