1911 Encyclopædia Britannica/Plata, Rio de la
PLATA, RIO DE LA, or River Plate, a funnel-shaped estuary, on the east side of South America, extending W.N.W. from the sea about 170 m. The discovery of the South Sea by Balboa, then governor of Castilla del Oro, of which Darien formed a part, created a lively desire to learn something of its coast-line, and the year following (in 1514), the Spanish monarch concluded a navigation contract with Juan Diaz de Solis, then Piloto Mayor, to search for a strait connecting the Atlantic with the newly found ocean, explore the coasts of the latter and communicate with Pedrarias de Avila, the new governor of Castilla del Oro; and, if it were found to be an island, to report to the superior authorities of Cuba. De Solis set sail from the port of Lepe on the 8th of October 1515, reached the Bay of Rio de Janeiro on the 1st of January 1516, and continuing southward to lat. 35° entered the great estuary now known as the Plata, which, for a short period of time, was called the de Solis and the Mar Dulce. Ascending it to the vicinity of the island of Martin Garcia, near the mouth of the Paraná river, de Solis was ambushed and killed in the early part of 1516 by Guarani Indians while attempting to capture some of them. In the first months of 1520 Magellan explored the Rio de la Plata, and afterwards, in the same year, discovered and navigated the straits which bear his name. This discovery led to the voyage of Sebastian Cabot, who fitted out an expedition in 1526 to reach the Spice Islands by the Magellan route. Owing, however, to shortness of provisions and the insubordination of his men Cabot abandoned his proposed voyage to the Moluccas, and, ascending the Mar Dulce, discovered the Paraná river and reached a point on the Paraguay near the site of the present city of Asuncion. Here he met many Guarani Indians wearing silver ornaments, probably obtained in trade across the Gran Chaco, from the frontier of the Inca Empire. In exchange for beads and trinkets Cabot acquired many of these ornaments and sent them to Spain as evidence of the richness of the country in precious metals and the great importance of his discoveries. The receipt of these silver baubles caused the name of Rio de la Plata to be applied to the third (perhaps the second) greatest river of the Western Continent.
The extreme breadth of the river at its mouth is 138 m. It narrows quickly to 57 m. at Montevideo, and at its head, where it receives the united Paraná and Uruguay rivers, its width is about 25 m. Its northern or Uruguayan shore is somewhat elevated and rocky, while the southern or Buenos Airean one is very low. The whole estuary is very shallow, and in no place above Montevideo exceeds 36 ft. in depth when the river is low. The bottom generally consists of enormous banks of sand covered with from 10 to 20 ft. of water, and there is a continuous and intricate channel, of about 22 ft. depth only, to within 14 m. of the port of Buenos Aires. The remaining distance has a depth of 18 ft. in the uncertain channel. The Plata is simply the estuarine receptacle of two mighty streams, the Uruguay and Paraná, which drain the Plata basin. This has an area of 1,198,000 sq. m., or over two and one-half times that of the Pacific slope of the Andes, and comprises the most fertile, healthiest and best part of Brazil, a large portion of the Argentine Republic, the whole of Paraguay and south-eastern Bolivia, and most of Uruguay.
The Uruguay river has a length of about 1000 m. Many small streams from the western slope of the Brazilian Serra do MarThe Uruguay and Affluents. unite, in about 27° 45′ S., to form this river, which then flows W.N.W., serving as the boundary between the states of Santa Catharina and Rio Grande do Sul, as far as 52° W., near which it receives a considerable tributary from the north, called the Pepiri-guazú. Between 27° 58′ and 33° 34′ S. three important tributaries join it from the east—the Ipui-guazú, the Ibicui and the Negro, the last being its main affluent.
The Pepiri-guazú was one of the limits between the possessions of Portugal and Spain. Its lower course is about 250 ft. wide, but higher up it narrows to about 30 ft., and runs with great violence between high wooded banks. It is navigable for canoes for about 70 m. above its mouth, as far as its first fall. The Rio Negro has a delta of several large islands at its confluence with the Uruguay. Its head-waters are in the southern part of Rio Grande do Sul, but the main river belongs entirely to the state of Uruguay, which it cuts midway in its course from north-east to south-west. Its lower reaches are navigable for craft of moderate draught.
