Gran Chaco

Gran Chaco (grän chä`kō) or Chaco, c.250,000 sq mi (647,500 sq km), extensive lowland plain, central South America. It is sparsely populated and is divided among Paraguay, Bolivia, and Argentina. Some of the highest temperatures in the southern continent are reached there. To the north of the Pilcomayo River and to the west of the Paraguay River is the section known as the Chaco Boreal, most of which belongs to Paraguay. This is arid land, dotted with swamps in the rainy season and with stretches of dense forest in which the quebracho tree abounds. Tannin extraction from the quebracho is an important economic activity there; large factories have been built for this purpose. The Chaco Central, in Argentina S of the Pilcomayo River, has much the same aspect. Cotton and quebracho are important there. The plains grow increasingly arid toward the west. The eastern part—the Chaco Austral and the region W of the Paraguay River—is the only habitable section of the Gran Chaco. The discovery of oil in a narrow strip of the barren section of the Chaco Boreal, at the foot of the Bolivian Andes, precipitated the

Chaco War, 1932–35, between Bolivia and Paraguay. This territory of the Gran Chaco had been disputed since 1810. Technically the Gran Chaco was intended to be part of Bolivia since it had been part of the audiencia of Charcas, but Bolivia paid little attention to this wasteland and Paraguayan settlers opened up the region while Paraguayan soldiers pushed back the natives. Thousands of Paraguayan colonists brought wealth to Paraguay by gathering quebracho and raising cattle. An armed conflict between Paraguay and Bolivia resulted as Bolivia sought access to the Paraguay River to ship oil to the sea and Paraguay refused to give up the lands. More than 100,000 lives were lost, and the war was concluded in 1935 only when both sides were exhausted. After three years of mediated negotiation following the end of hostilities, Paraguay and Bolivia signed (1938) a treaty. Three quarters of the disputed Chaco Boreal went to Paraguay; at the same time Bolivia was granted a corridor to the Paraguay River, the privilege of using Puerto Casado, and the right to construct a Bolivian port.

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Gran Chaco

 Spanish Chaco or El Chaco

Lowland alluvial plain, south-central South America. An arid lowland, it is bounded by the Andes Mountains to the west and the Paraguay and Paraná rivers to the east; its northern and southern margins, generally considered to be a marshy area in Bolivia and the Salado River in Argentina, respectively, are less well defined. Its area is about 280,000 sq mi (725,000 sq km). The region's heartland, in the fork of the Paraguay and Pilcomayo rivers, was fought over by Bolivia and Paraguay in the Chaco War (1932–35). By a 1938 treaty a larger eastern part went to Paraguay and a smaller western part to Bolivia. Chaco's wildlife is abundant, and there are at least 60 known species of snakes. Cattle grazing is a major economic activity. The area remains isolated and is only sparsely populated.

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Gran Chaco

a plain of S central South America, between the Andes and the Paraguay River in SE Bolivia, E Paraguay, and N Argentina: huge swamps and scrub forest. Area: about 780 000 sq. km (300 000 sq. miles)

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Gran Chaco 

a natural region in central South America, between 19° and 29°-30° S lat. in Paraguay and Argentina. The Gran Chaco includes the northern part of the La Plata Lowlands, 50 to 70 m above sea level, and the plains at the foot of the Andes, rising as they approach the west to an elevation of 500 to 600 m. The climate is subequatorial in the north, tropical in the middle, and subtropical in the south. The summers are very humid. The average temperature in July ranges from 12° to 21°C and in January from 26° to 30°C (with a maximum of 47°C, the highest on the continent). Precipitation is up to 1,200 mm per year in the northeast and up to 500 mm in the southwest. River networks (the main rivers are the Paraguay and Paraná) are found only in the west and east. The internal regions have no surface flow; the rivers (Pilcomayo, Bermejo, Salado) are without tributaries and have a sharply defined period of high flow in the summer. There are many swamps in the foothills, between the Pilcomayo and Bermejo, and in the east. Dry sparse forests occur on brown-red soil (quebrachos, Guaiacum, Ceratonia, water palms along the rivers, and chanares); xerophytic shrubs grow in the west. It is rich in fauna, such as tapirs, peccaries, coypus, swamp deer, pumas, jaguars, and many birds, snakes, and insects. Oil and gas deposits are known in the northwest. Industries include lumbering and hunting; in the south, sheep and beef cattle are raised and cotton is grown.

E. N. LUKASHOVA