he earth's geological time scale is divided into four main
Geologic time scale The primary defined divisions of time are eons, in sequence the Hadean, the Archean, the Proterozoic and the Phanerozoic. The first three of these can be referred to collectively as the Precambrian supereon. Eons are divided into eras, which are in turn divided into periods, epochs and ages.
Earth science Earth science or geoscience is a widely embraced term for the fields of science related to the planet Earth. It is the branch of science dealing with the physical constitution of the earth and its atmosphere. Earth science is the study of our planet’s physical characteristics, from earthquakes to raindrops, and floods to fossils. Earth science can be considered to be a branch of planetary science, but with a much older history. “Earth science” is a broad term that encompasses four main branches of study, each of which is further broken down into more specialized fields.