120 REPORTS ON INVESTIGATIONS AND PROJECTS. 



The Salton Basin is an irregular oblong depression, with an area of 2,000 

 square miles, having its long axis lying northwest and southeast, extending 

 from the angle formed by the San Jacinto Mountains and San Bernardino 

 foothills in California to a point across the international boundary line 

 between the United States and Mexico, being cut off from the Gulf of Cali- 

 fornia by the alluvial deposits in the delta of the Colorado River. The lowest 

 portion of this depression is 287 feet below sea-level, and the presence of an 

 old beach line 22 feet above sea-level shows that comparatively recently it 

 has been the site of a lake, which emptied southwardly into the Gulf of 

 California. Within historic times, however, the basin has been empty, and 

 this great bowl is one of the marked features of the Colorado Desert. The 

 rainfall is exceedingly scanty and the soil is highly charged wath salts of 

 various kinds, consequently the vegetation is of a pronounced spinose or 

 halophytic type. 



Several times within the last century the flood waters of the Rio Colorado 

 have been diverted to such an extent as to flow into the basin and form a 

 small lake, and the presence of several minor beach lines on the slopes of the 

 basin suggests that such inflows have taken place many times within the last 

 few thousand years, and also that the level of the ancient lake was not lowered 

 uniformly. 



During the last three years some faulty engineering operations have opened 

 a channel leading into the basin, with the result that the main flow of the 

 Colorado River has run into the depression for the greater part of the last 

 year, forming a lake with an area of nealy 500 square miles, accompanied, 

 of course, by the entire destruction of the desert flora on the submerged 

 lands. As a result of the engineering efforts of the Southern Pacific Railway 

 the channel leading from the main course of the river to the Basin was closed 

 early in October. The gradual shrinkage of the lake may now confidently 

 be expected, and the desert vegetation will probably reoccupy the areas left 

 bare by the recession of the water. As a fortunate prelude or beginning of 

 this study, Dr. D. T. MacDougal and Mr. Frederick V. Coville visited the 

 basin in 1903 and made some observations upon the vegetation, together with 

 some photographs of the manner of occurrence and habit. The evaporation 

 and seepage in the region are such that seven or eight years will be necessary 

 to empty the basin, which will thus afford experimental conditions on a large 

 scale of the re-vegetation by xerophytic plants of a submerged area. A sim- 

 ilar depression on the western side of the Cucopa Mountains, in Baja Cali- 

 fornia, is expected to offer corroborative evidence, while the altered condi- 

 tions offered by the diversion of the water in the delta lands will yield results 

 of great value as to distribution. 



An examination of the effect of the advancing water line upon the vegeta- 

 tion of the contiguous desert was made by Dr. D. T. MacDougal and Mr. 



