HISTORY AND GENERAL CONDITIONS 9 



absence of any adequate gradient between the districts 

 of the interior and the seaboard impedes the rapid 

 discharge of these additional waters, and consequently 

 the rise in the water-level is phenomenal through- 

 out all sections of the Amazon Valley. In the season 

 1912-13, at Porto Velho, 1,600 miles inland, the River 

 Madeira rose nearly 50 feet from the lowest point ; at 

 Manaos, distant 1,000 miles from the sea-coast, the rise 

 was 45 feet. Even in the main body of the Amazon, 

 between Manaos and Para, the differences of the water- 

 level were from 12 to 20 feet. In these periods of flood 

 the country is inundated for many miles from the 

 river-banks, and frequently is under water until the 

 beginning of May. The impossibility of controlling 

 these annual floods is one of the greatest difficulties 

 in the way of any successful colonization and the 

 establishment of permanent agricultural and industrial 

 enterprises. Owing to these conditions, agricultural 

 operations can be attempted only during some five 

 months of the year, and therefore all efforts at cultiva- 

 tion must be confined to crops coming quickly to 

 maturity, or such trees and plants as can resist the 

 effects of being constantly in water for months at a 

 time. In nearly all districts of the Amazon Valley 

 there exist certain lands above the annual flood-level ; 

 but as a rule the soil on these higher sections is of 

 poorer quality than on the flat, and they lie some miles 

 from the river, thus necessitating the construction of 

 costly roadways to maintain communication and trans- 

 port produce during the period of the inundations. 

 Indeed, the cost of any such work would be pro- 

 hibitive ; for, to be effective, a causeway above the 



