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Yosemite > Library > François Matthes > Appendix: Major Divisions of Geologic Time in Use by the U.S. Geological Survey >
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Era | Period or System | Epoch or Series | Approx. no. of million years ago.1 | Approx. length in millions of years1 |
Cenozoic | Quaternary | Recent Pleistocene | 0–1 | 1 |
Tertiary | Pliocene | 1–12 | 11 | |
Miocene | 12–28 | 16 | ||
Oligocene | 28–40 | 12 | ||
Eocene Paleocene | 40–60 | 20 | ||
Mesozoic | Cretaceous | 60–130 | 70 | |
Jurassic | 130–155 | 25 | ||
Triassic | 155–185 | 30 | ||
Paleozoic | Permian | 185–210 | 25 | |
Pennsylvanian (Upper Carboniferous) | 210–2352 | 25 | ||
Mississippian (Lower Carboniferous) | 235–2652 | 30 | ||
Devonian | 265–320 | 55 | ||
Silurian | 320–360 | 40 | ||
Ordovician | 360–440 | 80 | ||
Cambrian | 440–520 | 80 | ||
Proterozoic | Pre-Cambrian | 520–2100+ | 1600+ |
1Report of the National Research Council, Committee on the Measurement of Geologic Time, 1949–50.
2Estimate of J. P. Marble, Chairman of Committee on Measurement of Geologic Time, March 17, 1954.
Superintendent of Documents, Government Printing Office. Washington 25, D.C.:
The Geologic History of Yosemite Valley. Professional Paper 160, U. S. Geological Survey. 1930.
Reconnaissance of the geomorphology and glacial geology of the San Joaquin Basin, Sierra Nevada. California. Professional Paper 329, U.S. Geological Survey, 1960.*
Glacial reconnaissance of Sequoia National Park, California. (To be published by the U. S. Geological Survey.)*
The University of California Press. Berkeley 4, California:
Sequoia National Park: a geological album. 1950.*
The Incomparable Valley: a geologic interpretation of the Yosemite. 1950.*
* Posthumous works, edited by Fritiof Fryxell.
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