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CHAPTER XXVII. 



THE UNDERGROUND WATERS OF SOUTHERN CALIFOBNIA. 



By T. S. VAN DYKE, Civil B;ngineer and Author. 



The discovery of water underground available for irrigation at 

 prices that the products of Southern California will justify is nothing 

 new and its development has been going on for years. But the amount 

 found in the past year just after a series of six years of short rainfall, 

 of which four were only about one half the average, and the other 

 two not above it, exceeds all that has ever been imagined and is possi- 

 bly equal to the total of all other years combined. 



Nearly all of this development has been in the four counties of Los 

 Angeles, San Bernardino, Riverside and Orange where the older orange 

 orchards in full bearing made such a demand for water to mature the 

 present great crop. These tour counties once lay in the lap of a cres- 

 cent of granite mountains which were then far higher than they are 

 today, and the whole country from coast to mountain was also higher. 

 All lay open to the sea and the whole drainage downward was unin- 

 terrupted from the mountains to the coast. As the mountains began 

 to disintegrate and wear down and the valleys to fill up with the wash, 

 the heavier discharges of flood years carrying gravel and heavy boul- 

 ders far down the slope began to arrange their debris exactly as we 

 see them doing today. They swung from side to side to of an immense 

 flood plain, one river perhaps running into another at times of great 

 flood. Here the track was a vast wash of heavy gravel which, in suc- 

 ceeding years, became covered with fine sand if the flood waters moved 

 to the other side of the valley, or with fine wash if they stayed on that 

 side but were not so heavy for a series of years.. Or if the waters of 

 summer and succeeding years continued to fiow over them they became 

 covered with fine concrete lime or silica carried in solution. As in 

 the course of ages they became covered with other layers some of the 

 layers of sand or gravel decayed into clay just as they lay. By some or 

 all of these ways layers of gravel which were once old stream beds, 

 became separated from one another by layers of impervious material. 



