450 QUICKSILVER DEPOSITS OF THE PACIFIC SLOPE. 



which were leached out from masses uiulerlyiug the granite or from the 

 •granite itself. No one fact or locality absolutely demonstrates whether the 

 metals were originally components of the granite or came from heneath it, 

 but the tendency of the evidence at all points is to show that granite yielded 

 the metals to solvents produced by volcanic agencies, and, when all the 

 evidence is considered together, it is found that this hypothesis explains all 

 the known circumstances very simply, while the su[)position of an infra- 

 granitic origin leads to numerous difficulties. Though no one of tliese may 

 be by itself fatal, when taken as a whole they api^ear to be so. As there 

 is no known direct evidence pointing to an infragranitic origin of the quick- 

 silver and the gold, I consider it tolerably well established that botli were 

 actually derived from the granite. 



I regard many of the gold veins of California as having an origin entirely 

 similar to that of the quicksilver deposits. I also have some reason to sup- 

 po.se that some of the gold deposits were formed by the leacliing of their walls 

 by surface waters. The auriferous area is now under examination, and the 

 investigations on ore deposits described in this volume will be continued and 

 extended in connection with my survey of the gold belt. 



