Gorstian

In the geologic timescale, the Gorstian is an age of the Ludlow Epoch of the Silurian Period of the Paleozoic Era of the Phanerozoic Eon that is comprehended between 427.4 ± 0.5 Ma and 425.6 ± 0.9 Ma (million years ago), approximately. The Gorstian Age succeeds the Homerian Age and precedes the Ludfordian Age.[5] The age is named after Gorsty village southwest of Ludlow. The base of the age is marked by Graptolites tumescens and Graptolites incipiens. The type section is located in a quarry in the Elton Formation at Pitch Coppice, Shropshire, United Kingdom.[6]

Gorstian
Paleogeography of the late Gorstian, 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	FAD of the graptolite Saetograptus (Colonograptus) varians
Lower boundary GSSP	Pitch Coppice, Ludlow, U.K. 52.3592°N 2.7772°W / 52.3592; -2.7772
Lower GSSP ratified	1980[4]
Upper boundary definition	Imprecise. Near FAD of the graptolite Saetograptus leintwardinensis
Upper boundary definition candidates	None
Upper boundary GSSP candidate section(s)	None
Upper boundary GSSP	Sunnyhill, Ludlow, England 52.3592°N 2.7772°W / 52.3592; -2.7772
Upper GSSP ratified	1980[4]