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ti ., 1 ' BILLINGS SILTY CLAY, 0 to 2 percent slopes, Class IIIe Land (Ha) ' This soil is on alluvial materials - 4 to about 40 feet thick - t that largely came from Mancos shale. The 8- or 10-inch surface soil consists of light brownish-gray, ' gray, or olive-gray silty clay. The layer is similar to the surface layer of Billings silty clay loam soils but it is harder and, in ' many places, darker. The subsoil consists of similarly colored layers of silty clay loam, silt loam, and silty clay. In places the soil ' is silty clay to depths exceeding 4 feet. ' The entire profile is firm when moist and has a massive structure. The subsoil has many small irregularly soaped light-gray specks or indistinct mottles. Poorly defined light-colored streaks indicate the presence of lime, gypsum, or salts. The surface soil and subsoil are calcareous, the lime being well distributed. The fine texture t oS.the soil greatly retards penetration of roots, moisture, and air. ' Surface runoff is very slow to slow where the slope is less than 1 percent. Internal drainage is very slow because the subsoil.is . ' massive and very slowly permeable. E•ren with ample drainage ditches, the discharge of irrigation water is slow. 1 1 Tilth and workability are not good, because the soil has a fine texture and a low content o£ organic matter., Moreover, some fields contain areas 20 to 60 feet across that have excessive amounts of salts. Slick spots also occur. These salty areas and slick spots produce low or negligible yields of most crops and are extremely difficult to eliminate. Soil limitations are classified as severe for local roads and streets (poor traffic-supporting capacity, moderate to high water tables common), dwellings with basements (high shrink-swell potential, slow internal drainage, subject to water table build-up), sanitary land fill (poor drainage, clayey texturea),and septic tank absorption fields (slow permeability, poor internal drainage, seasonal high water table).