From the time the Uruguay leaves the coast range of Brazil it runs for a long distance through a beautiful, open, hilly country,Course of the Uruguay. but afterwards enters a forest belt of high lands. At the river Pepiri-guazú it turns suddenly to the south-west, and continues this course to its junction with the Paraná and Plata. Near Fray Bentos, 61 m. before reaching the Plata, it forms a great lake, about 56 m. long and from 4 to 6 m. wide. At Punta Gorda, where it debouches into the Plata, it is only 1 m. to 1½ m wide but is 90 ft. deep. From the Pepiri-guazú junction its banks are high and covered with forest as far down as 27° 30′ S., where the river is 2300 ft. wide and from 10 to 40 ft. deep. The Uruguay is much obstructed by rocky barriers. Four miles below its confluence with the Pepiri-guazú it has a cataract, about 8 m. long, with a total fall of 26 ft. at low water. The river near the Pepiri-guazú is 1550 ft. wide, but about 1½ m. before reaching the cataract its width is reduced to 600 ft. Along the cataract it is closed in between high precipitous walls of black rock only 70 ft. apart. Above Punta Gorda, 212 m., is the Salto Grande, which has a length of 15 m. of rapids, the greatest single fall being 12 ft., and the difference of level for the entire length of the reefs 25 ft. These cross the river diagonally, and during floods all, excepting a length of 1½ m. of them, are submerged. Nine miles below the Salto Grande is the Salto Chico, which bars navigation during six months of the year, but in flood-time may be passed in craft drawing 5 ft. of water. The Uruguay can be navigated at all seasons by vessels of 4½ ft. draught as far up as the Salto Chico, and of 14 ft. up to Paysandú for a greater part of the year. Fray Bentos may be reached all the year round by any vessel that can ascend the Paraná. Above the navigable lower river there is launch and canoe navigation for many hundreds of miles upon the main artery and its branches, between the rapids which are met with from time to time. The Uruguay has its annual floods, due to the rains in its upper basin. They begin at the end of July and continue to November, attaining their maximum during September and October. At the narrow places the river rises as high as 30 ft., but its average rise is 16 ft. It flows almost for its entire course over a rocky bed, generally of red sandstone, at times very coarse and then again of extremely fine composition. Except in floods, it is a clear-water stream, and even at its highest level carries comparatively little silt.
The Paraná (the “Mother of the Sea” in Guarani) drains a vast area of southern Brazil. It is formed by the union of the Rio The Paraná and its Affluents. Grande and Paranáhyba, and is about 1600 m. long from its extreme source in Goyaz to its junction with the Paraguay, and thence 600 more to the Plata estuary. Its average width for the latter length is from 1 to 3 m. Its Rio Grande branch descends from the slope of the Serra di Mantiqueira, in the region where the orographic system of Brazil culminates near the peak of Itatiaia-assú, almost in sight of Rio de Janeiro. It is about 680 m. long, but only navigable in the stretches between the many reefs, falls and rapids which interrupt its regular flow. Among its numerous affluents the principal one is the Rio das Mortes, rising in the Serra Mantiqueira. It is 180 m. long, with two sections, of a total of 120 m., which are navigable for launches. The main branch of the Paraná, the Paranáhyba, rises in about 15° 30′ S., on the southern slopes of the Pyreneos Mountains. It drains a little-known region of Goyaz and western Minas Geraes, lying upon the immediate southern watershed of Brazil.
Besides these rivers, the Paraná has many long and powerful affluents from the Brazilian states of São Paulo and Paraná. Most of them, although obstructed by rapids, are navigable for launches and canoes. Among the eastern tributaries are the Tiété, the Paraná-panema, formerly known as the Anemby, and the Iguazú.
The Tiété, over 700 m. long, rises in the Serra Paranápicaba and flows in a north-west direction. Its course is broken by fifty four raipids, and the lower river by two falls, the Avanhandava, 44 ft. drop, and the Itapurá, 65 ft.
