Rhuddanian | |||||||||||||
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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 Akidograptus ascensus | ||||||||||||
Lower boundary GSSP | Dob's Linn, Moffat, U.K. 55°26′24″N 3°16′12″W / 55.4400°N 3.2700°W | ||||||||||||
Lower GSSP ratified | 1984[4][5] | ||||||||||||
Upper boundary definition | FAD of the graptolite Demirastrites triangulatus | ||||||||||||
Upper boundary GSSP | Hlásná Třebaň section, Czech Republic 49°55′23″N 14°12′43″E / 49.9230°N 14.2119°E[6] | ||||||||||||
Upper GSSP ratified | 2024[7][8] |
In the geologic timescale, the Rhuddanian is the first age of the Silurian Period and of the Llandovery Epoch. The Silurian is in the Paleozoic Era of the Phanerozoic Eon.[9] The Rhuddanian Age began 443.8 ± 1.5 Ma and ended 440.8 ± 1.2 Ma (million years ago). It succeeds the Hirnantian Age (the last age of the Ordovician Period) and precedes the Aeronian Age.[10]
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