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FOREST CITY AND VICINITY. 



435 



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where the volcanic capping has also been worn away far enough to make the application of the. 

 hydraulic process pro ii table. The greater part of the yield of gold has been obtained by drifting. 

 In my description I will begin at the southern end and advance towards the north. 



Minnesota lies upon the northern slope of the canon of the Middle Yuba, nearly opposite Snow 

 Point or Orleans Flat. The town was built originally upon the exposed gravel. Hydraulic oper- 

 ations were confined to the eastern side of the spur, where the bed-rock has been uncovered over 

 an area of about seven hundred by one hundred and fifty feet. The altitude of this bed-rock I 

 made to be 4,220 feet. From my point of observation the whole of the southern slope of the 

 canon, from far above Snow Point to Woolsey Flat, was distinctly in view. According to the 

 hand-level, I was nearly as high as the top of the pipe-clay at Snow Point, and considerably higher 

 than the bed-rock at Orleans Flat. The altitude of the Snow Point bed-rock, as determined earlier 

 in the season, is 4,211 feet. The difference of level, therefore, between Minnesota and Snow Point, 

 as determined by the barometer, is not quite as much as it should be ; but as all my determinations 

 of the altitudes of points to the north of the Middle Yuba are affected by the possible error in the 

 estimated altitude of Oroville, it will be seen that the agreement is as close as any one could have 

 a right to expect. It can safely be asserted that the old channel, while keeping its average grade, 

 could easily have made connection with the channel to the south, at some point between Snow 

 Point and Orleans Flat. Seen from Minnesota, the bank at Snow Point looks like a mass of 

 clay, such as might have been deposited in some broad bay. The gravel banks at Minnesota are 

 scarcely more than twenty feet in height. The material is, for the most part, a line quartz, 

 mixed with large white quartz boulders of from eight to ten feet in diameter. Siliciiied wood is 

 very abundant, and there is a thick iron-cement on the bed-rock. Hydraulic mining was never 

 carried on very systematically at this point. Each small claim of sixty feet front, extending back 

 to the centre of the ridge, was worked by itself as far as it could be in this way, and then drifting 

 had to be resorted to. The town of Centreville, of which not even the ruins are now left, lay a 

 quarter of a mile to the west of Minnesota. Between the two places there was high bed-rock, 

 which, however, did not rise to the upper surface of the grave 1 !. A tunnel in gravel was formerly 

 driven through the main ridge, connecting Centreville with Chips's Flat, and it is now utilized as 

 an aid to ventilation by the Mammoth Company at Chips's. 



Above Minnesota, on the ridge between the Yuba, and Wolf Creek, there are said to be a few 

 unimportant banks of gravel, which probably have some connection with the deposits of American 

 and Bunker hills, which will be described on a, subsequent page. 



Upon the southern slope of the canon of Kanaka Creek the principal mining town has been 

 Chips's Flat, Balsam Flat is between a quarter and a half mile to the northeast of Chips's, and at 

 a little higher level. At Oak Flat, farther down the creek, there is also said to be a, deposit of 

 gravel. I did not go to either of the two places last mentioned. At McNulty's mine, at Chips's 

 Mat, the gravel lias been washed away over an area of three or four acres. The face of the present 

 high bank exposes next the bed-rock a stratum of six or eight feel of coarse white and bluish 

 quartz, with quartz boulders of from three to five feet in diameter; this stratum is followed by 

 about forty feet of line gravel, upon which lies a thin stratum of a ferruginous cement. Above 

 this there is a stratum of sandy and gravelly clay, thirty or forty feet in thickness, which reaches 

 to the red dirt or volcanic capping. Siliciiied wood is common. There are also in the gravel of 

 this mine some extraordinary masses of rock, known by the name of "grizzlies." They are like 

 rough, unwashed boulders in appearance, and are sometimes as much as sixty feet in length by 

 thirty in width or thickness. They are found at varying heights above the bed-rock. One of 

 the largest of them has its opposite surfaces nearly parallel, and looks like a block from a mineral 

 vein. The structure and mineral character of the grizzlies strengthen the belief that they are really 

 fragments of vein-stone. Where they came from it is difficult to say, but quartz lodes are quite 

 frequent in the vicinity, one in particular, the Rainbow, lying just to the west of the mine. The 

 proximity of this lode may also account for the auriferous quartz boulders which are met with near 

 the bed-rock. 



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