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
Famous quotes containing the words time and/or periods:
“A genius can never expect to have a good time anywhere, if he is a genuine article, but America is about the last place in which life will be endurable at all for an inspired writer of any kind.”
—Samuel Butler (1835–1902)
“It has no future but itself—
Its infinite contain
Its past—enlightened to perceive
New periods of pain.”
—Emily Dickinson (1830–1886)