LOCATION STEMILT WAEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, isotic, frigid Vitrandic Argixerolls
TYPICAL PEDON: Stemilt ashy silt loam, forested. (Colors are for dry soil unless otherwise noted.)
O--0 to 1 inch; moderately decomposed organic litter of needles, twigs, and leaves.
A--1 to 6 inches; dark grayish brown (10YR 4/2) ashy silt loam, very dark grayish brown (10YR 3/2) moist; moderate thin platy structure; slightly hard, friable, slightly sticky and slightly plastic; many fine roots; many very fine tubular pores; 5 percent cobbles; NaF pH 8.8; neutral (pH 6.8); clear smooth boundary. (2 to 12 inches thick)
AB--6 to 18 inches; brown (10YR 5/3) ashy silt loam, dark brown (10YR 3/3) moist; weak fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; many fine roots; many very fine tubular pores; 10 percent cobbles and gravel; NaF pH 8.6; neutral (pH 6.8); clear wavy boundary. (0 to 20 inches thick)
2Bt1--18 to 38 inches; brown (10YR 5/3) very cobbly silty clay loam, dark yellowish brown (10YR 3/4) moist; moderate fine subangular blocky structure; hard, firm, moderately sticky and very plastic; common fine roots; many very fine tubular pores; 60 percent cobbles and gravel; few faint clay films in pores and very few faint clay films on surfaces of peds; neutral (pH 6.8); gradual wavy boundary. (10 to 24 inches thick)
2Bt2--38 to 60 inches; pale brown (10YR 6/3) very cobbly silty clay loam, dark yellowish brown (10YR 4/4) moist; massive; very hard, firm, very sticky and very plastic; 60 percent cobbles and gravel, few faint clay films in pores and common faint clay films in pores; few clay bridges between sand grains; neutral (pH 6.8).
TYPE LOCATION: Chelan County, Washington; along Stemilt Hill Road; about 600 feet east and 500 feet north of southwest corner of section 13, T.21N., R.20E.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 45 to 47 degrees F. These soils are usually moist, but are dry for 60 to 75 consecutive days in all parts of the soil between depths of 4 and 12 inches. The mollic epipedon is 10 to 18 inches thick. The upper 20 inches of the argillic horizon averages 35 to 65 percent rock fragments and 18 to 35 percent clay. The upper 10 to 22 inches of the soil has an estimated moist bulk density of 0.85 to 1.30 g/cc, volcanic glass content of 5 to 20 percent, acid-oxalate extractable aluminum plus one-half of the acid-oxalate extractable iron of 0.4 to 1.0 percent and 15-bar water retention of 5 to 10 percent for air dried samples. Depth to bedrock and solum thickness is 40 to more than 60 inches. Reaction is slightly acid or neutral. Base saturation is less than 75 percent in some part between 10 and 30 inches.
The A horizon has value of 4 or 5 dry, 1 to 3 moist, and chroma of 2 or 3 dry and moist. Texture is ashy silt loam, ashy loam, or ashy sandy loam in the fine earth fraction and has 0 to 20 percent gravel, 0 to 5 percent cobbles, and 0 to 30 percent stones.
The AB or Bw horizon has value of 4 or 6 dry and chroma of 2 to 4 moist and dry. Texture is ashy silt loam, ashy sandy loam or ashy loam in the fine-earth fraction and has 5 to 45 percent gravel and 0 to 20 percent cobbles.
The 2Bt horizon has hue of 10YR or 7.5YR, value of 4 to 6 dry, 3 or 4 moist and chroma of 2 to 6 dry and moist. Texture is loam, sandy clay loam, silty clay loam or clay loam in the fine earth fraction and has 15 to 55 percent gravel, 5 to 45 percent cobbles, and 0 to 10 percent stones.
COMPETING SERIES: These are the Getaway, Klicker, Klickson, Larabee, Millerflat and Sycreek series. Soils with the same classification except for mixed mineralogy are the Ginserly (T), Inmaha, Needhill, Roundbarn, Skullhollow and Wilt series. Imnaha, Klicker, Larabee, Skullhollow and Wilt soils have lithic bedrock at 20 to 40 inches. Ginserly soils have a mollic epipedon 20 to 40 inches thick and are dry for 70 to 90 consecutive days. Klickson soils are dry for 45 to 60 consecutive days. Litbridge soils are similar and cannot be adequately competed. Needhill soils have a mollic epipedon 20 to 35 inches thick and are 40 to 60 inches deep to bedrock. Millerflat soils are dry for 45 to 60 consectutive days. Roundbarn soils have a paralithic contact at 40 to 60 inches and are dry for 90 to 100 consecutive days. Sycreek soils have a 2CBd horizon at a depth of 35 to 45 inches. Getaway soils have a mollic epipedon 20 to 35 inches thick.
GEOGRAPHIC SETTING: These soils are on mountains at elevations of 2,000 to 5,400 feet. Slopes are 0 to 75 percent. They formed mostly in material weathered from basalt or andesite and some sandstone with an influence of mixed volcanic ash and loess. The climate is characterized by warm, dry summers and moist, cold winters. The mean annual precipitation is 16 to 40 inches. The mean January temperature is 24 degrees F. and the mean July temperature is 68 degrees F. The mean annual temperature is 40 to 46 degrees F. The frost free season is 70 to 125 days. The growing season (28 degrees F) is 145 to 170 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Anatone, Bocker, Clint, Colockum, Loneridge, Tekison, and Tronsen soils. Bocker and Anatone soils are shallow to basalt and are on plateaus and mountain slopes. Clint soils are mesic, lack an argillic horizon and are on mountain slopes. Colockum soils are mesic, fine-loamy and are on mountain slopes. Loneridge and Tekison soils are clayey-skeletal and are on mountain slopes. Tronsen soils are mesic, clayey-skeletal and are on mountain slopes.
DRAINAGE AND PERMEABILITY: Well drained; very slow to rapid runoff; moderately slow permeability
USE AND VEGETATION: This soil is used for grazeable woodland, timber production, recreation, and watershed. Native vegetation is ponderosa pine and Douglas-fir, with an understory of pinegrass, arrowleaf balsamroot, elk sedge, bluebunch wheatgrass and Idaho fescue.
DISTRIBUTION AND EXTENT: Central and North-central Washington. The series is of moderate extent.
MLRA OFFICE RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Chelan County, Washington, 1969.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - the zone from 1 to 18 inches
Argillic horizon - the zone from 18 to 61 inches.
Vitrandic feature - the zone from 18 to 18 inches
Particle-size control section - the zone from 18 to 38 inches
Depths to diagnostic horizons and features are measured from the top of the first mineral layer.
Classification revised 6/95 from Loamy-skeletal, mixed, frigid Typic Argixerolls to loamy-skeletal, mixed, frigid Vitrandic Argixerolls.
Classification revised 6/01 from loamy-skeletal, mixed, frigid Vitrandic Argixerolls to loamy-skeletal, isotic, frigid Vitrandic Argixerolls.
The 40 to 60 inch range to bedrock represented in this series is only found in minor extent within two complex mapunits in Douglas County, Washington.
ADDITIONAL DATA: Laboratory data available for pedon number 90P722 and 92P019 (taxadunct); NSSL; Lincoln, NE.