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' • • EXHIBIT I/J (Cont'd) <br />normally more evident. The sandy layers -nary in thickness, and <br />the gravelly and cobbly layers vary both ir. thickness and in the <br />depth at which they occur. <br />' The cobblestones and gravel evident in this unit are only part of <br />the vast deposit that extends back from the Colorado River, ander <br />the Green River soils, and, for indefinite distances, under the <br />' Billings soils. The cobbly deposit ranges from 8 to 15 feet or <br />more in thickness. On the north side of the Colorado River the <br />belt of this material ranges from 4 to ~ mile wide and, except <br />' along the sharp bluffs, is found under most of the soils. On <br />the south side of the Colorado River the cobbly material underlies <br />practically all of the soils cn Orchard Mesa. <br />The pale-brown deposit of sandy material lying on the gravel, <br />cobbles, and stones is porous and absorbs water so rapidly that <br />irrigation would not be practical, even if small areas could be <br />' found that were smooth encugh to be irrigated. Except for a few <br />small patches used as gardens, little of this land is cultivated. <br />Many of the areas have almost no vegetation, but some of the larger <br />' ones support a scant growth of grasses, cottonwood trees, willows, <br />and a few shrubs. <br />At present, this land is used mainly as a source of material used <br />for road building and in concrete mixir_g. The smooth, rounded, <br />water-worn rocks and cobblestones in attractive shades of green, <br />gray, red, and black, have been used to limited extent for building <br />' or veneering residences in the area. The cobblestones consist <br />mainly of basalt and granite but some a_re from hard sandstone and <br />lava. <br />' YOUNGSTON SE2IES (yj) \ s - /~ <br />' The Youncston series consists of deep, well drained soils. <br />They Formed in alluvium on flood plains and alluvial fans. Slopes <br />are 0 to 3 percent. Elevation is 43CC to 54C0 feet. Natural vege- <br />' Cation is dominzntly saltbushes, rabbitbrush, gall eta, and Indian <br />ricegrzss. Average annual precipitation is about 9 inches, mean <br />annual air temperature is about 52°r., and the frost free season is <br />' 160 to 175 dzys. <br />In a typical profile the surface layer is grzy loam about 4 <br />' inches thick. The subsurface layer is light brownish gray very`ine <br />1 <br />34 <br /> <br />