12 



FIELD OPERATIONS OF THE BUREAU OF SOILS, 1903. 



material has been distributed and modified by mountain torrents and 

 floods. Subsequent wind action has in places also modified the deposits. 



Small quantities of gypsum sometimes occur in this soil. Some of 

 the heavier subsoils and the adjacent rocks are strongly impregnated 

 with sodium chloride, which, through percolating waters, gives rise to 

 the salt springs already mentioned. Sulphates are also of common 

 occurrence. 



The Maricopa gravelly loam lies entirely above the valley bottom 

 and beyond the reach of the irrigating systems. It is therefore at 

 present of no agricultural value except for grazing. The vegetation 

 consists of a growth of cacti, small flowering annuals, yucca, and other 

 plants of the desert. 



Should water be brought upon these lands the} T could, with the 

 exception of the broken and excessively gravelly areas, be made- to 

 produce all the general farm crops of this region. Fruit should do 

 well upon this soil, and the slight elevation should make damage from 

 frost less likely than in the valley lands. The irrigation of any portion 

 of these lands (barring the possibility of artesian irrigation) is out of 

 the question without the construction of extensive storage reservoirs. 



The results of a mechanical analysis of the fine earth'of this soil are 

 given in the following table: 



Mechanical analysis of Maricopa (jmrrlhj loam. 



GILA FINE SANDY LOAM. 



The Gila fine sandy loam is a mellow sandy loam 6 feet or more in 

 depth, of dark color and fine sand}- or silty texture. The coarser 

 sands of adjoining t} T pes are sometimes mingled with this finer sedi- 

 ment, but this occurs only to a slight extent. Jn lower areas lying 

 close to the course of the Gila River it is sometimes less than 6 feet 

 in depth, and is underlain by river sand and gravel. Gravel is of rare 

 occurrence upon the surface. 



This soil occurs in long, narrow bands lying near the course of the 

 Gila River and extending throughout the entire valley. It occupies 

 the intermediate position between the Pecos sand and the soil of the 

 higher valley slopes. Small bodies less uniform in texture sometimes 

 occur at the base of the terraces forming the valle} 7 borders, or extend 



