Pierre Denis

The use of the river before steam navigation—Floods—The river plain—The bed of the ParanÁ and its changes—The estuary and its shoals—Maritime navigation—The boats on the ParanÁ.

The problem of the use of the river-routes of the ParanÁ and the Paraguay is not of interest to Argentina alone. It affects the whole history of colonization in South America. The very name of the Rio de la Plata is a reminiscence of the anxieties of the early navigators who landed there, chiefly in search of a route to the mineral districts of the Andes [Plata = silver]. It is remarkable that the Amazon, which opens a more direct and better route to the Andes, was never used for reaching Peru. It was at the most, and only occasionally, used as a return-route, whereas expeditions to the Cordillera were organized on the banks of the ParanÁ during the whole of the sixteenth century. The routes linking the ParanÁ and the Paraguay with the tableland furrow the whole plain of the Pampa and the Chaco, from the latitude of the estuary to about 16° S. lat. (expedition of Ñuflo de Chavez in 1557). An especially close network starts from the river between 18° and 22° S. lat. and ends at Santa Cruz, the most northern centre established by the Spaniards on the plain, at the foot of the Andes, as a consequence of the use of the ParanÁ.118

Spanish colonization, however, did not succeed in making permanent settlements on the Chaco. The Indians, who were masters of it, disputed their passage, and the only practicable route was the southernmost of the roads to the tableland, south of the Rio Salado, which ends at the estuary. From this time onward the prosperity of Buenos Aires eclipsed that of AsunciÓn. The river ceased to be a great continental route.

The division of the ParanÁ between the Spanish and the Portuguese was a check upon the full development of the river-route. The Portuguese held the upper part of its basin, which now belongs to Brazil. They expelled the Spanish missionaries from the upper ParanÁ about the middle of the seventeenth century, and made themselves masters of the Paraguay north of 20° S. lat. Their forts at Coimbre and Albuquerque prevented any from ascending. D'Azara insists that it would have been Spain's interest to disarm these forts; it would have enabled them to go up the river as far as the Spanish missions to the Mojos and the Chiquitos. On their side, the Portuguese only used the upper section of the river, where it is joined by the Paulist road north of the Coimbre, as a means of access to the gold mines of the Matto Grosso. Even now, although the ParanÁ is open to every flag, the development of the river-route is not independent of political conditions. In making the railway from Saint Paul to Corumba, and so creating on its own territory a means of direct communication with the upper Paraguay, Brazil diverts from the lower districts part of the traffic which ought normally to go there. Again, the ports of southern Brazil and the lines which go to them try to attract to the Atlantic the produce of the basins of the Uruguay and the upper ParanÁ, which would have followed the thread of the river to foster the trade of Buenos Aires if the frontiers had been fixed otherwise.

Before the Revolution the river-trade was confined to exchanges between the Misiones and Paraguay on the one hand, and Buenos Aires and the Andean provinces on the other. After the extinction of the missions Paraguay was the chief centre of traffic on the river. At the close of the eighteenth century it had a fairly large population. According to D'Azara, it amounted to 97,000, and 47,000 for the area of the former Missions (Misiones), while Buenos Aires, Santa FÉ, Entre Rios and Corrientes had not more than 103,000 inhabitants collectively. Paraguay exported tobacco, matÉ and timber by the river. The Buenos Aires Estano received 800 tons of tobacco a year. The exports of matÉ from Paraguay to Peru, Chile and the interior provinces amounted to 1,725 tons, and 2,250 tons went to Buenos Aires. The timber came mostly from the Tebicuary, where the angadas (loads of timber) were formed. The chief constructive sheds also were on the Tebicuary. Boats of twenty to 200 tons were launched there; and they had armed boats, when they went down the river, to detect ambushes of the Indians, who were masters of the right bank north of Santa FÉ.

The development of navigation on the ParanÁ during the first half of the nineteenth century was checked by the disturbances and wars of the period of the emancipation and unification of Argentina. The river was blockaded several times and traffic interrupted. Only a few smuggling schooners succeeded in getting through the side branches, which the ships stationed in the river could not watch. Robertson escaped the Spanish vessels in this way. The picture which D'Orbigny has given us of the life of the river belongs to the year 1827. At that time the estuary was blockaded by the Brazilian fleet in the whole area of the delta as far as San Pedro. Piracy was so rife, and the insecurity so great, on the Uruguay and the ParanÁ, that few ventured as far as Buenos Aires, the ships being linked in convoys. Up stream, Corrientes was the limit of navigation. The dictator Francis closed the Paraguay, and even the small boats no longer sailed on the upper ParanÁ, along the frontier of Paraguay. The Correntinos, who spoke Guarani, could merely get permission at rare intervals to send a few boats up river. Armed boats convoyed these as far as Neembucu, and they returned with hides and matÉ. Corrientes thus became the market-centre of the upper river and replaced AsunciÓn in the trade. The flotilla on the ParanÁ included flat-bottomed barges, which were only used in coming down, and strong keeled ships—schooners, sloops and brigs—with their ropes made of leather. Down stream there was a little more diversity in the traffic. The island sent cargoes of firewood and charcoal to Santa FÉ and Buenos Aires. The orchards of the delta provided Buenos Aires with oranges and peaches. Hides for export were shipped at Goya and Santa FÉ. But the chief freight was lime from La Bajada, which was burned in the kilns on the Barranca, at the outcrops of the beds of conchiferous limestone.

