III. SOILS 



Analysis for evaluating soils will include DNRC managed land in the project area. Refer to the 

 Soil Map in Appendix D for soil type locations within the project area. 



A. General Description 



The project area is varied in geology from the alluvial deposits and glacial till in Section 4 to the 

 moderate to steep mountain sideslopes and ridge tops of Section 16 that were formed by the 

 mixing of residual rock material with colluvial gravels and cobbles from the non-calcareous 

 argillites and quartzites of the Ravalli group and Pritchard formation and the calcareous Wallace 

 limestones and Missoula group formations. 



Table 3- 5: Soil Types of the Richards Peak Project Area 



SOIL TYPE 



lOUD-Fluventic 

 Ustochrepts 



32UB- Andic 

 Cryochrepts 



SOIL DESCRIPTION 



Soils are well-drained, coarse textured gravelly sandy loams 

 and cobbly loams. These soils dry out early in the summer 

 and tend to be droughty. Small depressions and overflow 

 channels may have silty soils, which support moister 

 vegetation. 



30UC- Andic 

 Dystrochrepts/ 



30UD- Andic 

 Ustochrepts 



30MC- Typic 

 Ustochrepts 



72UD- Andic 

 Eutroboralfs 



Soils are moderately deep and well drained. Typical surface 

 soils are 8-12 inches thick and reddish brown in color. 

 Texture is gravelly silt loam. Subsurface soils are 15-20 

 inches thick. Texture is extremely gravelly loam. 



Soils are deep and well drained. Duff layers of litter and 

 organic matter of at least 1 inch occurs on the surface. 

 Typical surface soils are 5-15 inches of brown color. Texture 

 is very gravelly loam to sandy loam. Subsurface soils are 10- 

 20 inches thick. Texture is very gravelly sandy loam. 

 Volcanic ash influence is intermittent, infiltration is rapid and 

 soil moisture retention is moderate. 



Soils are deep and well drained. Typical surface soils are 8-10 

 inches thick and Hght brown in color. Texture is gravelly 

 loam lo clay loam. Subsurface soils are 10-15 inches thick. 

 Texture is very gravelly clay loams to silty clay loams. 

 Intermittent volcanic ash surface soils are mixed with 

 colluvium on northerly microsites. 



Soils are deep and well drained. Typical surface soils are 8-10 

 inches thick and hght brown in color. Texture is volcanic ash 

 influenced gravelly silt loam. Subsurface soils are 15-20 

 inches thick. Texture is very gravelly silty clay loam. 

 Infiltration and moismre holding capacities are moderate. 



B. Existing Condition 



Timber harvest was done in the 1940's and 50's in the Richards Peak area, using mostly ground 

 based harvest methods. Existing skid trails and old landings are still visible on the landscape. 

 Ground based harvest can affect soil productivity through displacement and compaction of 

 productive surface layers of soil, principally on heavily used skid trails. It is estimated that less 

 than 10% of the ground is affected by existing skid trails. 



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