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continental margin[¦känt·ən¦ent·əl ′mär·jən]
the peripheral area of the floor of the world’s ocean constituting, in geological structure and relief, a continuation of the continental land.
The total area of the continental margin is about 81.5 million sq km. It consists of the shelf, the continental slope, and the continental rise. The earth’s crust in the continental margin is of the continental type. In certain regions the continental margin is characterized by somewhat rugged relief and by the absence of a clear division into the shelf, slope, and rise. In tectonic terms, the continental margin is usually classified among the continental platforms, but, in some places, seismic and volcanic activity are observed. The continental margin is the arena of the most active submarine processes (wave action, tides, currents, floating ice and organisms).
Owing to the proximity of dry land, a great deal of terrigenous material is deposited in the continental margin. The thickest deposits form in the depressions of the shelf, on the marginal plateaus, and in the continental rise. The continental margin is noted for the great variety of benthic deposits, particularly within the shelf. This is explained not only by the diversity of facies distribution but also by the broad distribution of relic deposits of subaerial genesis on the shelf. The continental margin is the most accessible part of the ocean floor for development. Oil and gas deposits on the shelf are currently being exploited.
O. K. LEONT’EV