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THE AURIFEROUS GRAVELS OF THE SIERRA NEVADA. 



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entire width of the real channel may be as much as 200 or 300 feet, as indications of a rim-rock are 

 seen on each side, indicating about those dimensions. At Hornby's Tunnel, near Deadwood, the 

 width of the channel averages forty feet, and the bed-rock rises high on each side. 



At Weske's Claim, near Michigan Bluff, the rich channel has been followed lor 600 to 700 feet, 

 running in a direction nearly N. 45° W. (magnetic), with an average width of about sixty feet, 

 and in places as much as eighty. A. Bowen's Tunnel, near Michigan Bluff, has developed a chan- 

 nel having a width of from twenty-live to thirty-live feet, with a high rim-rock on both sides, the 

 direction of the channel being N. 68° W. (magnetic). The direction of the flow appears to have 

 been southeasterly, as indicated by the position of the fossil trees, and the occurrence of richer 

 patches of gold-bearing gravel under the lee of some of the boulders. 



At Forest Hill the channel is very wide and deep ; and the appearances are on such a grand 

 scale, that it is desirable to give quite full particulars in regard to the workings at that locality. 

 As an indication of the importance of this channel, it may be mentioned that between the southern 

 edge of the Bath District and Todd's Valley, there are twenty-five extensive tunnel and hydraulic 

 claims, along the north side of the Middle Fork of the American River. 



At the New Jersey Claim the tunnel starts in on the bed-rock, and runs in a direction of 

 N. 43° W. (magnetic), for a distance of 1,100 feet; it then forks, and one branch keeps on for 

 about 500 feet farther in the same direction, while the other one turns and runs nearly west for 

 about 400 feet, to the head of a slope going down into the " back channel," with a grade of twenty- 

 seven inches to the rod. This back channel is very wide, and appears to run from northeast to 

 southwest. In the New Jersey Mine it has never been worked, although prospected by the above- 

 mentioned incline, which has gone down for a distance of 900 feet on the slope of the southeastern 

 rim without reaching the bottom of the channel, the vertical depth attained in the incline being 

 forty feet below the level of the tunnel, which is itself thirty feet or more below the level of the 

 rim' on the southeastern side of the channel. Nowhere in this vicinity has the rising slope of the 

 other side, or northwestern rim, of the channel been seen. If the slope on the northwest side is as 

 long and gentle as that on the southeast, the channel must be not less than 3,000 feet wide, and it 

 is passible that it is considerably more. Immediately back of the highest southeast rim, where the 

 general slope of the rock is northwesterly towards the bottom of the great "back channel," there 

 are in the New Jersey Mine some five or six small channels or troughs, which are nearly parallel 

 with each other, hut at right angles with the great main or back channel, seeming to run down 

 towards its bed. It is from these that the gold has been taken ; and there lias been obtained, 

 mostly from a strip of ground 800 feet long and about 330 feet wide, not far from a million and a 

 half of dollars, the bed-rock between these little channels themselves being everywhere found 

 highly productive 



bed-rock gradually rises for a distance of about 900 feet from the front in to the southeastern edge 

 of the rim of the back channel, whence it begins to fall off, and more rapidly, towards the north- 

 west. An attempt was made to get to the bottom of the channel from the Devil's Canon, on the 

 northwest side. A slope was sunk down to the bed-rock, which it reached at a point ninety feet 

 vertically below the level of the main tunnel, and at the bottom of this slope the rock was found 

 to be still pitching to the northwest, and even more steeply than in the tunnel. From the foot of 

 this slope a counter-slope was sunk, following down the bed-rock for a distance of 300 feet, and 

 attaining an additional depth of thirty-five or forty feet, when the work had to be suspended 

 in consequence of the machinery not being sufficiently powerful to keep clown the water. The 

 travel is said to have been very rich, but extremely hard. It will be seen from the figures given 



These front channels are usually but a few feet deep. As a general tiling the 



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above that the foot of this counter-slope was 155 or 160 feet below the top of the southeastern rim 

 of the channel. From all that could be gathered at the New Jersey Mine, it appeared that the 

 inner slope of the southeastern rim of the back channel had been prospected for a distance of 

 1,900 feet, so that the probable width of the channel is 4,000 feet, while it may be over a mile. 



In Second Brushy Canon, about a quarter of a mile below " Young America," a tunnel has been 

 driven some 1,500 or 1,600 feet, in a direction a little east of south, and the bed-rock found hero 



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