



SOURCE AND DISTRIBUTION OF THE GOLD. 



355 





surpass all other regions in the world in metallic wealth; for hundreds of 

 years they have been supplying the world with a large part of its silver, and 

 no inconsiderable proportion of its gold. The richness of the Peruvian mines 

 long since became proverbial, and the word " bonanza " is now familiar to all 

 from its association with the mines on the Comstock Lode and others of the 

 Far West. These regions have been the seat of the most intense volcanic 

 activity during Tertiary times, and in all probability in previous geological 

 epochs. It is hardly possible, therefore, in view of all the facts, not to 

 admit that there is likely to be some genetic connection between the mani- 

 festations of igneous forces" and the impregnation of the rocks with the 

 precious metals and metalliferous ores. 



Quite a number of theories relating to the geological epochs at which the 

 various metals have made their appearance, or been introduced into the 

 formations where we now find them, have been put forth by chemists and 

 geologists. Gold has been specially favored in this respect. No theoretical 

 views regarding this metal have been so widely promulgated and generally 

 accepted as those of Murchison. According to this eminent authority, gold 

 in paying quantities is exclusively confined to the Paheozoic rocks, into 

 which, however, it was introduced at a very late geological epoch. It was 

 also a favorite dictum of this geologist that auriferous quartz veins are a, 

 superficial phenomenon, and that mines of this metal would not hold in 

 depth as persistently as those of other metals. The discoveries of the Cali- 

 fornia Survey in regard to the age of the gold-bearing formations of that 

 State have entirely refuted the (until 1864) generally accepted theory of the 

 exclusively Palaeozoic age of rocks of this kind, although this fact was not 

 admitted by Murchison in his latest publications. # The great depth to 

 which some gold mines have been wrought, with profit, both in California 

 and Australia, in connection with many other facts observed in various parts 

 of the world, justifies us in asserting that auriferous quartz veins are as per- 

 sistent, on the average, as those worked for the other metals. That the 

 impregnation of the rock with gold took place at a comparatively recent 

 geological epoch, at least in certain prominent and important mining regions, 

 cannot be denied. These are regions of former intense volcanic activity, and 

 the period to which that belongs is unquestionably Tertiary. In regard to 

 mining districts where gold and other metals and metalliferous ores have 

 been found in considerable quantity, and where there have been no striking 









* See mite, p. 34 ; also Siluria, ltli Edition (1867), p. 469. 



