Oregon Caves National Monument National monument, south¬ western Oregon, U.S. It is a single cave comprising a series of chambers joined by subterranean corridors on four levels. Located in the Siskiyou Mountains near the California border, the monument was established in 1909. It has an area of 488 acres (197 hectares). It contains many stalag¬ mites, stalactites, and other formations.
Oregon Question Dispute over ownership of the Pacific Northwest region of North America. Spain, Russia, the U.S., and Britain all had claims to the region based on exploration or settlement. Spain vacated its claims after the Nootka Sound controversy and in an 1819 treaty with the U.S. The U.S. and Britain established a joint claim over the Oregon Coun¬ try in 1818. Russia abandoned its claims in separate treaties (1824-25). A compromise Oregon Treaty between the U.S. and Britain (1846) drew the U.S.-Canada land boundary at 49°N.
Oregon Trail Major U.S. route to the Northwest in the 19th century. It stretched about 2,000 mi (3,200 km), from Independence, Mo., to the Columbia River region of Oregon. First used by fur traders and mission¬ aries, it was heavily used in the 1840s by travelers to Oregon, including settlers of the “great migration,” led by Marcus Whitman. Of all western trails, it was in use for the longest period, surviving competition from the railroad by serving as a trail for eastward cattle and sheep drives.
Orestes \o-'res-tez\ In Greek mythology, the son of Agamemnon and Clytemnestra. According to Homer, Orestes was away when his father returned from Troy to meet his death at the hands of Aegisthus, his wife’s lover. On reaching manhood, Orestes avenged his father by killing Aegis¬ thus and Clytemnestra. Aeschylus’s dramatic trilogy the Oresteia recounts the murder and the pursuit of Orestes by the Furies for the crime of matri¬ cide. In Euripides’ Iphigeneia in Tauris, Orestes is reunited with his sister Iphigeneia and regains his father’s kingdom.
Oresund Vce-ro-.sonV Almost tideless strait between SjalLLAND island, Denmark, and Skane, Sweden, connecting the Kattegat Strait with the Baltic Sea. It is one of the busiest sea lanes in the world, though ice some¬ times impedes navigation in severe winters. Three large islands within it divide the waters into channels. The strait’s principal ports are Copen¬ hagen and Helsing0r in Denmark and Malmo and Halsingborg in Sweden.
Orff, Carl (b. July 10, 1895, Munich, Ger.—d. March 29,1982, Munich) German composer and music educator. He trained at the Munich Acad¬ emy and held several musical posts thereafter. In the 1920s he grew inter¬ ested in early Baroque music and the association of music with movement.
© 2006 Encyclopaedia Britannica, Inc.
1416 I organ ► Orient Express
In 1924 he cofounded a school for which he devised a comprehensive music education program (Orff Schulwerk) involving improvisation on specially designed gamelan-like percussion instruments; the program has since come into wide international use. He typically used repetitive rhythms, bare harmonies, and powerfully direct vocal parts, as in his best- known work, the secular oratorio Carmina Burana (1937), which is based on a manuscript of medieval poems.
organ Keyboard instrument in which pressurized air produces notes by means of a series of tuned pipes. The simplest organs consist of a single rank of pipes, each corresponding to a single key. They are arranged over a wind chest connected to the keys by a set of valves and fed with a sup¬ ply of air by electrically or mechani¬ cally activated bellows. By pulling out knobs, called stops, the player engages new ranks of pipes. Two dis¬ tinct types of pipes are used: flue pipes (both open and stopped) pro¬ duce sound by directing air against the edge of an opening in the pipe, whereas reed pipes sound by means of a thin metal tongue inside the pipe that vibrates against a fixed projec¬ tion next to it. A large organ may have five or more banked keyboards, or manuals, each of which controls a distinctive group of pipes. Most organs also have pedalboards played with the feet. A large organ’s pipes may vary in length from about 1 in. to 32 ft (2.5 cm to 10 m), resulting in a huge nine-octave range. The earliest organ (c. 250 bc) was the Greek hydraulis, in which the wind was regulated by water pressure. The bellows-fed organ appeared about the 7th century ad. The organ became firmly associated with the church by the 10th century. As organs became widespread, different regions pursued different modes of construction and sought different tonal ideals. The Baroque German organ is ideally suited to polyphony, while the French taste for variety of timbres eventuated in Aristide Cavaille-Coll’s vast “orchestral” organs. See also harmonium.
Organ Pipe Cactus National Monument National monument, southwestern Arizona, U.S., at the Mexican border. It was established in 1937. With an area of 330,689 acres (133,929 hectares), it preserves seg¬ ments of the mountainous Sonoran Desert and is named for the organ- pipe cactus. Wildlife includes Gila monsters, antelope, coyotes, and a variety of birds.
organic compound Substance whose molecules contain one or more (often many more) carbon atoms (excluding carbonates, cyanides, car¬ bides, and a few others; see inorganic compound). Until 1828 (see urea), scientists believed that organic compounds could be formed only by life processes (hence the name). Since carbon has a far greater tendency to form molecular chains and rings than do other elements, its compounds are vastly more numerous (many millions have been described) than all others known. Living organisms consist mostly of water and organic com¬ pounds: PROTEINS, CARBOHYDRATES, FATS, NUCLEIC ACIDS, HORMONES, VITAMINS, and a host of others. Natural and synthetic fibres and most fuels, drugs, and plastics are organic. Hydrocarbons contain only carbon and hydrogen; organic compounds with other functional groups include carboxylic acids, alcohols, aldehydes, ketones, phenols, ethers, esters, and other, more com¬ plex, molecules, including heterocyclic compounds, isoprenoids, and amino
ACIDS.
organic farming or organic gardening System of crop cultiva¬ tion that uses biological methods of fertilization and pest control as sub¬ stitutes for chemical fertilizers and pesticides, which are regarded by supporters of organic methods as harmful to health and the environment and unnecessary for successful cultivation. It was initiated as a conscious rejection of modern agri-chemical techniques in the 1930s by the British agronomist Sir Albert Howard. Miscellaneous organic materials, includ¬ ing animal manure, compost, grass turf, straw, and other crop residues, are applied to fields to improve both soil structure and moisture-holding capacity and to nourish soil life, which in turn nourishes plants. (Chemi¬ cal fertilizers, by contrast, feed plants directly.) Biological pest control is achieved through preventive methods, including diversified farming, crop rotation, the planting of pest-deterrent species, and the use of integrated
pest management techniques. Bioengineered strains are avoided. Since organic farming is time-consuming, organically grown produce tends to be expensive. Organic produce formerly accounted for a minuscule por¬ tion of total American farm output, but it has seen a huge proportional increase in sales in recent years.