The table and timeline of geologic periods presented here is in accordance with the dates and nomenclature proposed by the International Commission on Stratigraphy. When used in formal writing, specific geological and historical periods and events are capitalized. Some examples: the Silurian Period, the Ice Age, the Neolithic, the Archean; however, when not specific, some historical events remain uncapitalized, as in ice ages.

The Earth is thought by geologists to be 4570 million years old. The geologic or "deep" time of Earth's past has been organized into various periods according to events which took place in each period.

Table of geologic periods

1. In North America, the Carboniferous is subdivided into Mississippian and Pennsylvanian Periods.
2. The Proterozoic, Archean and Hadean are often collectively referred to as Precambrian Time, and sometimes also as the Cryptozoic.
3. Dates are slightly uncertain with differences of a few percent between various sources being common. This is largely due to uncertainties in radiometric dating and the problem that deposits suitable for radiometric dating seldom occur exactly at the places in the geologic column where we would most like to have them. Dates with an * are radiometrically determined based on internationally agreed to GSSPs. The dates quoted above are according to the International Commission on Stratigraphy 2004 time scale. All dates given are for the end of the interval in question.
4. Paleontologists often refer to faunal stages rather than geologic Periods. The Stage Nomenclature is quite complex. See Harland for an excellent time ordered list of faunal stages. Also see the article on GSSPs.
5. Historically, the Cenozoic has been divided up into the Quaternary and Tertiary sub-eras, as well as the Neogene and Paleogene periods. However, the International Commission on Stratigraphy has recently decided to stop using the terms Quaternary and Tertiary as part of the formal nomenclature.
6. The time shown in the "Years Ago" column is that of the end of the interval named beside it.
7. Hadean is not a formal eon. It was sometimes called Priscoan.
8. The GSSP for the base of the Ediacaran, ratified in 2004, is a climatic/geochemical marker rather than biostratigraphic. It represents the end of a widespread glaciation event.
9. Defined by absolute age (Global Standard Stratigraphic Age ).

Graphical timeline

References

• GeoWhen Database
• International Commission on Stratigraphy Time Scale

See also

• Age of the Earth
• Fossils and the geological timescale
• Cosmological timeline
• Lunar geologic timescale
• Martian geologic timescale
• Anthropocene
• Logarithmic timeline

External link

• NASA: Geologic Time