Age (geology)
A geologic age is a subdivision of geologic time that divides an epoch into smaller parts. A succession of rock strata laid down in a single age on the geologic timescale is a stage.
| Segments of rock (strata) in chronostratigraphy | Time spans in geochronology | Notes to geochronological units |
|---|---|---|
| Eonothem | Eon | 4 total, half a billion years or more |
| Erathem | Era | 10 defined, several hundred million years |
| System | Period | 22 defined, tens to ~one hundred million years |
| Series | Epoch | 34 defined, tens of millions of years |
| Stage | Age | 99 defined, millions of years |
| Chronozone | Chron | subdivision of an age, not used by the ICS timescale |
See also
References
- Cohen, K.M.; Finney, S.; Gibbard, P.L. (2015), International Chronostratigraphic Chart (PDF), International Commission on Stratigraphy.
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