rock crystal Transparent variety of the silica mineral quartz that is val¬ ued for its clarity and total lack of colour or flaws. Rock crystal for¬ merly was used extensively as a gemstone, but it has been replaced by glass and plastic; rhinestones originally were quartz pebbles found in the Rhine River. The optical prop¬ erties of rock crystal led to its use in lenses and prisms; its piezoelectric properties (see piezoelectricity) are used to control the oscillation of electrical circuits.
rock glacier Tonguelike body of coarse rock fragments, found above the timberline on mountains, that moves slowly down a valley. The rock material usually has fallen from the valley walls and may contain large boulders; it resembles the material left at the end (terminus) of a true gla¬ cier. A rock glacier may be 100 ft (30 m) deep and nearly a mile (1.5 km) long.
rock music or rock and roll Musical style that arose in the U.S. in the mid-1950s and became the dominant form of popular music in the world. Though rock has used a wide variety of instruments, its basic elements are one or several vocalists, heavily amplified electric guitars (including bass, rhythm, and lead), and drums. It began as a simple style, relying on heavy, dance-oriented rhythms, uncomplicated melodies and harmonies, and lyr¬ ics sympathetic to its teenage audience’s concerns—young love, the stresses of adolescence, and automobiles. Its roots lay principally in rhythm and blues (R&B) and country music. Both R&B and country existed outside the mainstream of popular music in the early 1950s, when the Cleveland disc jockey Alan Freed (1921-65) and others began programming R&B, which until then had been played only to black audiences. Freed’s success gave currency to the term rock and roll. The highly rhythmic, sensual music of Chuck Berry, Bill Haley and the Comets, and particularly Elvis Presley in 1955-56 struck a responsive chord in the newly affluent postwar teenagers. In the 1960s several influences combined to lift rock out of what had already declined into a bland and mechanical format. In England, where rock’s development had been slow, the Beatles and the Rolling Stones were found to have retained the freshness of its very early years and achieved enormous success in the U.S., where a new generation had grown up unaware of the musical influences of the new stars. At the same time, Bob Dylan, Joni Mitchell, the Byrds, and others were blending the traditional bal¬ lads and verse forms of folk music with rock, and musicians began to explore social and political themes. Performers such as the Grateful Dead, Jim Mor¬ rison of the Doors, and Frank Zappa of the Mothers of Invention combined imaginative lyrics with instrumental virtuosity, typically featuring lengthy solo improvisation. Janis Joplin and Jimi Hendrix won large followings with their exotic elaborations on R&B. The 1970s saw the rise of singer- songwriters such as Paul Simon, Neil Young, Elton John, David Bowie, and Bruce Springsteen, and rock assimilated other forms to produce JAZZ-rock, heavy metal, and punk rock. In the 1980s the Disco-influenced rock of Madonna, Michael Jackson, and Prince was balanced by the post-punk “new wave” music of performers such as Laurie Anderson, Talking Heads (led by David Byrne), and the Eurythmics—all of whom illustrated their songs with music videos. By the 1990s rock music had incorporated grunge, rap, techno, and other forms.
Rock crystal from the Dauphine region of France.
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Rock River ► Rocky Mountains I 1631
Rock River River, north-central U.S. It rises in southeastern Wisconsin and flows across the northwestern comer of Illinois, emptying into the Mississippi River at Rock Island, Ill.; it is 300 mi (480 km) long. The bottomlands along the lower course are subject to spring floods and require levee protection.
Rockefeller, David (b. June 12, 1915, New York, N.Y., U.S.) U.S. banker and philanthropist. He was the grandson of John D. Rockefeller and brother of Nelson Rockefeller. After earning a Ph.D. in economics at the University of Chicago (1940) and serving in World War II (1942-45), he joined the staff of the Chase National Bank of New York in 1946. He became senior vice president in 1952 and effected the merger with the Bank of Manhattan Co. that resulted in the Chase Manhattan Bank (1955); he served as the bank’s chairman of the board from 1969 to 1981. His speciality was international banking, and he was a familiar figure to min¬ isters and heads of state of various countries around the world.
Rockefeller, John D(avison) (b. July 8, 1839, Richford, N.Y., U.S.—d. May 23, 1937, Ormond Beach, Fla.) U.S. industrialist and phi¬ lanthropist. He moved with his family to Cleveland, Ohio, in 1853, and in 1859 he established a commission business dealing in hay, grain, meats, and other goods. In 1863 he built an oil refinery that soon was the largest in the area. With a few associates he incorporated Standard Oil Co. (Ohio) in 1870. He bought out competitors to control the oil-refinery business in Cleveland (1872) and in the U.S. (1882). He placed the stock of the com¬ pany and its affiliates in other states under control of a board of trustees, establishing the first major U.S. business trust company. As a result of antitrust proceedings, he later converted the trust into a holding company. In the 1890s he turned his attention to philanthropy. He founded the Uni¬ versity of Chicago in 1892, the Rockefeller Institute for Medical Research (later Rockefeller University) in 1901, and the Rockefeller Foundation in 1913. He donated over $500 million in his lifetime, and his philanthropy continued through donations by his son, John D. Rockefeller, Jr. (1874- 1960), and other descendants.
Rockefeller, Nelson (Aldrich) (b. July 8, 1908, Bar Harbor, Maine, U.S.—d. Jan. 26, 1979, New York, N.Y.) U.S. politician. A grandson of John D. Rockefeller, he worked for several family enterprises, including Creole Petroleum in Venezuela (1935-40). He became coordinator of inter-American affairs at the U.S. State Department (1940-44), assistant secretary of state (1944-45), and undersecretary of health, education, and welfare (1953-55). As governor of New York (1959-73), he oversaw expansion of the state’s fiscal, cultural, and educational systems. He sought the Republican Party presidential nomination in 1964 and 1968. He served as U.S. vice president (1974-77) under Gerald Ford. A major art patron, he founded the Museum of Primitive Art (later incorporated into the Metropolitan Museum of Art).
Rockefeller Center Complex of 14 limestone skyscrapers set amid a series of outdoor spaces on a 12-acre (5-hectare) site, built between 1929 and 1940 in midtown Manhattan. It was designed by a team of architects headed by Henry Hofmeister, H. W. Corbett, Raymond Hood, and Wallace K. Harrison. Wood veneering, mural painting, mosaics, sculpture, metal¬ work, and other allied arts were integrated with the architecture. Radio City Music Hall (1932) is noted for its Art Deco interior.
Rockefeller Foundation U.S. philanthropic organization. It was endowed by John D. Rockefeller and chartered in 1913 to alleviate human suffering worldwide. Rockefeller was assisted in its management by his son John D. Rockefeller, Jr. Among its many activities, the foundation sup¬ ports medical research and education. It also provides grant and fellowship programs in the social sciences, agricultural sciences, and global environ¬ mental studies, and in building democracy and international philanthropy.
rocket Type of jet-propulsion device that uses either solid or liquid pro¬ pellants to provide the fuel and oxidizer needed for combustion. The hot gases provided by combustion are ejected in a jet through a nozzle at the rear of the rocket. The term is also commonly applied to any of various vehicles, including fireworks, skyrockets, guided missiles, and launch vehicles for spacecraft, that are driven by such a propulsive device. Typi¬ cally, thrust (force causing forward motion) is produced by reaction to a rearward expulsion of hot gases at extremely high speed (see Newton's LAWS OF MOTION).