232 D. T. MaeDougal—The Salton Sea. 



Circumstantial evidence points to the conclusion that hardly 

 twenty years have passed without some inflow from the river 

 into the Sink, but the only available record of any other inunda- 

 tion, beside the one the effects of which are considered, is that 

 of the overflow of 1891, when the passage from the river to 

 the small lake formed in the Sink was made by a single man 

 in a boat on the inflowing current for the purpose of ascertain- 

 ing the source of the water forming the lake. 



The formation of the lake in 1905, 1906, and 1907 occurred 

 under circumstances that gave unexcelled opportunities for a 

 study of the attendant phenomena. The Desert Laboratory of 

 the Carnegie Institution of Washington had completed its 

 organization and was able to focus the attention of members of 

 the staff and to secure collaborators upon the more important 

 problems which would be offered hy the recession of the lake 

 level : these may be briefly stated as follows : 



1. Composition and nature of the flora of the basin with 

 chief attention to the species inhabiting the Sink. 



2. Influence of the lake upon vegetation above the flood 

 level, either in increased humidity or hemmed underflow. 



3. Endurance and survival of the vegetation in the shallower 

 marginal portions of the flooded area. 



4. Geographical relations of the Sink with especial con- 

 sideration of the contributing drainage. 



5. Physical and chemical analyses of soils of the Sink, with 

 comparisons between those unaffected by the recent sub- 

 mergence and those taken from the bared strands. 



6. Composition of the water of the lake as varying with its 

 concentration. 



7. Algal and bacterial flora of the lake, and influence of 

 these plants upon the composition of the water. 



8. Alterations in plant tissues induced by submergence. 



9. Reoccupation of the bared strands left by the receding 

 lake by plants. 



10. Alternations or successions in the plant inhabitants of the 

 strands with increasing aridity. 



11. Environic response of plants gaining a foothold on the 

 strand and later becoming subject to desiccation. 



12. Pioneer occupants of sterilized islands emerging from 

 the water as a result of lowered level. 



13. Agencies effective in carrying seeds, spores, and pro- 

 pagula to bared strands and isolated areas on islands. 



14. Introductions, or invasions of the Sink by species not 

 hitherto native to the region. 



The Cahuilla basin is a structural trough lying immediately 

 to the eastward of an abruptly rising mountain range which 

 separates it from the Pacific. The depression is shaped much 



