Ocean Floor

Also found in: Dictionary, Thesaurus, Wikipedia.
Related to Ocean Floor: sea floor

ocean floor

[′ō·shən ′flȯr]
The near-horizontal surface of the ocean basin.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Ocean Floor


one of the principal elements of the relief and geological structure of the bottom of the world ocean. It covers the abyssal part of the ocean bottom except for the midocean ridges and is characterized by the development of typical oceanic crust. It occupies the lowest hypsometric level of the earth’s surface (average depth, 4,000 m; maximum depth, 7,000 m). Area, more than 185 million sq km (more than 50 percent of the total area of the bottom of the world ocean).

The largest elements of the relief of the ocean floor and its tectonic structure are ocean basins and the various types of oceanic rises that separate them. The basins occupy the largest part of the ocean floor and have average depths of about 5,000 m. Abyssal-type rolling relief occupies up to 80 percent of the bottom of the basins (relative variations in depth of the order of 500–1,000 m); the remainder is flat and sloping abyssal plains. It is believed that the abyssal rolling relief is the initial tectonic and volcanogenic relief of the surface of the earth’s crust which has been covered with blanket-like, shallow (up to 1 km) sediment. The flat abyssal plains occupy less than 10 percent of the surface of the ocean floor and are usually located on the margins of basins that lie close to continents. They form as the result of complete burial of the initial rolling relief owing to the intensified influx of sedimentary material from the continent. The sloping plains are also located along the margins of basins and gradually give way to the plains of the continental rise. They are also accumulative formations that occur owing to the intensive supply of sediment from the shelf and continental slope. A variety of such plains in the Pacific Ocean is the “train of archipelagoes” that rims the largest underwater volcanic chains and is composed of volcanogenic products. There are many separate underwater mountains (volcanoes, judging by their morphology) in the flat abyssal plains and abyssal hills. Some of them, called guyots, have flattened tops which are evidence that the latter were once at the surface of the ocean and later subsided. In tropical waters the tops of many underwater mountains have coral structures (atolls).

The mountain relief of the ocean floor consists of block or arched uplifts with linear and isometric outlines; often these are ridges that have chains of volcanoes on their crests. Uplifts with isometric outlines are also called oceanic plateaus. Some oceanic plateaus have a more level relief than the bottom of the basins. This is because of the greater speed of accumulation of sediments on the oceanic plateaus. The ocean floor also includes the marginal elevations that stretch along the oceanic side of the deep-water trenches.

Fractures play an important role in the structure of the relief of the ocean floor. The system of sublatitudinal oceanic fractures in the northeastern basin of the Pacific Ocean is the most immense. These fracture zones are usually represented in the relief of the bottom by complexes of grabens and horst uplifts that often stretch for thousands of kilometers.


Shepard, F. P. Morskaia geologiia. Leningrad, 1967. (Translated from English.)
Leont’ev, O. K. Dno okeana. Moscow, 1968.
Udintsev, G. B. Geomorfologiia i tektonika dna Tikhogo okeana. Moscow, 1972. (Tikhii okean [vol. 5].)
The Sea, vol. 3. New York-London, 1963; vol. 4, parts 1–2, 1970.
The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Corals look like rocks or big plants growing on the ocean floor, but they are actually invertebrates (animals without a backbone).
This would be achieved by creating "corrugations" or wavy ripples that are tuned to a specific wavelength on the ocean floor in front of the floating object to be cloaked.
AS THE WHALE TURNS From the time Smith first realized that whale falls are lively spots on the ocean floor, he predicted that different assemblages of creatures would appear at each site in turn.
There researchers hauled up four of the chimneys from the ocean floor in June 1998.
Most of the rest is fine-grained sediment that's been repeatedly lofted from the ocean floor by ocean currents to hopscotch its way to the canyon-frayed fringes of the continental shelf.
The new craft will have battery power more than triple that of Alvin and a maximum ascent and descent rate almost 50 percent faster, characteristics that will enable the new submersible to spend more time on the ocean floor.
The frigid water flows along the ocean floor toward the equator, where the sun heats it up.
Concrete "sand bars" are built into the "ocean floor."
At some points along these fissures, Malfait says, molten rock wells up to form new ocean floor. When the edges of the plates grind past each other, they produce many smaller, branching cracks.
The map (shown above) shows the rises and drops in the ocean floor, which scientists can use to figure out where mountains, valleys, and other seafloor features lie.
In many regions of the world, hydrocarbons slowly seep from the ocean floor, says biologist Cindy L.
"There's a tremendous amount of energy in the form of heat being released [from volcanoes] on the ocean floor," Walker explains.

Full browser ?