| The Columbia Encyclopedia, Sixth Edition. 2001-07. |
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| Geologic Timescale (table) |
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| Era | Period | Epoch | Approximate duration
(millions of years) | Approximate number of years ago
(millions of years) |
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| Cenozoic | Quaternary | Holocene | 10,000 years ago to the present | | | Pleistocene | 2 | .01 | | Tertiary | Pliocene | 11 | 2 | | Miocene | 12 | 13 | | Oligocene | 11 | 25 | | Eocene | 22 | 36 | | Paleocene | 71 | 58 | | Mesozoic | Cretaceous | | 71 | 65 | | Jurassic | | 54 | 136 | | Triassic | | 35 | 190 | | Paleozoic | Permian | | 55 | 225 | | Carboniferous | | 65 | 280 | | Devonian | | 60 | 345 | | Silurian | | 20 | 405 | | Ordovician | | 75 | 425 | | Cambrian | | 100 | 500 | | Precambrian | | | 3,380 | 600 |
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| | | The Columbia Encyclopedia, Sixth Edition. Copyright © 2007 Columbia University Press. |
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