ENDLiCH.] GEOLOGY INTEENATIONAL AND OTHER MINES. 299 



hand, it has the benefit that provisions can be kept in the mine for 

 months without deteriorating. Between walls that are well defined the 

 vein is 5 to 6 feet wide, dipping from 12° to 20^* to the north. 



A considerable quantity of ove is taken out of this mine, and trans- 

 ported down the wagon-road by axle. It is mostly galenit€, with spha- 

 lerite, some fahlerz, pyrargyrite, and native silver. From the east a 

 tunnel has been driven in on the vein, about 140 feet in length, and 

 there by overhand and underhand stoping ore is being taken out, while 

 the driving of the tunnel continues. Parallel to this lode, and appar- 

 ently similar to it, is the Belmont, situated a short distance to the north. 



Besides these mining-operations, two great tunnel-enterprises have 

 been undertaken, and are still being carried on. The one is the Mar- 

 shal, the other the Burleigh tunnel, sections of which are given on the 

 accompanying plate. (Plate YII.) The Marshal tunnel, pushed to 

 its present state by the energy of General Marshal of Georgetown, is 

 located on the southern slope of Mount Leavenworth, a short distance 

 below the mines spoken of before. It is driven at a course of north 

 43° west, and has continued in a straight line. The proposition is to 

 drive through Mount Leavenworth, strike all the lodes which it would 

 cut at some angle, and thus let the tunnel serve to facilitate trans- 

 portation of ores and regulation of waters. At the time I visited it, 

 the work had progressed to a distance of 1,147 feet from the mouth, and 

 a careful section was taken. 



At 175 feet from the entrance, the first lode was struck, crossing the 

 tunnel at an angle of about north 69° west. This is the Bulldog, or 

 No. 1 5 contains a small amount of black blende, not sufiiciently rich to 

 yield any pay. Thirty-six feet of loose gangue-rock (6), quartz, and de- 

 composed feldspar follow the narrow vein of ore, and a selvage of clay 

 more than 2 feet in thickness separates this lode from the following 

 gneiss. Arriving at 234 feet from the tunnel, lode l^o. 2 is reached, 

 dipping off to the north, bordered on the north side by porphyritic 

 granite (a), 20 feet in thickness. Following is a long stretch of gran- 

 itic gneiss, with' several slides dipping to the north, the rock being 

 partly decomposed, partly sound. In several instances white mica oc- 

 curs in this gneiss locally, but the black always predominates. Six 

 hundred and ninety-five feet from the mouth of the tunnel, a lode was 

 cut, supposed to be the Equator, and the strike approximately corre- 

 sponded with that of the Equator. Two more veins follow at intervening 

 distances of about 20 feet, edged on the north by granite of 25 feet thick- 

 ness. Vein No. 5 then set in, followed by 8 feet of gray quartzite (d), 

 and then by 22 feet of a light-gray compact porphyry (e), which strikes 

 parallel to its course. After this 73 feet of the granitic gneiss follow, 

 when vein No. 6 is cut, at a distance of 880 feet from the mouth of the 

 tunnel. The north wall of this vein is formed by 46 feet of hard por- 

 phyritic granite (»), identical with that of other localities. From the 

 end of this portion of granite to the present terminus of the tunnel at 

 1,147 feet, the rock remains granitic gneiss, with local accumulations of 

 mica or quartz, changing the character somewhat. Two more veins 

 were found, and 20 feet from the end of the tunnel a third occurs, strik- 

 ing across it. These nine lodes that are thus cut by the tunnel contain 

 more or less blende, more rarely galena, and as far as could be ascer- 

 tained neither fahlerz nor pyrargyrite, as the veins higher up on the 

 mountains do. 



Differing from this is the Burleigh tunnel, situated northwest of 

 Georgetown, at the base of Sherman Mountain, about half a mile east 

 of the Terrible. In June, 1873, it had reached a length of 1,490 feet, a 



