PLANT ECOLOGY AND FLORISTICS OF SALTON SINK. 



By S. B. Parish. 



TERRITORIAL LIMITATIONS. 



The area the vegetation of which is here discussed lies between the margin of the pre- 

 historic Lake Cahuilla and that of the present Salton Sea. The boundaries of this ancient 

 body of water are still indicated in many places by easily recognized "old beaches," the 

 gravelly ridges formed by the action of its waves; or, where rocky promontories abutted 

 upon the water, by the heavy coating of travertine deposited upon the subaqueous por- 

 tions. Everywhere the soil is full of bleached shells of the small mollusks which inhab- 

 ited this long-vanished lake. Time and again the lake bed has been partially refilled by 

 the irruption of the Colorado River, to again disappear by the slow evaporation of its waters. 

 The most recent replenishment occurred in 1905, through human negligence, and again this 

 present lake is contracting and dwindling to extinction. 



To the bed of Lake Cahuilla the name Salton Sink has been given. Its upper margin 

 is about 20 feet above present mean tide level, and its lowest point, now beneath the water 

 of the present lake, is 286 feet below. In the central depression lies Salton Sea. The whole 

 catchment area whose drainage is towards the sea is known as the Cahuilla Basin. 



The Sink is oblong in shape, its longer axis lying southeast and northwest, a distance 

 of about 80 miles, in an air-line from Indio to Calexico. Its greatest width is measured 

 by a line running slightly south of west through Imperial Junction, and is about 30 miles. 

 On either hand rise arid and sun-scorched mountains of low altitude. Desolate and barren 

 as these appear, and as they in reality are, their slopes and waterless canons sustain a 

 scanty but interesting flora, the consideration of which, however inviting, is beyond the 

 present purpose. The southern boundary is formed by the outward slope of the great 

 Delta which has been deposited by the turbid waters of the Colorado River, whose uncer- 

 tain channel follows the ridge it is continually building. 



BOTANICAL HISTORY OF THE SINK. 



Within the last dozen years an irrigation system has brought the water of the Colorado 

 River to a large area of the southeastern end of the Sink, now known as Imperial Valley, 

 and as a result about 275,000 acres of previously arid desert have been brought into culti- 

 vation, railways have been built, and busy towns have sprung up. At the northwestern 

 end a considerable but less extensive reclamation has been made by the development of 

 artesian water. These agricultural operations have entirely changed the character of a 

 large part of the Sink and have complicated the study of its flora. Especially is this the 

 case in Imperial Valley, where the peculiar conditions present problems at once interesting 

 and difficult. It is to be regretted, therefore, that the references in botanical literature to 

 the conditions formerly existing in the Sink are both scanty and unsatisfactory. The 

 papers mentioned below comprise all, so far as I have been able to ascertain, which relate to 

 the subject. 



The survey of the boundary between the United States and Mexico, made in 1856, 

 passed across the southwestern border of the Sink, and the first volume of Emory's Report 

 of the Survey contains a botanical paper by Dr. C. C. Parry, the botanist of the party, 



85 



