222 UNDERGROUND WATERS. 



made that will furnish considerable seepage water if not too heavily 

 drawn on. But they will not stand heavy work very long. It is much 

 the same with mere standing water in gravel. There is, however, very 

 little of this and it is doubtful if we have anywhere water under- 

 ground so nearly at rest that it would be called percolating water by 

 our courts. 



The decayed granite that lies upon the hard core of the granite 

 hills is one of the surest sources of supply for a small well. For do- 

 mestic use and a very little work wun a windmill they are quite cheap 

 and reliable in most seasons, holding out in years of drouth wonder- 

 fully if not too heavily drawn on. But they are of little use for heavy 

 work in irrigation but rather a vexation and a loss. 



It is much the same with wells bored into the hard core of granite 

 below the rotten top. Unless a seam is struck there is no chance for 

 water and when one is found that furnishes good water it cannot be 

 relied on for much beyond domestic use. I know of no artesian wells 

 in hard granite and any attempt to get one would probably fail. Even 

 finding a seam is quite accidental and I have known many to fail to find 

 that. 



The porphory is one of the most difficult formations in which to 

 find irrigating water. And it is none too good for domestic water. 

 It is fissured perpendicularly so much that the water falls through it. 

 Most all attempts that I have known to get a good well in it have 

 failed. I know of none that flow under pressure and have seen holes 

 made in it that were perfectly dry at over one hundred feet. At the 

 same time it is certain that water goes through the ledges of it on 

 which the Sweetwater dam and the old Mission dam at El Cajon are 

 built. And in Lower California on the San Domingo river are several 

 ledges that look solid enough to cut off the underflow, yet there is as 

 much water just below them as above. 



Even worse if possible than the porphory is the ancient wash from 

 the west. There is little hope of getting anything in it more than a 

 fair farm well, unless the boring is carried through it into some old 

 gravel channel beneath. The most solid looking conglomerates, such 

 as that in Orange county and the southern part of Ventura, as on the 

 Simi Rancho, are so fissured up and down that the water can drop 

 through them very readily. And one may often travel miles without 

 finding a single spring where in granite of the same elevation and 

 rainfall springs could be found in almost every gulch. 



