12 THE SALTON SEA. 



many dry channels are left. Great changes in the course of the river took place in the last 

 century. The length of the main channel abandoned was not less than 100 miles. There 

 is evidence that shiftings of the river-bed have been going on through all ages. 



An inland sea once covered the Rann of Kachh and the region is sometimes flooded 

 during the season of the southwest monsoons. 



The rate of advance of the shore-line of the Delta is rapid. It is stated that in ten 

 years the advance of the banks at the river mouth is 3.33 geographical miles, or one-third 

 of a mile yearly. It is estimated that the river brings down 217,000,000 cubic yards 

 annually. 



Changes very similar to the displacement of the waters of the Gulf of California by 

 the Colorado Delta have been in progress in other parts of the world, notably at the head of 

 the Persian Gulf, which, within a comparatively recent period, extended 250 miles farther 

 to the northwest than the mouth of the combined stream of the Tigris and Euphrates. 



In the interior valley of the upper California, which is topographically an extension 

 of the great trough of the Gulf, there are also analogous conditions of delta and lacustrine 

 deposits. In the valley of the Tulares there are broad regions of level lacustrine clays 

 where evidently there were formed broad lakes of fresh water, represented to-day by the 

 chains of shallow residual lakes from the Buena Vista to the Kern and the Tulare. These 

 lakes, ever varying in their extent according to the water supply, owe their origin as sep- 

 arate sheets of water to the diversion of the San Joaquin River by its own detrital deposits 

 from a southern and land-locked to a more northern outlet leading to the sea. The Delta 

 deposits of this river, by extending into and across this interior valley, divided it into two 

 parts near its center, so that the floods of the San Joaquin, which once swelled the volume 

 of the Tulares, were finally withdrawn into the sea at the Golden Gate. All such river and 

 lake deposits, both of the Old World and the New, are remarkable for their fertility and 

 capacity of sustaining large populations. From this point of view the value of the Delta 

 of the Colorado can scarcely be estimated. It fully justifies the great cost of its reclamation 

 and control of the water supply for the benefit of this and future generations. 



