Ashgill epoch - Llandovery epoch

International Chronostratigraphic TimescaleOrdovician of Britain
SilurianPridoli419.62
LudlowLudfordian422.7
Gorstian425
WenlockHomerian426.7
Sheinwoodian430.6
LlandoveryTelychian432.9
Aeronian438.6
Rhuddanian440.5
OrdovicianLate OrdovicianHirnantianAshgillHirnantian443.1
KatianRawtheyan445.2
Cautleyan448.8
Pusgillian449.2
CaradocStreffordianOnnian †449.5
Cheneyan451.3
Burrellian452.5
Sandbian452.8
Actonian †453
Marshbrookian †Woolstonian †454
Longvillian †455
Aurelucian456.6
Soudleyan †/Harnagian/Costonian457.2
Middle OrdovicianDarriwilianLlanvirnLlandeilian/Llandeilo/Late Llandeilo/Middle Llandeilo/Early Llandeilo/Late Llanvirn458.2
Abereiddian/Early Llanvirn461.1
ArenigFennian468
Dapingian469.4
Whitlandian470.7
Early OrdovicianFloian471.3
Moridunian473.8
TremadocianTremadocMigneintian477.1
Cressagian481.1 *
486.4 *
486.85