holes. These formed as masses of stagnant 

 ice isolated from the retreating ice sheet 

 and were partially or completely buried in 

 till or outwash before the glacier melted. 

 Upon full melt, a pit or depression was left 

 remnant in the drift. These depressions, 

 referred to as kettles or potholes, formed 

 Beaver, Murray, Little Beaver, Woods, 

 Dollar and Rainbow Lakes. 



• Continentally glaciated lands - These were 

 formed as a result of the Cordilleran Ice 

 Sheet that advanced south from British 

 Columbia, covering a large portion of the 

 Stillwater State Forest. Glaciated foothills, 

 ground moraines, and rounded ridgetops 

 dominate this landform. 



SOIL RESOURCE 

 MEASUREMENT INDICATORS 



In order to assess the potential effects to soil 

 resources in the Beaver Lake analysis area, 

 compaction potential, susceptibility to surface 

 erosion, and susceptibility to displacement are 

 analyzed for each soil map unit. 



COMPACTION 



Compaction results from soil particles packing 

 together as increased pressure is applied to the 

 soil surface. This may potentially result in 

 decreased infiltration capacity, porosity, and 

 productivity of the soil. Of particular concern 

 is the structure of soils containing a relatively 

 high percentage of fine-textured materials. 



EROSION 



Erosion generally occurs in areas where the 

 organic litter has been removed and water 

 accumulates and flows. As water concentrates 

 and flows, energy is generated to detach soil 

 particles, initiating the erosion process. Re- 

 moval of duff and litter layers increases ero- 

 sion potential in the presence of increased 

 water and overland flow. Forest organic 

 matter, both living and dead, is important in 

 controlling soil erosion. Vegetation recovery 

 and organic-matter deposition on bare soil is 

 important for reducing erosion potential. 



DISPLACEMENT 



Soil displacement refers to the actual removal 

 or movement of the surface soil. When surface 

 soils are displaced, organic matter and nutrient 

 sources are removed and site productivity may 

 decline. 



SOIL MAP UNITS (REFER TO I 



TABLE IV-15 - SOIL ' 

 MEASUREMENT INDICATOR 



RATINGS) \ 



Soil map units refer to land areas with similar 

 topography and soil patterns. Typically, a map 

 unit consists of one or more major soils and 

 some minor soils. Although general, the soil 

 map unit can be used to compare the suitability 

 of large areas for common land-use practices. 



SOIL MAP UNIT 23-8 



\ 



Soil Map Unit 23-8 comprises approxi- ■■{ 

 mately 80% of the project area and gener- 

 ally occurs on glaciated mountain slopes 

 and ridges. Soils are formed in dense, 

 brittle glacial till on the lower slopes, while 

 outcrops of argillites, siltites, and lime- 

 stones of the Belt Supergroup dominate the 

 upper slopes and ridges. 



'. 



Soil properties vary with topographic 

 position. Gravelly silt loam and cobbly 

 sandy loam generally characterize lower 

 slopes, 3,300 to 3,600 feet, within the project 

 area. Clayey material occurs throughout 

 most of the lower slopes and does not ; 

 extend upslope through the subsoil profile. 

 Soils are considered skeletal due to coarse 

 fragments of decomposed limestones and j 

 argillites (30% to 60% rock fragments). 

 Soils are considered moderately shallow 

 and contain angular subsoil rock fragments. 



Upper slopes (more than 3,600 feet) contain 

 ridges, benches, and outcrops of Precam- 

 brian belt rock. These upper slopes with | 

 ridges and outcrops have been further 

 classified as Soil Map Units 23-9 and 55. 



Chapter III: Affected Environment 



