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22
<br />slopes. Each of these included soils makes up about 10
<br />percent of the map unit.
<br />Permeability of this Norriston soil is rapid, and the
<br />available water capacity is very low. The effective rooting
<br />depth is 60 inches or more. Surface runoff is slow, and
<br />the hazard of erosion is slight.
<br />Most of the acreage is rangeland.
<br />The potential native vegetation is mainly Arizona
<br />fescue, needleandthread, and mountain muhly. As the
<br />range deteriorates, slimstem muhly, blue grama,
<br />Kentucky bluegrass, sun sedge, granite gilia, and
<br />rabbitbrush increase. The use of a planned grazing
<br />system, cross fencing, and livestock water developments
<br />helps to prevent range deterioration and promotes the
<br />production of the more desirable plants. Broadcasting is
<br />the only advisable method of seeding because a large
<br />number of rock fragments are near the surtace.
<br />The main limitation for homesites is slope. Excavation
<br />for foundations, roads, utility lines, and septic tanks is
<br />difficult because of the high content of small stones.
<br />Cutbanks are unstable. Because effluent from septic
<br />tank absorption fields rapidly penetrates the subsurtace
<br />layers, there is a risk of polluting the ground water. This
<br />soil is a good source of roadfill.
<br />This soil is in capability subclass Vlls, nonirrigated.
<br />23-Norriston extremely cobbly sandy loam, 15 to
<br />40 percent slopes. This is a deep, somewhat
<br />excessively drained soil on terraces and fans. It formed
<br />in glacial outwash. Elevation is 8,400 to 9,000 feet. The
<br />average annual precipitation is 16 to 20 inches, the
<br />average annual air temperature is 40 to 44 degrees F,
<br />and the frost-free season is 55 to 75 days.
<br />Typically, the surface layer is brown very cobbly sandy
<br />loam 6 inches thick. The subsoil extends to a depth of
<br />23 inches. It is brown extremely cobbly sandy loam in
<br />the upper 5 inches, light brown extremely gravelly sandy
<br />loam in the middle 7 inches, and light brown extremely
<br />gravelly loamy sand in the lower 5 inches. The
<br />substratum is light brown extremely cobbly loamy sand in
<br />the upper 11 inches and is light brown extremely cobbly
<br />sand to a depth of 60 inches or more. The soil is neutral.
<br />Included with this soil in mapping are areas of Libeg
<br />extremely cobbly sandy loam on less sloping parts of the
<br />landscape. They make up about 10 percent of the map
<br />unit.
<br />Permeability of this Norriston soil is rapid, and the
<br />available water capacity is very low. The effective rooting
<br />depth is 6o inches or more. Surface runoff is medium,
<br />and the hazard of erosion is slight.
<br />Most of the acreage is rangeland.
<br />The potential native vegetation is mainly Arizona
<br />fescue, needleandthread, and mountain muhly. As the
<br />range deteriorates, slimstem muhly, blue grama,
<br />Kentucky bluegrass, sun sedge, granite gilia, and
<br />rabbitbrush increase. The use of a planned grazing
<br />system, cross fencing, and livestock water development
<br />helps to prevent range deterioration and promotes the
<br />Soil sun
<br />production of the more desirable plants. Broadcasting
<br />seed is the only practical method, because slopes are
<br />steep and a large number of rock fragments are near t
<br />surtace.
<br />This soil is poorly suited to use as homesites. Slope
<br />the principal limiting feature.
<br />This soil is in capability subclass Vlls, nonirrigated.
<br />24-Northwater very stony loam, 20 to 45 percen '
<br />slopes. This is a deep, well drained soil on
<br />mountainsides. It formed in colluvium from granite.
<br />Elevation is 9,500 to 10,500 feet. The average annual
<br />precipitation is 20 to 25 inches, the average annual air
<br />temperature is 38 to 42 degrees F, and the frost-free
<br />season is 40 to 60 days.
<br />Typically, the surface layer is dark grayish brown ver)
<br />stony loam 7 inches thick over dark brown extremely
<br />stony sandy loam i8 inches thick. A mixed layer of
<br />subsurface material and subsoil follows. It consists of
<br />dark brown and dark yellowish brown extremely stony
<br />sandy loam 10 inches thick. The subsoil extends to a
<br />depth of 50 inches. It is dark yellowish brown extremely
<br />stony sandy clay loam in the upper 9 inches and
<br />yellowish brown very stony sandy clay loam in the lower
<br />6 inches. The substratum is yellowish brown very cobbly
<br />sandy loam to a depth of 60 inches. The soil is neutral
<br />throughout.
<br />Included with this soil in mapping and making up abou
<br />10 percent of the unit are areas of Woodhall cobbly
<br />sandy loam on the steeper parts of the landscape and
<br />areas of Lamphier loam on foot slopes and in
<br />drainageways. Also included are areas of Rock outcrop.
<br />The Lamphier soil and Rock outcrop each makes up
<br />about 5 percent of the unit.
<br />Permeability of this Northwater soil is moderately slow
<br />and the available water capacity is low. The effective
<br />rooting depth is 60 inches or more. Surface runoff is
<br />medium, and the hazard of erosion is moderate.
<br />Most of the areas are used for livestock grazing,
<br />woodland, wildlife habitat, and recreation.
<br />The potential native vegetation is mainly quaking
<br />aspen and some Engelmann spruce and Douglas-fir. The
<br />understory is Thurber fescue, nodding brome, Parry
<br />oatgrass, bearded wheatgrass, and Macoun wildrye.
<br />Much of the area supports a lush stand of quaking
<br />aspen and a fairly dense understory that is well suited to
<br />livestock grazing. As the understory deteriorates, sheep
<br />fescue, bluegrass, snowberry, rose, and elk sedge
<br />increase. Under proper woodland grazing, these stands
<br />can remain highly productive. Forage production is
<br />variable and depends primarily on the age and density of
<br />the aspen stand.
<br />This soil is suited to the limited production of quaking
<br />aspen. The site index is about 55, or moderate. About
<br />1,600 cubic feet, or 200 board feet; of merchantable
<br />wood can be produced from afully-stocked, even-aged
<br />stand of 80-year-old trees. Such tow productivity is
<br />typical for these areas. To minimize soil erosion and
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