The geologic time scale in historical perspective Berkely "Learn about the History of the Geologic Time Scale" History of Geologic Time Scale The Geologic Time Scale in Historical Perspective. History of Geologic Time Scale The Geologic Time Scale What are they http://www.ucmp.berkeley.edu/exhibit/histgeoscale.html UCMP « The Geologic Time Scale in Historical Perspective » History of Geologic Time Scale