Ludfordian

EtymologyName formalityFormalName ratified1980Usage informationCelestial bodyEarthRegional usageGlobal (ICS)Time scale(s) usedICS Time ScaleDefinitionChronological unitAgeStratigraphic unitStageTime span formalityFormalLower boundary definitionImprecise. Near FAD of the graptolite Lower boundary definition candidatesNoneLower boundary GSSP candidate section(s)NoneLower boundary GSSP, Ludlow, England
52°21′33″N2°46′38″W / 52.3592°N 2.7772°W / 52.3592; -2.7772Lower GSSP ratified1980Upper boundary definitionFAD of the graptolite Monograptus parultimusUpper boundary GSSP, Prague-Řeporyje, Czech Republic
50°01′40″N14°19′30″E / 50.0277°N 14.3249°E / 50.0277; 14.3249Upper GSSP ratified1984

In the geologic timescale, the Ludfordian is the upper of two chronostratigraphic stages within the Ludlow Series. Its age is the late SilurianPeriod, and within both the PalaeozoicEra and PhanerozoicEon. The rocks assigned to the Ludfordian date to between 425.0 ± 1.5 Ma and 422.7 ± 1.6 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 , overlying the in England.