[117] The transport of mineral stuff, apart from salt, has been greatly reduced by the war. In 1916 it was only 637,000 tons for the Southern and 157,000 tons for the whole of the lines of the Central Argentine, Pacific, Central Córdoba, and State.
[118] There is still a certain amount of goods traffic in this latitude between the river and the Santa Cruz district by the Puerto Suarez and Puerto Pacheco tracks.
[119] The local south winds which help the voyage upward below Rosario may be due to the high temperature of the water of the river; this also gives rise on the lower Paraná to thick fog of which warning is given.
[120] According to Rengger, sailing ships sometimes succeeded in crossing the Salto d'Apipé.
[121] At one time the boats on the upper Uruguay saved transport by going from Salto to Arapehy, midway between Monte Caseros and Concordia (see Isabelle).
[122] It is as well to notice that the profile determined by the altitude of the zero of these different scales, or the low-water profile, is of a purely theoretical character. The river is never at low-water over its whole course. The real profile is always varied by slight movements of flood and ebb.
[123] Observations of the sediment held in the water have been made at Campana, 32 miles from the estuary. At this point the Paraná only holds in suspension fine particles of clay, but sand travels slowly along its bed. The weight of the clay in suspension varies from 179 grammes per cubic metre in March during the flood, to 42 grammes at low-water in July. The stuff mostly comes from the Bermejo, which carries 5 kilogrammes of sediment per cubic metre. The load of the Paraná is much heavier than that of the Uruguay, but far lower than that of the Mississippi.
[124] The district on the right bank of the Paraná, above Santa Fé and Paraná, seems to be due to a recent subsidence. The river is, on the other hand, compelled to effect active erosion in crossing the high lands between Santa Fé and Buenos Aires. It is curious that the break or fall at Villa Urquiza occurs precisely above the bend of the Paraná. A less marked break has been recognized further north, in the latitude of Lavalle, above the Goya bend. It seems that the diminution in the excavation of the valley is due to the erosion which the current effects laterally on the cliffs of the left bank.
[125] In the space between the frontier of Entre Rios and the Rio Empedrado, south of Corrientes, the cliffs expose, above the red sandstone, beds of sand and clay, fluvial alluvia left by former beds of the Paraná, the traces of which can be followed from the north-east to the south-west diagonally across the province of Corrientes.
[126] In point of fact, the ridge is lower at the time of low water, when the current is concentrated in the main channel, so that one always finds one or two feet greater depth there at low water than soundings taken at high water would lead one to expect.