SIERRA CITY AND VICINITY. 



44° 



i 



* 



in the overlying material. From the bottom of the shaft, forty-two feet deep, some sandy matter 

 carrying woody fibre and a lew small rolled pebbles have been taken. Between the shaft and 

 the creek, and along the sides of the canon, there are frequent exposures of granitic rock, which, 

 I was told, dip underneath the volcanic capping, and are regarded as indications of a rim-rock. I 



could not examine these points in detail. 



The mouth of the 1001 tunnel is at the head of a small ravine upon the southeastern slope of 

 Chips's Hill. Its altitude I made to be 5,938 feet, exactly the same as that of the Blue Gravel 

 cabin. Its course is N. 42° W. (magnetic). The tunnel was started at the base of the rolled 

 gravel, the bottom of the tunnel being in a schistose rock. The rock was so much weathered and 

 broken that I could get no satisfactory observations for dip and strike. The tunnel is not driven 

 upon or through a sloping rim-rock; if there is a true channel here, the tunnel follows its bed, or 

 nearly so. At the point where the two branch tunnels were started and the raising of the air- 

 shaft was begun, 335 feet from the mouth of the tunnel, the bed-rock pitches down a little, but 



By lowering the tunnel four feet, the lowest point could be drained. The 

 northeasterly branch lias a length of one hundred feet ; the westerly, of fifty. The main tunnel 

 has been extended to a total length of 500 feet. The air-shaft will be 179 feet deep. The gravel 

 is made up of volcanic and granitic pebbles and boulders, with occasional bunches of micaceous 

 sand and some carbonized wood. In the latter, the original woody structure is unusually well 

 preserved. The boulders are of all sizes, up to six or eight feet through. I saw no quartz pebbles 

 at all, with the possible exception of a, few very small ones. The boulders are usually well 



The air-shaft has been raised forty feet, and without any essential change in the 



— if one exists — 



soon rises again. 



rounded. 



character of the gravel. 



It is evident that the channel 



was formed and Idled 



under quite different conditions from those which prevailed at the time of the formation of the 

 lower channels, which have been previously described. Some coarse gold has been found in 

 this gravel, but I have no information as to its amount. 



The prospecting tunnel at Haskell's Peak, or Mount Haskell, I should have tried to visit, if the 

 weather had been more favorable ; but, as the tunnel was still in bed-rock, not much information 

 of a decisive character could have been expected. In regard to this tunnel I have been informed 

 in a private letter from Dr. Sawyer, under date of March 30, 1880, that, after running through 

 about 450 feet of granite bed-rock, the prospecters have struck the channel. "They found very 

 nice washed gravel, more than half quartz. They are too high, however, and will have to sink 

 down after running in some distance." This points very clearly to the existence of a rim-rock, 

 but our knowledge of the district is so far from complete that it will not be worth while to specu- 

 late upon the probabilities of there being a connection between Mount Haskell and Chips's Hill, or 



the Blue Gravel claim. 



The Gold Lake region, a few miles to the west of Mount Haskell, I had to leave entirely 



unexplored. 



Gravel deposits of more recent origin may be seen at many points along the present canon of 

 the Yuba below Sierra City, certainly as far as Downieville. At Loganville, about three miles 

 below Sierra City, there is a bench of gravel extending for more than a quarter of a mile, nearly 

 parallel with the present stream, and about fifty feet higher. The bed-rock rises rapidly to the 

 south, and is again visible beyond the gravel, upon the steep slope of the canon, three or four 

 hundred feet farther back from the river. At the time of my visit the face of the bank was about 

 seventy feet in height. The gravel is well-rounded, but there is a great quantity of large boulders* 

 some of them as much as twelve or fifteen feet in diameter. The boulders are largely hornblendic, 

 granitic, or porphyritic in character, with but few of quartz. They must have been brought from 

 the higher Sierra, the bed-rock in the vicinity being all slate. 



The grade of the former bed of the l r uba, to which this and similar deposits evidently belong 



r>? 



was considerably less than that of the present stream, for the benches are at higher and higher 

 levels above the river, the farther they are removed from its source. I noticed this fact particularly 

 at Downieville, but did not take any measurements. The cation of the North Yuba River, between 



