Ludfordian

Ludfordian
425.6 ± 0.9 – 423.0 ± 2.3 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Paleogeography of the Ludfordian, 425 Ma
Chronology
−444 — – −442 — – −440 — – −438 — – −436 — – −434 — – −432 — – −430 — – −428 — – −426 — – −424 — – −422 — – −420 — – −418 — Paleozoic O Silurian D L Llandovery Wenlock Ludlow Přídolí E Hirnantian Rhuddanian Aeronian Telychian Sheinwoodian Homerian Gorstian Ludfordian Lochkovian             ← Lau event ← Mulde event[1] ← Ireviken event[2] Subdivision of the Silurian according to the ICS, as of 2021.[3] Vertical axis scale: millions of years ago.
Etymology
Name formality	Formal
Name ratified	1980[4]
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 / 52.3592; -2.7772
Lower GSSP ratified	1980[4]
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 / 50.0277; 14.3249
Upper GSSP ratified	1984[5][6]

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.