scientific discipline that is concerned with all geological aspects of the continental shelves and slopes and the ocean basins. In practice, the principal focus of marine geology has been on marine sedimentation and on the interpretation of the many bottom samples that have been obtained through the years. The advent of the concept of seafloor spreading (seafloor spreading hypothesis) in the 1960s, however, broadened the scope of marine geology considerably. Many investigations of midoceanic ridges, remanent magnetism of rocks on the seafloor, geochemical analyses of deep brine pools, and of seafloor spreading and continental drift may be considered within the general realm of marine geology.