Central America(redirected from Central American Isthmus)
Also found in: Dictionary, Thesaurus.
Central America,narrow, southernmost region (c.202,200 sq mi/523,698 sq km) of North America, linked to South America at Colombia. It separates the Caribbean from the Pacific. Historically, geographers considered it to extend from the natural boundary of the Isthmus of Tehuantepec, S Mexico, to that of the Isthmus of Panama. Generally, it is considered to consist of the seven republics (1990 est. pop. 29,000,000) of Belize, Guatemala, Honduras, El Salvador, Nicaragua, Costa Rica, and Panama. The mountains of N Central America are an extension of the mountain system of W North America and are related to the islands of the West Indies. The middle portion of Central America is an active zone of volcanoes and earthquakes; it contains the Nicaragua Depression, which includes the huge lakes Nicaragua and Managua. The ranges of S Central America are outliers of the Andes Mts. of South America. Tajumulco (13,846 ft/4,210 m high), a volcano in Guatemala, is the region's highest peak. Central America's climate varies with altitude from tropical to cool. The eastern side of the region receives heavy rainfall. Bananas, coffee, and cacao are the chief crops of Central America, and gold and silver are mined there. The economies of the countries in the region are becoming increasingly diversified. Though agriculture is still the largest employer, more technical positions are being produced as the industrial and service sectors develop. The Inter-American Highway traverses W Central America.
See R. C. West and J. P. Augelli, Middle America (2d ed. 1976); J. L. Flora and E. Torres-Rivas, Central America (1989); H. P. Brignoli, A Brief History of Central America (1989).
a region in the southern part of North America, stretching from the Balsas Basin at the southern foot of the Mexican Highlands to the Gulf of Darién in the northwestern part of South America and bounded by the Pacific Ocean on the southwest and the Gulf of Mexico and Caribbean Sea on the northeast. The boundaries are sometimes drawn through the isthmuses of Tehuantepec and Panama.
Central America covers an area of about 770,000 sq km. From a maximum breadth of 960 km in the northwest, it narrows to 48 km in the southeast at the Isthmus of Panama. Central America forms a kind of “bridge” between the two American continents. Its natural features tend to resemble those of North America in the north and those of South America in the south. The Nicaragua Basin is an important natural boundary.
Central America includes southeastern Mexico, Guatemala, El Salvador, Honduras, Nicaragua, Costa Rica, Panama, and the British possession of Belize. Its population of about 25 million (1974) includes representatives of the three major human races. The indigenous Indians, who belong to the Mongoloid race, have typical Americanoid features, a short stature, and brachycephaly. The descendants of Europeans belong to the Europeoid race and the descendants of African slaves, to the Equatorial, or Negro-Australoid race.
Most of the present population of Central America is racially mixed, primarily of Indian and Spanish descent. This is true of the majority of the inhabitants of El Salvador, Nicaragua, Honduras, and Panama. About half of the population of Guatemala consists of Indians, who speak their own languages. In Costa Rica the descendants of the Spanish colonists have hardly mixed at all with the local Indians. Negroes make up 12–15 percent of Panama’s population. There is a large English-speaking group in the Panama Canal Zone.
Coastline. The Pacific coast, with its narrow, discontinuous strip of coastal lowland, is straight in the north and broken by gulfs in the south, the largest of which are those of Fonseca, Nicoya, Chiriqui, Montijo, and Panama. The southern Pacific coast forms a series of peninsulas (Nicoya, Osa, Azuero) and is fringed by a number of continental islands, among them Coiba, Cébaco, and El Rey. The shores of the Gulf of Mexico (Gulf of Campeche) and the Caribbean Sea are for the most part low and dissected by numerous lagoons (Caratasca, Chiriqui). The only large inlet is the Gulf of Honduras, which cuts deep into the southeastern base of the Yucatán Peninsula. Off the coast of the Gulf of Mexico and the Caribbean there are numerous small, predominantly coral, islands.
