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Related HowStuffWorks Articles

• How Dinosaurs Work
• How Fossils Work
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• How Atoms Work
• How the Earth Works
• How Volcanoes Work
• What's a fossil?

More Great Links

• USGS: Geologic Time

Sources

• Lewin, Roger. "Rock of Ages - Cleft by Laser." New Scientist. 9/28/1991. (1/2/2008)
  http://space.newscientist.com/article/mg13117884.900-rock-of-ages--cleft-by-laser-if-you-want-to-date-a-rockget-a-laser-thats-the-message-for-geologists-interested-in-the-preciseageof-anything-from-moon-rocks-to-hominid-fossils-.html
• Museum Victoria. "Determining the Age of Rocks and Fossils." (1/2/2008)
  http://museumvictoria.com.au/prehistoric/what/fossilage.html#absolute
• University of California at Berkeley. "Understanding Evolution for Teachers: Radiometric Dating." (1/2/2008)
  http://evolution.berkeley.edu/evosite/evo101/IIE1aAtomicclocks.shtml
• USGS. "Geologic Time." Version 1.2 (1/2/2008)
  http://pubs.usgs.gov/gip/geotime/
• USGS. "How do geologists date rocks? Radiometric dating!" (1/2/2008)
  http://wrgis.wr.usgs.gov/docs/parks/gtime/radiom.html
• USGS. "The Age of the Earth." (1/2/2008)
  http://wrgis.wr.usgs.gov/parks/gtime/ageofearth.html