2007-3015 at http://pubs.usgs.gov/fs/2007/3015/ for ages of geologictime periods. Ages in the spiral have been rounded from the age estimates in the Fact Sheet
[[:File:Geologicaltimespiral.png]], for improved legibility |Source=Graham, Joseph, Newman, William, and Stacy, John, 2008, The geologictimespiral—A path
have been heavily sampled. Derivative works of this file: Geologictime scale Climate Change.png Arabic French Portuguese (SVG) Spanish English Spanish (formal
2007-3015 at http://pubs.usgs.gov/fs/2007/3015/ for ages of geologictime periods. Ages in the spiral have been rounded from the age estimates in the Fact Sheet