THE 



National Geographic Magazine 



Vol. X JULY, 1899 No. 7 



PHYSIOGRAPHY OF THE NICARAGUA CANAL ROUTE 



By C. Willard Hayes, 



United States Geological Survey 



The region whose topography and geology have a most inti- 

 mate bearing upon the problems connected with the proposed 

 Nicaragua canal embraces northern Costa Rica and southern Nic- 

 aragua. It is sharply limited on the south by the high volcanic 

 range of Costa Rica, which rears its massive form diagonally 

 across the isthmus. It is limited to the north somewhat less 

 definitely by the increasing height of a deeply dissected plateau, 

 which merges with the mountains of northern Nicaragua. Be- 

 tween these limits lies a broad irregular depression, which extends 

 very nearly across the isthmus in a diagonal direction parallel 

 with the Costa Rican range. This depression is now occupied 

 chiefly by Atlantic drainage, the continental divide lying within 

 a short distance of the Pacific. It contains the basins of Lakes 

 Nicaragua and Managua and their outlet, the San Juan river. 

 It is important to note that the Nicaraguan depression is not a 

 simple river valley. The portion with which we are chiefly con- 

 cerned, that lying between the lake and the Caribbean, embraces 

 two distinct drainage basins, whose streams formerly flowed in 

 opposite directions, although by a geologically recent reversal 

 of the drainage they now have a single outlet to the sea. 



When examined in detail the surface of the Nicaraguan de- 

 pression presents considerable relief, and its topographic features 

 naturally group themselves into three classes. 



Extending from the base of the Costa Rican volcanoes north- 

 ward to the >an Juan river and beyond are many hills whose 



17 



