300 RESUME AND THEORETICAL DISCUSSION. 
wandering miner. The position of the large, nearly isolated patches of 
gravel which occur in the Coast Ranges it seems not easy to account for. 
The probability is strong, however, that the localities where such masses 
exist were situated at the mouths of large streams, which drained consider- 
able areas of the land forming the uplifted masses along the edge of the 
ocean. The material which is accumulated near Sufol Valley, for instance, 
must almost certainly have been brought down by fluviatile agencies from 
the great area of metamorphic rocks lying to the south, where the Monte 
Diable Range is from thirty to forty miles in width. That these Coast Range 
gravels are not sufficiently auriferous to pay for working, it is not difficult 
to understand. The rocks themselves, out of which this detritus was formed, 
have not been mineralized in their present position. They may have come 
originally from the Sierra Nevada, which, as it seems reasonable to believe, 
was the source of much the larger portion of the material out of which the 
Coast Ranges have been built. But it is not certain that the impregnation 
of the Sierra rocks with gold had already taken place at the time when the 
Coast Range material was eroded from them; and this is a point which will 
be discussed somewhat further on. If, however, such impregnation had al- 
ready occurred before the beginning of this erosion, it is still altogether prob- 
able that much the larger part of the gold which the abraded material might 
have contained would have been deposited before it had reached an area so 
distant from the place from which it started. Be this as it may, it is certain 
that the Coast Range formations have not been independently mineralized 
with the precious metals since their deposition. They are destitute of pro- 
ductive quartz veins, and contain among the valuable ores of the metals only 
those of quicksilver in sufficient quantity to pay for working.* 
The distribution of the detrital formations in the Sierra Nevada is well 
indicated by the character and extent of the mining operations, which are at - 
the present time, or have been formerly carried on. ‘The geological struc- 
ture, the topography, and the climatalogical peculiarities of different parts of 
the State are all reflected in the development of the mining interests. 
In order to apprehend clearly the distribution of the detrital formations 
along the western slope of the Sierra, the nature of the different kinds of 
mining operations in use in California must be borne in mind, and may again 
be briefly noticed.t We have to distinguish, first: ver, bar and gulch nuning, 
* Chromic iron is also considerably abundant in the Coast Range rocks, and may at some future time be worked 
with profit. 
t See ante, pp. 65, 66, and 74-78. 
