20 



FIELD OPERATIONS OF THE BUREAU OF SOILS, 1903. 



The following- table shows the results of -mechanical analyses of fine 

 earth of this soil type: 



Mechanical analyses of Pecos sand. 



RIVERWASH. 



Riverwash consists of coarse sand, well-rounded gravel, and small 

 bowlders, and varies in depth from a few inches to several feet. It 

 is of small extent and no agricultural value in this" area, occurring only 

 as a few narrow streaks in the mesa lands and in areas of Maricopa 

 sand and Maricopa sandy loam. Poorly defined areas, too small to be 

 shown upon the soil map, frequently occur within the limits of these 

 two soils. 



WATER SUPPLY FOR IRRIGATION. 



The entire water supply for irrigation in this area is taken from 

 the Gila River. Over twenty canals, the most of them small and of a 

 more or less private nature, or else operated in cooperation by those to 

 whom water is supplied, furnish water to the valley lands. These 

 canals are well distributed throughout the entire area. 



The largest and oldest of the canals is the Montezuma, constructed 

 in 1871, covering lands along the southern part of the area surveyed. 

 Some of the other more important S} T stems are the San Jose, Union, 

 Central, Graham, Smithville, Bryce, Oregon, and Fort Thomas canals. 



A considerable part of the water of the Gila River comes from the 

 melting snows in the higher mountains near the headwaters of the main 

 stream and its tributaries. Frequent rains and showers in the higher 

 altitudes supplement this supply. During the late summer the rainy 

 season occurs and the supply is greatly augmented by floods. In gen- 

 eral the water supply of the area has been satisfactory. Excessively 

 dry seasons have occurred at times, during which crops under nearly 

 all the canal s\ T stems have suffered, but usually no continued or wide- 

 spread crop failures have occurred. The extension of the canal sys- 

 tems and the increasing activity in agriculture are, however, beginning 