Yguassu and ParanÁ

CONFLUENCE OF THE YGUASSU AND THE PARANÁ.

In the foreground is the left bank of the Yguassu, on Argentine territory. The right bank is Brazilian territory. At the back, on the right bank of the ParanÁ, is Paraguayan territory.

Plate XX.

Click to view larger image.

The navigation was fairly easy, the journey from Corrientes to Buenos Aires (675 miles) lasting, as a rule, from fifteen to twenty days. Going up, the time was more irregular. They had to stop when there was no south wind, or a little progress was made by hauling (silgar). D'Orbigny took a month to travel up.119 In 1822, before the war with Brazil, there were 651 boats entered at Buenos Aires for coasting trade on the rivers and 1,035 at San Fernando or on the Tigre, the advance port of Buenos Aires. In 1833 Isabelle put at one thousand the number of vessels at work on the ParanÁ and the Uruguay.

In 1841 Rosas forbade navigation on the river. There was then a double blockade checking the trade of Argentina. The Franco-British fleet closed the Rio de la Plata and blockaded Buenos Aires, where the Government of Rosas was established. In addition, Rosas's troops on the barranca of the right bank prevented any from going up the ParanÁ, and cut off the interior provinces from the rest of the world. The injury then done to interests which were already fully self-conscious may be gathered from the agitation provoked by the decision of France and England in 1845 to break the blockade of the river. A convoy was at once organized at Montevideo, consisting of no less than ninety-eight ships, of 6,900 tons in all (MacKann). It went up the ParanÁ under the protection of war-ships, which removed the chains slung across it by Rosas. The convoy dispersed up river as soon as it was out of range of Rosas. But it had needed so great an effort that the attempt could not be made again before the fall of Rosas.

The closing of the ParanÁ compelled a diversion of the trade of Paraguay toward the south-east. It crossed the isthmus of Misiones, between the ParanÁ and the Uruguay, and passed down the Uruguay. At this time the whole commercial activity of Paraguay was concentrated at Itapua, on the upper ParanÁ. The prosperity of the Uruguay was some compensation for the misery that reigned on the ParanÁ. The populations of Paysandu and Montevideo greatly increased.

In 1852, at the fall of Rosas, the modern period began for the ParanÁ. The river-population changed rapidly. It ceased to be exclusively creole. Basques, and later Italians, had settled upon the Uruguay ten years before, and they now spread along the ParanÁ. In 1850 MacKann found fifty vessels, of 20 to 100 tons, belonging to Italians at Santa FÉ. This wave of immigration coincided with the development of relations between the ParanÁ and the port of Montevideo. From 1852 to 1860 Buenos Aires was isolated, and it remained outside the economic life of Argentina. Montevideo took its place. Urquiza's administration sought, in addition, to establish direct maritime communication between over-seas ports and the ports on the river: Gualeguy in Entre Rios, and Rosario in Santa FÉ. Under a system of preferential duties (1857-59), which reduced the burden on goods carried by the river, Rosario grew rapidly, and between 1853 and 1858 increased its population from 4,000 to 22,700. The period from 1852 to 1860 was also the time when steam-navigation was developing, and this doubled the value of the river-route. From 1860 onward Buenos Aires was connected by regular services of steamboats with Rosario, Santa FÉ, Corrientes, AsunciÓn and Cuyaba. On the upper ParanÁ goods (timber, tobacco and oranges) were still carried by sailing boats between Corrientes and ApipÉ, where they stopped at the commencement of the rapids. Steamboats did not sail up the rapids of ApipÉ until 1868.120 From 1850 to 1860 there were repeated explorations of the Salado and the Bermejo, as the interior provinces hoped to be able to find a connection with the vivifying artery of the ParanÁ (voyage of Page on the Salado from Salta in 1855, and of Lavarello on the Bermejo in 1855 and 1863).

In 1860 the entry of Buenos Aires into the Confederation re-established the normal condition of free competition between Buenos Aires and Rosario. From that time the life of the river reflects the advance of colonization in the Pampean region. The ParanÁ became the highway for the export of cereals.

