In the geologic timescale, the Sheinwoodian is the age of the Wenlock Epoch of the Silurian Period of the Paleozoic Era of the Phanerozoic Eon that is comprehended between 433.4 ± 0.8 Ma and 430.5 ± 0.7 Ma (million years ago), approximately. The Sheinwoodian Age succeeds the Telychian Age and precedes the Homerian Age.^[5]

Quick Facts Chronology, Etymology ...

Sheinwoodian
433.4 ± 0.8 – 430.5 ± 0.7 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Paleogeography of the late Sheinwoodian
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. Currently placed between acritarch biozone 5 and LAD of Pterospathodus amorphognathoides. See Llandovery for more info.
Lower boundary definition candidates	A conodont boundary (Ireviken datum 2) which is close to the murchisoni graptolite biozone.
Lower boundary GSSP candidate section(s)	None
Lower boundary GSSP	Hughley Brook, Apedale, UK 52.5811°N 2.6389°W / 52.5811; -2.6389
Lower GSSP ratified	1980[4]
Upper boundary definition	FAD of the graptolite Cyrtograptus lundgreni
Upper boundary GSSP	Sheinton Brook, Homer, England 52.6156°N 2.5647°W / 52.6156; -2.5647
Upper GSSP ratified	1980[4]

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The Wenlock-Llandovery boundary is defined by the first occurrence of Cyrtograptus centrifugus. The stage is named after Sheinwood village, north of Much Wenlock. The Buildwas Formation of Shropshire, United Kingdom contains the type section.^[6]