160 



SOUTH AMERICA— THE ANDES REGIONS. 



San Juan, projects far beyond the normal shore-line, but is too shallow to admit 

 any but light craft. The lower reaches, however, bet-ween the delta and the 

 Cordilleras, might be utilised for navigation if this almost uninhabited region 

 stood in need of any such facilities. 



The discharge of all the Colombian rivers flowing to the Pacific and to the 

 Caribbean Sea is estimated by Yergara at 320,000 and 460,000 cubic feet per 

 second respectively, while the enormous quantity of 910,000 cubic feet is sent to 

 the Atlantic, partly through the Orinoco, partly through the Amazons. The 

 annual rainfall being estimated at 73 inches, or 2,500,000 cubic feet for the whole 



Fig. 61. — TuatTEEEES Plateau and Valley of the Guaitaea. 

 Scale 1 : 500,000. 



12 Miles. 



territory, it would appear that about one- third is lost hj evaporation, or absorbed 

 by the roots of the plants. 



The Colombian Lakes. 

 At present there are scarcely any lakes in Colombia, unless such shallow 

 riverine depressions as the Zapatosa lagoon are to be regarded as such. But 

 although the lacustrine basins were emptied at an unknown geological epoch, the 

 traces that they have left on the plateaux show that some of them were of vast 

 extent. There can be no doubt that the elevated plain of Bogota was formerly 

 covered by the glacial waters descending from the Suma Paz highlands, but was 

 gradually drained by the erosions of the Funza (Bogota) emissary. The Chibcha 

 (Muysca) Indians appear to have had traditions of this geological fact, for they 



