Trempealeauan age - Gasconadian age
| International Chronostratigraphic Timescale | Cambrian of Britain | Ordovician of North America | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| 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 * | |||||||||
| Cambrian | Furongian | Stage 10 | Merioneth | Dolgellian/Trempealeauan | 486.85 | ||||||
| 488.9 * | |||||||||||
| Festiniogian | 490.2 * | ||||||||||
| Jiangshanian | 491 | ||||||||||
| Maentwrogian | 493.6 * | ||||||||||
| Paibian | 494.2 | ||||||||||
| Miaolingian | Guzhangian | St Davids | 497 | ||||||||
| Drumian | 500.5 | ||||||||||
| Wuliuan | 504.5 | ||||||||||
| Series 2 | Stage 4 | Caerfai | 506.5 | ||||||||
| Stage 3 | 514.5 | ||||||||||
| Terreneuvian | Stage 2 | 521 | |||||||||
| Fortunian | 529 | ||||||||||
| 538.8 | |||||||||||