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University of California Publications. 



[Geology 



the north, in the concavity caused by the bending of the ' ' vein ' ' 

 to the east at the north end. This northeastward swing causes 

 the secondary opening to become nearly parallel to the Sierra 

 Nevada fork, as shown diagrammatically in figure 2. The thick- 



ness of the ore body within this opening increases with depth up 

 to the present time of working, and some very rich ore is being 

 extracted. Exact distances and figures cannot be given, on account 

 of the methods of mining now in vogue. The "vein" has been, 

 and is, productive up to the 1800 level of the C. & C. mine and 

 down to the 2250 level now being worked. The ore is not evenly 

 distributed, but is in more or less well-defined chimneys or 

 shoots, connected by material of too low grade to be worked. The 

 form of this secondary vein, then, is a nearly vertical fissure 

 about parallel to the main lode and east of it. In portions of this 

 vein, particularly where opened best in stoping, a dip to the east 

 is present. 



The lode at the surface shows an arrangement of vein filling 

 and ore in every way due to the same causes which produced the 



