How old is the Earth?
4600 million years old
What method do scientist use to find out the Earths age?
radioactivity
What do Geologist call the time periods of the Earth?
Eons
In what eon do we live?
Phanerozoic eon
In what eon did the ocean appear?
Hadean Eon.
When did the first microscopic organism appear in the ocean?
Archean eon 3800–2500 million years ago
In what EON did oxygen form?
Proterozoic eon 2500–542 million years ago
What are eons divided into?
Eras and Periods
In which era did dinosaurs roam the Earth?
The Mesozoic era