The two rivers, of which the Rio de la Plata forms the common estuary, differ considerably in their features. The Uruguay has irregular floods, especially in autumn (May) and at the end of the winter (August-October). Low water is in summer (January-February). Its basin belongs to the temperate zone, and does not extend northward as far as the area of tropical summer-rain. The Uruguay also differs from the ParanÁ in its low capacity for transport and alluvial deposit. While the ParanÁ has built up a vast deltaic plain, the Uruguay ends in an ordinary estuary, with rocky or sandy bed and clear water. The estuary of the Uruguay is 130 miles long and five or six miles wide. The eastern shore is rocky and broken. The Argentine shore is low. It is formed in the south by the deposits of the delta of the ParanÁ, while further north, from Gualeguacha to ConcepciÓn, the hills of Entre Rios are hidden behind a screen of flat islands covered with palms, formed by the stuff brought by the streams of Entre Rios. The river-floods are lost in the great sheet of the estuary. The tide in the estuary or a flood in the ParanÁ is enough to turn the current.

Maritime navigation goes beyond the estuary and beyond Paysandu, as far as the rapids which prevent further advance at Salto. The twin towns of Concordia (right bank) and Salta (left bank) mark the limit of navigation on the inner course of the river. It begins again above the falls, at Monte Caseros, from which the river-boats go to San TomÉ and occasionally to ConcepciÓn. Small ships go higher, as far as Salto Grande in Misiones (27° 20' S. lat.).121

The navigable system of the ParanÁ is four times as large. The first survey of the river was made about the middle of the nineteenth century by the British Navy. At the beginning of the twentieth century the Argentine Government took up the study of the bed and the peculiarities of the ParanÁ, and the Ministry of Public Works published a map, on the scale 1:100,000, of the course of the river between Posadas and San Pedro, at the beginning of the delta. A precise survey was made, and twenty-six fluvio-metrical scales were established, the zero of which represents mean low-water.122 Transverse soundings were taken at equal distances of 670 and 1,000 feet, the distance being reduced to 160 and even 80 feet at critical points. Thanks to this work, the ParanÁ is now, no doubt, the best known of all rivers of that size.

Its output is estimated at 6,000 cubic metres a second at mean low-water, in the latitude of Rosario, and 25,000 to 30,000 cubic metres a second during flood at a height of six metres above low-water.123 Its features bear the mark of its tropical origin. The tropical character is typical on the Paraguay, which is, by its situation in the central South-American plain, the real continuation of the lower ParanÁ. The slightness of the fall of the Paraguay, however, and the extent of the marshes over which it spreads in Brazil and Paraguay, have the effect of regulating and retarding the flood, which only attains its maximum at AsunciÓn in May. The flood of the Paraguay extends the period of high water on the lower ParanÁ until the end of autumn. The upper ParanÁ has most of its basin in the tropical zone of summer rain. But its behaviour is also influenced by the spring or autumn rains of the southern part of the Brazilian tableland. Its floods are sudden and violent. They reach a height of sixty or seventy feet in the region of the confluence of the Yguassu. They sweep rapidly down stream, and reach the lower ParanÁ before the flood of the Paraguay, which they hold back.

From Posadas the flood-waves reach Corrientes in five days (235 miles). From Corrientes they reach ParanÁ in eight days (380 miles), travelling about two miles an hour. That is one-third the speed of the current, as the flood is retarded, and more or less absorbed, by the ramifications of the broader bed in which it moves.

At Bajada Grande the lowest water is in September. The flood appears in December or January, though sometimes in October or November. The maximum is in March or April. The rise is rapid at first, but it gradually moderates, and the level of the water is raised about one metre per month during three months. It then sinks in corresponding order. The ebb is often interrupted in June, and sometimes as late as August, by a sudden leap upward of the curve, representing an ascensional movement of the water three times as rapid as that of the main flood (one metre in ten days). The level reached in this late flood is sometimes higher than that of the normal flood in April or May. The range of the ordinary flood-movements is from ten to sixteen feet. Exceptional floods rise to a height of twenty-three feet above the low-water mark.

The curves established for the years 1908 to 1910 by the Argentine hydrographical service enable us to analyse the mechanism of the flood with a good deal of confidence. The beginning of the flood at Bajada Grande in October corresponds to the first flood of the upper ParanÁ. During this first phase the curve of the Bajada is parallel (thirteen days later) to that of Posadas. There is the same parallelism in November, December and January. If the summer rains are light on the upper ParanÁ, the flood is late on the lower ParanÁ, and the water is still low there in December (0.20 below the low-water mark on December 31, 1910). At the beginning of March, before the maximum of the flood, the curve of Bajada Grande differs from the curve of Posadas. It is the time when the flood of the lower river is caused by the rise of the Paraguay. The secondary floods of June and July again have their origin in the upper ParanÁ, but, as they are added to the flood of the Paraguay on the lower river, they reach a higher level there than at Posadas; the difference gradually disappears as the flood of the Paraguay subsides. It is the addition of the late floods of the upper ParanÁ to the flood of the Paraguay that causes on the lower river the abnormal floods that occur there at irregular intervals (in 1825, 1833, 1858, 1878, 1905 and 1917).

