MOGOLLON SYSTEM — ELEVATION AND STRUCTURE. 165 



pentine of that range, and in the conglomerates of the Calitro and Santa Catarina. Veins of 

 argentiferous lead ore might, if looked for, be found in Ghiricahui, since it exists in the same 

 rock east. 



During the series of elevations which finally uplifted this entire range to its present altitude, 

 the upheaving force must have been exerted even upon the southern portion of the range, 

 raising the table land of northern Sonora and Ghiricahui to so great a height. This strain may 

 have produced a fissure from east to west, or cracked, and perhaps depressed, the strata along 

 parallel 33°, and thus enabled the Gila to take that as its permanent course. Some such catas- 

 trophe must have occurred ; for it is scarcely probable that the river, unaided, could have cut 

 through such lofty hills and hard rock as it appears to have done in its passage through these 

 mountains, running, as it does, at right angles to the strike of the ranges. 



The valley east of the San Francisco river separates the Pinaleno mountains from the western 

 ranges of the Mogollon and Sierra Blanca hills. The table land on which these ranges are 

 placed varies from 3,000 to 4,000 feet, and the summits of the highest hills reach 6,000 and 

 6,400 feet above the sea level. Mount Graham is the loftiest mountain in the entire system. 



MOGOLLON SYSTEM. 



The Mogollon mountains lie north of the Gila river, and east of the San Francisco, one of its 

 tributaries. In this region, by many heads, the Gila rises, and from it it derives five-sixths of 

 its whole volume of water. They are a lofty series of mountain ranges, between 108° and 110° 

 west longitude, and 33° and 35° north latitude, lying north and east of the Pinaleno moun- 

 tains, with which they have been confounded. But the different trend of the ranges show that 

 these two series of mountains are distinct from each other, the dividing line of which upon the 

 Gila is between the rivers San Carlos and San Francisco. The Pinaleno ranges run more 

 north and south, never exceeding N. 45° W, while the Mogollon ranges run more east and 

 west, and have an average trend of N. 65° W. and S. 65° E., or nearly twenty degrees more 

 east and west than the former range.* 



Little of the country embraced within these limits is known to white men ; it is the country 

 of the Gila Apaches, where they have their strongholds and their lands of cultivation. 



The Sierra Blanca range, which lies the most eastward, is very lofty, and, viewed from the 

 north, appears to have an east and west strike. 



The rocks which enter into the composition of this great mass of mountain, are whitish 

 felspar granite, and amphibolic granite, metamorphic quartz, old red sandstone, and, according 

 to Mr. Marcou, magnesian grits of the carboniferous system, magnesian limestone, and trias 

 beds. 



They are a very lofty range of mountains, reaching to an elevation of 10,000 feet in many of 

 their summits. Snow is seen upon these for many months of the year, the meltings of which 

 give rise to the Gila, and form the Salinas, which joins the Gila lower down. 



The snow-capped region, thus yielding water during the summer months, is the cause of the 

 fertility of the mountain vallies in the range, producing fine grass and corn to the Indians. 



The ranges of hills which lie between the Santa Catarina range and Fort Yuma, and round 

 which the Gila travels in its course westward, are of lesser importance than those enumerated. 

 With the exception of the Sierra Estrella west of the Pimas plains, and east of the Jornada, 



" Mr. Marcou, in his geological chart and sketch, (report to the Geological Society of France,) describes the Mogollon 

 mountains as extending from longitude 108° to 114° W., and throughout having a dip of N. 60° W. This is erron&m.'i ; 

 it makes the Mogollon mountains occupy a district much larger than it actually does. 



