Geologists divide the ages of the Earth into "eras." Each era covers millions of years. There are four basic eras from oldest to newest:
Precambrian. Paleozoic Mesozoic and Cenozoic Eras are divided into periods, and the two most recent periods are divided in turn into epochs.
What is the best title for this paragraph?
1. How Geologists Work
2. The Ages of the Earth
3. Important Geology Facts
4. How Old Is the Earth?
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