Below the Bajada the height of the floods progressively declines. On the estuary they are no longer perceptible; variations of level are due entirely to the tides. In the channels of the delta of the ParanÁ the tide does not reverse the current as it does in the estuary of the Uruguay, but it causes a slight rise of the water; and this has been observed sometimes, at very low water, as far as Rosario.

It is near Corpus, about forty miles above Posadas, that the upper ParanÁ escapes from the restraint of the Brazilian tableland, which imprisons its valley, from the falls of the Guayra, in a deep fissure between lofty basalt cliffs. Below Posadas the river leaves the region of hills and red earth. Below Corrientes it flows everywhere over its own alluvia. Even above Corrientes its form has surprising characteristics of youth. The precise survey done on its banks has brought to light a very distinct break of its fall above Villa Urquiza, about 400 miles from Buenos Aires. The fall, which from Corrientes onward remains between sixty and forty millimetres per kilometre, sinks suddenly to thirteen over a stretch of twenty-five miles, and then rises again to thirty to forty-five millimetres.124 Below Rosario the mean descent is twelve millimetres to the kilometre, below San Pedro only six.

Above Corrientes the width of the main arm of the ParanÁ varies, as a rule, from 2,600 to 6,500 feet. The width of the river-plain over which the floods spread is still more irregular. Between Santa FÉ and ParanÁ, where it is especially narrow, it is still ten miles wide. Lower down it gradually broadens to a width of sixty-five miles at the head of the estuary. The scenery is not the same in all sections of it. The vegetation on the islands is richer and more varied up river, and tropical essences (laurel-timbo) are found below the Bajada, forming clumps of trees covered with creepers.

THE PARANÁ AT CORRIENTES.

Banks and islands partially fixed by vegetation.

Photograph by Widmayer.

Click to view larger image.

But the different scenes of the river region are most of all due to different conditions of erosion and formation. Above Rosario the configuration is due to floods. Each succeeding flood alters it and leaves some trace of itself in the topography. The beds of sand that it lays down are fixed by rushes and floating weeds, then by willows (Salix humboldtiana). This screen of vegetation encourages accretion, and the edges tend to rise higher. In the middle of the island are low, marshy lands. The irregularity of the alluvial deposits causes marked undulations in the whole region of the river, and everywhere gives rise to alternate beds of clay and sand. Below Rosario the river gradually loses its power. The islands become more stable and flatter. Clumps of willow and spiny ceibos (Erythrina cristagalli) still cover the edges of them, and sometimes spread over the interior. But as the climate is now less humid, the vegetation fixes the soil less firmly, and the wind becomes the chief sculptor of the landscape. It heaps up the sand during the low-water season, and makes dunes which rise above the level of the greatest floods. These dunes form an unbroken line along the land in the southern part of Entre Rios, in the north of the main arm, with ridges at right angles, advancing toward the south, which rest upon the river clay; like the one which the Ibicuy railway follows across the floodable area. The cattle of the district take refuge on the dunes during floods. During periods of drought, on the other hand, they retain a quantity of water, and this is drawn from surface-wells at their base.

The limits of the zone of the river are clearly marked on the whole of the lower ParanÁ. It is enclosed on both sides by high barrancas (cliffs), vertical in places where the main current washes their feet, but sloping slightly where there is only a secondary arm with little erosive power. The cliff is broken only at the confluences of small valleys, the flat, filled-up bottoms of which are on the level of the alluvial plain of the ParanÁ. The cliffs are at their highest in the district of Villa ParanÁ, where they rise in places to a height of 300 feet. On the right bank the cliffs show a section of the upper layers of the Pampean clays. On the left bank there are Æolian clays only at the top of them. Below these are Tertiary marine strata (marls and sandstones with beds of shells). The cliffs of the left bank stretch northwards, with a few breaks, as far as Corrientes, and even into Misiones. Their height gradually diminishes, and the Tertiary marine strata are replaced by granitic red sandstone.125 On the right bank the height of the cliffs gradually diminishes up river. They are still conspicuous at the confluence of the CarcaraÑa, but at Santa FÉ they rise only about thirty-four feet. North of 31° S. lat., and for some distance beyond Pilcomayo, the plain of the Chaco is very low, and it is impossible to define exactly the limit of the alluvial zone of the ParanÁ. The fine clays, grey and white, which form the soil of the Chaco, reach the left bank north of Corrientes, in the esteros of Neembucu. The red sandstone hills of the AsunciÓn district rise like an archipelago out of this level bed of lacustrine deposits.

There is no obstacle to navigation in the entire stretch from Posadas to the falls of the Guayra on the ParanÁ and the Salto Grande on the Yguassa. Sixteen miles below Posadas the ParanÁ passes through a series of graduated rapids for about sixty miles (1,467 kil. to 1,558 kil. from Buenos Aires) wrongly called the Salto de ApipÉ. The current then rises to a speed of eight knots, and the depth is three feet at low water. These rapids are due to beds of melaphyre, which emerge amongst the granitic sandstone, and the water makes its way between large rocky islands. At Ituzaingo (1,455 kil.) the current loses force. There is, however, still a rocky bottom lower down, for ninety miles, at a depth of five feet. Below this the rock only appears on the left bank, and in a few ridges near the bank, or in isolated reefs which it has been easy to mark with buoys.

