Katian
The Katian is the second stage of the Upper Ordovician. It is preceded by the Sandbian and succeeded by the Hirnantian Stage. The Katian began 453 million years ago and lasted for about 7.8 million years until the beginning of the Hirnantian 445.2 million years ago. During the Katian the climate cooled which started the Late Ordovician glaciation.
| Katian | |||||||||||
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Paleogeography of the Katian, 450 Ma | |||||||||||
| Chronology | |||||||||||
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| Etymology | |||||||||||
| Name formality | Formal | ||||||||||
| Usage information | |||||||||||
| Celestial body | Earth | ||||||||||
| Regional usage | Global (ICS) | ||||||||||
| Time scale(s) used | ICS Time Scale | ||||||||||
| Definition | |||||||||||
| Chronological unit | Age | ||||||||||
| Stratigraphic unit | Stage | ||||||||||
| Time span formality | Formal | ||||||||||
| Lower boundary definition | FAD of the graptolite Diplacanthograptus caudatus | ||||||||||
| Lower boundary GSSP | Black Knob Ridge section, Oklahoma, United States 34.4305°N 96.0746°W | ||||||||||
| Lower GSSP ratified | 2006 | ||||||||||
| Upper boundary definition | FAD of the graptoliteNormalograptus extraordinarius | ||||||||||
| Upper boundary GSSP | Wangjiawan section, Wangjiawan, Yichang, China 30.9841°N 111.4197°E | ||||||||||
| Upper GSSP ratified | 2006 | ||||||||||
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