24 FIELD OPERATIONS OF THE BUREAU OF SOILS, 1^17, 



The silty phase is better adapted to farming than the typical Mc- 

 Clellan loam and practically all of it is cultivated, being devoted to 

 alfalfa, grain, and the sorghums. 



m'clei.lan clay loam. 



The McClellan clay loam consists of a brown, rather smooth, 

 sticky, compact clay loam, relatively high in silt from 3 to 12 inches 

 deep. The soil is somewhat darker than the soils of the Mohave 

 series and the red color is much less pronounced, though a reddish 

 or purplish brown tint is noticeable in most of the ai'eas. The con- 

 tent of organic matter also is higher than in the Mohave soils, but 

 nevertheless the type bakes and hardens upon drying, and assumes a 

 dense, impervious structure which retards percolation and absorp- 

 tion of water. The subsoil is a light reddish brown or pinkish, 

 stick}' clay loam, which becomes more compact with depth and is 

 weakly and irregularly cemented in places, in character approaching 

 a hardpan. Its close structure renders the percolation of water very 

 slow and retards root development. The subsoil usually becomes 

 lighter colored or reddish brown at a depth of 3 feet or more. In 

 some places, where the shallow, silty surface material has been 

 removed, the entire soil column consists of the impervious, com- 

 pacted subsoil material. A substratum, consisting of gravel and 

 bowlders, lies at about 25 feet below the surface. Both surface soil 

 and subsoil, but particularly the latter, contain large amounts of 

 lime. 



The McClellan cla}^ loam is a very extensive soil, occurring prin- 

 cipally in the southern, western, and northwestern parts of the 

 survey. Many of the areas are large " playa " flats, or smooth flat 

 areas of puddled soil, barren of vegetation. Others occupj^ elongated, 

 shalloM' depressions or channels which may carry the run-off or may 

 hold water until it is ren^oved by evaporation and percolation. The 

 elongated areas roughly parallel the principal drainage ways. 



Areas of this type are frequently separated from each other by 

 ridges of lighter textured, wind-blown material, and the flats are 

 usually bordered by such ridges. In general the areas of this soil 

 lie near the principal drainage ways in the desert part of the area. 



The surface is uniformly level and flat, drainage ways being very 

 feebly developed except in the case of the larger washes. During 

 periods of drought these flats are dry and the soil is baked, but 

 during the rainy season, or after heavy showers, they are occupied 

 by shallow lakes. The surface material, consisting mainly of silt and 

 clay, is largely the result of deposition from the turbid drainage 

 waters. Alkali salts are usually present in greater or less concentra- 

 tions. In the southern part of the survey only small amounts of 



