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SIERRA CITY AND VICINITY. 443 
in the overlying material. From the bottom of the shaft, forty-two feet deep, some sandy matter 
carrying woody fibre and a few small rolled pebbles have been taken. Between the shaft and 
the creek, and along the sides of the caiion, 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. | 
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 
soon rises again. By lowering the tunnel four feet, the lowest point could be drained. The 
northeasterly branch has 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 voleanic 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 
rounded. The air-shaft has been raised forty feet, and without any essential change in the 
character of the gravel. It is evident that the channel — if one exists — was formed and filled 
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 cafion 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 hornblendie, 
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 Yuba, to which this and similar deposits evidentiy belong, 
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 caion of the North Yuba River, between 
