THE GEAVEL: NEAR GRASS VALLEY AND NEVADA CITY. 



181 



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top of the Green Mountain shaft, and bearing N. 78° W. (magnetic) from it, is another shaft, in 

 which bed-rock rising to the west was found at a depth of only forty feet. This seems almost 

 conclusive as to the position of the west rim of the channel at this point. The course of the chan- 

 nel being pretty nearly south, it will be seen that it crosses the present Green Mountain Canon 

 at a rather acute angle. From near the mouth of Gas Canon, which joins Green Mountain 

 Canon a quarter of a mile from Greenhorn, the left bank of Green Mountain Canon is bed-rock f tu- 

 ft distance of six or eight hundred feet, while on the right (west) bank the gravel is seen in or 

 near the canon, and crosses Gas Canon quite near its mouth. On the right bank of Gas Canon 

 near its junction with Green Mountain Canon is the Empire Mine and Mill. On the opposite 

 side are Eisner's Diggings. At the Empire Mill there is a tunnel, on a course S. 40° W. (mag- 

 netic), which was started in bed-rock, and which, for 400 feet, had bed-rock for its bottom, though 

 the top was usually in gravel. The grade of the tunnel was " water grade," — say one fourth of an 

 inch to twelve feet. At the end of the tunnel the bed-rock was still pitching slightly in a westerly 

 direction. Higher up Gas Canon, above the boarding-house, there is high bed-rock again, so that 



the eastern and western limits of the channel can be established with a tolerable degree of approxi- 

 mation. 



The country between the Empire Mill and Red Dog I did not visit at all. I will only add that, 

 taking our altitude determinations as approximately correct, there is a fall of about fifty feet be- 

 tween the Empire Mill and Bunker Hill bed-rock ; which gives a very convenient grade, the 

 distance being only a little over a mile. At the Gouge-Eye Mine, which lies between these two 

 places, we determined an intermediate value for the altitude of the bed-rock. The course of the 

 channel, then, may bo taken as pretty well established from Quaker Hill southward. 



There was another small extent of country around the heads of Green Mountain Canon and Gas 

 Canon, which I wished to explore for the sake of finding high gravel or overflows, if any existed, 

 out was obliged to leave that part of the work unfinished. 



§ 4. Grass Valley and Nevada City. 



The next group of hydraulic mines to be described comprehends those 

 S1 tuated on both sides of Deer Creek, in the neighborhood of Grass Valley 

 and Nevada, City. A reference to the map will show that extensive lava 

 Wows have made their way from the higher portions of the Sierra far down 

 toward the foot-hills on both sides of Deer Creek. The flow which hi 



course 



already been described as forming the high and conspicuous ridge known as 

 ■Aount Oro, on the upper waters of the Greenhorn, seems to be connected 



"With the gravel deposits at Quaker Hill, being there interrupted for a dis- 

 ance of somewhat less than a mile, but again resuming its regular 



and continuing, not southwardly parallel with the present Greenhorn, but in 



w nat may be called the normal southwesterly direction of the Sierra slope, 

 nis flow forks again just beyond Banner Mountain, one portion continuing 



southwest, and soon terminating at a point three miles east of Grass Valley. 



r °m this termination a mass of gravel of considerable area extends off to 

 \ 1 

 le west, nearly reaching the last-mentioned town. On this area are the 



° Wn -Talk mines; and there are also shallow patches of gravel, south of 

 th ese, and between those mines and Osborn Hill. 