The Paraná-panema is about 600 m. long, and rises in a ramification of the Serra Paranápicaba which overbooks the Atlantic Ocean. Its general course is north-west. It is navigable for a distance of only about 30 m. above its mouth, and for its whole course it has so many obstructions that it is useless for commercial purposes.
The Iguazú, also called the Rio Grande de Curutiba, has its sources on the slopes of the Serra do Mar of Brazil, and flows nearly west, through thick forests, along the line of 26° S. Its navigation is difficult even for small craft, as it is full of reefs, rapids and cataracts. Sixteen miles above its mouth is the magnificent Salto del Iguazú, sometimes called the Victoria Fall, round which canoes have to be transported 37 m. before quiet water is reached again. The width of the falls, measured along their crest or edge, is 2½ m.; part of the river takes two leaps of about 100 ft each, but a portion of it plunges down the whole depth in unbroken mass. Its mouth is about 800 ft. wide, and the depth in mid-river 40 ft.
The Paraná, at a point 28 m. above the mouth of the Tiété, is interrupted by the falls of Urubuponga, but below these it hasCourse of the Paraná. unobstructed navigation for about 400 m., as far down as the falls of Guaira, in 24° 3′ S., where the river forms a lake 4½ m. long and 2½ m. wide, preparatory to breaching the Serra de Mbaracayú, which there disputes its right of way. It has torn a deep gorge through the mountains for a length of about 2 m., where it is divided into several channels, filled with rapids and cataracts. It finally gathers its waters into a single volume, to plunge with frightful velocity through a long cañon only about 200 ft. wide. From these so-called falls of Guaira, or “Sete Quedas,” as far as its confluence with the Paraguay river, the Paraná has carved a narrow bed through an immense cap of red sandstone, along which it sometimes flows with great rapidity, occasionally being interrupted by dangerous narrows and rapids, where the banks in some places close in to a width of 450 to 600 ft., although the average is from 1200 to 1600 ft. At the south-east angle of Paraguay the Paraná is prevented from continuing its natural southern course to the river Uruguay by the highlands which cross the Argentine province of Misiones, and connect those of Rio Grande do Sul with the Caa-guazú range of Paraguay. Here, therefore, it is turned westwards; but before escaping from its great sandstone bed it is obstructed by several reefs, notably at the rapids of Apipé, which are the last before it joins the placid Paraguay, 130 m. farther on. From the Apipé rapids there is a vast triangular space at the south-western corner of Paraguay but little above sea-level, consisting of low, sandy ground and morasses, at times flooded by the Paraguay river. This district, united to the equally enormous area occupied by the Yberá lagoon and its surrounding morasses, in the northern part of the Argentine province of Corrientes, was probably the delta of the Paraná river when it emptied into the ancient Pampean Sea.
The river Paraguay, the main affluent of the Paraná, rises in Matto Grosso, in the vicinity of the town of Diamantino, aboutThe Paraguay. 14° 24′ S. It flows south-westwards, as far as Villa Maria, along the foot of the high plateau which divides it from the Cuyabá River to the east, and then, turning southwards, soon reaches the morass expansion of Xarayes, which it traverses for about 100 m. A few miles below Villa Maria it receives an affluent from the north-west, the Jaurá, which has its source nearly in contact with the head-waters of the Guaporé branch of the river Madeira. The Cuyabá, which is known as the São Lourenço for 90 m. above its confluence with the Paraguay, has its sources in 13° 45′ S., almost in touch with those of the Tapajos branch of the Amazon. Above the town of Cuyabá it is from 150 to 400 ft. wide, and may be navigated up stream by canoes for 150 m.; but there are many rapids. The town may be reached from the Paraguay River, at low water, by craft drawing 18 in. According to the observations of Clauss, Cuyabá is only 660 ft. above sea-level From the junction of the São Lourenço (or Cuyabá) with the river Paraguay, the latter, now a great stream, moves sluggishly southwards, spreading its waters, in the rainy season, for hundreds of miles to the right and left, as far south as 20°, turning vast swamps into great lakes—in fact, temporarily restoring the region, for thousands of square miles, to its ancient lacustrine condition.
