242 GEOLOGY OF THE BLACK HILLS. 



depth of the shaft, and the pay dirt and gravel from off the bed-rock tested 

 by washing a number of pans and comparing the results. Scales of mica 

 largely composed the lighter gravels and white quartz, and slightly water- 

 worn garnet crystals were found in the more clayey layers. The pay streak 

 was not on bed-rock, but nearly 6 feet above it, in the first compact layer 

 of gravel. 



Finding a number of prospecting pits in the vicinity, which had been 

 sunk by a party of miners from French Creek, I had the pay dirt from 

 these holes tested, and obtained results similar to the above. Encountering 

 the miners, they informed me that they had experienced great difficulty in 

 reaching bed-rock on account of water, and that nothing had been found by 

 them up to that time better than the deposits in Custer's Gulch. Spring 

 Creek at this point was 8 feet wide and 6 inches deep, with a moderate cur- 

 rent, probably at this time (June 25) affording 250 to 300 miner's inches 

 of water. The placer gravels of this portion of the Spring Creek district 

 may be classed as elevated bars and gulch deposits. The elevated bars are 

 bank of quartz-gravel, occupying flat points and rocky benches at the 

 bends of the creek from 10 to 40 feet above the present channel, and 

 formed by the stream when ages ago, it flowed at that level through the 

 valley. 



The gulch deposits cover the bottom flats of the valleys along every 

 branch where there is flowing water, and are much more extensive in area 

 than the higher bars, and include gravel-deposits resting on bed-rock near 

 the present water-level, old channels of the stream, filled with gravel and 

 soil, winding through the flats, and the more recent placers occupying the 

 present bed of the creek. 



The result of prospecting on this branch of Spring Creek seemed to 

 show a general diffusion of gold in nearly paying quantities through quite 

 extensive gravel deposits, which in many respects resemble the bars in 

 Custer's Gulch. The water-supply was, however, considerably greater, and 

 the grade or descent of the valley sufficient to enable the deposits to be 

 worked with much less expenditure of time or labor, so that, were the de- 

 posits of equal richness, they would be more valuable here than on French 

 Creek.. These head branches were, however, only partially prospected up 