From Corrientes to La Paz the river flows from north to south at the feet of the Corrientes cliffs. These line the main stream between Corrientes and Empedrado, and for thirty-five miles south of Bella vista. In the latitude of Riachucho, especially about Bellavista, the cliffs form a series of creeks and capes, in which the west winds create a heavy sea that was dreaded by ships of light draught coming down the river. North of Bellavista, and for more than a hundred miles south of Goya, the main stream is separated from the cliff by a series of alluvial islands; behind these are lateral arms (riachos) into which pour the rivers of Corrientes. These arms were much used by the early navigators.

Between Esquina and La Paz the main bed, which is not in touch with the land on either of its banks, flows in a meandering path for some seven miles, the scale of the bends being double that of the meandering of the Paraguay north of the confluence. The islands are very small, and are strung in a rosary at the top of each bend. The depth is sixty feet at the top of the bend. The shallows are in a line with the islands at the point where the current runs evenly again before the next curve. The depth here is seven, and sometimes even five feet.126 These shallows change their places quickly, and it is not always the same bad spot that determines the maximum draught for ships that are to be used in this section. This migration of the shallows is very different from the permanence of the rocky bottom of the stretch between Corrientes and Posadas.

From La Paz to ParanÁ the main course is outlined by the Entre Rios cliffs. There is no further meandering. The cliffs of hard rock offer far more resistance than the soft alluvia over which the river wanders freely. The permanence of the bed in front of the cliffs leads to a depth of as much as eighty feet. Only here and there a fringe of alluvial stuff separates the channel for a time from the cliff. These curves seem, as a rule, to coincide with the confluence of rivers, which bring a heavy load of clay from the tableland; as, does, for instance, the San Feliciano, north of Hernandarias. They are marked by shallows, in strong contrast to the great depths of the straight sections. The San Feliciano paso, which is twelve feet broad to-day, was only six feet broad in 1908. It appeared on Sullivan's map in 1847.127

Below ParanÁ, as far as the estuary, the careful observations that have been made since 1903 on the movement of the river have enabled us to learn some of its laws.128 We can distinguish four sections of unequal length. From ParanÁ to Diamante the river remains in touch with the cliffs of the left bank. It is not straight; it describes a series of linked crescents of equal radius, which seem to be traces of so many meanders. Only one in two of the windings of the cliff is followed by the channel. The wandering of the river is confined within limits as in a fixed mould. The Paracao shallow, which for a long time prevented ships from reaching Santa FÉ (gradually deepened by dredging from eight to nineteen feet between 1907 and 1911) is at the angle where two of these curves meet. On the right bank the secondary arms continue to follow the river (ParanÁ viejo, Riacho de Coronda).129

Below Diamante the river leaves the cliff on the left bank and slants across the alluvial plain to the cliff on the right bank, which it reaches at San Lorenzo. Over the whole of its thirty miles width it resumes the freedom and regularity of features which it had above La Paz. A comparison of the successive maps of the river shows that the scheme of its movements, which one would be tempted to draw up with a regular migration of the islands and loops down river, would not be accurate. The changes of the bed of the river are essentially due to variations in the volume of the different arms, which are constantly changing their size and adapting their shape to the body of water that flows in them. The radius of the curve of each arm is proportional to its volume. A long island is formed between two arms of equal size which both describe symmetrical curves. If the volume of one of them is reduced, its original curve is replaced by sinuosities of smaller radius, and these nibble the edges of the island and give it an irregular shape. If the volume increases again, the winding bed is abandoned and becomes a dead bed, and a larger meander begins. The track followed by the ships then breaks up into a series of meanders over a course of about eight miles and a half, and this means the concentration in a single channel of the greater part of the water of the river, and in narrower bends in the sections where the current is divided between several arms.

From San Lorenzo to San Pedro the river flows by the cliff of the right bank. It is remarkably regular, and has only one slight bend: an exceptionally good site, on which the town of Rosario is built. At almost equal intervals, differing by only about ten to thirteen miles, the river leaves the cliff, and is separated from it by an alluvial strand, or by an insular zone a few miles in width.130 Below this bend the current again touches the cliff and landing is easy. The small, older ports of the ParanÁ—ConstituciÓn, San Nicolas, Puerto Obligado and San Pedro—are built on similar sites. It does not seem that the islands at the foot of the cliff tend to extend downward in front of these ports; the points where the river reaches the cliff are fixed. The depth is often considerable at the foot of the cliff (138 feet opposite Puerto Obligado). The shoals are distributed irregularly at the bends, where the channel moves away from the cliff. They all have to-day a minimum depth of twenty-one feet.131 On the left bank the secondary arms sprawl over the alluvial plain for thirty-five miles north of the river.

