http://www.yearofplanetearth.org/
http://www.geology.bas.bg/planetearth/plearth_bg.html
http://www.stratigraphy.org/
http://www.nhm.ac.uk/hosted_sites/ina/
http://www.cimp.ulg.ac.be/
http://www.le.ac.uk/geology/conodont/pander/index.html
http://www-sst.unil.ch/interrad/
http://www.isdr.org/
http://www.sepm.org/
Last update: 1 July 2010