Scientific Investigations Report 2007–5041
U.S. GEOLOGICAL SURVEY
Scientific Investigations Report 2007–5041
Table 1. Geologic time scale with simplified geologic units of the Spokane Valley-Rathdrum Prairie aquifer study area, Spokane County, Washington, and Bonner and Kootenai Counties, Idaho.
[Modified from https://pubs.usgs.gov/gip/geotime/divisions.html and http://www.geosociety.org/science/timescale/timescl.htm, accessed March 22, 2007. Abbreviations: ya, years ago; mya, million years ago; –, indicates a gap in the geologic record resulting from erosion and(or) nondeposition]
| Geologic Time | Simplified geologic unit | |||
|---|---|---|---|---|
| Phanerozoic Eon (544 mya to present) | Cenozoic Era (65 mya to present) | Quaternary Period (1.8 mya to present) | Holocene Epoch (8,000 ya to present) | Recent non-glacial sediment |
| Pleistocene Epoch (1.8 mya to 8,000 ya) | Glacial deposits and catastrophic flood deposits | |||
| Tertiary Period (65 to 1.8 mya) | Pliocene Epoch (5.3 to 1.8 mya) | – | ||
| Miocene Epoch (23.8 to 5.3 mya) | Basalt and older sediments | |||
| Oligocene Epoch (33.7 to 23.8 mya) | – | |||
| Eocene Epoch (55.5 to 33.7 mya) | Intrusive igneous rocks | |||
| Paleocene Epoch (65 to 55.5 mya) | ||||
| Mesozoic Era (248 to 65 mya) | Cretaceous Period (145 to 65 mya) | |||
| Jurassic Period (213 to 145 mya) | – | |||
| Triassic Period (248 to 213 mya) | ||||
| Paleozoic Era (544 to 248 mya) | Permian Period (286 to 248 mya) | |||
| Carboniferous Period (360 to 286 mya) | ||||
| Devonian Period (410 to 360 mya) | ||||
| Silurian Period (440 to 410 mya) | ||||
| Ordovician Period (505 to 440 mya) | ||||
| Cambrian Period (544 to 505 mya) | Sedimentary rocks | |||
| Precambrian Time (4,500 to 544 mya) | Proterozoic (2,500 to 544 mya) | Metamorphic rocks | ||
| Archean (3,800 to 2,500 mya) | – | |||
| Hadean (4,500 to 3,800 mya) | ||||
U.S.
Department of the Interior | U.S. Geological
Survey
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