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1 <br />Environmental Assessment Bowie Resources, LL.C. <br />August 2005 Spruce Stomp Federal Coal Ezplomtion License (150- 2005 -43) <br />The quaternary deposits (the most recent) within the SSCEL are an unsorted mixture of soil and <br />' rock formed by various mass - wasting processes such as landslides, earth flows, soil creep, and <br />debris avalanches (BLM and GMUG 2000). These deposits also include slope colluvium and <br />quaternary unconsolidated deposits derived from the Tertiary Wasatch Formation. <br />Soils <br />The soil types in the area were characterized in the Soil Survey of Grand Mesa -West Elk Area <br />' (Cryer and Hughes 1997). Of the 32 soil map units characterized, there are 9 soil units that occur <br />within the SSCEL. These are listed in Table 3 -2 and shown in Figure 3 -7. The major soils were <br />formed as a result of the diversity of parent materials, elevations, slopes, aspects, and rates of <br />material weathering common to the SSCEL (BLM and GMUG 2000). <br />Each of the soils listed above is characterized by its respective soil series, family, or <br />miscellaneous grouping, as designated by the Cryer and Hughes soil survey. The principle soils <br />in the SSCEL are Wetopa - Wesdy complex, Herm - Fughes complex, Henn - Fughes - Kolob <br />family complex, and Shawa - Sandia family - Kolob family complex and are characterized by <br />' being shallow to very deep, well drained soils (Cryer and Hughes 1997). Their parent materials <br />are residuum and colluvium (Cryer and Hughes 1997). <br />Wetopa - Wesdy complex is characterized by slow permeability, with low to high erosion hazard <br />and mass movement potential on steep slopes and it has a high shrink -swell potential. The soil <br />unit is characterized by subsurface rock fragments. <br />Shawa- Sandia -Kolob is characterized by deep and very deep well - drained soils. The parent <br />material is residuum and colluvium from mixed volcanic sources and interbedded sandstone and <br />shale with volcanic rock overburden. The soil unit is typically loamy (Cryer and Hughes 1997). <br />Herm- Fughes are expected to be very deep, well drained soils, consisting of residuum, alluvium, <br />and colluvium from interbedded sandstone and shale and the Mancos shale. These soils are <br />typically found on mountain slopes, alluvial fans, mesa summits and side slopes, and valley <br />floors and toeslopes. The taxonomic class is Typic and Pachic Argiborolls, fine <br />montmorillonitic (Cryer and Hughes 1997). <br />Soils within the SSCEL are typified as mollisols (Foth 1984). The typical mollic soil horizon is <br />characterized as dark - colored, thick, and with base saturation greater than 50 percent (Foth <br />1984). A major feature of the Mollie horizon is a strong structure causing the soil to not be hard <br />or massive when dry (Foth 1984). Thickness of the mollic epipedon vanes with soil type (Cryer <br />and Hughes 1997). <br />Erasion <br />The potential for erosion vanes by soil type. When soil surfaces are not protected by vegetative <br />cover, the erosion rate increases. Erosion also increases as the slope of the land increases. The <br />major causes of soil erosion include water and wind. The most prevalent types of soil erosion by <br />water are sheet and gully erosion, where sheet erosion comprises a combination of the sheet and <br />rill erosion processes (Foth 1984). Sheet erosion is characterized by a combination of splash and <br />surface water movement downhill. Rill erosion is characterized by movement of surface water <br />into small depressions where it gains depth and velocity, initiating erosion. In comparison, gully <br />3-40 <br />