STRUCTURE OF CHIRICAHUI RANGE — PUERTO. 149 



The order of the strata on the western slope of the Chiricahui, along the trail, was — 



Granite, felspathic. 



Serpentine, auriferous. 



Hornblendic black slate. 



Quartz, ferruginous and drusic. 



Jaspery conglomerate, (exposed,) 90 feet. 



Sandstone, with cleavage lines, 60 feet. 



Limestone, compact and metamorphosed, TOO feet. 

 As has been stated already, it is difficult to give the estimate of the jasper conglomerate with 

 any approximation to truth, as it is not fully exposed. The serpentine is in thin beds, and the 

 black slate is not more than fifty feet thick. The ferruginous quartz is rather an altered or 

 metamorphic sandstone ; an interval of 500 feet at least here separates the limestone from the 

 primary rock, and it is i^robable that, though not observed at the mouth of the San Francisco 

 river, this intervention exists there also. 



It may be remarked of the limestone strata which were encountered on the slope of the 

 Calitro range dipping eastward, that they showed themselves there for the first time, that rock 

 not having been observed on the eastern slope of the Sierra Nevada, nor at any of tire small 

 ranges on the desert or up the Gila. At Goat hills, and a few other points, the conglomerate is 

 the only rock exposed which should not be confounded with the sandstones and conglomerates 

 below the limestone ; lithologically dissimilar, they are also of very different ages. 



"PUERTO DEL DADO." 



The pass through the Chiricahui, so called, is a narrow, winding trail ; it opens up into 

 small valleys of unusual fertility, enclosed by mountain walls. There are no secondary rocks 

 in the Puerto. The whole mountain is a mass of primary rock, of which a reddish felspar 

 granite^ mostly of a coarse character, forms the chief part ; veins and dykes of porphyry felspar 

 cut through this and reach the summit, and, from its being of a finer texture and less acted on 

 by the weather, form those turretted summits which, visible from a great distance, and situated 

 upon the apex of the hill, constitute what are called the Dos Cahezos. These cabezos are 

 repeated in several places along the crest wherever the porphyry dyke happens to be produced, 

 but those which are known as such are on the most prominent point of the mountain. At the 

 western entrance of the caiion several quartz veins running north and south cross the trail, one 

 of these being 40 feet in width ; accompanying these is a blue quartzose chalcedonic rock. In 

 the granitic rock the felspar crystals are large, distinct, and reddish, and everywhere through 

 these smaller, as well as the larger hills, felspar dykes, rising at an angle of 60° from the east, 

 cut their way and form the angular crests. 



The whole mass of the mountain is more felspathic than granitic — thus, felspathic rock; rock 

 felspar crystals, in a felspar paste ; felspar rock amorphous ; felspar rock, with rhomboidal 

 cleavage ; porphyritic felspar, i. e., quartz and felspar — a rare rock ; quartz veins, both ferru- 

 ginous and vitreous, which usually run at a right angle to the felspar dyke, whose general 

 direction is N. 60° E. Such is the constitution of the whole mass of the Chiricahui, from the 

 entrance to the exit of the caiion, a breadth of nearly ten miles. 



Dykes of augite, in some places 15 feet in width, cut through the felspar rock in the creek bed 

 on the east slope of the Puerto, and thin beds of serpentine are found occurring on this as well 

 as on the western entrance of the Puerto. 



Although properly considered as one mountain mass, elevated synchronously, yet, in crossing 



