

SIERRA CITY AND VICINITY. 



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slope, unless possibly some of the granite was rock in place. Boulders of granite and of volcanic 

 rock were abundant. Granite bed-rock is also to be seen near the Blue Gravel claim on the eastern 

 side of Milton Creek, a tributary which joins the southern branch already mentioned about four 

 miles above Sierra City. Upon Chips's Hill, which is the name given to the high point a couple 

 of miles to the east of Sierra City, between the northern and the southern branches of the main 

 stream, the relations of the bed-rock are not easy to make out. I saw schistose or slaty rock on 

 the northwestern slope of the hill, and at the mouth of the 1001 tunnel, which is at the head of 

 a ravine on the southeastern slope. The rock at an intermediate point is called porodite by Mr. 

 Wadsworth, who has examined it microscopically. 



The crests of the principal ridges and high points above and about Sierra City (I cannot speak 

 positively about the Buttes) are, covered with rock of volcanic origin, but it is not always clear that 

 it was brought into its present position by volcanic agencies alone. Upon the granite near the 

 Blue Gravel claim I saw distinct signs of glacial action. No report of much value can be made 

 upon this portion of the volcanic capping without a prolonged study in the field. There is no 

 good map to refer to, and the country is not an easy one to explore. The canons are deep ; the 

 ridges are difficult of access ; trails are very infrequent ; there are no permanent settlements at 

 the higher altitudes, and but few even temporary mining camps. One stage-road leads across 

 the ridge from Sierra City to Sierraville, passing through the Yuba Gap at an altitude of about 

 6,625 feet, or 2,450 feet above Sierra City. To make a satisfactory geological survey of this region 

 an explorer ought to go provided with camp outfit and all the instruments ordinarily used in a 



topographical reconnaissance. 



The volcanic capping of the ridge between the Middle and the North Yuba rivers is in all prob- 

 ability continuous from Forest City upwards as far as Milton Creek; and it is possible that it is 

 also unbroken alono- the narrow ridge in which this creek takes its rise. To the east and north- 

 east of the creek the ridge which forms the divide between the creek and the main stream (the 

 two streams here following nearly parallel directions) is capped with lava. Farther north, upon 

 the northern slope of the principal eanon above Sierra City, there appears to be a succession of 

 bed-rock spurs, rising higher and higher towards the head of the stream, the whole capped with a 

 volcanic deposit, of which one of the lower extremities is to be seen at Chips's Hill. Still farther 

 north, beyond the line of the stage-road, the Mount Haskell ridge is said to be covered with the 

 same kind of materia,!, but I am not able to speak from personal observation. My own examina- 



tions were confined to Chips's Hill, and the ridge northeast of Milton Creek, and the trails leading 



to them from Sierra City. 



Upon the trail to Chips's Hill I saw a great number of small and large boulders, porphyritic 

 with feldspar or hornblende, or with both. Their weathered surfaces in particular attracted my 

 attention. The highest portions of the hill, however, are free from boulders of this character. I 

 saw none at any higher altitude than 5,800 feet, nearly a thousand feet below the crest of the hill 

 as it rises above the 1001 tunnel. The top of the hill and ridge is said to be capped with hard 

 and compact lava, but I saw nothing of the kind, though I climbed to within two hundred feet of 

 the top, where the snow lay so deep as to make any farther ascent useless. The whole surface 

 was covered with large masses of rock, apparently of volcanic origin. Some of these masses seemed 

 to be quite different from the other rock in the vicinity, and it is not unlikely that they were 

 brought into their present position through the agency of ice. 



Upon my trip to the Blue Gravel claim I was accompanied and guided by Dr. J. J. Sawyer, of 

 Sierra City. Our trail led us up the southern branch of the river to the mouth of Milton Creek, 

 thence along the creek in a southeasterly direction, and finally up the steep slope on the northeast 

 or right bank of the creek. Along the river trail there was no bed-rock to be seen, but there was 

 an abundance of granitic and porphyritic boulders, similar to those seen on Chips's Hill. After 

 entering the valley of Milton Creek we saw no more boulders of this character, which shows that 

 their origin must be looked for more to the east or northeast. The bed-rock, which rises to great 

 heights both to the east and the west, is very hard, compact, and dark-blue in color. About a 







