Recent studies of the sea floor are forcing drastic revisions of many of our basic geological concepts. The concept of vertical stability of the ocean basins is challenged by the discovery of “guyots”; sea-mounts whose flat tops, now several thousand feet beneath the sea surface, give evidence of wave truncation. The belief that the deep ocean floor is essentially a flat, featureless plain has been completely discredited by the discovery of fault scarps and mountain ranges comparable in size and complexity to any of those existing on the continents. The concept of the continental shelf as a simple wave-cut, wave-built terrace covered with sedimentary material grading uniformly from coarse sediments at the shore to very fine ones at depth has been shown to be quite erroneous for most of the continental shelves of the world. The belief that the waters of the ocean are completely still below a few hundred feet has been disproved by photographs of ripple marks at depths of several thousand feet.
One of the most challenging of recent discoveries is the finding of relatively coarse sediments (coarse silt and sand) in deep basins and on the open ocean floor at depths of several thousand feet and many miles from land. Cores showing alternations of such coarse sediments with fine muds indicate that the process responsible for their transportation and deposition is not a unique but a recurring one.