Doc. No. 9.] 6? 



ations in which they were individually interested, and which in nearly 

 every case was caused by inadequacy of means and mismanagement of 

 their operations, is no criterion whereby to form an opinion that would 

 be just or reasonable, with reference to these metallic veins, and those in 

 this country who would still propagate those opinions, do so in the face 

 of every evidence to the contrary which reason or sober judgment would 

 demand or can be found in this or any other country. 



With these preliminary remarks on the general impressions at home 

 and abroad, respecting their theoretic value, founded as they are on pre 

 sumption rather than evidence, we shall proceed to consider the geolog 

 ical position which the quartz veins of this State hold to the rocks with 

 which .they are found in connection, hoping thereby to elucidate more 

 clearly their present as well as prospective value. 



QUAKTZ VEINS AND THEIR RELATIVE AGES IN CALI 

 FORNIA. 



The quartz veins of this State are" found distributed in nearly parallel 

 lines throughout the west flank of the Sierra Nevada, and consist of 

 three distinct lines separated by intervals ranging from four to eleven 

 miles ; as these divisions are found in nature they constitute what may 

 be denominated the principal or main ranges. Between these are to be' 

 found smaller lines of these rocks at times running parallel with the 

 former, at others having strikes more or less oblique^ and even at right 

 angles in some instances with, the principal veins. 



From the peculiar distribution of these rocks, as. relates to their con 

 nection and position with the formations in which they are found, it 

 would be difficult to refer them all to the same age ; this would be man 

 ifest only by observing the different sections in which they occur. They 

 will therefore be designated, in this report as the Older and Recent groups, 

 in order to better describe the peculiarities that may be found in both, 

 and with reference also to the age of the rocks which they have been the 

 apparent cause of disturbing. 



OLDER GROUP. 



The eastern and also a part of what may be termed the central line 

 of dikSs are included under this head. This group is found to have in 

 truded itself through the primitive formations only, or through the tra- 

 pean rocks which immediately succeed the primitive. The principal 

 rocks which appear to have suffered the greatest amount of local dis 

 turbance and .dislocation from these quartz veins, have been the granite 

 serpentine and the earlier trapean rocks, which appear to under-lie both 

 the former. The veins or dikes that occur in the primitive series are 

 usually much more massive than those of a later period, and are not 

 distributed over so wide an area, or possess so great a number of lateral 

 veins, or cross-courses incident to the more recent group of these rocks. 



The mineral characteristics of the Older Group are more uniform 

 and regular so far as known, and are found to possess a firmness of 



