Ludfordian
| Ludfordian | |||||||||||||
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Paleogeography of the Ludfordian, 425 Ma | |||||||||||||
| Chronology | |||||||||||||
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| Etymology | |||||||||||||
| Name formality | Formal | ||||||||||||
| Name ratified | 1980 | ||||||||||||
| 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 | Imprecise. Near FAD of the graptolite Saetograptus leintwardinensis | ||||||||||||
| Lower boundary definition candidates | None | ||||||||||||
| Lower boundary GSSP candidate section(s) | None | ||||||||||||
| Lower boundary GSSP | Sunnyhill, Ludlow, England 52°21′33″N 2°46′38″W / 52.3592°N 2.7772°W | ||||||||||||
| Lower GSSP ratified | 1980 | ||||||||||||
| Upper boundary definition | FAD of the graptolite Monograptus parultimus | ||||||||||||
| Upper boundary GSSP | Požáry Section, Prague-Řeporyje, Czech Republic 50°01′40″N 14°19′30″E / 50.0277°N 14.3249°E | ||||||||||||
| Upper GSSP ratified | 1984 | ||||||||||||
In the geologic timescale, the Ludfordian is the upper of two chronostratigraphic stages within the Ludlow Series. Its age is the late Silurian Period, and within both the Palaeozoic Era and Phanerozoic Eon. The rocks assigned to the Ludfordian date to between 425.6 ± 0.9 Ma and 423.0 ± 2.3 Ma (million years ago). The Ludfordian Stage succeeds the Gorstian Stage and precedes the Pridoli Epoch. It is named for the village of Ludford in Shropshire, England. The GSSP for the Ludfordian is represented as a thin shale seam, coincident with the base of the Leintwardine Formation, overlying the Bringewood Formation in England.