CHAPTER IV. 



MII^ES. 



The accompanying map was kindly prepared by Mr. Wilson, to serve 

 as an illustration for Bulletin No. 3, second series 1875. By means of 

 lines running in different directions the geology of the region given has 

 been represented, and an explanation thereof will be found below the title 

 of the map. All the volcanic area, which has been treated of at some 

 length in chapter II of this report, has been left blank. 



A number of the lodes visited during the summer of 1874 have been 

 indicated by heavy straight lines. Starting from the southeast corner 

 of the map, near station 17, it will be observed that the metamorphics 

 extend over from the quartzite mountains toward the volcanic area. 

 They are mainly schistose at that locality, containing a great deal of (luartz 

 and some micaor chlorite. At several points their junction with the over- 

 lying trachyte can be seen ; for instance, at the narrow ridge running south- 

 ward, about four miles east of the Animas. Although the connection 

 has been broken by overflowing trach^tic materials, the metamorphics 

 extend over into Cunningham Gulch, \v];ere they crop out. They form 

 the great canon of the Animas, below Silverton, that for a long time 

 was considered inaccessible both for man and beast. Another outcrop 

 of the same kind of rocks is found to the northwest of Handie's Peak 

 (station 14), where granite forms the lower portions of the caiion lead- 

 ing down in a northerly direction from the mountain. The oldest sedi- 

 mentary strata that are found within the area given by this map are 

 the Carboniferous. Ked sandstone, belonging to the upper group of this 

 formation, occurs first about one and a half miles west of the Animas, 

 unconformably underlying the trachyte that flowed from the north. 

 From there it continues west and northwestward, and is exposed on 

 Bear Creek. A blue limestone is found covering it at one point north- 

 east of station 31. Cretaceous covers a considerable area in the west- 

 ern portion of the map. No. 1 is found in the deeper canons, while the 

 marshy or grassy soil along the San Miguel is composed of No. 2. On 

 the banks of the Dolores and a few of its tributaries No. 1 crops out, 

 overlying the red Carboniferous sandstone, while it is covered in turn 

 by volcanic rocks. 



At the time of my visit at the San Juan mines, August and Septem- 

 ber, 1874, but comparatively little work had been done. The greater 

 portion of the miners' time and energy was devoted to prospecting, and 

 but a few had then developed their lodes to any extent. One difficulty 

 under which they labored was the want of available capital, and of a 

 place where the ore might readily be converted into cash. It would be 

 impossible to give any fair estimate of the number of men scattered 

 over the country there, but I think that usually given is too high. 



Mining is carried on at several points in the vicinity, and on tribu- 

 taries of the Animas Eiver. Near its head, at the so-called " Forks," is 

 a complex of lodes (one of the early discoveries), and from it the locality 

 has received the name of " Mineral Point." Traveling down the river for 

 a distance of about six miles, Eureka Gulch is reached, another locality 



229 



