The earth where we live is the only planet of our solar system that holds a mass of water we know as the ocean, covering 70.8% of the earth's surface with a mean depth of 3,800 m. When using the term ocean, we mean not only the water and what it contains, but also the bottom that supports the water mass above and the atmosphere on the sea surface. Modern oceanography thus deals with the water, the bottom of the ocean, and the air thereon. In addition, varied interactions take place between the ocean and the land so that such interface areas are also extended domains of oceanography. In ancient times our ancestors took an interest in nearshore seas, making them an object of constant study. Deep seas, on the other hand, largely remained an area beyond their reach. Modern academic research on deep seas is said to have been started by the first round-the-world voyage of Her Majesty's R/V Challenger I from 1872 to 1876. It has been only 120 years since the British ship leftPortsmouth on this voyage, so oceanography can thus be considered still a young science on its way to full maturity.

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.