Earth:Rhuddanian
| Rhuddanian | |
|---|---|
| 443.8 ± 1.5 – 440.8 ± 1.2 Ma | |
| 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 Akidograptus ascensus |
| Lower boundary GSSP | Dob's Linn, Moffat, United Kingdom [ ⚑ ] 55°26′24″N 3°16′12″W / 55.4400°N 3.2700°W |
| GSSP ratified | 1984[4][5] |
| Upper boundary definition | FAD of the graptolite Monograptus austerus sequens |
| Upper boundary GSSP | Trefawr Track Section, Llandovery, Wales, United Kingdom [ ⚑ ] 52°01′48″N 3°42′00″W / 52.0300°N 3.7000°W |
| GSSP ratified | 1984[5] |
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.[6] The Rhuddanian Age began 443.8 ± 1.5 Ma and ended 440.8 ± 1.2 Ma (million years ago). It succeeds the Himantian Age (the last age of the Ordovician Period) and precedes the Aeronian Age.[7]
GSSP
The GSSP for the Silurian is located in a section at Dob's Linn, Scotland, in an artificial excavation created just north of the Linn Branch Stream. Two lithological units (formations) occur near the boundary.[6] The lower is the Hartfell Shale (48 metres (157 ft) thick), consisting chiefly of pale gray mudstone with subordinate black shales and several interbedded meta-bentonites.[6] Above this is the 43 metres (141 ft) thick Birkhill Shale, which consist predominantly of black graptolitic shale with subordinate gray mudstones and meta-bentonites.[8]
See also
- Ordovician-Silurian extinction events
- Early Palaeozoic Icehouse
References
- ↑ Jeppsson, L.; Calner, M. (2007). "The Silurian Mulde Event and a scenario for secundo—secundo events". Earth and Environmental Science Transactions of the Royal Society of Edinburgh 93 (02): 135–154. doi:10.1017/S0263593300000377.
- ↑ Munnecke, A.; Samtleben, C.; Bickert, T. (2003). "The Ireviken Event in the lower Silurian of Gotland, Sweden-relation to similar Palaeozoic and Proterozoic events". Palaeogeography, Palaeoclimatology, Palaeoecology 195 (1): 99–124. doi:10.1016/S0031-0182(03)00304-3.
- ↑ "Chart/Time Scale". International Commission on Stratigraphy. http://www.stratigraphy.org/index.php/ics-chart-timescale.
- ↑ Lucas, Spencer (6 November 2018). "The GSSP Method of Chronostratigraphy: A Critical Review". Frontiers in Earth Science 6: 191. doi:10.3389/feart.2018.00191. Bibcode: 2018FrEaS...6..191L.
- ↑ 5.0 5.1 Holland, C. (June 1985). "Series and Stages of the Silurian System". Episodes 8 (2): 101–103. doi:10.18814/epiiugs/1985/v8i2/005. https://timescalefoundation.org/references/Silurian1.pdf. Retrieved 11 December 2020.
- ↑ 6.0 6.1 6.2 Gradstein, Felix M.; Ogg, James G.; Smith, Alan G. (2004). A Geologic Time Scale 2004. ISBN 9780521786737.
- ↑ "GSSP Table - All Periods". http://www.stratigraphy.org/GSSP/index.html.
- ↑ "GSSP for the Rhuddanian Stage". http://www.stratigraphy.org/GSSP/Rhuddanian.html.
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