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submarine canyon ► suckering I 1837
indefinitely. Only the navies of the U.S., Russia, Britain, France, and China have nuclear-powered submarines; other navies rely on conven¬ tional diesel-electric power. Subs may be armed with torpedoes, cruise missiles, or ballistic missiles fitted with nuclear warheads. Because they are so difficult to locate, they are of great importance in the forces of almost all maritime states. See also depth charge; sonar; Trident missile.
submarine canyon Narrow, steep-sided underwater valley cut into a continental slope. Submarine canyons resemble river canyons on land, usually having steep, rocky walls. They are found along most continental slopes. Those of the Grand Bahama Canyon, which are thought to be the deepest, cut nearly 3 mi (5 km) deep into the continental slope. Most sub¬ marine canyons extend only about 30 mi (50 km) or less, but a few are more than 200 mi (300 km) long.
submarine fan Accumulation of land-derived sediment on the sea¬ floor; a fan is shaped like the section of a cone, with its apex at the mouth of a subbmarine canyon. The sediments consist largely of sandy material that drops from the canyon current in successively finer layers. Subma¬ rine fan valleys, with low relief and natural levees, often occur on sub¬ marine fans. Several fans may coalesce laterally.
submarine fracture zone Long, narrow, and mountainous subma¬ rine lineation that generally separates ocean-floor ridges differing in depth by as much as 1 mi (1.6 km). The largest fracture zones, in the eastern Pacific, are more than 1,000 mi (1,600 km) long and 60-125 mi (100- 200 km) wide. Numerous shorter fracture zones in the Atlantic are asso¬ ciated with the Mid-Atlantic Ridge.
submarine mine In military and naval operations, a stationary explo¬ sive device placed in the water and designed to destroy ships that touch or approach it. Submarine mines have been used since the mid-19th cen¬ tury. They consist of an explosive charge fitted with a device that deto¬ nates the charge when a ship or submarine is nearby. Placed by vessels called minelayers or dropped by aircraft, they are anchored to the sea floor by a cable. Various types of submarine mines are detonated by contact, by an approaching ship’s magnetic field, by changes in water pressure, or by the sound of a ship’s propellers. The mine was the most effective antisubmarine weapon in World War I. Its role was even greater in World War II, when mines sank 1,118 Allied ships and 1,316 Axis ships. See also LAND MINE, MINESWEEPER.
submarine plateau See oceanic plateau
submarine slump In a submarine canyon or on a continental slope, a relatively rapid and sporadic downslope moving mass composed of sedi¬ ment and organic debris that has built up slowly into an unstable or mar¬ ginally stable mass. After an individual slump in a canyon, however, the material tends to continue falling in a series of slumps until the sediment mass attains a shallower, more stable slope. A slumping episode may also trigger other slumps farther down the canyon.
subpoena \s3-'pe-n3\ In law, a writ commanding the person upon whom it has been served to appear in court or before a congressional committee, grand jury, or some other body, under a penalty for failure to comply. Unlike a summons, a subpoena may command the recipient to produce evidence necessary to the resolution of a legal matter or contro¬ versy.
subsidy Financial assistance, either through direct payments or through indirect means such as price cuts and favourable contracts, to a person or group in order to promote a public objective. Subsidies to transportation, housing, agriculture, mining, and other industries have been instituted on the grounds that their preservation or expansion is in the public interest. Subsidies to the arts, sciences, humanities, and religion also exist in many nations where the private economy is unable to support them. Examples of direct subsidies include payments in cash or in kind, while more- indirect subsidies include governmental provision of goods or services at prices below the normal market price, governmental purchase of goods or services at prices above the market price, and tax concessions. Although subsidies exist to promote the public welfare, they result in either higher taxes or higher prices for consumer goods. Some subsidies, such as pro¬ tective tariffs, may also encourage the preservation of inefficient produc¬ ers. A subsidy is desirable only if its effects increase total benefits more than total costs (see cost-benefit analysis).
subsistence farming Form of farming in which nearly all the crops or livestock raised are used to maintain the farmer and his family, leav¬
ing little surplus for sale or trade. Preindustrial agricultural peoples throughout the world practiced subsistence farming. As urban centers grew, agricultural production became more specialized and commercial farming developed, with farmers producing a sizable surplus of certain crops, which they traded for manufactured goods or sold for cash. Sub¬ sistence farming persists today in sub-Saharan Africa and other develop¬ ing areas.
subsoil Layer (stratum) of earth immediately below the surface soil, consisting predominantly of minerals and leached materials such as iron and aluminum compounds. Humus remains and clay accumulate in sub¬ soil, but the teeming macroscopic and microscopic organisms that make the topsoil rich with organic matter spend little time in the subsoil layer. Below the subsoil is a layer of partially disintegrated rock, and underly¬ ing bedrock. Stripping topsoil while clearing land for crop growth or commercial development exposes the subsoil and increases the rate of erosion of soil minerals.
substantive law See procedural law
subsurface water See groundwater
Subud \'su-biid\ Indonesian religious movement based on spontaneous and ecstatic exercises. Founded in 1933 by Muhammad Subuh, a student of Sufism who underwent a mystical experience in 1925, the movement was largely confined to Indonesia until it spread to Europe and the U.S. in the 1950s, chiefly because of the work of George Gurdjieff. The cen¬ tral feature of Subud is the latihan, a group spiritual activity in which practitioners allow the power of God to express itself through unrestrained spontaneous activity. Unprogrammed singing, dancing, shouting, and laughter are thought to give rise to feelings of rapture and release and to promote psychological and physical healing.
subway Underground railway system used to transport passengers within urban and suburban areas. The first subway line, 3.75 mi (6 km) long, opened in London in 1863 and carried 9Vi million passengers in its first year. The first electrified subway opened in 1890 in London (where it is called the underground or tube). Subways opened in Budapest in 1896 (the first on the European continent), Boston in 1897, Paris in 1900 (where it is called the metro), Berlin in 1902, New York in 1904, and later in Madrid (1919), Tokyo (1927), and Moscow (1935). Improvements in sys¬ tems built from the 1970s on (including San Francisco, Washington, D.C., and Los Angeles) include computer technology to run subway trains by remote control, and refinements in track and car construction for faster, smoother, and quieter rides.
succubus See incubus and succubus
succulent Any plant with fleshy, thick tissues adapted to water storage. Some succulents (e.g., the cactus) store water only in the stem and have no leaves or very small leaves; others (e.g., agaves) store water mainly in the leaves. Most have deep or broad root systems and are native to either deserts or regions that have a semiarid season. In succulents, the stomata (see stoma) close during the day and open at night—the opposite of the usual pattern—in order to minimize transpiration.