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Atencio-Azeltine Complex, 3 to 6 Percent Slopes <br />~~ <br />These nearly-level to gently-sloping soils are on alluvial fans and <br />high terraces at elevations of 6,000 to 7,500 feet. The Atencio soil <br />occupies the somewhat concave parts of the landscape. It makes up <br />about 60 percent of the unit. The Azeltine soil occupies the slightly <br />convex positions and makes up about 30 percent of the unit. About 10 <br />percent of the unit is gravel bars or finer textured soils. <br />This unit occurs on the old flood plain terrace on both sides of the <br />Roaring Fork River. Much of the surface development for the loadout <br />facility occurs on this unit (see soils map). The two soils making up <br />the complex are differentiated by the occurrence of coarse fragments <br />in the profile--essentially a function relief, The Azeltine on the <br />higher spots is gravelly or skeletal throughout. This is a "younger" <br />soil than the Atencio soil, more "Torriorthentic." The unit is predo- <br />minated by the Atencio series which has a non-skeletal surface layer <br />and a developed B horizon, Typical profile and sampling descriptions <br />• for this unit are based on the Atencio soil. This is the most signi- <br />ficant source of topsoil. Topsoil stripping in this area is limited <br />by the occurrence of coarse fragments of clayey subsoils or both, <br />which are easily discernible in the field. The unit should yield an <br />average of 12 inches of salvagable topsoil overall. <br />Both soils are moderately deep and well drained. Both are formed in <br />mixed sandstone, shale, and quartzitic alluvium. The Atencio soil is <br />comprised of a loamy dark reddish-brown surface layer about 7 inches <br />thick (A1) and a 4-inch loamy subsoil {B1). The substratum is a <br />stony sandy loam grading to sand, cobble, and gravel at 25 to 30 <br />inches. The Azeltine soil is a dark reddish-brown gravelly loam about <br />10 inches thick underlain by sand, gravel, and cobble. <br />Permeability of these soils is moderately rapid to rapid. Effective <br />rooting depth varies from 10 to 30 inches. Available water holding <br />capacity is from 0.09 to 0.14 inches per inch. Surface runoff is slow <br />• and erosion hazard is slight. <br />3-116 <br />