The delta begins at San Pedro. The ParanÁ Guazu, or main arm, leaves the cliff on the right bank and passes to the Uruguayan bank opposite Carmelo. The ParanÁ de las Palmas, which branches off from it to the south and passes before Campana and Zarate at the foot of the tableland, is deep and easy to navigate, but it is closed at the bottom of the estuary by a six-foot bar, which makes it a sort of blind alley opened only above. The arms of the zone of the delta differ from those of the river-zone proper in the irregularity of their course. Flowing between long islands, they sometimes lie in straight stretches and at other times in meanders or almost perfect buckles. The channels of the southern part of the delta, near Buenos Aires, are called caracoles (snails) on account of their winding shape. The weakness of the current, which is held up by the tide, is seen also in the distribution of the greater depths; they are no longer uniformly found along the concave edge of the bends, but are scattered irregularly. On the ParanÁ Guazu a depth of 130 feet has been ascertained. Its minimum depth is twenty-two feet.

The study of the estuary may be taken separately from that of the river. It consists of three parts, unequal in size, which open with increasing breadth toward the Atlantic. The upper Rio de la Plata, above Colonia and PuntÁ Lara, has a width of about thirty-five miles. The middle Plata, twice as wide, extends to the latitude of Montevideo and PuntÁ de las Piedras. Then the outer harbour opens between Maldonado and PuntÁ Rasa. The water is still fresh in the middle estuary up to eighty miles below Buenos Aires.

The bottom is alluvial except in the channels between Martin Garcia and Colonia.132 Differently from up the river, where the channels have sandy bottoms, while the banks are of fine clay, the channels of the estuary have bottoms of mud and clay. In the outer harbour the pilots recognize the approach of banks by the sand which is brought up by the sounding-lead. The action of the waves, which is not found in the river, accumulates stuff of comparatively large size and weight on the banks.

In spite of the conclusions embodied in the nautical instructions, which describe the estuary as a theatre of rapid changes "occasioned by the continual deposits of sand brought down by the ParanÁ and the Uruguay,"133 the estuary is, as a matter of fact, in a remarkable state of equilibrium, and there is no trace of a gradual accumulation of alluvia, or of important changes of channel. The shore of the delta north of the ParanÁ de las Palmas, covered with rushes which protect it from the attack of the waves, shows neither advance nor retreat. The broad lines of the hydrography of the Rio de la Plata are plainly indicated on Woodbine Parish's map. The English Navy map of 1869 (on the basis of observations in 1833, 1844 and 1856) only differs in detail from the present map. The stability of the channels is surprisingly different from the changes in the bed of the river in the flood-zone. The permanence of the bottom, in spite of the loose deposits of the estuary, is explained by the regularity of the currents. These currents, which determine the submarine topography of the Rio de la Plata and the distribution of the banks, are not of river origin. They are tidal currents.

There are two groups of shoals in the estuary. The first, the Playa Honda, occupies the whole western part of it up to a line drawn from Buenos Aires to Colonia. These banks leave a narrow passage in the north, opposite the Uruguayan shore, and this is followed by ships going to Uruguay and the ParanÁ Guazu. The second group of shoals is the Ortiz Bank, triangular in shape, which rests in the north on the Uruguay coast below Colonia, while its point extends south-eastward to eighteen miles north of the PuntÁ de las Piedras. It keeps the zone of deepest water in the middle estuary to the south, near the Argentine shore. In the latitude of the point of the Ortiz Bank, on a line from Montevideo to PuntÁ de las Piedras, the middle estuary is separated from the outer harbour by a bar (barra del Indio) with thirty-eight feet of water, caused by the transverse currents which circulate from point to point inside the English Bank.

The tide in the estuary is very irregular. The south-east winds increase the flow and retard the ebb. When they are blowing, it often happens that the level of the water in the upper estuary keeps up from one tide to the next, sometimes for several days. The tide, which is slight at Montevideo, is greater at the bottom of the harbour on the Barra del Indio, sometimes rising nearly forty inches there. From there it advances with difficulty northward, over the Ortiz Bank, along the Uruguayan shore, whereas it passes freely into the deeper zone on the Argentine side.134 At Buenos Aires it still has a depth of thirty inches. From there it advances northward by the Martin Garcia channels beyond the Playa Honda. The channel of the Pozos del Barca Grande, which crosses the Playa Honda bank from north to south, parallel to the edge of the delta, is oriented in conformity with the tidal currents and maintained by them. It is not attached to the river, and it is separated from the mouths of the ParanÁ de las Palmas or the ParanÁ Mini by shallows which are navigable only to small boats. The Rias of the Uruguay, where the tide raises the water twelve inches, forms a sort of reservoir which, at the ebb, feeds a strong current round Martin Garcia and sweeps the channels there.

