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 spreading theory". Therefore, today, scientists understand that the plate tectonics theory was born by the ocean floor spreading theory, which is able to cover the weak points of the latter. D/V Glomar Challenger started her Leg Ion 20 July, 1968 from Orange, Texas to implement the Deep Sea Drilling Project. The timing almost coincided with the proposal period of the plate tectonics. After carrying out a few legs of the drilling operations, the results obtained by D I V Glomar Challenger well proved the rightness of the newly proposed theories of the ocean floor spreading and the plate tectonics. For us, the successful processes started by the ocean floor spreading theory, improved by the concept of plate tectonics and proved by the DSDP results have been a golden monument in the field of earth sciences probably for several centuries.