On the west side of the upper Paraguay, between about 17° 30′ and 19° S., are several large, shallow lagunas or lakes which receive Lagoons of Upper Paraguay. the drainage of the southern slopes of the Chiquitos sierras, but represent mainly the south-west overflow of the vast morass of Xarayas. The principal of these lakes, naming them from north to south, are the Uberaba, the Gaiba, Mandioré and the “Bahia” de Caceres. The Uberaba is the largest. The northern division of the lake belongs entirely to Brazil, but the southern one, about two-thirds of its area, is bisected from north to south by the boundary line between Brazil and Bolivia, according to the treaty of 1867. It is in great part surrounded by high ground and hills, but its southern coast is swampy and flooded during the rainy season. The west shore is historic. Here, in 1543, the conquistador, Martinez de Irala, founded the “Puerto de los Reyes,” with the idea that it might become the port for Peru; and from Lake Gaiba several expeditions, in Spanish colonial days, penetrated 500 m. across the Chaco to the frontier of the empire of the Incas. At the Puerto de los Reyes Bolivia laid out a town in December 1900, in the forlorn hope that the “Port” may serve as an outlet for that commercially suffocated country, there being no other equally good accessible point for Bolivia on the Paraguay River.
South of the São Lourenço, the first river of importance which enters the Paraguay from the east is the Taquary, about 19° S. Affluents of the Paraguay. It rises in the Serra Cayapó, on the southern extension of the Matto Grosso table-land. South of this stream about 50 m. a considerable river, the Mondego, with many branches, draining a great area of extreme southern Matto Grosso, also flows into the Paraguay; and still farther south, near 21°, is the Apá tributary, which forms the boundary between Paraguay and Brazilian Matto Grosso.
The Pilcomayo is of more importance from its length than from its volume. It rises among the Bolivian Andes north of Potosi and north-west of Sucre, races down the mountains to their base, crosses the Chaco plains, and pours into the river Paraguay near Asunción. Nor does it receive any branch of importance until it reaches about 21° S., where it is joinedThe Pilcomayo. from the south-west by the river Pelaya, upon which Tupiza, the most southerly city of Bolivia, is situated. The Pelaya rises upon the lofty inter-Andean plateau, and, taking an easterly course, saws its way across the inland Andean range, turns northwards and then eastwards to unite with the Pilcomayo, which it is said at least to equal in volume. Just below the junction is the fall of Guarapetendi, 23 ft. high. From this point to the mouth of the Pilcomayo the distance in a straight line is 480 m., although by the curves of the river, which is extremely tortuous, it is about double that distance. According to Storm, who quotes Captain Baldrich, the river bifurcates at 21° 51′ S., but again becomes a single stream at 23° 43′, the right channel being the greater in volume. It is probable that between 23° and 24° S. it throws E.S.E. three great arms to the river Paraguay, the upper portions of which have yet to be explored, but the lower parts have been examined for 100 to 200 m. up from the Paraguay. Enumerating from north to south, they are called the Esperanza, the Montelindo and the Macá. From 180 to 200 m. above its mouth the Pilcomayo filters through a vast swamp about 100 m. in diameter, through which there is no principal channel. This swamp, or perhaps shallow lagoon, is probably partly drained by the river Confuso, which reaches the Paraguay between the Pilcomayo and Macá. A northern branch of the Pilcomayo, the Fontana, the junction being at 24° 56′ S., is probably also a drainage outlet of the same great swamp.
For the first 100 m. below the fall of Guarapetendi the Pilcomayo is from 600 to 1000 ft. wide, but it so distributes its waters through its many bifurcations, and loses so much from infiltration and in swamps, and by evaporation from the numerous lagoons it forms on either side of its course, that its channel is greatly contracted before it reaches the Paraguay. From Sucre to the Andean margin of the Chaco, a distance of about 350 m. by the river, the fall is at least 8000 ft.—a sufficient indication that its upper course is useless for purposes of navigation.
The missionaries in 1556 first reported the existence of the Pilcomayo, which for a long period of time was known as the Araguay. In 1721 Patiño and Rodriguez partially explored it, and since then numerous attempts have been made to test its navigability, all of which have been failures; and several of them have ended in disaster and loss of life, so that the Pilcomayo now has a sinister reputation.
