The New International Encyclopædia/Plata, Rio de la

PLATA, plä′tȧ, Rio de la. The estuary of the combined Paraná and Uruguay rivers (qq.v.) in South America. It forms a large marine inlet between the republics of Uruguay and Argentina (Map: Argentina, J 14). It is 143 miles wide at its mouth and tapers gradually inland for a distance of 200 miles to the delta of the Paraná. The Plata is the outlet for an enormous volume of water, amounting during floods to over two million cubic feet per second. Vast quantities of sediment are also brought down by the two rivers, and are gradually filling up the estuary, which formerly extended more than 100 miles farther inland. Shoals are everywhere forming rapidly, and, together with the strong currents and violent storms, make navigation dangerous. The best natural harbor on the estuary is Montevideo; artificial harbors have been constructed at La Plata and Buenos Ayres by means of jetties projecting beyond the shallows which line the Argentine shore. The Plata estuary was discovered in 1509 by Diaz de Solis, and received its present name (‘silver river’) from Sebastian Cabot.