294 GEOLOGICAL SUKVEY OF THE TEERITOKIES. 



as if selected for the beauty of the spot more than for the metal riches 

 surrounding it. Unlike Central, the mines are not located within and 

 all around the townj the mountains have not been deprived of their tim- 

 ber, have not had every stone on their slopes overturned in the search 

 for treasures ; nothing reminding too strongly of civilization has marred 

 the natural harmonj^ of this secluded valley. Steep, rocky slopes of the 

 mountains, with deep-cut ravines, set off to advantage the peaceful ap- 

 pearance of the town they surround. 



Two branches of South Ol'ear Creek unite a little below Georgetown, 

 and it is on the sides of the caiions that they have formed that the greater 

 portion of the principal silver-lodea are found. A number of veins have 

 been claimed, and temporarily worked, east of Georgetown, on the north- 

 ern slope of Bald Mountain and several others, but little progress had 

 been made there. 



The main rock of that locality is a granitic gneiss, a curious mixture' 

 of the two, at times shading into each other very gradually, at times 

 showing an abrupt line of junction. Slides and local faults have dis- 

 turbed it to a considerable extent ; noteworthy it is, however, that the 

 lodes have been affected thereby but very little. Local contortions have 

 taken place in the schistose gneiss, which appears as such in a great 

 many places, but within it can be found masses of greater or less dimen- 

 sions that would be regarded as granite. Characteristic of that forma- 

 tion may be regarded the almost entire absence of mica in those gran- 

 itoid portions, while the gneiss is very abundantly supplied with it. 

 Besides this granitic gneiss, a typical granite occurs in these mountains,, 

 which I have become accustomed to associate withihe appearance of the 

 main lodes. It is of a brownish-gray to light-brown color, rising up in 

 steep bluffs parallel to the trend of the mountains on their slopes- 

 and sometimes crests. Harder and more compact than the surrounding 

 material, it has better resisted the destroying agents of atmospheric influ- 

 ences. Frequently the line of demarkation between the granitic gneiss, 

 which I am inclined to regard as older, is sharp and well defined for 

 some distance, while at other points the two gradually change, one 

 into the other, similar to the fusing together of two differently-colored 

 glass rods in high temperature. In several instances, bands of white 

 and yellowish quartzite accompany the junction, or local accumulations 

 of mica alter the rock into a mica-schist near those places, while the 

 feldspar is then represented but very sparingly, quartz more abun- 

 dantly. Black mica is a prominent constituent of this granite that 

 belongs to the porphyritic varieties ; oligoclase, quartz, and orthoclase 

 making up the rest. At the time of my visit, early in June, almost all 

 the mountain-tops were still covered with several feet of snow, so that 

 examinations regarding the horizontal extent of this granite could not 

 be made so carefully and comprehensively as I might have wished it, 

 although more time would have been required than I could spare. One 

 of the most typical points of exposure is to be found on Brown Mountain, 

 at the Terrible lode, where this material rises considerably above the 

 granitic gneiss, presenting a long line of steep, smooth surface toward 

 the caiion. Going farther westward, the granite seems to partake more 

 of its normal character, until that of Mount McOlellan, about nine miles 

 from Georgetown, cannot be identified with the one just mentioned. So 

 large is the number of varieties presented by the granitoid rocks of this 

 region that local observations of this kind can give but a very poor 

 conception of the great changes- that take place and repeat themselves- 

 within comparatively limited areas. I will, therefore, take the liberty of 



