Some things to look for (commonly missed):
| Eon | Era | Period | Epoch | |
| Phanerozoic | Cenozoic | Quaternary | Holocene | |
| Pleistocene | ||||
| Tertiary | Neogene | Pliocene | ||
| Miocene | ||||
| Paleogene | Oligocene | |||
| Eocene | ||||
| Paleocene | ||||
| Mesozoic | Cretaceous | |||
| Jurassic | ||||
| Triassic | ||||
| Paleozoic | Permian | |||
| Pennsylvanian | Carboniferous | |||
| Mississippian | ||||
| Devonian | ||||
| Silurian | ||||
| Ordovician | ||||
| Cambrian | ||||
| Proterozoic |
Precambrian |
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| Archean | ||||
| Hadean | ||||