1. A Time Line

2. Alfred Wegener (1910-1920) Proposed Theory of Continental Drift – based on puzzle-like fit of continents Discovered three key pieces of evidence Fossil clues (glossopteris and mesosaurus) Glacial clues (striations in no-glacial areas) Rock clues (Appalachian Mtn and Greenland/Europe) Died without substantial proof of HOW continents could move

3. Arthur Homes (1930s) Explained Continental Drift Power of magma convection in the mantle Sea-floor spreading mountain building Still had no hard data for proof, but answered the question of HOW the continents COULD move

4. Harry Hess (1960s) Proved seafloor spreading Sonar – mapped the ocean floor Molten material Drilling samples Geomagnetism Technology finally caught up with the great minds of the scientists