14 FIELD OPERATIONS OF THE BUREAU OF SOILS, 1903. 



MARICOPA SAND. 



The Maricopa sand consists of the coarser materials of the secondary 

 deltas. Typically it is a medium coarse-textured, sharp sand, mainly 

 of quartz or feldspar, light gray or whitish in color and 6 feet or more 

 in depth. Near the margin of the soil areas, where it has been washed 

 and blown over the adjacent types, the depth of the soil sometimes 

 becomes less than 6 feet and the texture somewhat finer, approaching 

 that of a sandy loam in character. In the vicinity of the canyon 

 mouths it is often striated with layers of micaceous fine sand or tine 

 sand}^ loam, which gives to the soil the properties of a fine sandy loam. 

 Such areas are, however, local in character. It is here also often cut 

 b} r streaks and beds of coarse, wellworn gravel deposited in flood time 

 b} T the canyon streams. These beds are sometimes cemented by cal- 

 cium carbonate into a hardpan similar to that underlying parts of the 

 Maricopa gravelly loam. 



Gravel is a prominent feature throughout the greater portion of the 

 areas of this type. The particles are usually more or less wcrn and 

 well rounded and consist chiefly of fragments of quartz, feldspar, and 

 granite, although fragments of volcanic rocks are common. As the 

 outer margins of the fans are approached the gravel gradually dis- 

 appears, the soil in its nongravelly phase sometimes covering large 

 areas. 



The Maricopa sand in its typical form occurs as long, narrow areas 

 skirting the valley margins and extending along the base of the slopes 

 of the Maricopa gravelly loam, or as broad, extensive tracts extending 

 into the valle} T from the secondary fans and canyon washes. This type 

 is one of the most extensive of the soils in the area, covering over 25 

 per cent of the total area. The surface is usually level or gently slop- 

 ing. In the vicinity of the canyon mouths it is sometimes cut by 

 channels of small, intermittent streams. Along the upper and middle 

 slopes of the fans, where exposed to the action of strong winds, small 

 dunes and drifts are sometimes formed. These are, however, not 

 extensive and are easily leveled. This soil in its typically loose, porous 

 condition is well drained and at no place is artificial drainage necessary. 



The Maricopa sand is derived from the coarser materials washed 

 from the terrace margins of the Maricopa gravelty loam and the sand 

 of the streams borne from longer distances. These materials have 

 been further modified by wind action and the boundaries of the type 

 are still being shifted and extended b} T the strong winds. 



The alkali salts are present in this soil only in small quantities and 

 need cause no apprehension unless they should accumulate through 

 seepage from higher irrigated land or are brought to the surface by 

 irrigation in the few places where the soil is shallow and underlain by 

 a heavy, alkaline subsoil. 



