The ocean floor spreading theory was proposed during 1961 and 62 by Robert Dietz and Harry Hess. This concept was a revolutionary one, and renewed the scientists thoughts on the dynamics of the ocean bottom. Then, for example, the coincidence of the Wadati-Benioff Zone with the subduction zone proposed by new concept was well understood. Further development of the ocean floor spreading theory was the proposal of new concept "plate tectonics" proposed by Xavier LePichon and by a few others during 1967 and 68. This new idea could solve the various conflicts involved in the "ocean floor...