Topography. Much of Central America is occupied by medium-elevation mountains belonging to the Cordilleras system, among them the Sierra Madre del Sur and the Sierra Madre de Chiapas. The rugged mountain massifs are cut by deep canyons; in places flat plateaus alternate with tectonic basins. The rugged massifs are flanked on the Pacific side by the Volcanic Range, which stretches from the Mexican border (where the Tajumulco volcano, the highest point in Central America, rises to 4,217 m) to western Panama. The Volcanic Range has numerous active volcanoes, some of which originated in historic times: Santa María, Atitlán, Santa Ana, Consigüina, Poás, and Irazú. Large lowlands, found only in the north, include the aggradational Tabasco Lowlands, the Mosquito Coast, and the Yucatán Peninsula, which is composed chiefly of limestones with extensively developed karst.
Geological structure and useful minerals. The northern part of the region is occupied by the relatively stable blocks of the Central American Massif and Yucatán Plate and the southern part, by the Cordilleras Folded Belt.
The Central American Massif is composed of an intricately folded complex of Paleozoic and, possibly, Precambrian metamorphic rocks (graywackes, siliceous schists, diabases, amphibolites, gneisses) unconformably overlain by Carboniferous-Permian and Triassic-Jurassic continental deposits and Cretaceous limestones. Devonian, Carboniferous, and Cretaceous granitoids occur widely.
The Yucatán Plate is an Epipaleozoic platform whose folded basement, composed of metamorphic rocks of Paleozoic and, possibly, Precambrian age, is unconformably overlain by an almost horizontal cover of Mesozoic and Cenozoic sedimentary rock up to 6 km thick. The cover is composed of Triassic red beds, Jurassic and Cretaceous evaporites and limestones, and Paleogene-Neogene terrigenous sediments.
The Cordilleras Folded Belt is a considerably reduced continuation of the structures of the Mexican Cordilleras. Southeast of the Isthmus of Tehuantepec the folded belt is separated from the Central American Massif by the Chiapas Foredeep, filled with Paleogene and Neogene marine and continental deposits. The Paleozoic metamorphic folded complex that lies at the base of this belt crops out in places; in Guatemala it is covered by a Late Paleozoic molasse. The predominant structures are Mesozoic, chiefly Cretaceous, carbonate and flysch strata containing large bodies of hyperbasites. In the southern regions, products of underwater volcanic activity, basic in composition and formed under oceanic conditions, were widely distributed in the Mesozoic. These regions are characterized by the development of salt domes. The primary folding occurred between the late Cretaceous and early Paleogene. The band of folded Cretaceous and more ancient rocks forms a gently curving arc that disappears in the northeast beneath the waters of the Gulf of Honduras.
The belt of Neogene and contemporary volcanoes that stretches from Mexico to the Panama Canal along the Pacific coast parallel to the Middle America Trench rests on various older structures. The formation of the Isthmus of Panama, which separates the Caribbean Sea from the Pacific Ocean, is linked with relatively recent volcanic and tectonic activity.
Among Central America’s principal mineral resources are gold and silver ores, occurring in medium (El Rosario in Honduras) and small (Pis Pis Mountains and La Luz in Nicaragua) hydrothermal deposits associated with Cretaceous intrusions. Gold and silver also occur in placers (Coco in Nicaragua). The region has small deposits of antimony and mercury. Small deposits of chromite are associated with the hyperbasite bodies, and Panama’s large porphyry copper deposits (Cerro Colorado, Cerro Petaquilla) are linked to Neogene volcanic intrusions. Petroleum and gas deposits are associated with the salt domes of the Isthmus of Tehuantepec.
V. D. CHEKHOVICH
Climate. Central America straddles the tropical, as far as the Nicaragua Basin, and subequatorial climatic zones. Situated in the low latitudes (7°–22°N lat.), the region receives a great deal of solar heat (the annual radiation balance exceeds 80 kcal/sq cm, or 335.2 kj/sq cm), and it has high temperatures throughout the year. In the lowlands the average temperature of the coolest month ranges from 22°–24°C in the north to 26°C in the south; the mean temperature of the hottest month is 26°–28°C. In the mountains, at elevations of 1,000–2,000 m, temperatures are 5°–8° lower. The northeastern windward slopes (in relation to the trade winds from the Gulf of Mexico and Caribbean Sea) have a permanently humid climate. These slopes receive 1,500–2,000 mm of precipitation annually in the north and as much as 3,000 mm in the south; in some places in the south the precipitation reaches 7,000 mm. On the leeward Pacific slopes precipitation is associated with the summer cyclones in the north and equatorial monsoons in the south; here winters are usually dry, and the annual precipitation varies from 1,000 mm to 1,800 mm. The interior basins and the low northwestern part of the Yucatán Peninsula, lying parallel to the tradewinds, receive less than 500 mm of precipitation a year. In the southern part of Central America the differences related to exposure disappear, and the dry winter season on the Pacific slopes is less marked.
