33 



its present prices in this country; yet I think there is but little risk as to ob 

 taining an abundant supply, if these rocks are perforated. There is one condi 

 tion, however, that should be mentioned, which is that in the event of striking 

 a bed ot loose sand or gravel beneath the heavy clay bed, there is almost a 

 certainty of obtaining an abundant supply of water, without descending below 

 that point. I have seen but one or two instances which would lead us to sup 

 pose that such a presence is to be found beneath the clay, and above the rocks, 

 and they were not of sufficient extent to found an opinion upon, and it may be 

 reasonably doubted that such a bed of sand and gravel would be met with ; 

 the evidences, I think, are against it. 



The thickness of the superficial deposits and stratified rocks, beneath the sur 

 face, so far as my opportunities of examination extended, are as follows: (The 

 thickness of the rocks is from my own measurement, and the thickness of their 

 superficial covering is from the results of the boring of an Artesian well near 

 the town of Los Angeles.) Commencing with the alluvium and descending: 



Alluvium, - 6 feet. 



Blue clay, - - - 30 



Bed of drift gravel, - 22 



Arenaceous clay, - 16 



Tenaceous blue clay, - 160 



Coarse sandstone, - 35 



Infusorial sandstone - 100 



Clay, - - 16 



Fossil Clay slate, - - 30 



Total, - 415 feet. ".- 



This is the smallest depth at which water will probably be found, except in 

 the contingency above named, and it is more than probable that a greater 

 depth will be necessary, but of this we have no direct evidence. A careful ex 

 amination of each stratum belonging to the entire group of rocks, so far as the 

 same are uncovered on both sides of the plains, did not enable me to discover 

 any point through which water would probably percolate and issue, except at 

 the points named, to wit: immediately below the bituminous shales, and we can 

 not reasonably expect to find it short of that point in boring on any part of these 

 plains. I speak thus positively, for the purpose of preventing, if possible, any 

 useless expenditure of money, in undertakings of this character, wnen they have 

 not for their object the penetrating of the whole, or a part, at least, of the rocks 

 which underlie the basin; as from the evidences before us, there are no grounds 

 for the supposition that a permanent supply would be obtained short of that 

 depth. * 



It may be expected that some additional reason should be given, besides what 

 lias already been advanced, why water might be expected to flow unremittingly 

 from the depths designated. In order to meet such expectation, I will state 

 that an examination of the accompanying diagram exhibits the fact that the 

 Los Angeles River flows for miles at an altitude much greater than that occu 

 pied by any of the sedimentary rocks which have passed under our considera 

 tion, and that for several miles its course is along the line of strike and parallel 

 with the dip of the series belonging to this group, and crosses those lines only 

 when it approximates the edges of the plains, and where the drift and alluvium 

 covers the whole. 



Again, the sources of the river furnish a much greater supply than is found 

 to reach the valley sections, the proportion arriving at the latter point compri- 

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