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:
“All questions rely on the present for their solution. Time measures nothing but itself. The word that is written may be postponed, but not that on the lip. If this is what the occasion says, let the occasion say it.”
—Henry David Thoreau (1817–1862)
“Those who weep for the happy periods which they encounter in history acknowledge what they want; not the alleviation but the silencing of misery.”
—Albert Camus (1913–1960)