what were the different geological eras called
The Geological period consists of time periods in the origin and evolution of earth. The earth is about 4.5 billion years old. The time from the origin of the earth to the present is divided into super eons, eons, eras and periods. The Precambrian period is a super eon that is sub-divided into three eons: â¢ the Hadean Eon (4.5 to 3.8 billion years before present), â¢ the Archean Eon (3.8 to 2.5 billion years before present),, and.