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<br />'.::j< <br />co <br />:~ <br />.... <br />--:J <br />c:) <br /> <br />SOILS <br /> <br />2 <br /> <br />The soil survey of the Grand Junction Area (issued 1955) covers 121,600 <br /> <br />3 <br /> <br />acres of land in the Grand Valley within the boundaries of the irrigation <br /> <br />4 canal system. The soils as described in this survey are typical of <br /> <br />5 desert soi Is -- they are low in organic matter, high in weatherable <br /> <br />6 minerals and associated salts and are chemically similar to the geologic <br /> <br />7 materials from which they were derived. <br /> <br />8 Extens ive field and. laboratory checking of sal inity during the progress <br /> <br />9 of the survey found that about one-thi rd of the area \~as affected by <br /> <br />10 accumulations of salts, alkal i, or both, and that sodium sulfate is by <br /> <br />11 far the most prevalent salt. <br /> <br />12 Strongly sal ine Cretaceous formations (primari ly Mancos shale) dominate <br /> <br />13 the parent material of the area, with approximately 78 percent of the <br /> <br />14 area having soils directly related to the Mancos shale. The deep Fruita, <br /> <br />15 Geno1a, Green River, Hinmon, Mesa, Naples, and Thoroughfare soils which <br /> <br />16 are formed in mixed material of other than Mancos shale amount to about <br /> <br />17 22% of the area. <br /> <br />18 Of those soils directly related to the Mancos shale the shal low Chipeta <br /> <br />19 and Persayo soils and the moderately deep phases of the Fruita and Mesa <br /> <br />20 soils resting on Mancos shale amount to 31 percent of the total area. <br /> <br />21 The deep Billings (29%), Mack (3%) and Ravola (15%) soils developed in <br /> <br />22 alluviam from the Mancos shale comprize about 47 percent of the total <br /> <br />23 area. <br /> <br />16 <br />