PHYSIOGRAPHY OF NICARAGUA CANAL ROUTE 237 



Lake Nicaragua has a regular oval outline, its longer axis 

 extending about northwest-southeast. Its area is very nearly 

 3,000 square miles, and the mean elevation of its surface is about 

 104 feet above tide. Its shores present considerable diversity, 

 depending cbiefly on the character of the rocks which form 

 them and the direction of the prevailing winds. The trade 

 winds blow with great persistency throughout a large part of 

 the year. They are deflected from their normal course by the 

 high volcanic range of northern Costa Rica, so that instead of 

 being northeast winds the}' vary from east to east-southeast. 

 As a result of this constant wind direction the southeastern end 

 and northeastern side of the lake rarely experience any surf, 

 and hence those portions of the lake shore have no beach, but 

 are bordered by swamps, with vegetation constantly encroach- 

 ing upon the lake. Along the southwestern side and western 

 end of the lake, on the other hand, there is a constant heavy 

 surf and as a result a broad sand beach, generally backed by a 

 wave-cut cliff. The accompanying map (page 239), based upon 

 surveys made by the U. S. Nicaragua Canal Commission, shows 

 the configuration of the lake basin. The most interesting fea- 

 ture shown is the old channel, evidently a drowned river chan- 

 nel formed when the southern half of the lake basin was dry 

 land. This channel marks the course of a river formed by the 

 union of the several streams now entering the lower end of the 

 lake with the one which occupies the upper portion of the San 

 Juan valley. It is first detected in the vicinity of the Solenti- 

 name islands, and if it was ever excavated between this point 

 and the mouth of the Frio this portion has subsequently been 

 filled by sediment brought into the lower end of the lake. From 

 the Soleiitiname islands for about 10 miles northwestward there 

 i> only a slight indication of the channel. Thence to the base 

 of Madera it is continuous and distinct. The greatest depth in 

 the lake, over 200 feet, is near the western end of this channel. 



To the west of the bay, which, as shown on the map, plate 6, 

 formerly indented the Pacific coast, was a long cape or peninsula. 

 This now forms a part of the narrow strip of land occupied by 

 the continental divide between Lake Nicaragua and the Pacific. 

 This part of the isthmus, although intimately connected with 

 the Nicaraguan depression, is not properly a part of it. Its to- 

 pography is particularly interesting in connection with the pro- 

 posed i 'anal, since it contains the lowest gap in the continental 

 divide between the straits of Magellan and the Arctic ocean. 



