240 THE RIVER-ROUTES 



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 Parana in its low capacity for transport and 

 alluvial deposit. While the Parana 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 Parana, 

 while further north, from Gualeguacha to Concepcion, 

 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 Parana 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 Con- 

 cordia (right bank) and Salt a (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 Tome and occa- 

 sionally to Concepcion. Small ships go higher, as 

 far as Salto Grande in Misiones (27 20' S. lat.). 1 



The navigable system of the Parana 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 Parana, and 



* 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). 



