Alexandrian age - Ontarian age
| International Chronostratigraphic Timescale | Silurian of North America | |||||
|---|---|---|---|---|---|---|
| Silurian | Pridoli | Cayugan | 419.62 | |||
| Ludlow | Ludfordian | Niagaran | 422.7 * | |||
| Gorstian | 425 | |||||
| Wenlock | Homerian | Lockportian | 426.7 | |||
| Sheinwoodian | 430.6 | |||||
| Llandovery | Telychian | Ontarian | 432.9 | |||
| Alexandrian | 438.1 * | |||||
| Aeronian | 438.6 | |||||
| Medinan | Clinton | 439.4 * | ||||
| 440.1 * | ||||||
| Rhuddanian | 440.5 | |||||
| 443.1 | ||||||