Page:EB1911 - Volume 21.djvu/819

 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 joined 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

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 are 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

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 2 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.

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.

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 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