250 THE RIVER-ROUTES 



it by an alluvial strand, or by an insular zone a few 

 miles in width. 1 Below this bend the current again 

 touches the cliff and landing is easy. The small, older 

 ports of the Parana Constitution, 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. 3 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 Parana Guazu, 

 or main arm, leaves the cliff on the right bank and 

 passes to the Uruguayan bank opposite Carmelo. 

 The Parana 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 navi- 

 gate, 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, 



1 As between La Paz and Parani, it seems possible to show some 

 relation between these alluvial stretches at the foot of the cliff and 

 the confluence of the small valleys of the Pampean plain. 



> The Paso Paraguayo, which has cost the Argentine hydrographic 

 service most work, did not exist at the middle of the nineteenth cen- 

 tury. It seems that the channel then kept to the cliff as far as 

 Benavidez, and was continued as far as the source of the Parank 

 Pavon by a very pronounced buckle, of which the Monriel lagoon 

 is a scar. In 1895 the Paso was only fifteen feet deep. 



