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83 The 1975 SCS soil map car referenced for this updated east pit • survey. Map units were delineated by relating the soils to land- forms and topography, geology, drainage patterns, vegetation, and visible surface soil features. Map unit names contained in the SCS legend (1975) and used later by Fly and Associates (1979) in the west pit area (Section 25) were correlated to east pit (Section 31) soils. The SCS map unit boundary lines were transferred to high ' quality black and white stereo prints that were flown October 26, 1979. Soil boundaries were refined in an office photo-interpretive study using a mirror stereoscope. The refined mapping was then transferred to a revised and updated 1" = 400' topographic base map. SURVEY RESULTS Three map units were identified within the field soil survey area (see Exhibit 9-1). These are 9904/D2, Persayo clay loam and sandy clay loam, 10 to 208 slopes; 9904/F2, Persayo clay loam and sandy • clay loam, >25$ slopes; and 18/F2, Torriorthent-Rock Outcrop Com- plex, >25~ slopes. The Persayo soils occupy the moderately steep ridgetops and steep north facing sideslopes. The Torriorthent-Rock Outcrop Canplex occupies steep to very steep stoney south facing sandstone ridges, sideslopes, bluffs, and sharp rolling lards. The Persayo map unit and series descriptions with laboratory analysis data are found in the Soil Survey Text, Tab 9. The steep Persayo soil is very similar to the moderately steep Persayo soil. However, slopes are slightly steeper and the soil profile is smrewhat thinner. All pit disturbance in Section 31 will occur within the moderately steep Persayo map unit. Disturbance associated with highwall re- duction will extend furthar to the northwest into the steep Persayo map unit. There will be no additional disturbance in the Torriorthent- Rack Outcrop Complex. •