GENERAL GEOLOGY

Detailed explanation-1: -The great Precambrian expanse of time is divided into the Proterozoic, Archean, and Hadean eons in order of increasing age. The names of the eras in the Phanerozoic eon (the eon of visible life) are the Cenozoic ("recent life"), Mesozoic ("middle life") and Paleozoic ("ancient life").

Detailed explanation-2: -Geologists divide the time between Precambrian and the present into three long units called eras (Paleozoic, Mesozoic, Cenozoic).

Detailed explanation-3: -It began 4.55 billion years ago (4 550 million years) and continues to the present day. The eras are the four major divisions of the geological time scale: Precambrian, Paleozoic, Mesozoic, and Cenozoic.

Detailed explanation-4: -The Phanerozoic Eon is divided into three eras, the Paleozoic, Mesozoic and Cenozoic eras. These were named for the kinds of fossils that were present. The Cenozoic is the youngest era and the name means “new life”. This is because the fossils are similar to animals and plants that are common today.

Detailed explanation-5: -An eon is the largest (formal) geochronologic time unit and is the equivalent of a chronostratigraphic eonothem. As of April 2022 there are three formally defined eons/eonothems: the Archean, Proterozoic, and Phanerozoic. The Hadean is an informal eon/eonothem, but is commonly used.