Hirnantian
General info
| Belongs to |
Upper Ordovician
|
| Type | chronostratigraphy |
| Rank | Stage |
| Original rank | regional formation and stage |
| Scope | global |
| Status | formal standard |
| Author | Bancroft |
| Year | 1933 |
| Etymon | Cwm Hirnant near Bala, in northern Wales |
| Age top (Ma) | 443.8 |
| Age base (Ma) | 445.2 |
| Date changed | 2022-11-04 |
| Reference | Content | Year1 | Pages | Remarks |
|---|---|---|---|---|
| Gradstein et al., 2012 | updated numeric age |
2012
| ||
| Goldman et al., 2020 |
2020
| 630-694 |
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