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:
“Who first seduc’d them to that fowl revolt?
Th’ infernal Serpent; he it was, whose guile
Stird up with Envy and Revenge, deceiv’d
The Mother of Mankinde, what time his Pride
Had cast him out from Heav’n, with all his Host
Of Rebel Angels,”
—John Milton (1608–1674)
“It has no future but itself—
Its infinite contain
Its past—enlightened to perceive
New periods of pain.”
—Emily Dickinson (1830–1886)