150 



THE AURIFEROUS GRAVELS OF THE SIERRA NEVADA. 



From that point on the rise is more rapid for a short distance, — perhaps 100 feet, — -so that the 

 sluice is entirely in blue gravel, and then the blue pitches off suddenly and disappears. Com- 

 mencing at the bottom of the present bank, then, the order of deposit in this claim is, first, the 

 blue gravel and then a fine red gravel, above which is a coarser streak of about sixty feet in thick- 

 ness in which the pebbles are mostly angular and unwashed. Mr. Kelsey says this streak can be 

 traced across the Dutch Flat Canon to the upper part of Thompson's Hill, and is remarkable for 

 containing a noticeable quantity of copper. 1 had no opportunity of testing the correctness of this 

 latter statement for myself, but have full confidence in Mr. Kelsey's honesty in making it. This 

 cupreous streak is not wide, — -only about 100 or 125 feet. It looks as if it lay lengthwise in a 

 stream, and gives additional reason for thinking that a current once ran in a southerly direction 

 at this point. Above the cupreous streak there lies about twenty-five feet more of red gravel. 



A short distance beyond the point where the blue gravel disappears there are sandy deposits 

 dipping at angles varying from ten to twenty degrees (mostly about twelve degrees) to the south 

 and west of south. There are also extensive deposits, in alternating layers, of soft yellow and 

 blue clay, the blue being made up largely of bark of trees and other unmistakable vegetable mat- 

 ter. These beds of clay dip to the south, or nearly south, at a considerable angle, as much as 10° 

 or 15° on the average. These different clays are not, moreover, in all cases superposed quietly one 

 upon the other. In one or two instances it seems as if a pipe of blue clay had managed to effect a 

 connection through the yellow clay between two otherwise distinct blue beds. A similar phenome- 

 non was also observed at the lino between red and blue gravel. It looks as if a stream of blue color- 

 ing matter had made its way up through some open channel and soaked into the red until it was 

 completely absorbed. The effect on the face of the red gravel was as if some blue gerrymander- 

 like figures had been drawn there. I looked at this phenomenon pretty closely. The line be- 

 tween the red and blue was always distinct and well defined ; there was no shading off of tint. 

 In many cases, if a pebble as large as a man's fist was in the line of division, one half of it would 

 be red and the other half blue, showing that the cause of the coloring is to be sought for in some 

 agency acting after the gravel had been deposited. 



The boundary line of the blue gravel presents also another peculiarity in this claim. At a point 

 a few hundred feet from the canon Mr. Kelsey has a shaft sunk forty-five feet in a red sandy mate- 

 rial without striking any blue gravel at all ; but twenty feet to the west of the shaft blue gravel 

 sets in and rises abruptly. It is seen at the top of the shaft, but was not met with below within 

 the distance of forty-five feet. 



The yellow clays in this mine abound also in little nodules of rather irregular shape, but still 

 so uniform as to have given the impression that they are " fossil oysters." There is indeed a cer- 

 tain resemblance to small oysters, and the nodules are all found lying on their flat sides in the 

 clay. "When broken open the central portion is, in almost every instance, a black powder differing 

 entirely in appearance from anything else found in the neighborhood. I saved a few specimens in 

 the hope of being able to determine the character of the interior black powder at some future time. 

 Up to the date of this writing, however, nothing has been done about it. I, am hardly of the 

 opinion that these nodules had any organic origin, still the fact of their all lying upon the flat side 



is rather striking. 



Some cause undoubtedly acted at this point of the gravel deposit to introduce irregularities which 

 are rare or less marked at other localities near by. The dipping of the line between the blue 

 and the red gravel in opposite directions, the deposits of vegetable mould, the coarse streak with 

 angular pebbles, all taken in connection with the form of the bed-rock as indicated in the three, 

 old. shafts near the outlet of the Jehoshaphat Claim, seem to corroborate to some extent the idea 

 previously advanced that at some time in the history of the old river there was a sudden change in 

 the direction of the current ; that it perhaps found itself choked up, and then broke through or 

 over some small divide and continued its way in quite a different direction. As has been before 

 remarked, there is evidence of a channel's having also once gone from Dutch Flat to Little York, 



and if there ever was any such change of channel as I have supposed, the Jehoshaphat Claim is 



