The primary division of geologic time. A large division of geologic time comprising one or more periods. A standard geologic time unit corresponding to a system. Age in units of million years; eg, 2 000 000 = 2 Ma.
View Phanerozoic Time Slice Sequence View Cainozoic Time Slice Sequence View Quaternary Time Slice Sequence 65 Ma
View Mesozoic Time Slice Sequence View Cretaceous Time Slice Sequence 141 Ma
View Jurassic Time Slice Sequence 205 Ma
View Triassic Time Slice Sequence 251 Ma
View Palaeozoic Time Slice Sequence View Permian Time Slice Sequence 298 Ma
View Carboniferous Time Slice Sequence 354 Ma
View Devonian Time Slice Sequence 410 Ma
View Silurian Time Slice Sequence 434 Ma
View Ordovician Time Slice Sequence 490 Ma
View Cambrian Time Slice Sequence 540 Ma