Richmondian age - Llandovery epoch
| International Chronostratigraphic Timescale | Ordovician of North America | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Silurian | Pridoli | 419.62 | |||||||
| Ludlow | Ludfordian | 422.7 | |||||||
| Gorstian | 425 | ||||||||
| Wenlock | Homerian | 426.7 | |||||||
| Sheinwoodian | 430.6 | ||||||||
| Llandovery | Telychian | 432.9 | |||||||
| Aeronian | 438.6 | ||||||||
| Rhuddanian | 440.5 | ||||||||
| Ordovician | Late Ordovician | Hirnantian | Cincinnatian | Gamachian | 443.1 | ||||
| Katian | 445.2 | ||||||||
| Richmondian | 445.5 | ||||||||
| Maysvillian | Rocklandian †/Shermanian/Ashbyan/Kirkfieldian/Blackriveran/Wildernessian/Trentonian/Franklinian | 449.6 | |||||||
| Edenian | 450.2 | ||||||||
| Mohawkian | Chatfieldian | 451 | |||||||
| Sandbian | 452.8 | ||||||||
| Turinian | 453.8 | ||||||||
| Whiterockian | Canadian † | Chazyan †/Marmor | 457.3 | ||||||
| Middle Ordovician | Darriwilian | 458.2 | |||||||
| Dapingian | 469.4 | ||||||||
| Rangerian | 470.3 | ||||||||
| Early Ordovician | Floian | Ibexian | Blackhillsian | Jeffersonian † | Cassinian † | 471.3 | |||
| Tulean | 475.3 * | ||||||||
| Tremadocian | 477.1 | ||||||||
| Stairsian | 481.7 * | ||||||||
| Skullrockian/Demingian | 483.4 * | ||||||||
| 486.85 * | |||||||||
| 488.9 | |||||||||