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mapping unit, the Tellura soils make up about 40 percent, and about 15 percent is rock outcrop <br />and soils that are moderately deep over bedrock. <br />The Bushvalley is a shallow, well- drained, cobbly soil, formed in colluvium from volcanic rocks. <br />Typically, the surface layer is dark brown cobbly loam about four inches thick. The subsoil layer <br />is brown, extremely cobbly, clay loam about nine inches thick. Hard bedrock is below 13 <br />inches. <br />Permeability is moderate. Effective rooting depth is ten to 20 inches. Available waterholding <br />capacity is low. Surface runoff is medium to rapid and erosion hazard is moderate. <br />The Tellura soil is deep, well- drained, very cobbly soil formed in alluvium and slopewash <br />materials from igneous rocks. Typically, the surface is dark gray, very cobbly loam about 13 <br />inches thick. The subsoil layer is brown, very cobbly, heavy clay loam about 24 inches thick. <br />The substratum is very pale brown extremely cobbly clay loam extending to 48 inches or more. <br />Permeability is moderately low. Effective rooting depth is 48 inches or more. Available water <br />holding capacity is high. Surface runoff is medium to rapid, and erosion hazard is moderate. <br />ROCK OUTCROP <br />This unit consists of about 90 percent bedrock outcrops and ten percent shallow and very <br />shallow soils on very steep slopes. The most important soil characteristics are shallowness and <br />stoniness. The exposed bedrock consists of tuff, rhyolite, andesite, breccia, and other volcanic <br />rocks. Slopes range from about 30 to more than 100 percent. <br />Effective rooting depth is limited by depth to bedrock in the areas where soil is present. <br />Available water holding capacity is low. Surface runoff is rapid and erosion hazard is moderate. <br />SEITZ VERY STONY LOAM <br />This deep soil occurs on moderately steep to very steep (15 to 65 percent) slopes on mountain <br />sides and ridges. It developed in slopewash materials derived from igneous rocks at elevations <br />of 9,000 to 9,800 feet. Included in this unit are a few small areas of Bushvalley and Comodore <br />soils. <br />Typically, there is a thin organic layer consisting of partially decomposed needles, twigs, and <br />grass on the surface. This layer overlies a dark grayish brown, very stony loam surface clay <br />about two inches thick. The subsurface layer is a pale brown, very stony loam about four inches <br />thick. Subsoil is a brown or yellowish brown, very stony clay or heavy clay loam about 24 inches <br />thick. The substratum is a yellowish brown, extremely stony clay loam that extends to 60 <br />inches or more. <br />Permeability is low. Effective rooting depth is 60 inches or more. Available water capacity is <br />moderate. Surface runoff is moderate and the erosion hazard is moderate. <br />