SOILS AND FERTILIZERS 337 



portant soils in the production of alfalfa, sugar beets, melons, and 

 to a limited extent, fruits. A number of the soils of the series, how- 

 ever, are so situated as not to be susceptible to irrigation, and have 

 not been developed for agricultural purposes. 



Finney Series. Brown to nearly black soils derived from glacial 

 material underlain by lighter colored subsoils. The heavier soils 

 may be dry farmed to advantage and would become very productive 

 with irrigation. The lighter soils have a broken surface, are porous 

 and easily drifted by the wind. They are best adapted to grazing. 



Fruita Series. Reddish-brown soils, formed by reworking of 

 sandstones and shales, occurring as stream terraces. When well 

 drained and free from alkali the members of this series are admirably 

 adapted to the production of choice fruits, alfalfa, sugar beets, grains, 

 and truck crops. 



Laramie Series. Dark-colored soils, with light-colored gravelly 

 subsoils, derived from colluvial mountain wash. These soils have 

 not been extensively developed owing to their elevation, and are 

 used principally for grazing purposes. 



Laurel Series. Light-gray to black soils, underlain by river 

 sands or gravels, occurring in good plains along streams. Under fa- 

 vorable moisture conditions these are fertile soils, adapted according 

 to locality to corn, alfalfa, sugar beets, and truck crops, but the areas 

 are often subject to overflow, and in some cases can not be drained. 



Mesa Series. Light-gray to brown soils derived from old flood- 

 plain deposits, now elevated to form mesa lands. Where these soils 

 have been developed and are susceptible of irrigation they are used 

 mainly for alfalfa and sugar beets. One member of the series has 

 been quite extensively and very successfully used for the production 

 of apples and peaches. 



Morton Series. Brown residual soils, derived from sandstones 

 and shales. The soils lie in the semiarid region, and give good 

 yields of wheat, flax, oats, and potatoes when rainfall is sufficient. 



San Luis Series. Reddish-brown gravelly soils, formed from 

 lacustrine sediments of volcanic rock materials. On account of the 

 position and the danger from alkali these soils have not been suc- 

 cessfully developed, but have been used mainly for pasturage and 

 forage crops. 



Wade Series. Brown to dark-brown alluvial soils, formed by 

 reworking of sandstones and shales. Used for oats, flax, millet, and 

 wheat. 



ARID SOUTHWEST. 



The soils of the arid Southwest are mainly of colluvial, allu- 

 vial and lacustrine origin. They occupy mountain foot slopes, allu- 

 vial fans, debris aprons, or sloping plains of filled valleys, sloping or 

 nearly level plains, and bottoms of stream valleys or sinks and drain- 

 age basins. The principal colluvial soils of this region are also com- 

 mon to the Pacific coast. The climate of the arid Southwest is char- 

 acterized by semitropical desert conditions, and where the soils are 

 not capable of irrigation they have little or no present agricultural 

 value. 



