1988-04-29_PERMIT FILE - C1981008A (51)

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82 SOIL FORMING FACTORS Natural soils form under the influence of five soil-forming factors: parent materials, organisms, climate, relief, and time. Differ- entiation of natural soils into different taxoncnuc groupings therefore result from differences in one or more soil-forming factors. In this survey area, it appears that parent material is fairly constant and that vegetation, climate, relief, and soil age vary gradually over the landscape. Soils within the permit area have developed primarily in inter- bedded sedimentary strata and locally transported valley-filling sideslope deposits. Generally, the soils overlie soft interbedded shale and sandstone formations at depths ranging from two (2) to eighteen (18) inches. Depth to this paralithic contact increases on less steep landscapes and concave north facing sideslopes. Here, soils are more developed (older) and less eroded. The vegetation type is generally upland sage. Thinner less developed (younger) soils with drier micro-climates are found on the very steep southwest facing sideslopes that are adjacent to the dis- sected drainages. The vegetation type is predaninantly Juniper. A detailed discussion of local climate and topography for the Nucla Mine is presented in the soil survey text, Tab 9. THE SOILS Peabody Coal Company, in conjunction with the U.S. Department of Agriculture, Soil Conservation Service, Norwood, Colorado conducted a reconnaissance of Nucla rune surface soils in 1975. This soil survey, completed on aerial photos flown July 22, 1975, included the east pit area. The survey showed soil 9904, Persayo-Shavano clay loams occurring on sloping to moderately steep ridgetops and steep north facing sideslopes. Soil 18, Torriorthent-Rock Outcrop Complex (Rough Broken Land) occupies steep to very steep stoney sandstone ridges, bluffs, and sharp rolling lands.