DEPARTMENT OF BOTANICAL RESEARCH. 



91 



concentration. During the past year potassium has been coming back 

 and shows a rate of concentration far in excess of that of the other 

 constituents. The fresh water received from the Colorado probably 

 accounts for this in part, but more hkely potassium has been returned 

 to the water by the decay and disintegration of organic forms and of 

 tufas that had been deposited by them. The behavior of potassium is 

 shown very strikingly by the potassium-sodium and the potassium-total 

 solids ratios in the last two Unes of the table given below: 



Interpretation of Travertine Record of Blake Sea, hy D. T. MacDougal and 



Godfrey Sykes. 



An outlying mass of fragmental granite projects from a spur of the 

 Santa Rosa Mountains into the Cahuilla Basin in southeastern CaU- 

 fornia, the crest of the rocks rising above the ancient shore-line of 

 Blake Sea, which filled the basin to a level something above that of 

 present high tide in the GuK of California.-^ This cape is designated as 

 ''Travertine Point" in our pubUcations, as the surface of the granite 

 boulders is covered to a varying depth with dendritic and lithoid tufa. 

 Some marks and figures, presumably carved by Indians in the traver- 

 tine, have long been known and were seen by us on our first visit to the 

 place in 1906. In the continuation of our work on the Salton Sea it was 

 reahzed that these figures might possibly yield some evidence as to the 

 duration and variations of the ancient Blake Sea and of the smaller 

 modern Salton Lake. 



A visit to the formation was accordingly made in March 1915, and a 

 careful inspection showed that the number of carvings on the rock was 

 very large, and that some, made in the earlier layers of travertine, 

 have been coated over to such depth that they may be made out only 

 in the most favorable illumination or shading. Others show as deep 

 furrows with weathered surfaces, visible at a hundred yards or more, 

 while none of recent origin have yet been found. 



iSee plate 1, The Salton Sea. MacDougal et al., Carnegie Inst. Wash. Pub. No. 193. 1914. 