The work done for the improvement of the estuary includes the deepening to thirty feet of the Barra del Indio and the dredging of a straight channel from that point to Buenos Aires. Steamers of large tonnage going up the ParanÁ leave this channel twenty-six miles east of Buenos Aires, and turn north in order to pass east of Martin Garcia, and enter the river by the ParanÁ Guazu or the ParanÁ Bravo. Since 1901 the Argentine Government has considered a plan of opening a direct route from Buenos Aires to the ParanÁ de las Palmas, either by cutting an artificial canal at the foot of the cliffs, across the Tigre archipelago, or by using the channel of the Pozos del Barca Grande and cutting the narrow bar which closes the ParanÁ de las Palmas below. If this were done, the ports of the ParanÁ de las Palmas would have direct access to the sea. Moreover, the new route from the ParanÁ to the Atlantic would be entirely within Argentine territory, out of range of the Uruguayan shore, and Buenos Aires would become a necessary port of call both on departure and return.

Above the estuary, the work for the improvement of the ParanÁ began in 1904 and 1905. Since 1910 the material dredged from the bed of the river has risen to 3,500,000 cubic metres a year on the average. The experience gained in the course of this work has enabled the Argentine hydrographic service to adjust its methods to the incomparable force of the river. It is impossible to maintain a general rectification of the bed and the banks, as is possible with European rivers. The only thing to do is to submit quietly to the plan which the river sketches for itself, and be content to deepen the difficult passages on the line of the main arm. Suction dredges, which work easily in the sand, attack each ridge or paso from below, making a channel into which the waters flow, so that it tends to enlarge itself up stream. The dredges are shifted from bank to bank according as the soundings tell of the formation of fresh obstacles to navigation. They were at first concentrated below Rosario, where the Argentine Government had to carry out certain engagements contracted with the Port Company; then they were scattered as far up as Santa FÉ. The actual equipment suffices to carry out the programme that had been drawn up—to maintain a depth of twenty-one feet as far as Rosario and of nineteen feet as far as Santa FÉ.

As regards the section above Santa FÉ, the engineer Repossini advises that, instead of adopting a programme of expensive dredging with uncertain results, they should first think of adjusting navigation to the natural conditions, and they are such as would be considered very favourable in Europe. The hydrographic service would, however, still have two functions: in the first place, the topographical study of the river and the constant placing of buoys, and, in the second place, the observation of its behaviour and anticipation of variations of level. The utility of the work of foreseeing floods, which has been carried on since 1907, has been abundantly proved. It published a daily bulletin of forecasts, based upon observation of the pluviometric scales of the upper river, which is equally valuable to the navigators and to breeders in the floodable area. It enables the breeders to get their cattle into safety before the floods come. On the other hand, the ship can, thanks to the bulletin, foretell what depth of water it will find at critical passages, and calculate exactly the load it can carry, and so complete its cargo lower down. The service of forecast of floods has morally improved navigation on the ParanÁ by suppressing every possible pretext for wilful stranding, which had become a current form of speculation.

Nothing is more varied than the fleet which now serves the ParanÁ. It includes tramps, and long, slim European ships, which load up with cereals and meat; large river boats, luxurious and light; barges and tugs, lighters and schooners, which have compensation for their slowness in their cheapness.

As regards navigation, the river is now divided into three sections. Maritime navigation ascends as far as Santa FÉ. At Rosario and Santa FÉ it goes right to the heart of the zone of cereals and to the fringe of the forest area. The upper section, between Rosario and Santa FÉ, is less safe than the lower section, and this is reflected in the cost of freightage from Santa FÉ.

The ports of the lower ParanÁ, between Santa FÉ and Buenos Aires, may be classed in three categories. The ports of the first group are built on low land that is liable to be flooded. Every year the floods threaten their traffic. That is the character of ColastinÉ, east of Santa FÉ, which specializes in shipping quebracho timber, or Ibicuy, on the ParanÁ Pavon, in the south of the province of Entre Rios, which, however, is protected by excellent works. The small ports of the barranca of the southern bank, on the main river and on the ParanÁ de las Palmas, form a second group. They ship meat (Campana and Zarate) and cereals (San Nicolas and Villa ConstituciÓn), and they are admirably adapted for this by their natural situation. Steamers come right up to the cliff without any need of special works on the shore. The sacks of wheat are let into the ships down sloping gangways from stores excavated in the cliff or from wagons. None of these ports are equipped for receiving imports. The third group comprises ports with complete apparatus for both export and import. The chief of these is Rosario. It was the increase of imports between 1850 and 1860 that stimulated its early progress. To-day the tonnage of the goods unloaded at Rosario is nearly one-half the tonnage of the cereals shipped there. Yet, in spite of appearances, it is the imports that account mainly for the busy life of its quays. The port company does the unloading itself, as well as the handling and storing of the goods imported, but it is content to receive dues on all exports within the area for which it has a monopoly. Only a small part of the cereals exported uses its elevators. A deep-water port, equipped like that at Rosario for import and export, has just been constructed at Santa FÉ. Already it competes with ColastinÉ for the export of quebracho. Its import trade is still small, as such trade requires large capital and a whole network of relations with the adjoining country, and that is not the work of a day.

