The present monograph is published to honour Dr. Tech. Flemming Bo Pedersen, Professor Emeritus in Hydrodynamics at the Technical University of Denmark, on his seventy year’s birthday and in gratitude for his continuous support to LICengineering A/S. The monograph collects Professor Emeritus, Dr. Tech. Flemming Bo Pedersen research and findings on plate tectonics during the last fifteen years. A new theory for plate tectonics and the evolution of Earth is introduced in the monograph. The governing force for the movement of the continents is concluded to be the long period earth tides.