MOVEMENTS OF VEGETATION IN THE SALTON SINK. 129 



glandulosa, Baccharis glutinosa, and Distichlis had made a luxuriant growth in the clayey 

 deposits on the shore of East Bay, emersion of 1907. The larger Prosopis glandulosa, on 

 the exposed gravelly and sandy shore of the southeastern part of the island, had attained 

 a height of 10 feet and was in bloom. Four smaller P. pubescens were coming up as seed- 

 lings, although it could not be determined whether they were the offspring of the larger 

 plant or not. Another P. pubescens in bloom was seen on the strand of 1907 West Bay, 

 thus making a total population of six individuals of one species. Cucurbita was present 

 in the same strand. This census indicates no farther introductions into the highest part 

 of the beach, from which (since the previous census of 1908) Heliotropium, Sesuvium, 

 Lippia, Aster spinosus, A. exilis, and Eriogonum thomasii had been lost. Here, as else- 

 where, some of the missing constituents might have been represented by a crop of seeds. 



A visit to the Imperial Junction beach only was made in May 1910. The two species 

 of Atriplex, Suceda, and Spirostachys were arranged about as previously described, while 

 Pluchea sericea continued to endure the desiccation. 



A second inspection of the shore stations was made in September and October 1910. 

 The emersion of 1907 at the Travertine Terraces bore Distichlis, Prosopis, Phragmites, and 

 Astragalus. In the two years since the last visit was made, Heliotropium, Pluchea cam- 

 phorata, Juncus, Bouteloua, Sesuvium, Spirostachys, Suceda, Phragmites, and the two species 

 of Atriplex had been lost from the population. 



The return from this locality was made along the shore, so that many miles of the 

 beach were seen. The surviving pioneers on this gentle slope were Distichlis, Spirostachys, 

 Atriplex, Prosopis, and Suceda. 



Visits were again made to the shore stations in October 1911. The emersion of 1907 

 Travertine Terraces bore Distichlis, Pluchea sericea, Salix nigra, Prosopis, and Phragmites, 

 but Spirostachys had disappeared. 



The shores of Obsidian Island were visited by a boat put off with difficulty from the 

 Imperial Junction beach. The only survivors of the population of the strand of 1907 were 

 Prosopis, Heliotropium, Baccharis, and Cucurbita. A registering thermometer, placed on 

 this island two years before, recorded 41° and 109° F. The losses recorded in 1909 for this 

 place seem to be permanent and the desiccation of the soil may be taken to have reached 

 a point where it would be difficult for any of the lost species to regain a foothold. 



The Imperial Junction beach was much in the same condition in 1911 that was re- 

 ported in 1910. Two species of Atriplex, Suceda, and Spirostachys comprised the plants 

 that seemed to be holding their own, while the stand of Pluchea was still undergoing great 

 losses from increasing aridity. 



It being desirable to bring together the results of the various investigations upon the 

 problems of the Salton, at the close of 1912 arrangements were made for a careful examina- 

 tion of the various beaches at some time during the year. Those at Travertine Terraces 

 and Mecca were visited twice. 



In June Atriplex (two species), Prosopis pubescens, and Suceda were seen in the upper- 

 most portion of the emersion of 1907 at Mecca, and the lower limits of this strand could 

 not be made out on the gentle slope. 



The emersion of 1907 at Travertine Terraces bore Prosopis pubescens, Distichlis, 

 Astragalus, Salix, and Pluchea sericea, from which it may be seen that there had been no 

 change in the population since 1910. 



The final examinations were begun at Mecca on October 14, 1912. The gentle slope 

 at this place had operated to prevent any clear delimitation of the limits of the seasonal 

 emersion, but some estimate was made from the known vertical recession of the lake. 

 Suceda, Prosopis, Pluchea sericea, Atriplex canescens, A. lentiformis, with Distichlis probably 

 represented the total population, and a photograph was made \vith all of these species in 

 view. Reclamation operations had been begun in this region, so that it is probable that 

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