I 



424 



SUPPLEMENTARY INVESTIGATIONS IN THE GRAVEL REGION. 



are washed away in the form of clay, leaving scarcely anything else to be seen on the bottom of 

 the mine besides quartz. Masses of quartz as large as a man's head are said to be frequently met 

 with in the fine graVel. The quartz is quite smooth and well rounded. As the original surface of 

 the ground was very irregular and much cut up by ravines, the gravel has not been of uniform 

 thickness. The highest banks at present exposed are between two hundred and two hundred and 

 fifty feet high, and are nearly uniform in character for the whole thickness. On the northwestern 

 side of the mine there are frequent streaks of sand, which do not appear to belong to any well- 

 defined continuous stratum. Where clay streaks occur, they are, as a rule, in the upper portions 

 of the travel, near the original surface of the ground. The gravel in the western bank, near the 

 shaft-house, is noticeably lighter in color than that farther to the east. The lava gravel previously 

 alluded to * is seldom seen excepting near the Sugar Loaf, to the west of which the channel is 

 supposed to cross the ridge. 



In regard to the lithological character of the lower gravel I have no direct information. It has 

 been reached by means of a shaft and drift, as is shown in the diagram (Plate P, Fig. 3). For 

 the details in respect to these underground workings I am indebted to Mr. Jacobs, with whom I 



spent an hour or two at the mine. The first shaft was sunk over the supposed centre of the channel, 

 but reached bed-rock at a depth of only 133 feet. Sinking was continued for seventy feet further, 

 and at that depth a drift was run in a westerly direction with a slight rising grade. For 360 feet 

 this drift was entirely in bed-rock. At the distance of 474 feet from the shaft the first "pay 

 gravel" was struck, and the bed-rock was twelve feet below the drift. The deepest gravel was 

 found fifty-six feet farther west, bed-rock there being nineteen feet below the drift. The drift was 

 continued seventy feet beyond the deepest channel, when it became evident that the western rim 

 was near. The gravel was then only four feet in thickness. The width of the " pay channel " is 

 126 feet, and its working thickness is from six feet or less up to sixteen. The position of this shaft 

 is nearly in the prolongation of the old Hotellen Incline. The true course of the deep channel 

 having been found, it was decided to sink a new shaft, which will soon be completed. Through 

 this shaft the bottom dirt will be hoisted to the surface, where it will, be treated in cement mills to 

 be built at the mine. 



s 



The new shaft is about a third of a mile above the old shaft at the Green Mountain mine,t and 

 at an altitude about eighty-live feet higher, according to Mr. Jacobs's estimate. The difference of 

 level between them by our barometric measurements, one made in 1870 and the other in 1879, is 

 only fifty-eight feet, but these results cannot be regarded as anything more than an approximation, 

 and the agreement with Mr. Jacobs's estimate is as close, as could be expected. 



In regard to the sources and the amount of water used, I did not have time to collect many 

 data. The Gold Run Ditch and Mining Company, which formerly drew eight hundred inches of 

 water from Bear Eiver, now takes water also from the Yuba, and its ditches have a capacity of 

 2,150 inches, but the supply is not constant through the year. Last season, work did not begin 

 in the mines until February, and it continued for only five months. In some years the mining 

 season lasts for eight months. The company has $450,000 represented in ditches, flumes, reser- 

 voirs, and tunnels. 



The water for the Quaker II ill mines is taken from Greenhorn Creek. Washing usually begins 

 in the month of December; it has begun in November only four times in twenty years. When 

 begun, it continues day and night until midsummer or into the month of September. The amount 

 used is 800 inches per day through two 4|- inch nozzles. 



The character of the gold varies to some extent in the different mines and in the different strata 

 of gravel. At Indiana Hill the upper gold is fine and floury or scaly, while that near bed-rock is 

 smooth and rounded. Large nuggets are seldom found, but pieces worth one or two dollars are 

 not uncommon. The mint value of this gold, as Mr. Gould tells me, is $ 18.50 per ounce. 



The Polar Star gold is also coarser on bed-rock than it is in the upper gravel. A handy way of 

 estimating the coarseness of the gold is to determine the value of a pound of amalgam. The Polar 











■ i 





* See ante, p. 180. 



t See ante, p. 180. 





