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Great advances in knowledge of the sea bed and ocean floor have been made during the past two decades; nevertheless, investigation of the usefulness of this part of the environment of Man is at an early stage of reconnaissance only. Elaborate techniques and expensive equipment are necessary to advance marine geophysics and geology and for these researchers must depend upon industrial or governmental support. The current theoretical results are exciting; some have practical significance. The continental terrace (slope, shelf and underlying crust) appears to contain on the average a higher proportion of thick, young sediments than the adjacent continents, and is correspondingly more important as a potential source of petroleum. The chances of finding workable solid mineral deposits such as occur in older rocks are less than in the continents.
These points are illustrated with reference to the terrace around the British Isles. The superficial sediments on the shelf may include concentrations of useful detrital minerals, submerged during the late Pleistocene–Holocene rise of sea level. The deep ocean bottoms may some day be a source of certain non-ferrous elements from ubiquitous manganese nodules, and of phosphates. Special concentrations of valuable elements may be found in ocean water, associated both with regions where upwelling promotes high biological activity and with restricted basins receiving hot hydrothermal fluids from below; but the feasibility of recovering these elements has not yet been demonstrated. The geology of the sea bed affects creatures living in the sea and thus influences Man's food supply.
