294 ANNUAL OF SCIENTIFIC DISCOVERY. 



south of the Cosumes was in a state of disturbance produced by a most 

 energetic action of internal forces, which have brought to the surface 

 lava, tufa, &c. These volcanic masses do not seem to have been pro- 

 duced during the era in which the intrusive rocks between the American 

 and Feather Rivers were formed. Still further north, volcanic action 

 continued also to a later period, as well as further southeasterly. On 

 the Stanislaus, vast developments of basalt are reported to exist. 

 Near the Mokelemy River there is evidence to sho\v that the sedi- 

 mentary rocks have been uplifted 2,000 feet at least since their forma- 

 tion, which is certainly not anterior to the eocene period. North of 

 the country between the Russian River and the Laguna, lofty vol- 

 canic peaks are said to exist along the coast range. Southwest of San 

 Francisco, the mountains also attain a considerable altitude, and fur- 

 nish ample testimony of volcanic action. This region contains the 

 mines of cinnabar ; also ores of silver and copper. Many of the re- 

 ports of the existence of cinnabar in California owe their foundation 

 to the occurrence of rocks colored red by peroxide of iron. Lead ore 

 occurs north of Sonoma. The gold-bearing slate rocks, which are the 

 prevailing rocks upon the flanks of the Sierra Nevada, extend north- 

 wardly into Oregon, \vhere it may also be expected that gold will be 

 found. Circumstances favorable to the occurrence of gold exist in 

 that Territory. These may be briefly stated to be the existence of 

 veins of quartz in slates, in the vicinity of, or penetrated by, rocks of 

 igneous origin. 



In regard to the extensive distribution of gold in California, some 

 writers have attributed it to volcanic action. For this belief, Mr. 

 Tyson remarks, there is not the slightest foundation. Gold abounds, 

 it is true, among the detritus of slate valleys near the volcanic region 

 of the Mokelemy River ; but it is not mixed with any of the volcanic 

 products of the vicinity. In the extensive auriferous region along the 

 Yuba, for a distance of 70 miles, there is a total absence of all vol- 

 canic products. Gold occurs in other countries under precisely the 

 same circumstances as it exists in California. On the Atlantic slope 

 of the United States, it was first discovered in Georgia (where there 

 are no volcanoes) among transported stony matter in ravines, and sub- 

 sequently traced to the vein in slate, in which it is known to exist as 

 far north as Maryland. Larger pieces of gold have been found in North 

 Carolina than have yet been actually seen in California ; but whether 

 the smaller amount produced is owing to the destruction of a less 

 amount of rock and its included veins, or whether the metalliferous 

 veins are fewer in number and less rich than those in California, we 

 have no means of determining. Mr. Tyson is of the opinion, that the 

 whole extent of the Sierra Nevada has on its western flank metallifer- 

 ous veins, in a belt of country varying in width from 30 to 40 miles, 

 at least in that portion between the Yuba and the Stanislaus. The 

 mountains of the coast range contain, perhaps, several metalliferous 

 regions, separated from each other. 



Calculating from the amount of gold sent out from California, and 

 from the number of persons engaged in mining, Mr. Tyson conclu- 

 sively shows, that the average yield per day to each person engaged 