The Bermejo river flows parallel to the Pilcomayo, and enters the Paraguay a few miles above the junction of this with the Parana. Its numerous sources are on the eastern frontage of the inland Andes, between the Bolivian town of Tarija and the Argentine city of Jujuy. Its most northerly tributary is the San Lorenzo, which, after being augmented by several The Bermejo. small streams, takes the name of Rio de Tarija. This running east, and then taking a general south-easterly course, joins the Bermejo in 22° 50′ S. at a point called the Juntas de San Antonio. Thence, flying southwards, the Bermejo finally, in 23° 50′ S., receives its main affluent, the San Francisco, from the south-west. The latter has its source in about 22° 30′ S., and, under the name of Rio Grande, runs directly southwards, in a deep mountain valley, as far as Jujuy. It then turns eastwards for 50 m., and is joined by the Lavayen from the south-west. These two streams form the San Francisco, which, from their junction, runs north-eastwards to the Bermejo. The average width of the San Francisco is about 400 ft, it is seldom over 2 ft. deep, and has many shoals and sandbanks. From its junction with the latter stream the Bermejo flows south-eastwards to the Paraguay with an average width in its main channel of about 650 ft., although narrowing at times to 160 and even 100. In its course, however, it bifurcates and ramifies into many channels, forming enormous islands, and frequently leaves old beds for new ones.
Since the exploitation of the Bermejo by Patiño in 1721, it has often been examined from its sources to its mouth, with a view to ascertain its navigability. Captain Page in 1853 and 1859 found it impracticable to ascend it over 135 m. in the dry season, with a little steamer drawing 23 in. of water; but in flood-time, in December 1871, he succeeded, in 60 days, in reaching a point 720 m. from its mouth, in the steamer “Alpha,” 53 ft. long and 30 in. draught. He afterwards penetrated another 100 m. up stream. The round voyage took a year, owing to the swift currents, shoals, quicksands, snags and fallen trees.
The Salado, about 250 m. south-west of and approximately parallel to the Bermejo, is the only great tributary which the Paraná receives from the west below its confluence with the Paraguay. Its extreme head-waters are in the Argentine province of Salta, and they drain a much broken Andean region lying between 24° and 26° 30′ south. The most westerly sources areThe Salado. the rivers Santa Maria and Calchaqui, which unite near the town of San Carlos and form the river Guáchipas. Having received the Arias, the Guáchipas runs north-eastwards about 50 m., and then it changes its name to the Juramento, which is retained until the river reaches the Chaco plains at the base of the foot-hills of the Andes. Here it becomes the Salado, a name it preserves for the remainder of its course. It joins the Paraná near Santa Fé in 31° 39′ south and 60° 41′ west. Explorers of the Salado, inclusive of Captain Page in 1855, claim that its lower half is navigable, but the many efforts which have been made to utilize it as a commercial route have all resulted in failure.
As the Pilcomayo, the Bermejo and the Salado wander about the country, ever in search of new channels, they erode and tear away great quantities of the Pampean material, dissolve it into silt, and pour it into the Paraguay and Paraná rivers. The engineer Pelleschi estimates that “the soil annually subtracted from the territory of the Chaco by the Bermejo alone equals 6,400,000 cubic yards.”
South of its confluence with the river Paraguay, the Paraná washes the western foot of a series of sandstone bluffs for 30 miles.Thence for 240 m. the bordering hills are about 80 ft. high, but at Goya the country is almost on a level with the river. Near the boundary-line between Corrientes and Entre Rios the banks are very low on South-easterly Course of Paraná. both sides of the river, and continue so for nearly 100 m.; but farther down, for 150 m., the left bank is margined, as far as Diamante, by a range of hills from 125 to 160 ft. high, at times boldly escarped. At Diamante they trend inland, south-eastwards, for about 50 m., and probably once bordered an ancient channel of the river. From 31° 30′ south to the head of the Plata estuary the western bank of the Paraná is a precipitous bluff of reddish clay, varying from 25 to 75 ft. above mean river level. It is being gradually undermined, and tumbles into the water in great blocks, adding to the immense volume of silt which the river carries. According to Ramon Lista, “the lowest level of the Paraná is in October and November, and, save an occasional freshet, it remains stationary until the beginning of summer, when its waters begin to rise, reaching their maximum about the middle of February in the lower part of their course.” The difference between low and high river is generally about 12 ft., depending upon the varying quantity of rains in Brazil and the melting of the Andean snows. Below its junction with the Paraguay the Paraná has an average current of 212 m. an hour, and the river varies in width from 1 to 3 m., at low water; but in floods it seems almost a continuous lake, broadening to 10 and 30 m. and burying many of its numerous islands and marginal swamps under a vast sheet of water, and obliterating its many parallel lateral channels and intricate systems of connecting canals.
