D. T. MaeDougal—The Salton Sea. 24 7 



first two feed upon fish and habitually alight either on rocks 

 or branches of trees rising above the level of the water, or 

 upon the arid rocky soil about their nests as noted on various 

 islands. In one case the seeds would be dropped in the water 

 and their origin would escape analysis, while in the second 

 instance the soil would be too dry to induce germination, which if 

 it did take place would end disastrously, since the surface about 

 the nesting-grounds was trampled and worn so that green plants 

 had little chance of survival. 



The lake occupied the bottom of the Cahuilla Basin and 

 streamways from all of the converging slopes led toward 

 it. In none of these, however, were there constant streams. 

 The run-off or surface flow resulted from the precipitation 

 accompanying the heavier storms, and when the streams were 

 formed in this manner the water rushing down the steep slopes 

 of the bajadas undoubtedly would pick up the accumulation 

 of seeds lying in the shallow channels and carry them down into 

 the lake, or perhaps cover some with sand and silt which with 

 the implied moisture would be very favorable to germination and 

 survival. The invasions thus facilitated would result simply 

 in the advance of species down the slopes crossing the strands 

 at right angles, generally in places perhaps occupied previous 

 to the making of the lake. Such action Avas of course notice- 

 able on the uppermost beaches left bare during the first year's 

 recession of the lake, and transportation by this method became 

 less and less efficient as the distance from the maximum-level 

 shoreline was left behind. 



The flotation by run-off streams becomes a more effective 

 method for carrying plants onto the bared strands, especially 

 from the fact that no prolonged subjecting to soaking would 

 be endured. The subjection of the seeds to the brief action of 

 the ephemeral stream and its subsequent contact with the 

 moistened sand or soil would be of a character highly favorable 

 to survival. It is evident that the soil conditions of the beaches 

 during the first year of recession were different from those 

 offered in any following year. Briefly stated, the surface layer 

 had been leached to a slight depth by water containing the 

 lowest proportion of salts. Another thing bearing upon the 

 comparatively heavy vegetation of the emersion due to the 

 first year was the fact that the rapid rise of the lake would 

 have lifted seeds from the ground and thus at the theoretical 

 moment, when the lake was at its maximum level, the number 

 of floating seeds which might be driven ashore by wind and 

 wave action was greater than at any subsequent time in the 

 history of the lake. The toxic activity of the water itself 

 was least at the maximum level and began to increase at 

 once. As was noted in the history of the earliest strand, 



Am. Jour. Sci.— Fourth Series, Vol. XXXIX, No. 231. -March, 1915. 

 17 



