El Morro National Monument Rock formation and archaeological site, west-central New Mexico, U.S. Established in 1906, it has an area of 2 sq mi (5 sq km). El Morro, or Inscription Rock, is a soft sandstone mesa rising 200 ft (60 m) above the valley floor and covering several acres. Spaniards and Americans left their inscriptions (1605-1906) on the cliff sides of the mesa. El Morro also has a number of pre-Columbian petroglyphs, and on its top lie ruins of Indian pueblos.
El Nino In oceanography and climatology, the appearance, every few years, of unusually warm surface waters of the Pacific Ocean along the tropical western coast of South America. It affects fishing, agriculture, and local weather from Ecuador to Chile and can cause global climatic anoma¬ lies in the equatorial Pacific, Asia, and North America. The name (Span¬ ish for “the Christ Child”) was originally used by 19th-century Peruvian fishermen to describe the annual flow of warm equatorial waters south¬ ward around Christmastime. The term is now used for an intense ocean warming that stretches from the western Pacific to South America. This “anomalous occurrence” is caused by an unusual weakening of the nor¬ mally westward-blowing trade winds, which in turn allows warm surface waters to spread eastward. See also La Nina.
El Paso City (pop., 2000: 563,662), western Texas, U.S. Located on the Rio Grande opposite Ciudad Juarez, Mex., it is the largest of the U.S.- Mexican border cities. The area was the site of several missions from the 17th century; the first village was built on the site of El Paso in 1827. It became U.S. territory in 1848, when an army post was erected; the town was laid out in 1859. It grew slowly until 1881, when four railways arrived; in a decade El Paso’s population increased more than tenfold. Spanish language and culture distinguish the modern city. The commer¬ cial and financial centre for an extensive trade territory, it is the site of the University of Texas at El Paso (1913) and Fort Bliss (home of the U.S. Army Air Defense Center); the White Sands Missile Range is nearby.
© 2006 Encyclopaedia Britannica, Inc.
El Salvador ► Elbe I 605
El Salvador officially Republic of El Salvador Country, Central America. Area: 8,124 sq mi (21,042 sq km). Population (2005 est.): 6,881,000. Capitaclass="underline" San Salvador. The majority of the people are mesti-
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zos; most of the rest are Indians. Lan¬ guage: Spanish (official). Religion: Christianity (predominantly Roman Catholic; also Protestant, other Christians). Currency: U.S. dollar. The smallest and
most densely populated Central American country, it is crossed by two volcanic mountain ranges and has a narrow coastal region and a high cen¬ tral plain in the south. The climate ranges from hot and wet in the low¬ lands to cooler and wetter in the highlands. Cloud forests predominate at the highest elevations. El Salvador has a developing economy based on trade, manufacturing, and agriculture, with coffee, sugarcane, and cotton the major export crops. It is a republic with one legislative house; its chief of state and government is the president. The Spanish arrived in the area in 1524 and subjugated the Pipil Indian kingdom of Cuzcatlan by 1539. The country was divided into two districts, San Salvador and Sonsonate, both attached to Guatemala. When Spanish rule ended in 1821, the Sal¬ vadorans opposed incorporation into the Mexican Empire (confronting both Guatemalan and Mexican armies), and, upon its collapse in 1823, Sonsonate and San Salvador combined to form the new state of El Sal¬ vador within the United Provinces of Central America. The country attained independence in 1841. From its founding, it experienced a high degree of political turmoil; powerful economic interests controlled the country through most of the 19th and early 20th centuries but were replaced by a military dictatorship that lasted from 1931 to 1979. Elec¬ tions held in 1982 set up a new government, and, though a new consti¬ tution was adopted in 1983, civil war continued throughout the 1980s. An accord in 1992 brought peace, but violent crime became a major prob¬ lem. Despite attempts at economic reform, the country was plagued by inflation and unemployment into the 21st century.
Elagabalus \,e-b-'ga-b3-bs\ or Heliogabalus \,he-le-o-'ga-b3-bs\ officially Caesar Marcus Aurelius Antoninus Augustus orig. Varius Avitus Bassianus (b. 204, Emesa, Syria—d. 222) Roman emperor (218-22) notable for his eccentric behaviour. Passed off as Car- acalla’s illegitimate son, he became emperor with the support of the army. He identified himself with the Syrian god Baal and imposed Baal worship on the empire. His execution of dissidents, promotion of favourites, and homosexual orgies outraged the Romans. After he named his cousin Alex¬ ander heir and then changed his mind, the Praetorian Guards mutinied, murdered him, and made Alexander emperor.
Elam Ve-bm\ Ancient country of the Middle East. It was located in what is now southwestern Iran, at the head of the Persian Gulf and east of
ancient Babylonia; its capital was Susa (the country, thus, is sometimes known as Susiana). It had close cultural ties to Mesopotamia and was in conflict with the Sumerians (see Sumer) and Akkadians (see Akkad) from c. 3000 bc. In the 13th century bc, it became a dominant power that included most of Mesopotamia east of the Tigris and reached almost to Persepolis. Its domination ended when Nebuchadrezzar I of Babylon (r. 1124-1103 bc) captured Susa. Later, Elam formed a satrapy of the Per¬ sian Achaemenian dynasty, and Susa became one of its capitals.
eland \'e-bnd\ Either of two species of easily tamed, oxlike antelope (genus Taurotragus) found in herds on the plains or in lightly wooded areas of central and southern Africa.
The largest of the antelope, they may stand up to 6 ft (1.8 m) tall at the shoulder and weigh as much as 2,200 lbs (1,000 kg). They have a short, dark mane, a dewlap hanging from the throat, and long horns twisted in a tight spiral. The common eland is pale brown, becoming blue-gray with age, and often marked with nar¬ row, vertical white stripes. The giant, or Derby, eland is reddish brown with a blackish neck and vertical white stripes and horns heavier than those of the common eland.
elapid Ve-b-pod\ Any of about 200 species of venomous snakes (fam¬ ily Elapidae) that have short fangs fixed in the front of the upper jaw. Elapids are found in the New World, Africa, southern Asia, Pacific Islands, and Australia. Slender and agile, most are small and harmless to humans, but they include the largest and most lethal of snakes. Their venom is primarily neurotoxic but often contains substances that damage body tis¬ sues or blood cells. The relatively painless bite may cause a swift death from paralysis of the heart and lungs. See also black snake, cobra, coral SNAKE, MAMBA.
elastic modulus or elastic constant In materials science and physi¬ cal metallurgy, any of various numbers that quantify the response of a material to elastic or springy deflection. When tensile stress is applied to a material, the resulting strain is determined by Young’s modulus (see Thomas Young), a constant defined as the ratio of the stress in a body to the corresponding strain. It has dimensions of (force)/(length) 2 and is measured in units such as the pascal or newton per square meter (1 Pa = 1 N/m 2 ), dyne/cm 2 , or lbs per sq in. (psi). See also elasticity.
elasticity Ability of a deformed material body to return to its original shape and size when the forces causing deformation are removed. Most solids show some elastic behaviour, but there is usually a limit—the mate¬ rial’s “elastic limit”—to the force from which recovery is possible. Stresses beyond its elastic limit cause the material to yield, or flow, and the result is permanent deformation or breakage. The limit depends on the material’s internal structure; for example, steel, though strong, has a low elastic limit and can be extended only about 1% of its length, whereas rubber can be elastically extended up to about 1,000%. Robert Hooke, one of the first to study elasticity, developed a mathematical relation between tension and extension.