The second section of the river stretches from Santa FÉ to Corrientes, and is continued up the Paraguay. The transport of quebracho timber and tannic acid is the chief item of its trade. The maximum draught of the vessels it admits at normal low water is six feet. Some of the ports on the left bank (Esquina, Goya) and all the ports on the right bank (Reconquista, Barranqueras, etc.) are at some distance from the main bed, or lateral arms. The Chaco works have generally a flotilla of steamers and barges. It is the exporters of timber and extract of quebracho to Europe who most strongly demand the deepening of the bed of the ParanÁ above Santa FÉ. Sailing ships share with the river steamers the transport of the products of the Paraguay and of Corrientes (hides, tobacco and matÉ). The transport of oranges alone from San Antonio, Villeta, Pilar and HumaÏta represents an item of tens of thousands of tons.

The third section of the river stretches from Corrientes to Posadas, and beyond. Sailing ships have disappeared from this section, as they cannot make the ApipÉ rapids. Steamers of four and a-half feet draught and 150 tons are now used on it, but they cannot proceed at low water. They provide a direct service between Buenos Aires and Posadas, though the service is not very economical, because it does not permit them to use to the full the transport-capacity of the river below Corrientes. Most of the goods for Posadas are, therefore, trans-shipped at Ituzaingo, below the rapids, or at Corrientes. The steamboat companies which serve Posadas are obliged, in order to secure the economical transport of goods shipped on the upper ParanÁ, to maintain lines which go up the Paraguay as far as AsunciÓn, and take on at Corrientes the goods that come from Posadas. Higher up, the falls of the Guayra and the Yguassu set an impassable limit to the enterprise of Argentine vessels. Boats on the stretch above Yguassu on the ParanÁ feed the railways of the Brazilian tableland. The traffic of the upper ParanÁ consists chiefly of matÉ from Misiones and cedar-planks from the Posadas saw-mills. Rafts of timber are stopped at Posadas and rarely follow the river further.

The Argentine statistics of navigation are obscure. They confuse under one heading the river-traffic between Posadas and Brazilian territory, or between Corrientes and the Paraguay, and the exports of the Pampean region to Europe. It is difficult to get from them an idea of the real traffic, or to distinguish the tonnage loaded or unloaded at each port from that which merely touches its quays in ships going up or coming down the river. They credit a score of ports with a total tonnage of (entries and clearances together) more than 500,000 tons.

At all events, they do enable us to distinguish between ports exclusively devoted to river traffic and those with direct relations to oversea ports. Nearly all the boats destined for the ParanÁ touch at Buenos Aires, which remains the chief importing centre, on the way up, and unload there. They then go empty to Rosario, San Nicolas, or Santa FÉ to take on a full cargo of cereals or timber, and set out down the ParanÁ for Europe without calling at Buenos Aires. Clearances for interior navigation at the port of Buenos Aires are far more numerous than entries. From 1912 to 1914 Buenos Aires received on the average, coming from interior ports, 1,750,000 tons, of which 1,635,000 were cargo. It cleared for the same ports ships totalling 3,275,000 tons, of which 1,580,000 were in ballast. The latter figure fairly represents the tonnage of sea-going ships sent up river empty after discharging on the quays of Buenos Aires. At Rosario, San Nicolas and San Pedro, on the other hand, the tonnage of clearances for Argentine ports is much less than the tonnage of entries.135 The total movement of goods at the port of Rosario is 410,000 tons entries and 375,000 tons clearances for interior navigation, and 1,100,000 tons entries and 1,824,000 tons clearances for navigation abroad.

According to Repossini's calculations the tonnage of exports on the lower ParanÁ south of Santa FÉ rose in 1910 to 4,000,000 or 4,500,000. The imports, almost entirely confined to Rosario, were about a fourth of this figure. For the middle and upper ParanÁ, Repossini estimated the volume of the traffic at 800,000 tons, of which quebracho was two-fifths.

The navigation of the ParanÁ is one of the chief sources of the prosperity of Buenos Aires. Even if the development of the import trade at Rosario or Santa FÉ is partly at the expense of the capital, and the boats laden with cereals do not stop at its quays, still the coasting traffic on the river is in great part meant for Buenos Aires. In returning, rather than go empty, the boats take cargoes of European products bought from the Buenos Aires importers. By means of the ParanÁ the import-trade sphere of influence of Buenos Aires reaches beyond the frontiers of Argentina, as far as Paraguay and part of Brazil. Buenos Aires is, moreover, the main centre for equipping the steamboats of the river. Its capital dominates the ParanÁ. Lastly, the ParanÁ supplies it with an export freight which must not be overlooked. It is at Buenos Aires that the hides, tobacco and timber and extracts of quebracho for oversea markets, shipped on schooners in the upper reaches of the river which are impassable for steamers, are trans-shipped for abroad.