In the middle Paraná, from the mouth of the Iguazú to the mouth of the Paraguay river, there are many islands, some of them large,rocky and high above the river. From Paraguay to the city of Rosario, islands are numerous, many of them of great area; and again below Rosario they soon increase in number and size until the Plata estuary is reached. Islands of Paraná. In flood-time the upper portion of the trees being out of water, they have the appearance of floating forests. Then the river often makes wild work with its banks, and builds up or sweeps away entire islands, leaving deep channels instead. Mouchez in 1857, searching for two islands the position of which he had fixed in the previous year, found in their place 25 and 32 ft. of water. The lower delta of the Paraná does not share in these phenomena; its islands and main channels appear more fixed. This probably is due to the less elevation attained by the waters in flood-time, and the numerous branches which distribute them into the Plata estuary. This must have extended, in a very recent geological period, in and from its present head to at least 32° S.; but the enormous quantity of silt which the Paraná receives from its Paraguay affluent, and from the tributaries which reach it from the Andes, has filled this length of about 220 m. with these muddy islands, which rest upon a sandy bed of great depth.
The frontage of the Paraná delta is 40 m. across, almost in a straight line from north to south. Through this the river finds its way to the Plata by eleven outlets, large and small, the two principal ones being the Paraná-guazú and the Paraná de las Palmas.Paraná Delta.
The mean flow of the Mississippi river at New Orleans is 675,000 cub. ft. per second, and its flood maximum about 1,000,000 ft. The minimum of the Plata past Buenos Aires is 534,000, the maximum 2,145,000. It may therefore be fairly assumed that the yearly discharge of the great North American river is not superior, and may be inferior, to that of the Plata.
The Paraná is navigable at all times as far up as the São Lourenço river by craft drawing 3 ft. of water, and to within a few miles of Asunción, the capital of Paraguay, by vessels drawing 9 ft. The city of Paraná may always be reached with a draught of 12 and Rosario with 15 ft. of water.
The commercial development of the Plata basin may be conveniently illustrated by statistics for the year 1822, which marks the beginning of independent rule in its republics; for 1854, when the steamboat and the railway first began to play a part in this quarter of the world; and in 1898 and 1899, as indicating approximately the state of affairs at the end of the 19th Commerce.century. In Buenos Aires, for example, the foreign trade (entered and cleared) in 1822 aggregated 107,170 tons; in 1854, 342,463 tons; and in 1899, 5,046,847 tons. The coasting and river trade of the same port increased from 150,741 tons in 1854 to 3,695,088 tons in 1899. But taking into account all the Argentine ports, except those which lie to the south of the Plata, there was for the six years ending with 1899 an annual average of 14,000,000 tons for the overseas commerce and 11,000,000 tons for the river and coasting trade. On the other, or northern, bank of the stream the chief port is Montevideo; and its foreign commerce increased from an aggregate of 50,000 tons in 1822 to 150,000 tons in 1854 and to 4,069,870 tons in 1898, the river and coasting trade having increased from 50,000 tons in 1822 to 150,000 tons in 1854 and to 3,915,421 tons in 1898. The total foreign trade of the Plata valley thus increased from over 157,000 tons in 1822 to nearly 18,100,000 tons in 1898-1899. Its growth since the opening of the 20th century has been phenomenal and promises to become gigantic. The Andes on the west, the interior of South America on the north, great rivers, and the Brazilian mountains on the east of the Plata basin are obstacles which compel the rich and varied products of at least 1,500,000 sq. m. of fertile country to seek access to the ocean by a single avenue—the Plata estuary. (G. E. C.)