84 ROUTE NEAR THE THIRTY-SECOND PARALLEL. 



From the Rio Mimbrcs to the Rio San Pedro, 152.5 miles. 



Intermediate is Valle de Sauz, 72 miles, where water is always found; 25 miles furl her 

 on, is a sprint; in the Puerto del Dado. 



From the San Pedro to Tuczon, 53 miles. 



From Tuczon to the Gila, 79 miles. 



There are springs between some of these points which it is not necessary to particularize. 



For the working of a railroad after construction, the greatest even of these distances, 152.5 

 miles, is not too great to be overcorre by special arrangements. But for the working parties 

 engaged in building the road, supplies of water must be had at every few miles. Fortunately, 

 the formation of these basins is such as to afford, at comparatively small cost, sufficient supplies 

 of water at distances convenient for the construction of the ro;id. During certain portions of the 

 year, the bottoms of some of these basins are converted into lakes, which may be drained into 

 tanks. 



The following description of these basins by Dr. C. C. Parry, geologist upon the Mexican 

 boundary survey, shows that artesian wells, of no great depth, c;m be resorted to successfully: 



&quot; All the so-called mesa formations and jornadas* of this district belong to a distinct system 

 of basin deposites, tertiary, or post-tertiary, in age, and still showing in outlines of greater or 

 less extent the original areas in which these depositions were made. These basins exhibit, 

 quite uniformly, central depressions, and margins gently rising to the limit of the mountain bound 

 aries. The l mesa, or table-land character, is exhibited only along the line of river-valleys, as 

 high bluffs, the result of denuding forces subsequent to the original basin depositions. 



&quot;These deposites are characterized, as a whole, by a great preponderance of porous mate 

 rials, consisting of gravel, sands, marls, and clays. 



&quot;The natural supplies of fresh water for these open wastes are derived from uncertain accu 

 mulations of rain products in small reservoirs, or occasional permanent springs, the latter gen 

 erally occupying situations in close proximity to mountain ranges. 



&quot;All these basins not directly connected with the Rio Grande valley receive and absorb the 

 drainage of their respective mountain boundaries, except in the higher elevations, rarel} 7 showing 

 running water, unless as the temporary result of local rains. 



&quot;The above indications are favorable to the formation of aqueous substrata, which may be 

 reached by sufficiently deep boring, and when located at the lower depressions of these basin 

 areas, the water would necessarily be brought to the surface.&quot; 



Nearly all the rain that falls upon the scattered mountains probably passes underneath the 

 surface before reaching the foot-slopes, since the coarse angular debris of the moun ains extend 

 high up thfir sides, permitting the water to percolate through and descend into the permeable strata. 



It will be noticed that nearly all the mountain stieams and drains sink before reaching the 

 plains, and others sink on the plains when they reach a porous soil. Where a deep vertical cut 

 has been made in the strata, as, for instance, in the valleys of large rivers, they reappear, 

 running under the permeable and above the impermeable strata. From these facts and consid 

 erations it appears that this country, at times almost destitute of water on its surface, has sub 

 terranean ponds, and streams, at no great depth below, which can be made to furnish water at 

 the surface, in some instances by artesian wells, and in others by ordinary wells. 



This opinion is confirmed by that of Mr. Blake, geologist of the party commanded by Lieutenant 

 Williamson, whose description of the series of small basins lying in the Great Basin applies strictly 

 to those under consideration. The formations are identical. Mr. Blake has detected the existence 

 of regularly stratified tertiary formations in these basins, in which the success of artesian wells 

 is certain. This question Will, however, be satisfactorily solved by boring, as the economy of 

 construction is involved to some degree by the facilities of finding water sufficient for working 

 par ies during the construction of the road. 



