WHAT IS MEANT BY THE CHANNEL. 



75 



that surface is what would be naturally expected from well-known condi- 

 tions ; the much heavier metal must be ever tending, as the accumulations 

 of detritus are being swept onward in their course towards what would be 

 their final resting-place, if they were carried for enough, namely, the surface 

 of the bed-rock. These deeper regions where the miners expect to find the 

 gravel richest, and which, when connected together, must evidently approxi- 

 mately mark the course of the former current or river, are always called the 

 " channel." Whenever the miner is looking for some place rich enough 

 to make it worth while to commence washing for gold as a permanent oper- 

 ation, he will say that he is "looking for the channel." Not that the richest 

 places are always the lowest, or that the gold is limited in its range exclu- 

 sively to the vicinity of the bed-rock surface ; but, as a general rule, these 

 are the conditions with which the miner expects to meet. The position of 

 the channel, therefore, and its direction in any mining district, become a 





matter of great importance. It is with reference to these circumstances that 

 all exploratory work must be laid out. The miner runs his drift — or tunnel, 

 as a horizontal excavation is universally called on the Pacific coast — with a 

 view to striking the channel, guided by what he knows, or thinks he knows, 

 of its probable position, from a study of the results of adjacent mining opera- 

 tions; if in an unprospected region, he must in drawing his conclusions be 

 guided by the form of the surface, or other circumstances which his previous 

 experience has shown him to be of most value as a guide in prospecting. 

 Everything, then, connected with the form, size, direction, and variations in 

 character of the « channel/ ' or the bed-rock frame which holds the gravel, 

 is a- matter of importance to the miner, and not less so to the geologist in 

 search of the facts necessary as a basis for his theories. If we knew the 

 exact position of the lowest surface of all the detrital masses in the Sierra, 

 we could then reconstruct the ancient system of drainage with accuracy ; 

 hut, of course, as but a very small portion of these ancient channels has 

 been, or ever will be, revealed by mining operations, and as much that is 

 laid open will never be examined and recorded while accessible, we can 

 never expect to know exactly what were the relations of all parts of the old 

 river system to each other. This will be evident enough when the facts 

 presented in the following pages come to be examined. 



If the channels of ancient rivers exist in the mining region of the Sierra, 

 and at a, high level above the present streams, there must be, in places at 

 least, more or less of the sides or banks of these channels still in existence. 



