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State Reg. <br />Soils within the permit area have developed primarily in interbedded • <br />sedimentary strata and locally Transported valley-filling sideslope deposits. <br />Generally, the soils overlie fractured interbedded shale and fine-grained <br />sandstone formations at depths ranging from about eight (8) to greater than <br />sixty (60) inches. Depth to bedrock usually increases on less steep <br />landscapes and concave north facing sideslopes. Here, soils are more <br />developed (older) and less eroded. The vegetation types are generally aspen, <br />oak, shrubs, grasses, and forbs. Vegetation types on the thinner less <br />developed (younger) soils with drier micro-climates are predominantly <br />shrubs, grasses, forbs, and aspen. A detailed discussion of local climate and <br />topography for the Seneca Mine is presented in the soil survey text, Tab 9. <br />IV. THE SOILS <br />Seneca Coals, Ltd., in conjunction with the U.S.D.A. Soil Conservation <br />Service, Craig, Colorado, conducted a reconnaissance of Seneca Mine <br />surface soils in 1977. In 1978, Seneca requested Texas Instruments, Inc. to <br />complete a more detailed soil survey of the 4-40's property. Then, in 1979, • <br />the S.C.S. updated their soil mapping in the Seneca Mine area by making <br />numerous field checks and later by transferring all mapping to 1:24,000 <br />aerial photos. <br />Soil types identified and located by these three surveys were very similar. <br />The two major map units which comprised 75% of the area were X8: <br />Winevada-Splitro loam complex and 99:Cryoborolls. The remaining 25% <br />consisted of 66:Skylick clay looms, 50:Cochetopa loam, 34:Coutis silt loom, <br />and 35:Aaberg silty clay loam. The deeper soils (Unit Nos. 66, 50, and 35) <br />were located on the less steep concave slopes and in the major southwest <br />drainageway near the Wolf Creek cropline. <br />The previous three soil surveys were referenced for this updated 4-40's <br />survey by Seneca Coals, Ltd.. Approximately 25 shallow pits (6-36 inches <br />deep) were dug by hand in each potential sampling location to assess the <br />accuracy of the initial surveys. Mop units were delineated by relating the • <br />soils to landforms and topography, geology, drainage patterns, vegetation, <br />and visible surface soil features (soil surface depth, textures, horizons, <br />9-II <br />