LOCATION OSBORN WAEstablished Series
TAXONOMIC CLASS: Coarse-loamy, isotic, frigid Andic Dystroxerepts
TYPICAL PEDON: Osborn ashy sandy loam under a coniferous forest on a 30 percent southeast-facing slope at an elevation of 4,700 feet. The soil was moist when described. (Colors are dry soil unless otherwise stated.)
Oi--0 to 1 inch; decaying forest litter; clear wavy boundary. (1/4 to 2 inches thick)
A--1 to 9 inches; yellowish brown (10YR 5/4) ashy sandy loam, dark yellowish brown (10YR 3/4) moist; moderate fine granular structure; soft, very friable, nonsticky and nonplastic; common fine and few medium roots; 5 percent sandstone paragravel; NaF pH 10.5; slightly acid (pH 6.4) clear wavy boundary. (7 to 10 inches thick)
2Bw1--9 to 16 inches; light yellowish brown (10YR 6/4) sandy loam, dark yellowish brown (10YR 4/4) moist; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine, fine roots; 10 percent sandstone paragravel; NaF pH 10.1; slightly acid (pH 6.4); abrupt smooth boundary. (6 to 9 inches thick)
2Bw2--16 to 24 inches; light yellowish brown (10YR 6/4) paragravelly sandy loam, dark yellowish brown (10YR 4/4) moist; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; common fine roots; 20 percent sandstone paragravel; NaF pH 9.4; slightly acid (pH 6.2); clear wavy boundary. (5 to 9 inches thick)
2BC--24 to 33 inches; pale yellow (2.5Y 7/4) paragravelly sandy loam, light olive brown (2.5Y 5/4) moist; massive; soft, very friable, nonsticky and nonplastic; common very fine, fine roots; 30 percent sandstone paragravel; moderately acid (pH 5.8); abrupt wavy boundary. (0 to 14 inches thick)
2Cr--33 inches; weathered sandstone.
TYPE LOCATION: Kittitas County, Washington; about 4 miles west of Tamarack Spring, 1,250 feet north and 1,300 feet east of the southwest corner of section 9, T. 18 N., R. 15 E.; USGS Frost Mountain, Washington topographic quadrangle; Latitude - 47 degrees, 03 minutes, 33 seconds N. and Longitude - 120 degrees, 58 minutes, 36 seconds W. (NAD83).
RANGE IN CHARACTERISTICS: Depth to the paralithic contact with soft sandstone ranges from 24 to 40 inches. The average annual soil temperature ranges from 45 to 47 degrees F. The soils are usually moist, but are dry in all parts in the moisture control section for 45 to 60 consecutive days during summer and fall. The particle-size control section averages 45 to 70 percent sand in the fine earth fraction. The upper 7 to 10 inches of the pedon has an estimated moist bulk density of 0.75 to 1.00 g/cc, glass content of 20 to 30 percent, acid-oxalate extractable aluminum plus iron of 1.0 to 2.0 percent, and 15-bar water retention of less than 12 percent.
The A horizon has value of 5 to 7 dry, 3 or 4 moist and chroma of 2 to 4 moist and dry. The A2 horizon, when present, is ashy sandy loam or gravelly ashy sandy loam. Reaction is moderately acid or slightly acid.
The 2Bw horizon has value of 6 or 7 dry, 4 or 5 moist and chroma of 3 or 4 moist and dry. Texture is gravelly sandy loam, paragravelly sandy loam, sandy loam or loam and contains 0 to 20 percent gravel and 10 to 20 percent sandstone paragravel. Reaction is moderately acid to neutral.
The 2BC horizon has hue of 2.5Y or 10YR, value of 6 or 7 dry and 4 or 5 moist. Texture is paragravelly sandy loam or very paragravelly loam and contains 0 to 10 percent gravel and 30 to 60 percent sandstone paragravel. Reaction is moderately acid to neutral.
COMPETING SERIES: These are the Bercumb, Moscow, Moso, Paige (T), Roslyn, Smith (T) and Volperie soils. Bercumb, Roslyn and Smith soils are greater than 60 inches deep to bedrock. Moso soils are 40 to 60 inches to paralithic granite bedrock. Moscow soils lack sandstone paragravel in the particle-size control section. Paige soils cannot be competed due to lack of an OSD within the database. Volperie soils are dry for 60 to 75 consecutive days following the summer solstice and have 5 to 15 percent mica in the particle-size control section. Soils with similar classification with mixed mineralogy are the Aits, Apex, Canteen, Centralpeak, Leadpoint, and Waits soils. Aits, Apex, Canteen, and Waits soils are deep. Centralpeak soils are dry 60 to 75 days and have no weathered sandstone in the particle-size control section. Leadpoint soils have a value of 2 to 5 dry, 2 or 3 moist and chroma of 0 to 2 throughout and are neutral to moderately alkaline.
GEOGRAPHIC SETTING: Osborn soils are on mountain side slopes. Slopes are 30 to 70 percent. They formed in colluvium and residuum from sandstone with a mantle of volcanic ash. Elevations are 2,900 to 4,600 feet. The soils are in a continental climate with warm, dry summers and cool, moist winters. The mean annual precipitation is 30 to 50 inches. The mean January temperature is about 26 degrees F. and the mean July temperature is about 64 degrees F. The mean annual temperature is 43 to 45 degrees F. The growing season at 28 degrees F. is 145 to 170 days and the frost-free season is 70 to 100 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Ainsley, Cliffdell and Terence soils. Ainsley soils are on mountain side slopes and benches, and are clayey-skeletal, and cryic. Cliffdell soils are on mountain side slopes and broad summits and are loamy-skeletal. Terence soils are on mountain side slopes, toe slopes and summits and are ashy-skeletal.
DRAINAGE AND PERMEABILITY: Well drained, medium to rapid runoff; moderately rapid permeability.
USE AND VEGETATION: These soils are used for timber production, wildlife habitat, and recreation. Vegetation is Douglas-fir, grand fir, western larch, lodgepole pine and ponderosa pine with an understory of pinegrass, rose, princes pine and pachystima.
DISTRIBUTION AND EXTENT: East slopes of the Cascade Mountains in south-central Kittitas County; MLRA 6. This series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Wenatchee National Forest, Kittitas County, Washington, 2003.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone from 1 to 9 inches
Cambic horizon - the zone from 9 to 24 inches
Paralithic contact - the zone beginning at 33 inches
Andic feature - the zone from 1 to 9 inches
Particle-size control section - the zone from 11 to 33 inches
Depths to diagnostic horizons and features are measured from the top of the first mineral layer.