^-:- 



THE DIVIDE BETWEEN SLATE AND CA^ON CREEKS. 



457 



main stream from Rowland Flat, for, between the ravine and the crest of the ridge, gravel has 

 been found, and drift mining has been carried on at several places. I cannot speak of this branch 

 channel from personal observation, but it seems to have taken its rise somewhere near Table Rock. 

 The St. Louis travel, between Cedar Grove Ravine and Sackett's Gulch, has been worked to a 

 considerable extent by the hydraulic process, particularly at the northern and the southern ends 

 of the field. The central portion, where the town stands, has hardly been touched. The gravel is 

 favorably situated for mining, but the process of washing will go on at a slow rate, unless the 

 available quantity of water be in some way increased. The altitude of the bed-rock at the lower 

 end of the mines, near Cedar Grove Ravine, is 4,993 feet. 



Between Sackett's Gulch and Harris Gulch the town of Chandlerville used to stand, but there 

 are no houses there now, and the gravel deposit is exhausted. Pine Grove also was once one of 

 the principal mining towns of this vicinity J but since its destruction by fire it has never been 

 rebuilt. It is at this place that the most of the Slate Creek water is at present used. Mr. G. W. 

 Cox, of the Sears Union Company, says that in the busy season the supply of water amounts to 

 three or four thousand inches. The altitude of Mr. Cox's business office I made to be 5,486 feet, 

 and that of the bed-rock in the Pine Groves mines, about midway of the present opening, 5,396 

 feet. The gravel in these mines has been disturbed in several ways since it was first deposited. 

 Just back of Pine Grove there is a small sugar-loaf knoll of volcanic material, standing by itself, 

 quite detached from the main volcanic capping at Table Rock. Whether this represents an ancient 

 slide from the higher ridge or not cannot be told with certainty, but there is evidence that there 

 has been a flow of lava or mud to cut away a part of the original gravel. There is also a so-called 

 " horse " of similar material on the old rim of the channel, on the side opposite to the Sugar Loaf. 

 The section (Plate S, Fig. 4) is not drawn to scale, but shows the relations of the gravel and lava 

 as I sketched them roughly on the spot. I have Mr. Cox's authority for saying that the presence of 

 gravel under the ©astern body of lava has been proved by drifting. In this connection I will add 

 that I was told by Mr. Wallis, the superintendent of the Bald Mountain Company at Forest City, 

 of a mass of lava at Pine Grove, " like a bell upside down," which covered gravel under its rim on 

 all sides without there being any bed-rock discoverable under the apex of the bell, even though 

 tunnels were driven in and shafts sunk. I did not make the acquaintance of Mr. Wallis until 

 after I had left this part of the country, and could not return for any revision of my work. An- 

 other interesting occurrence at Pine Grove is that of gravel in thin seams, two or three inches 

 wide, in bed-rock. The quartz fragments which this gravel contains are angular. 



Above Pine Grove the old channel is traceable through Howland Flat to Potosi, though its 

 precise winding course cannot be shown upon any published map. A detailed topographical map 

 on a laro-e scale is needed. Howland Flat is not quite a mile from Pine Grove, and Potosi is about 

 half a mile to the cast of Howland Flat. The altitude of the lower floor of Becker's Hotel, at the 

 latter place I made to be 5,600 feet, and that of the mouth of the Bonanza tunnel, at Potosi, 5,655 

 feet. There are everywhere signs of former mining activity. At Howland Flat there have been 

 both hydraulic and drift mines. The banks now exposed to view to the north and west of the 

 town are small and low, and do not appear to have been worked very recently. The drift mines 

 at Potosi have been developed pretty extensively. Tunnels have been driven in a northeasterly 

 direction in the hope of finding the continuation of the old channel under Alturas Mountain, and 

 other tunnels like the new Bonanza, have been made to follow a more easterly or southeasterly 

 course on the hypothesis that the channel came across the ridge near where the low gap now is 

 between Table Rock and Alturas. To go through all the mines and collect data for a satisfactory 

 independent judgment would require several days' time. The Bonanza tunnel was the only one I 

 was able to visit though I could easily have obtained access to others. This tunnel follows a 

 course N. 83° W E. (magnetic) for 1,547 feet, and then S. 65° 5V E. (magnetic) for 2,289 feet 

 farther rising in the whole distance, twenty feet. The tunnel was started in volcanic material, 

 the probable position of the gravel being pretty well known from the developments in the adjoin- 

 ing claim, the Empire. The successive rock formations met with in the tunnel are as follows : 













