88 THE SALTON SEA. 



The Salton Sink is practically a level plane, everywhere exposed to an equal insola- 

 tion, no irregularities of surface serving to vary the effects of sun and wind; with a uni- 

 form temperature and a uniform deficiency of atmospheric humidity and of rainfall. 

 With these variations of environment eliminated or negligible, the question of distribution 

 is left to depend directly upon the chemical and mechanical character of the soil and its 

 water-content. 



WATER SOURCES OF THE SINK. 



There are four sources from which the Sink derives its supply of water. 



(1) The precipitation upon its immediate area; this is scanty and irregular, and its 

 effect is almost negligible. 



(2) The run-ofT from the surrounding mountains; these are subject to torrential 

 downpours, which running at once down their steep and naked acclivities are gathered 

 by the branching canons and poured out into the so-called "washes," These are shallow 

 channels, broadening as they proceed, and often permitting the water to "flood out" 

 over wide areas of mesa. In a few hours the torrents cease and the washes are again empty. 



(3) A third water supply is derived from the San Gorgonio and San Jacinto Moun- 

 tains, some 50 miles northwest of the Sink. These are respectively 11, GOO feet and 10,800 

 feet high, and enjoy a precipitation considerable for the region. Their eastern drainage 

 is carried into the great cone of stones, gravel, and sand which fills the San Gorgonio 

 Pass, into which it promptly sinks. Passing down by percolation, it reaches the northern 

 rim of the Sink, where it is brought so near the surface that, raised by capillary action, it 

 produces the extensive area of alkaline flats between Indio and Mecca. The percolating 

 water itself is remarkably pure, as is demonstrated by the artesian wells which have been 

 sunk into it, but in passing upward it becomes heavily impregnated with mineral matter. 

 The same percolation waters are the sources of the springs which occur along the upper 

 end of the Sink, and they supported the saline marsh which formerly occupied the lowest 

 part of the depression, now drowned beneath the Salton Sea. 



(4) The fourth water source of the Sink is supplied by the Alamo' and the New Rivers, 

 two diffluents of the Colorado, forming a part of the intricate distributory system of chan- 

 nels, sloughs, and lagoons, which, in its Delta, relieves the floods of that stream. By the 

 irruption of the Colorado, in 1906, the character of these diffluents has been greatly changed. 

 They now carry considerable volumes of water throughout the year, and run for most of 

 the way through channels cut 20 to 50 feet deep in the alluvial soil, whose perpendicular 

 banks inclose a strip of moist bottom-lands which becomes wider as the rivers approach 

 their point of discharge in Salton Sea. 



Previous to the settlement of Imperial Valley, and the consequent changes which 

 have taken place in the character of the diffluents, these appear to have consisted of a 

 series of lagoons, or shallow lakes, connected by much less deeply eroded streams. The 

 names of many of these lakes still appear upon the maps, but they no longer exist; they 

 have been drained and their beds are in cultivation. Annually, or at least in most years, 

 these streams and lakes were refilled by the spring floods of the Colorado River, and when 

 these ceased they contracted as their waters evaporated. Some became dry, but others 

 were permanent. At all events, the New River country was regarded by desert travelers 

 as affording reliable watering-places at aU seasons of the year. 



About these natural reservoirs, and in the land moistened by them, doubtless grew 

 most of the paludose and halophytic vegetation which now lines the rivers and irrigation 

 canals of Imperial Valley. Parry speaks of camping by one of these lagoons in September, 

 where the party found sufficient grama grass for the mules, and where he noticed an 

 abundant vegetation. 



' The Alamo appears on tno3t old maps as "Salton River," and on at least one as "East River." 



