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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.

Also see:

U.S. Geological Survey Geologic Names Committee, 2007, Divisions of geologic time—Major chronostratigraphic and geochronologic units: U.S. Geological Survey Fact Sheet 2007-3015, 2 p. http://pubs.usgs.gov/fs/2007/3015/.

The URL is: http://3dparks.wr.usgs.gov/coloradoplateau/timescale.htm
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Last modified: 11/22/2009