Earth Science: Earth's History

 Geological Ages

•  Geological Time Machine.  The University of California Museum of Paleontology, Berkeley.  <http://www.ucmp.berkeley.edu/help/timeform.html>.

•  Geologic Time Scale.  Enchanted Learning Software.   <http://www.zoomschool.com/subjects/Geologictime.html>.

•  MacRae, Andrew.  Geological Time Scale.   1996. <http://www.talkorigins.org/faqs/timescale.html>.

 Cenozoic Era

•  Kaslev, M. Alan. The Cenozoic Era: The Age of Mammals.  1998-2002. <http://www.palaeos.com/Cenozoic/Cenozoic.htm>.

 Mesozoic Era

• Blanchard, Donald L.  Guide to the Dinosaurs of Colorado.  <http://webspinners.com/dlblanc/paleo/dino-colo/index.php>.

• Kaslev, M. Alan. Mesozoic Era.  1998-2003. <http://www.palaeos.com/Mesozoic/Mesozoic.htm>.

• Jacobson, Russ.  Dino Russ's Lair. Illinois State Geological Survey.  <http://www.isgs.uiuc.edu/dinos/dinos_home.html>.

• Poling, Jeff.  Dinosauria On-line.   <http://www.dinosauria.com/>.

 Paleozoic Era

• Kaslev, M. Alan. The Paleozoic.1998-2002.  <http://www.palaeos.com/Paleozoic/Paleozoic.htm>.

• Gon, S. M.  A Chart of Geological Time.  <http://www.trilobites.info/geotime.htm>.