Geologic System | Sequence | Time Begin (MYA) | Time End (MYA) |
Tertiary | Tejas | 60 | 2 |
Upper Cretaceous | Zuni III | 96 | 65 |
Lower Cretaceous | Zuni II | 138 | 97 |
Jurassic | Zuni I & Upper Absaroka | 206 | 144 |
Triassic | Upper Absaroka | 243 | 213 |
Permian | Middle Absaroka | 268 | 245 |
Pennsylvanian | Lower Absaroka | 330 | 286 |
Mississippian | Upper Kaskaskia | 362 | 330 |
Devonian | Lower Kaskaskia & Upper Tippecanoe | 401 | 362 |
Silurian | Upper Tippecanoe | 438 | 408 |
Ordovician | Lower Tippecanoe & Upper Sauk | 488 | 438 |
Cambrian | Sauk | 548 | 505 |
Pre-Cambrian | ? | 590 |