116 Adventures in Scenery 



area of the sea had fallen to 300 square miles in 1915, and is 

 still receding. Had the river not been brought back to its old 

 channel leading to the Gulf, and had it continued to pour its 

 waters into the Salton Sea, this would have meant the return of 

 Lake Cahuilla. This is what did happen in the geologic past, 

 and probably occurred many times as the river meandered over 

 its delta, alternately delivering water to the Gulf and to the lake. 

 Evidently the ancient Lake Cahuilla disappeared by evaporation 

 with the loss of the supply of water from the Colorado. 



The inland basin, known as Lake Cahuilla, was at one time 

 filled with water till it covered an area of 2,200 square miles. 

 This is shown by a well-defined beach line around the present 

 Salton Sea, about 40 feet above sea level, 327 feet above the 

 present surface of Salton Sea. The vast basin that lies below 

 this ancient beach, on the lowest part of which is the present 

 Salton Sea, is what is known as the Salton Sink. Water filled 

 the basin to the height of the ancient beach line. Probably this 

 ancient inland sea overflowed to the Gulf, but its ultimate disap- 

 pearance was due to diversion of the waters of the river south- 

 ward, and evaporation of the waters of the lake. A guess has 

 been made, based on Indian traditions and such field evidence 

 as can be gathered, that the desiccation of the lake may have 

 been 500 to 1,000 years ago. (This is a mere guess.) The rate 

 of evaporation in this basin has been determined to be 113 inches 

 per annum, or 43 times the average annual precipitation. With 

 the evaporation and disappearance of the waters of Lake 

 Cahuilla the basin bottom became a salt-covered plain. The 

 present Salton Sea is the remnant not yet evaporated of the 

 restored "sea" caused by the influx of the Colorado River. 

 Salton Sea is now disappearing by evaporation, and will prob- 

 ably in a short time (geologically) become again a "dry" 

 salt plain. 



The Colorado Desert lies in a long deep valley or trough, 

 the northern extension of the trough in which lies the Gulf of 

 California. The waters of the Colorado enter the Gulf after 



