FKOM VALLE DEL SAUZ TO MOUTH OF RIO SAN PEDRO. 23 



is somewhat broken, and the slopes of the opposite sides meet, forming broad and smooth, 

 summits. That selected is about four and one-half miles south of the Sugar Loaf, and has an 

 altitude above the basin bottom on the east of 391.3 feet, and above the bottom of the Valle 

 del Sauz of 712.5 feet. The approaches to this summit are of such a character as to permit a 

 decrease of gradients by an increase of distance. 



SECTION 3. 



Second Division. — From Valle del Sauz to mouth of Bio San Pedro. — The Valle del Sauz 

 and valley of the San Pedro are tributary valleys of the G-ila, whose axes are nearly parallel, 

 and distant about fifty-five miles. They embrace an interior plain and valley district which 

 is separated from the two bounding valleys by divides, whose peaks and ridges are as lofty 

 and imposing as the passes are inviting and easy of transit. This division affords a striking 

 illustration of the parallelism of the ridges of this interior region, and their bearings upon 

 the directions of the valleys and their drainage. The Yalle del Sauz trends off to the northwest, 

 a broad and open valley, receiving in its course the valley of the G-ila as it opens out 

 from the northeast, playing rather the part of tributary than main valley, since it imme- 

 diately assumes the direction of the Valle del Sauz, and preserves it for about sixty miles. 

 Here the Gila again changes its course to the southwest, and, piercing the Pinaleiio mountains, 

 opens from a rugged caiion into the valley of the San Pedro, and trends off twenty-one miles in 

 the direction of its axis, where, encountering another and the last obstacle, it again runs to the 

 west and enters a canon leading through to a jDlain, affording a free flow to the Colorado of 

 California. The western limit of the Valle del Sauz is made up of two mountain masses — 

 Mounts Graham and Chiricahui — the grandest and most imposing yet encountered, whose axes 

 topographically form a continuous line, with an intervening gap or break of about eight miles, 

 lying directly in our course westward. That on the north of this gap. Mount Graham, looms 

 up, solid and massive, with an apparently continuous outline, trending off to the northwestward 

 until lost below the horizon. This continuous range is called Pinaleiio mountains. 



The Chiricahui on the south is not so compact, but broken into radiating ridges and spurs, 

 whose crests are serrated and pinnacled, rendering the mass easily distinguishable at great 

 distances. Near the northern end of this mountain two of these pinnacles stand conspicuously 

 above the profile of the surrounding height, and, from their great uniformity in fio-ure and 

 dimension, are called the Dos Cabezas (Two Heads.) These mountains rise abruptly from the 

 slopes of the surrounding valleys, and are generally rugged, bare, and destitute of timber, a 

 small growth of dwarfish oak, wild cherry, ash, and walnut, (black,) and cedars, being found in 

 the valleys and caiions. On the right bank of the San Pedro trends off a ridge or chain of 

 ridges, which, by their interlocking, form an apparently continuous divide between the San 

 Pedro valley and the interior plain district, of the Playa de los Pimas. This chain, the 

 Calitro* mountains, although secondary to the one preceding, in point of elevation and extent 

 nevertheless plays a conspicuous part in the physical geography of the narrow belt or zone of 

 our continent contiguous to the thirty-second parallel route, it being the western limit of the 

 great central plateau which extends eastward to the sources of .the Colorado of Texas, 

 embracing an area of about ten degrees of longitude, where the mean elevation does not exceed 

 5,000 feet. 



The area embraced by these two mountain chains, is made up of two distinct features, basin 



" This name was ohtained from the oldest inhabitants of Tuczon, and is, probably, a corruption of calizo, (lime,) there 

 being an abundance of this material there. — A. H. C. 



