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Geologic Time Scale
 
Time subdivisions and geologic ages in millions of years (Ma) are after the Geological Society of America 1999 Geologic Time Scale: http://www.geosociety.org/science/timescale/timescl.pdf. Web-safe colors choices are arbitrary but follow standard map colors for geologic ages. Another generalized geologic time scale is available at: http://geology.er.usgs.gov/paleo/geotime.shtml.

U.S. Department of the Interior - U.S. Geological Survey - Geology Discipline
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Last modified: 10/13/2004 (ps)

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