The New International Encyclopædia/Orinoco

ORINOCO, ṓ'rḗ-nō'kṓ. The smallest of the three great rivers of South America (Map: Venezuela, D 2). The main stream runs wholly within Venezuelan territory, except for a short distance in its middle course, where it forms the boundary between Venezuela and Colombia. It rises on the Parima uplands near the Brazilian frontier, and flows first northwest to the Colombian boundary, then north into Central Venezuela, and finally eastward until it empties into the Atlantic Ocean through a large delta beginning near the boundary of British Guiana. The total length of the main stream is 1490 miles. Its course forms a large curve around the edge of the Parima plateau; hence its right banks are generally higher, and the tributaries received from that side smaller, while on the left side are the large plains or llanos (q.v.), and through these are received several tributaries equaling or exceeding the main stream. About 150 miles from its source and 920 feet above sea level the Orinoco branches, sending one-sixth of its volume into the Cassiquiare, which flows into the Rio Negro, an affluent of the Amazon. The remainder flows as a navigable river until it is broken by the romantic Maypures and Atures rapids, 870 miles from its mouth. These rapids are the only serious obstruction in the main stream, which below them flows with a very gentle current over a bed so nearly level that the tides are felt at Ciudad Bolivar, 260 miles from the sea. Though the country around the upper courses of the river and its tributaries is heavily forested, the lower reaches traverse open savannas where only the banks are lined with trees, and where the adjacent country is periodically flooded so that the natives are compelled to live in pile dwellings. The marshy but heavily forested delta occupies an area of 7000 square miles, and has a coast line of nearly 200 miles, through which upward of 50 channels enter the ocean. Many of these shift their beds, but seven are permanently navigable for large vessels. The principal navigable tributaries of the Orinoco are the Guaviare, the Meta, and the Apuré (qq.v.), and the total navigable length of the system is 4300 miles. This great waterway, however, is but little used, since the adjacent regions are thinly inhabited, and the great natural wealth practically untouched. In 1900 only one steamer of the Royal Mail Steamship Company plied once every two weeks between Trinidad and Ciudad Bolívar. Smaller steamers continue the service as far as Nutrias on the Apuré, but above the Apuré confluence there is no regular navigation. Consult: Humboldt, Travels in South America, trans., Bohn Library (London, 1877); Chassanjon, L'Orénoque et le Caura (Paris, 1889); Triand, Down the Orinoco in a Canoe (London, 1902); Guzman, “La exploración del Orinoco,” in La España Moderna, vol. clxvi. (Madrid, 1902).