Rivers and lakes. Because of the abundant precipitation and mountainous topography, the annual runoff of Central America’s rivers usually exceeds 600 mm. The runoff reaches 1,500 mm or more on the Caribbean slopes of Costa Rica and Panama, and only on the southern slopes of the Sierra Madre del Sur and in the northwestern Yucatán Peninsula does it decrease to less than 100 mm. With the exception of the Yucatán Peninsula, which has virtually no surface streams, the river network is dense. Most rivers are short and turbulent, with many rapids. The largest rivers are the Motagua, Patuca, and Coco. The rivers that drain into the Atlantic have an abundant flow throughout the year; those that flow into the Pacific show sharp fluctuations in discharge and have summer freshets. The largest of the many lakes that lie in tectonic troughs are Lakes Nicaragua, Managua, Izabal, and Atitlán.
Soils and vegetation. The soils and vegetation of Central America are highly diverse. In the lowlands and on the northeastern windward slopes to elevations of 800 m—the tierra caliente belt—tropical rain forests flourish on red-yellow lateritic, chiefly ferrallitic, soils. These forests contain many palms, trees with valuable wood, lianas, and epiphytes. Large areas, especially in the Tabasco Lowland, are swampy; the shores are lined with mangrove thickets. Tropical crops, including bananas, cacao, and pineapples, are cultivated near the coast. Agave plantations have been established in the arid northwestern part of the Yucatán Peninsula, where the natural vegetation consists of xerophilic forests and scrub.
Altitudinal zonality is clearly evident in the mountains. The tierra templada belt, where heat-loving species disappear and treelike ferns predominate, lies at elevations of up to 1,700 m. It is in turn succeeded by the tierra fría belt, which has mixed forests of evergreen broadleaf trees, chiefly oak and magnolia, and conifers. Above 3,200 m there are patches of alpine meadows and, in the south, paramos. In the highlands coniferous and hard-leaved forests, or sometimes pure pine forests, grow on red and cinnamon-red laterized mountain soils. Here, the main economic activities are pasture livestock raising, and the cultivation of corn, potatoes, and legumes.
The Pacific slopes are clothed with predominantly deciduous (during the dry season) tropical forests of ceiba, coccoloba, and other species, growing on red ferrallitic mountain soils. At lower elevations, these forests are supplanted in the drier areas and interior basins by sparse thorn woodlands, scrub, cactus thickets, and secondary savannas, occurring on cinnamon-red soils. Coffee is grown at elevations of 600–900 m; tobacco, sugarcane, and cotton plantations have been established. North American plant species predominate north of the Nicaragua Basin, and South American species to the south.
Fauna. Central America is part of the Neotropical Zoogeographic Region. Typical species include platyrrhine monkeys, peccaries, tapirs, armadillos, jaguars, and blood-sucking bats. There are numerous birds, reptiles, and insects. In the northern areas North American species are also common, notably lynx, raccoons, and such rodents as ground squirrels, hares, squirrels, red-toothed shrews, and kangaroo rats. There are endemic species among the tapirs, rodents, bats, and birds.
REFERENCESJames, P. Latinskaia Amerika. Moscow, 1949. (Translated from English.)
Fizicheskaia geografiia chastei sveta. Moscow, 1963.
Natsional’nye protsessy v Tsentral’noi Amerike i Meksike. Moscow, 1974.
Khain, V. E. Regional’naia geotektonika. Moscow, 1971.
Roberts, R. J., and E. M. Irving. Mineral Deposits of Central America. Washington, 1957.
Dengo, G. Estructura geológica, historia tectónica y morfología de América Central. Mexico City, 1968.
Schmieder, O. Geografía de América Latina. Mexico City, 1965. (With bibliography.)
E. N. LUKASHOVA