DUNE SAND. 



The sand dunes of the area mapped are found along the eastern 

 boundary, limiting the irrigable land along Salton River. The dune- 

 are from 2 to 10 feet high, crescent shaped, and very rough and 

 unlevel. They have been formed by the strong winds of the valley. 

 The sand is of a reddish brown color, rather rotten, and often mixed 

 with small particles of flocculated "soil. When wet these particles 

 break down, producing a sandy loam soil. These dunes are underlaid 

 by the heavier soils of the delta. 



Owing to the strong winds which have formed these aunes and 

 which would blow the sands around if leveled, and the roughness of 

 the country, requiring great expense for leveling it. it is doubtful if 

 these sand dunes are of present agricultural value. 



The sand dunes are usuall}* free from alkali salts, 95 per cent of the 

 soil carrying less than 0.2 per cent alkali, but directly south of Mesquite 

 Lake there is an area of sand dunes the western part of which contains 

 a high percentage of alkali. 



IMPERIAL SAND. 



The Imperial sand is found in only small areas and is composed of 

 the same material as the sand dunes, the only difference being that 

 the surface is level enough to permit of leveling for irrigation. It is 

 usually found in the vicinity of the dunes. Only small isolated areas 

 were mapped. The surface soil is sand. 5 feet deep, underlaid !>y 

 loam or clay loam which contains alkali. This soil will undoubtedly 

 prove to be the best in the valley for all of the garden crops or any 

 crop requiring cultivation. It is adapted to cultivated crops and 

 fruits which will withstand this climate. 



This soil will very likely always be well drained and practically free 

 from alkali salts, but if the subsurface water should rise to within 6 

 or 8 feet of the surface by reason of excessive irrigation great danger 

 should be feared of the accumulation of alkali. The cultivation of the 

 sand is safe at present, but the movements of water and alkali salts in 

 it are rapid, and should a subsurface accumulation of water be per- 

 mitted the alkali would speedily rise to the surface and injure the soil. 

 Eighty-two per cent of the soil has less than 0.'2 per cent alkali, and 18 

 per cent from 0.2 to 0.4 per cent alkali. 



IMPERIAL SANDY LOAM. 



This soil is found scattered pretty generally throughout the- area 

 mapped, there being in all 37 square miles, or 24,000 acres. As a rule 

 the surface is covered with small dunes, which consists of the sandy 

 loam soil blown by the wind and lodged beside bushes and other 

 obstructions. In T. 16 S., R. 15 E.; T. 16 S., R. U E.; T. 15 S., R. 



