674 



IDAHO MINING DISTRICTS. 



ceases. Across Ophir Creek the bed rock rises rapidly in all direc- 

 tions, and no possible continuation can be suggested except down the 

 narrow canyon of Ophir Creek. Furthermore, the nature of the peb- 

 bles indicates that the stream came from some point to the northwest, 

 whereas the present grade of the bed rock is in exactly the opposite 

 direction. The conclusion is almost unavoidable that the channel 

 has been cut off by a fault and its grade reversed. 



On the point between Wolf Creek and Boyles Gulch a little of the 

 same compact gravel occurs just at the edge of the tailings. Placer- 

 ville appears to be built on a similar compact gravel, in which narrow 

 benches were cut by the present stream, though just below the town 

 granite bed rock appears at the edge of the tailings. Due southwest 

 of Placerville, on the slope up to the summit of the level ridge between 

 Granite and Wolf Creek, no bed rock appears to have been found. 

 Neither has there been any bed rock found on the opposite slope from 

 this ridge down to Granite Creek. A broad, low bench fringes the 

 northeast side of Granite Creek below Granite. Bed rock has never 

 been found for some distance below Granite in the creek. All this 



appears to indicate 



I 



12 feef, Granite Sand 



8 feeh, C/ay 

 reef', Coarse Gravel 



FIG. 61. Bank at the Ranch Company's claim, Placerville. 



that the Ranch 

 Company's channel 

 continues with grad- 

 ually sinkin'g bed 

 rock across Granite 

 Creek. 



Interesting c o n - 

 ditions also obtain 

 across Granite Creek 

 on the broad flood plain of Fall Creek, where it emerges from the nar- 

 row canyon in the Boise Ridge, here suddenly rising as a steep escarp- 

 ment facing west. This place, called Norwegian Flat, at present 

 worked by the Kennedy Company, is extensively covered with rich 

 bench gravels up to the mouth of the canyon. This bench gravel, which 

 is rarely over 25 feet in thickness, does not rest on granite, but on a 

 harder, more compact gravel, which contains some gold and which is 

 of the same general character as the Ranch Company's gravel. At 

 the upper end of the claim, near the mouth of the canyon and the foot 

 of the escarpment, this "false bed rock" is found to suddenly abut 

 against the granite, strongly suggesting that it is cut off by a fault. 

 No shafts have ever been sunk in this lower gravel. It is probable 

 that it is the same channel continuing across Granite Creek, and that 

 it is cut off at both ends by faulting. On the hills to the right and 

 left of Fall Creek a similar compact gravel also occurs, seemingly con- 

 tinuous with that of the deepest chanuel. Thus the low ridge between 

 Fall and Canyon creeks is covered, up to an elevation of 80 feet above 

 Fall Creek at the upper end of Kennedy's claim, and a similar body 



