Marine geology

Article By:

Hayes, Dennis E. Formerly, Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York.

Last reviewed:November 2019

DOI:https://doi.org/10.1036/1097-8542.406200

The study of the portion of the Earth beneath the oceans. Approximately 70% of the Earth's surface is covered with water. Marine geology involves the study of the seafloor; of the sediments, rocks, and structures beneath the seafloor; and of the processes that are responsible for their formation. For the marine geologist, the presence of the oceans masks the principal features of interest. The average depth of the ocean is about 3800 m (12,500 ft), and the greatest depths are in excess of 11,000 m (36,000 ft; the Marianas Trench). The study of the seafloor necessitates employing a complex suite of techniques to measure the characteristic properties of the Earth's surface beneath the oceans. Contrary to popular views, only a minority of marine geological investigations involve the direct observation of the seafloor by scuba diving or in submersibles. Instead, most of the ocean floor has been investigated by surface ships using remote-sensing geophysical techniques, and more recently by satellite observations.

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