180 



THE AURIFEROUS GRAVELS OF THE SIERRA NEVADA. 



bed-rock below the present level of the gravel, — the last twenty feet of the sinking having been in 

 i: blue cement, good and solid." At a point about four hundred feet to the east of this shaft there 

 was bed-rock ten feet higher than the top of the shaft and pitching rapidly to the west. There 

 was no drifting at the bottom of that shaft, but the bed-rock was still pitching rapidly to the west. 

 This circumstance in itself, however, has but little weight, for the shaft might have struck upon the 



edge of some hole in the bed of the stream. 



Prior Ravine has its head in the volcanic rock of the west gap of Quaker Hill and flows in a 

 general S. 33° E. (magnetic) direction for about a mile to Greenhorn. In this ravine, I under- 

 stand, there has been no northerly rim of slate-rock found. The bottom of the ravine itself, where 

 it crosses the mines, is still in gravel \ and the depth to bed-rock is not known. I am inclined to 

 think, however, that the depth will not prove to be very great. On the western side of the Rail- 

 road Mine the bank of gravel is nearly or quite 150 feet high. The bottom of the gravel as ex- 

 posed is a bluish cement for about thirty feet. And nowhere else in this district, at Red Dog, or 

 You Bet, has there been a much greater depth than thirty feet of blue cement found at the bot- 

 tom. I have no observation for altitude at this point, nor indeed at any other in the neighbor- 

 hood. Owing to the storm and other unfavorable circumstances I made no use of the barometer. 

 In July, however, Mr. Bowman took a few observations, of which I can make some use here. The 

 altitude of the blacksmith's shop in the Railroad Mine he makes to be 2,974 feet j but whether that 

 was near the bottom of the mine or not I do not know. 



The main mass of the gravel in the Rail 



The length of the 



road Mine is fine and of a reddish or grayish color. In both the red and the blue gravel there is 

 also considerable clay and sand. Charred wood is also plenty. One peculiarity of this gravel 

 deposit is the presence of a large number of rather angular volcanic pebbles and boulders (up to a 

 foot or more in diameter) found thickly distributed in the upper eight or ten feet only, indicating 

 that a portion of this channel was filled after the main flow of lava. It is possible, however, that 

 we shall have to seek no farther than the west gap of Quaker Hill for the origin of these particular 

 pebbles, and that they were brought down by the waters of the original Prior Ravine. 



About an eighth of a mile below the lower outlet of the Railroad Mine slate-rock is seen on 

 both sides of Prior Ravine. On the left (east) bank there was an overflow of gravel upon the 

 bed-rock to a point a little farther south than on the right bank. On the right bank of the ravine, 

 not far from the outlet of the Railroad Mine, I was shown the top of " Hoteliers Incline." This 

 was meant to be sunk on the bed-rock, which was here pitching to the west, 

 incline is 600 feet, and it has a fall of one foot in ten. It followed pretty nearly the line of the 

 rim for some distance and was then run through gravel until it struck the bed-rock, or western 

 rim, rising on the opposite side of the channel. This fact is much depended upon by the advo- 

 cates of the theory of a deep north and south " blue lead/' as showing the presence of a deep 

 channel, with an unmistakably north and south direction. It needs but a glance at the map, 

 however, to sec that the present Greenhorn, which had been following a nearly southwest course 

 for some distance, bends to the south, not far from Quaker Hill, and flows in that direction for 

 nearly two miles. It is not strange that a similar curve should be made by the old stream if, as I 

 have supposed, the ancient and recent drainages are essentially the same. 



West of Prior Ravine is the Green Mountain Canon, the ridge between having the general 



course S. 30° E. (magnetic) ; though half a mile distant from Greenhorn the general course of 



Green Mountain Canon is S. 57° E. (magnetic). The ridge between the two ravines terminates in 



a prominent hill of slate rock. To the west of Green Mountain Canon there is slate rock at an 



altitude of 3,009 feet, which would be sufficient to turn the channel to the south. In Green 



Erom the bottom of 



I find the altitude 



Mountain Canon there is a shaft sunk about 130 feet in gravel to bed-rock. 

 the shaft there has been drifting, mainly in a direction a little west of south, 

 of the mouth of the shaft at the Green Mountain Mine to be 2,810 feet, from which 130 is to be 

 taken to give us the altitude of the bed-rock, viz. 2,680 feet. My informant could not say posi- 

 tively as to the depth of the shaft, and so this result is not to be taken as the most accurate deter- 

 mination possible. Higher up the same canon, probably between forty and fifty feet above the 



