GEOLOGICAL SUEVEY OF THE TEREITORIES. 171 



quartz porphyries, or elvanite, which passed into felstone, or petrosilex. 

 In some places there appeared to be a dike running- through the granite. 

 The elvauite I found of two varieties, one having a gray-coiored matrix 

 with feklspar crystals of a pink tinge, and the other having a red matrix 

 with white crystals disseminated through it. The petrosilex, or felstone, 

 was of various shades, blue, gray, yellow, and red, predominating. The 

 yellow variety has a specific gravity of 2.01 ; the blue, 2.53 ; and the gray, 

 2.72. These rocks seem to pass into gneiss, which itself at some distance, 

 becomes granitoid, thus proving them to be of the same composition as 

 granite, only in a more compact state, having been forced through the 

 granite and therefore of later origin. 



We camped in the evening of the 2d of July on Black-Tail Deer Creek. 

 Leaving here the following morning, the first i)art of our course led us 

 up over hills that were once the bottom of some large lake. Beaching 

 the top, a grand view burst on our sight. We stood on the rim of a 

 vast amphitheater. At its bottom, far beneath us, was a green line 

 marking the course of a stream, one of the branches of the Stinking 

 Water Eiver. The rounded hills converged toward the stream, while 

 here and there, on their sides, were projecting strata of white Pliocene 

 sandstones, contrasting well with the grassy slopes. On the top, even 

 underneath our feet, was a capping of black basaltic rock, which on some 

 sides projected over the edge. So regular was it that it seemed as 

 though it had been laid with mathematical accuracy. The background 

 completing this picture was composed of sharp peaks and hills, with a 

 blue, snowy range in the extreme distance. We now began to descend, 

 proceeding down the canon, which is named the DeviFs Pathway. Our 

 road led us between masses of gneissic and granitoid rocks. Here again 

 we found dikes of elvanite, quartz-porphyries, and felstones, some of 

 beautiful colors, red, blue, gray, and violet. I obtained a striped or 

 slaty i>orphyry, looking very much like riband jasper. 



Emerging from the rocky walls we pitched our tents on the bank of 

 the Passamaria, or Stinking Water Kiver. The next day we again 

 passed over modern formations in an old lake basin until within some 

 ten miles of Virginia City, when we came across quartzose rocks mostly 

 auri fero us. H ere we found the first evidences of minin g. i^Tear the road 

 {I man by name David Lloyd was industriously washing out the gravel 

 fi'om the side of a foot-hill. He informed me that he was averaging 

 about $3 per day. 



Passing between quartzose and gneissic hills containing veins of gar- 

 netiferous hornblende schist we soon began to ascend, and crossing the 

 hills, passed through Nevada, a small mining tovni below Virginia City. 

 All about us were the evidences of mining in the heaps of bare pebbles, 

 numerous water-courses, and upturned barrows. It being the anniver- 

 sary of our national inde[)endence, all were idle save a few Chinamen. 



Virginia City is situated in Madison County, in the southern part of 

 Montana, and is one of the chief mining centers of the Territory. It is 

 on Alder Gulch, one of the tributaries of the Stinking Water, or Passa- 

 maria Iviver. The mines about Virginia City are princii)ally placer-dig- 

 gings. Gold was discovered on Alder Gulch in 1803, being the second 

 discovery in the Territory ; the placer-diggings of Bannack liaving been 

 discovered in 1SG2. Since that time enormous quantities of gold have 

 been taken out, althoiigli it is impossible to say exactly how much, as 

 the estimates are conliicting. 



Alder Gulch is about sixteen miles long, and has a number of tribu- 

 taries, all of which contain gold. Bald Mountain stands at the head of 

 the gulch, l^ear it the gold is coarse, and the farther we go frou) it 



