Geologic Time Periods
The geologic time scale covers the extent of the existence of Earth, from about 4600 million years ago to the present day. It is marked by Global Boundary Stratotype Sections and Points. Geologic time units are (in order of descending specificity) eons, eras, periods, epochs, and ages; and the corresponding chronostratigraphic units, which measure "rock-time", are eonothems, erathems, systems, series, and stages.
The second and third timelines are each subsections of their preceding timeline as indicated by asterisks. The Cenozoic is sometimes divided into the Quaternary and Tertiary periods, although their use is no longer official.
Read more about this topic: List Of Time Periods
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“The time must come, my friend ... when brutality and the lust for power must perish by its own sword.... For when that day comes, the world must begin to look for a new life, and it is our hope that they may find it here. For here we shall be, with their books, and their music, and a way of life based on one simple rule: Be kind.”
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