essential questions 11-6-12

The 3 major geological events in the history of the earth were the ice age, the major extinction of life (dinosaurs) and the appearance of humans.


There are 3 eras and 4 eons

Eon and era are 2 different geochronological unities, of which eon is the first, and era the second Between an era and an epoch there is a period.
Each eon is divided into eras, each era into periods and each period into epochs

Scientists created eras and eons to better keep track of geological events