342 MINING INDUSTET. 



It is fine-grained and has a general resemblance to that found in San Juan 

 Canon, and at the mouth of the South Twin River. A vein of mixed pyrites 

 and galena, carrying some silver, has been prospected in the slates, above the 

 granite, striking w^ith the formation; a mill was commenced at the mouth of 

 the canon to reduce the ore from it. The main ridge of the head of the canon 

 is in the slates, and from here south to near Ophir Canon continues in the 

 slates and limestones, bending across the formation around the head of Summit 

 Canon. 



Clay Canon, the next south of Park Canon, is cut through the granite 

 body, which extends down to its very mouth. 



In Summit Canon the granite no longer comes to the surface. This is a 

 steep, narrow gorge in the quartzite cliffs as high up as the Buckeye mine, 

 where the formation changes ; the canon having a more gentle ascent, opens 

 out into a high mountain valley in the slates and limestones, bending round the 

 quartzite body to the north near its head. The lower part of the canon 

 affords an excellent section of the quartzite body, showing a thickness of over 

 3,000 feet of strata, mainly white, compact quartzite, with occasional intercalated 

 strata of limestone which are metamorphosed into a white crystalline marble- 

 like rock. In one of these, which seems to mark the dividing line between 

 the quartzite and slate series, are the deposits of the Buckeye mine. These 

 strata have a nortji and south strike, and dip at an angle of 45° to the 

 west. In the lower part of the canon they are traversed by a dike 

 about 50 feet wide of a dark, compact rock, having a conchoidal fracture, in 

 parts of which are found large rounded grains of limpid quartz, apparently 

 filling previously formed cavities. 



In Wisconsin Canon, the next south from Summit, the quartzite series is 

 represented only by a few of the white limestone strata, which are found at 

 the mouth of the canon ; these are conformable in dip with those of Summit 

 Canon, but strike to the west of north. The rock from one of these strata is 

 used for making lime. In the canon above the forks, the slates are found dip- 

 ping at a very steep angle, much confused, and highly metamorphosed. Near 

 the forks is a dark-green hornblende schist ; their structure is therefore not 

 easily recognizable, though probably the same in general as that of the next 

 canon south. 



