EARTH SCIENCE |
Platte Canyon High
School |
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GEOLOGIC TIME SCALE Ordovician after Harland et al., 1982 |
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Period | Epoch | Age | Ma age | Comments |
438 | ||||
Ordovician | Ashgill | Hirnantian | ||
Rawtheyan | ||||
Cautleyan | ||||
Psugillian | 448 | |||
Caradoc | Onnian | |||
Actonian | ||||
Marshbrookian | ||||
Longvillian | ||||
Doudleyan | ||||
Harnagian | ||||
Costonian | 458 | |||
Llandeilo | Late | |||
Middle | ||||
Early | 468 | |||
Llanvirn | Late | |||
Early | 478 | |||
Arenig | 488 | |||
Tremadoc | 505 |