45 



feet above the floor of the valley, this sea was perhaps con- 

 nected with the Pacific Ocean, thus making an island of 

 Lower California. 



With the uprising of the land and retreat of the waters, 

 the ancient sea first was cut off from direct continuity with 

 the Pacific, and subsequently the Cahuilla and Pattie Valleys 

 became separated north of the Cocopah Mountains, their 

 waters still being continuous in the south with the Gulf of 

 California. But the Colorado River deposited its incalculable 

 tons of alluvium^ along the southern margin of the Cahuilla 

 Valley and began to build up the great delta that eventually 

 formed a land junction with the Pattie Basin, south of the 

 Cocopahs. In this constructive process the Colorado was 

 materially aided by the huge tidal bores characteristic of the 

 head of the Gulf of CaHfornia, these tending to form successive 

 barriers of marine deposits behind which the river might 

 spread out during its overflow, and drop its burden of sus- 

 pended soil over the widest possible area. Thus the two 

 basins of the Colorado Desert came to be landlocked and to 

 contain each a residual lake, of which that occupying the 

 Cahuilla is now called the Salton Sea, that of the Pattie the 

 Laguna Salada, or, as the native Indians say, ''Laguna 

 Maquata." 



As stated above, these basins have been again and again 

 completely dried up, a condition which has recently prevailed 

 up to the year 1905, when a winter flood of the Colorado 

 broke the barriers of an insufficient irrigation canal supplying 

 the cultivated part of the Cahuilla Valley, known as the 

 Imperial Valley. The water made new and destructive cuts 

 across the plain, and turned practically the whole volume of 

 the river into the Salton Sink. Not until 1907, after an 

 enormous expenditure of money, could the flow be checked, 

 and by that time the Salton Sea had attained such size that 

 it will hardly have entirely evaporated before the year 1930.^ 

 During the deflection of the river, moreover, its former bed, 



1 The sediment brought down by the river has been estimated as sixty 

 milUon tons yearly (MacDougal, 1906). 



2 This calculation does not take into consideration the ever-increasing 

 drainage from irrigation canals, which may perpetuate the Salton Sea. 



