132 THE 8ALTON SEA. 



Junction strand was about 1,400 feet; about 600 feet of this had been laid bare on May 

 1908, when a visit was made to this place and to the beaches of Obsidian Island. This 

 visit was opportune, as it confirmed the observation of the previous year that a series of 

 germinations ensued customarily on this beach on the mud laid bare in April. Scirpus 

 paludostis was in moist depressions near the margin of the water; Leptochloa imbricata 

 was a few yards back from the shore; numbers of plantlets of Atriplex fasdculata were 

 established in the moist soil near the water, a small plant of Typha was found coming up 

 through the mud, probably from a rhizome floated to thie place; a few seedUngs of Suceda 

 and Spirostachys were also present, and some mature plants of Polypogon monspeliensis 

 were shedding seeds. 



Numbers of shallow trough-shaped channels, a few inches in width, extended into 

 the soil from the actual margin of the shallow water, and these were filled when the wind 

 was on shore, with the result that loads of debris (including seeds and other parts of plants) 

 were carried up into the land in narrow bands, in which seedlings of an Atriplex polycarpa 

 were found. The steep beach of Obsidian Island, which had been uncovered since the 

 midwinter, was totally bare, and nothing had germinated there when visited again in 

 November 1908. 



The strand of 1908 at Imperial Junction beach bore only scattering plantlets of Spiro- 

 stachys and Suceda with one Sesuvium in the stretch visited. The lowermost portion nearest 

 the water showed an efflorescence of salts. No change was reported in the constitution 

 of the population in November of the same year. 



Returning again to the area on the Imperial Junction beach in November, the whole 

 emersion for the year presented the aspect of a stretch of dried and fractured mud, at the 

 upper margin of which could be seen only a few plants of Suceda, Spirostachys, and Atriplex. 



Typha, Heliotropium, Distichlis, Pluchea sericea, Phragmites, Bouteloua arenosa, Salix 

 nigra, and Populus were present on the Travertine Terrace strand of 1908, the upper margin 

 of this emersion being marked by the beach ridge of midwinter formation. 



These introductions being evidently due either to the action of the wind or waves, a 

 long stretch of beach to the southeast was visited for supplementary observations. The 

 total census of several miles of this strand gave the following : Heliotropium, Distichlis, 

 Prosopis, Atriplex, Coldenia, Chamoesyce, Polycarpa hirtella, Scirpus paludosus, Parosela 

 eirwryi, P. spinosa, and Bouteloua arenosa. The effect of the run-off streams coming down 

 the bajadas from the Santa Rosa Mountains to the westward was plainly evident. These 

 streams might also have an additional effect suggested by some observations on the south- 

 western part of the lake, where seedlings of Pluchea sericea were seen pushing up through 

 sand which had been deposited over the seeds by such streams in times of precipitation. 

 Without such a protecting layer the moisture would be insufficient for germination. • 



Only two of the four observational areas were visited in 1909, and this inspection was 

 made in October. The summer had been characterized by a heavy rainfall over most of 

 the Sink, with the result that numerous channels had been formed and that some salts 

 had been leached from the soil, at least from the surface layers. The total precipitation 

 measured at the U. S. Weather Bureau station near Salton, from July to October, was 3.5 

 inches, of which 2.887 inches were received in 24 hours and most of this fell within 2 hours. 



But little effect had been produced on the Imperial Junction beach. The strand of 

 1908 at that place bore only four species, Atriplex (two species), Suceda, and Spirostachys. 



The steep clayey and gravelly slopes of Obsidian Island had been deeply eroded, and 

 the strand of 1908, on which nothing had been seen previously, now bore Heliotropium, 

 Sesuvium, Spirostachys, Cyperus speciosus, Isocoma veneta var. acradenia, Baccharis glu- 

 tinosa. Aster exilis, Distichlis spicata, Parosela emoryi, Eclipta alba, Sonchus asper, and 

 Cucurhita palmata. This heavy census suggests both delayed germinations and also possible 

 wind dissemination, especially of the winged compositaceous seeds. 



