54 



THE AURIFEROUS GRAVELS OF THE SIERRA NEVADA 



Lakes, as well as in many other parts of the world where the formations, 

 being hard and crystalline, are not easily ground to a fine powder, and where 

 other necessary conditions — partly climatological and partly geological 

 have prevailed. Some hints as to the nature of these conditions may be 

 found in a subsequent chapter. The chief interest of the gravels of the 

 Sierra Nevada depends, it must be admitted, on the fact that they are aurif- 

 erous : were a large portion of the gravels of New England sufficiently rich 

 in o-old to render it possible that at any point there might be obtained a 

 sufficient quantity of the precious metal to pay a handsome profit to the 

 miner it will be readily understood that everything relating to the mode of 

 occurrence and the distribution of these detrital deposits would be of the 

 greatest interest, while the face of the country would, over a great part of 

 the surface, bear the traces of the most extensive mining operations, as does 

 now the western slope of the Sierra Nevada. 



The gravels of the California range, however important they may be from 

 the economical point of view, present also facts of the greatest geological 

 interest. The phenomena revealed by the many years of mining work upon 

 these deposits are peculiar, almost unique. Most remarkable is it, that these 

 peculiarities are repeated in a manner which almost amounts to identity, in 



an antipodal region, 



Australia. But there are differences, of a curious 



kind, between the Californian and the Australian gravel deposits, and these 

 will be pointed out farther on. At present we will proceed to describe what 

 is to be seen in California. 



* 



Gravel deposits of considerable magnitude are not limited, even on the 

 Pacific slope, to the Sierra Nevada. As already mentioned (pages 19, 22, 23), 

 there are quite extensive gravel beds in the Coast Ranges. They have even, 

 in one district (page 19), been worked to some extent for gold. Generally, 

 however, they are not auriferous, at least not sufficiently so to encourage 

 working. Neither have these Coast Range gravel deposits those peculiar 

 features which make the Sierra gravels so interesting. The manner in which 

 they have been accumulated would, it is true, form an interesting object of 

 geological inquiry, and this problem will, at some future time, no doubt, be 

 taken up; and some hints in this direction may perhaps be given in the 

 course of the succeeding chapters. There are also gravel beds of consider- 

 able magnitude in the extreme southern and northern portions of the State 

 of California, which are more or less auriferous, but in regard to which we 

 have little or no definite information. The gravels in the canons of the San 





