Timelines and pictures
http://www.childrensmuseum.org/geomysteries/timeline.html

http://www.bbc.co.uk/wales/nature/sites/naturalhistoryofwales/pages/ttest.shtml

http://cybersleuth-kids.com/sleuth/Science/Geology/Geologic_Timeline/Geological_Periods/index.htm

http://pubs.usgs.gov/gip/fossils/contents.html

http://www.oum.ox.ac.uk/thezone/fossils/history/scale.htm