Ordovician
Ordovician යනු වසර මිලියන 485-444 කට පෙර Paleozoic යුගයේ දෙවන කාල පරිච්ඡේදය වේ,
| Ordovician | |
|---|---|
| Chronology | |
සැකිල්ල:Ordovician graphical timeline | |
| Etymology | |
| Name formality | Formal |
| Name ratified | 1960 |
| Usage information | |
| Celestial body | Earth |
| Regional usage | Global (ICS) |
| Time scale(s) used | ICS Time Scale |
| Definition | |
| Chronological unit | Period |
| Stratigraphic unit | System |
| First proposed by | Charles Lapworth, 1879 |
| Time span formality | Formal |
| Lower boundary definition | FAD of the Conodont Iapetognathus fluctivagus |
| Lower boundary GSSP | Greenpoint section, Green Point, Newfoundland, Canada 49°40′58″N 57°57′55″W / 49.6829°N 57.9653°W |
| GSSP ratified | 2000 |
| Upper boundary definition | FAD of the Graptolite Akidograptus ascensus |
| Upper boundary GSSP | Dob's Linn, Moffat, U.K. 55°26′24″N 3°16′12″W / 55.4400°N 3.2700°W |
| GSSP ratified | 1984 |
| Atmospheric and climatic data | |
| Sea level above present day | 180 m; rising to 220 m in Caradoc and falling sharply to 140 m in end-Ordovician glaciations |
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Wikisource has original works on the topic: Paleozoic#Ordovician
Ordovician හා සබැඳි මාධ්ය විකිමාධ්ය කොමන්ස් හි ඇත.
- Ogg, Jim (June 2004). "Overview of Global Boundary Stratotype Sections and Points (GSSP's)". 2006-04-23 දින මුල් පිටපත වෙතින් සංරක්ෂණය කරන ලදී. සම්ප්රවේශය 2006-04-30.
- Mehrtens, Charlotte. "Chazy Reef at Isle La Motte". An Ordovician reef in Vermont.
- Ordovician fossils of the famous Cincinnatian Group
- Ordovician (chronostratigraphy scale)
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