Edenian age - Gamachian age
| International Chronostratigraphic Timescale | Ordovician of North America | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Ordovician | Late Ordovician | Hirnantian | Cincinnatian | Gamachian | 443.8 | ||||
| Katian | 445.2 | ||||||||
| Richmondian | 446 * | ||||||||
| Maysvillian | Rocklandian †/Shermanian/Ashbyan/Kirkfieldian/Blackriveran/Wildernessian/Trentonian/Franklinian | 449.8 * | |||||||
| Edenian | 450.4 * | ||||||||
| Mohawkian | Chatfieldian | 451.1 * | |||||||
| Sandbian | 453 | ||||||||
| Turinian | 453.7 * | ||||||||
| Whiterockian | Canadian † | Chazyan †/Marmor | 457 * | ||||||
| Middle Ordovician | Darriwilian | 458.4 | |||||||
| Dapingian | 467.3 | ||||||||
| Rangerian | 469.1 * | ||||||||
| Early Ordovician | Floian | Ibexian | Blackhillsian | Jeffersonian † | Cassinian † | 470 | |||
| Tulean | 473.9 * | ||||||||
| Tremadocian | 477.7 | ||||||||
| Stairsian | 480.3 * | ||||||||
| Skullrockian/Demingian | 482 * | ||||||||
| 485.4 | |||||||||
| 487.5 | |||||||||