Sandbian
The Sandbian is the first stage of the Upper Ordovician. It follows the Darriwilian and is succeeded by the Katian. Its lower boundary is defined as the first appearance datum of the graptolite species Nemagraptus gracilis around 458.4 million years ago. The Sandbian lasted for about 5.4 million years until the beginning of the Katian around 453 million years ago.
| Sandbian | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Chronology | |||||||||||
| |||||||||||
| 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 Nemagraptus gracilis | ||||||||||
| Lower boundary GSSP | Fågelsång section, Sularp Brook, Skåne, Sweden 55.7137°N 13.3255°E | ||||||||||
| Lower GSSP ratified | 2002 | ||||||||||
| Upper boundary definition | FAD of the Graptolite Diplacanthograptus caudatus | ||||||||||
| Upper boundary GSSP | Black Knob Ridge section, Oklahoma, United States 34.4305°N 96.0746°W | ||||||||||
| Upper GSSP ratified | 2006 | ||||||||||
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.