PLATA, RO DE LA

(SpanishRiver of Silver) English River Plate estuary on the southeast coast of South America, formed by the Paran and Paraguay rivers and the Uruguay River and covering about 13,500 square miles (35,000 square km). Roughly triangular in shape, the Ro de la Plata is bounded on the north by Uruguay and on the south by Argentina; it drains eastward into the Atlantic Ocean. The Argentine coast of the estuary is low-lying; its banks are of marine debris and coarse sand. By contrast, the Uruguayan coast stands much higher and consists largely of rocks and dunes. The estuary's major tributaries, the Paran-Paraguay system and the Uruguay River, drain about 1,600,000 square miles (4,144,000 square km), which includes northwestern Argentina, southern Brazil, southeastern Bolivia, Paraguay in its entirety, and most of Uruguay. The combined annual average rate of discharge of the rivers is about 777,000 cubic feet (22,000 cubic m) per second, bringing with it immense quantities of silt each year. Because the estuary is shallow, constant dredging is required to keep the sand and silt from obstructing the channel to the Argentine port of Buenos Aires. The shoals formed by these deposits are dominant features of the Ro de la Plata. The ocean tides are relatively weak but may flow 120 miles (193 km) up the Paran and the Uruguay rivers from their mouths on the estuary. The average tidal range is 6 inches (15 cm) at Montevideo (in Uruguay) and 2.5 feet (76 cm) at Buenos Aires. ((Spanish: River of Silver), ) The Ro de la Plata system and its drainage network and the Gran Chaco. English River Plate, a tapering intrusion of the Atlantic Ocean on the east coast of South America between Uruguay to the north and Argentina to the south. While some geographers regard it as a gulf or as a marginal sea of the Atlantic, and others consider it to be a river, it is usually held to be the estuary of the Paran and Uruguay rivers (as well as of the Paraguay River, which drains into the Paran). The Ro de la Plata receives waters draining from the basin of these rivers, which covers much of south-central South America; the total area drained is about 1,600,000 square miles (4,144,000 square kilometres), or about one-fourth of the surface of the continent. Montevideo, the capital of Uruguay, is located on the northern shore of the estuary, and Buenos Aires, the capital of Argentina, is on the southwestern shore. The delta of the Paran and the mouth of the Uruguay meet at the head of the Ro de la Plata. The breadth of the estuary increases from the head seaward, a distance of about 180 miles (290 kilometres): it is 31 miles from the city of Punta Lara on the southern (Argentine) shore to the port of Colonia del Sacramento on the northern (Uruguayan) shore, and 136 miles from shore to shore at the Atlantic extremity of the estuary. To those who regard the Ro de la Plata as a river, it is the widest in the world, with a total area of about 13,500 square miles.