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36
<br />42 degrees F, and the average frost-free period is 50 to
<br />80 days.
<br />The surface layer is typically dark grayish brown very
<br />gravelly loam about 14 inches thick. The upper 19
<br />inches of the subsoil is very gravelly clay loam, and the
<br />lower 7 inches is extremely cobbly sandy clay loam.
<br />The substratum to a depth of 60 inches or more is
<br />extremely cobbly sandy loam. The soil is slightly acid to
<br />a depth of 10 inches. It is neutral to a depth of 23
<br />inches and is mildly alkaline below that depth. In some
<br />areas the surface layer is very cobbly loam or very
<br />stony loam.
<br />Included with this soil in mapping are areas of
<br />Bushvalley soils in the steeper areas. These soils have
<br />a surface layer of cobbly loam. They are shallow. They
<br />make up about 10 percent of the unit. Also included are
<br />small areas of tuff and breccia rock outcrop. In a few
<br />areas the substratum has a lower content of pebbles
<br />and cobbles, by volume.
<br />Permeability is moderate or moderately slow in the
<br />Ess soil. Available water capacity is low. Effective
<br />rooting depth is 60 inches or more. Runoff is rapid, and
<br />the hazard of water erosion is very high.
<br />This soil is used as rangeland or for wildlife habitat.
<br />The slope limits access by livestock, and thus
<br />overgrazing is a concern in the less sloping areas.
<br />The potential plant community is mainly Arizona
<br />fescue, mountain muhly, Parry oatgrass, and prairie
<br />junegrass. A few small areas, above an elevation of
<br />10,500 feet, support Thurber fescue. The average
<br />annual production of air-dry vegetation is about 1,000
<br />pounds per acre. Ii the condition of the range
<br />deteriorates, needleandthread, blue grama, sedges,
<br />fringed sagebrush, and other shrubs increase.
<br />This soil is poorly suited to homesite development. It
<br />is limited mainly by the slope.
<br />The capability classification is Vlle, nonirrigated. The
<br />soil is in the Skeletal Loam #377 range site.
<br />33-Ess-Bushvalley complex, 10 to 45 percent
<br />slopes. These soils are on hills, mesas, fan terraces,
<br />and mountainsides. The native vegetation is mainly
<br />grasses. Elevation is 8,000 to 9,200 feet. The average
<br />annual precipitation is 15 to 18 inches, the average
<br />annual air temperature is 40 to 44 degrees F, and the
<br />average frost-free period is 50 to 80 days.
<br />This unit is about 55 percent Ess soil and 35 percent
<br />Bushvalley soil. The Ess soil is on side slopes, and the
<br />Bushvalley soil is on ridges and steep side slopes.
<br />Included with these soils in mapping are areas of
<br />Adderton soils on foot slopes and in drainageways.
<br />These included soils have a surface layer of loam. They
<br />are less gravelly than the Ess and Bushvalley soils.
<br />They make up about 5 percent of the unit. Also included
<br />Soil Survey
<br />are areas of breccia or tuff rock outcrop on the steep,
<br />upper side slopes. These areas make up about 5
<br />percent of the unit. Small areas of Youga soils are on a
<br />few fan terraces. These soils have a surface layer of ~
<br />sandy loam. They have a lower content of gravel than
<br />the Ess soil.
<br />The Ess soil is deep and well drained. It formed in
<br />colluvium derived dominantly from tuff, breccia, granite,
<br />and gneiss. The surface layer is typically dark grayish
<br />brown very gravelly loam about 14 inches thick. The
<br />upper 19 inches of the subsoil is very gravelly clay
<br />loam, and the lower 7 inches is extremely cobbly sandy
<br />clay loam. The substratum to a depth of 60 inches or
<br />more is extremely cobbly sandy loam. The soil is
<br />slightly acid to a depth of 10 inches. It is neutral to a
<br />depth of 23 inches and is mildly alkaline below that
<br />depth. In some areas the surface layer is very stony
<br />loam, very cobbly loam, or very gravelly sandy loam. In
<br />sec. 10, sec. 11, sec. 14, and sec. 15, T. 16 S., R. 71
<br />W., the soil is commonly calcareous below a depth of
<br />about 3 feet. These areas are commonly known as the
<br />Bare Hills.
<br />Permeability is moderate or moderately slow in the
<br />Ess soil. Available water capacity is low. Effective
<br />rooting depth is 60 inches or more. Runoff is medium or
<br />rapid, and the hazard of water erosion is high or very
<br />high.
<br />The Bushvalley soil is shallow and well drained. It
<br />formed in residuum derived dominantly from tuff,
<br />breccia, granite, and gneiss. The surface layer is
<br />typically dark grayish brown cobbly loam about 4 inches
<br />thick. The subsoil is very cobbly sandy clay loam about
<br />7 inches thick. Breccia is at a depth of about 11 inches.
<br />The soil is neutral.
<br />Permeability is moderately slow in the Bushvalley
<br />soil. Available water capacity is very low. Effective
<br />rooting depth is 7 to 20 inches. Runoff is rapid, and the
<br />hazard of water erosion is very high.
<br />This unit is used as rangeland.
<br />The potential plant community is mainly Arizona
<br />fescue, mountain muhly, Parry oatgrass, and prairie
<br />junegrass. The average annual production of air-dry
<br />vegetation is about 1,000 pounds per acre in areas of
<br />the Ess soil and about 700 pounds in areas of the
<br />Bushvalley soil. If the condition of the range
<br />deteriorates, blue grama, fringed sagebrush, and woody
<br />shrubs increase. Range seeding is suitable if the range
<br />is in poor condition. Mechanical treatment is difficult in
<br />some areas because of surface stoniness and the
<br />slope.
<br />Most areas of this map unit are poorly suited to
<br />homesite development. The main limitations are the
<br />slope and the depth to bedrock. The depth to bedrock is
<br />
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