| Tertiary |
|---|
|
|
−70 — – −65 — – −60 — – −55 — – −50 — – −45 — – −40 — – −35 — – −30 — – −25 — – −20 — – −15 — – −10 — – −5 — – 0 — | | |
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| Name formality | Informal |
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|
| Celestial body | Earth |
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| Regional usage | Regional(?) |
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| Time scale(s) used | ICS Time Scale (formerly) |
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| Formerly used by | ICS |
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| Chronological unit | Period |
|---|
| Stratigraphic unit | System |
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| Time span formality | Informal |
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| Lower boundary definition | K-Pg extinction event |
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| Lower boundary GSSP | None |
|---|
| Lower GSSP ratified | N/A |
|---|
| Upper boundary definition | Beginning of the Quaternary glaciation |
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| Upper boundary GSSP | None |
|---|
| Upper GSSP ratified | N/A |
|---|
The Tertiary ( TUR-shər-ee, TUR-shee-err-ee) is an obsolete geologic period spanning 66 million to 2.6 or 1.8 million years ago. The period began with the extinction of the non-avian dinosaurs in the Cretaceous–Paleogene extinction event, at the start of the Cenozoic Era, and extended to the beginning of the Quaternary glaciation at the end of the Pliocene Epoch. The Tertiary has not been recognised by the International Commission on Stratigraphy (ICS) since the late 1980s, with the timespan of the Tertiary now being split into the earlier Paleogene and the more recent Neogene periods, though the term continues to be used in some scientific publications.