LOCATION THOWSON WAEstablished Series
TAXONOMIC CLASS: Ashy, glassy, mesic Typic Vitrixerands
TYPICAL PEDON: Thowson ashy fine sandy loam, under a coniferous forest, with grass and shrubs, on a 23 percent, concave, north facing slope at an elevation of 2,080 feet. (Colors are for dry soil unless otherwise stated. All textures are apparent field textures.)
A--0 to 4 inches; light brownish gray (10YR 6/2) ashy fine sandy loam, very dark grayish brown (10YR 3/2) moist; weak fine granular structure; soft, very friable, nonsticky and nonplastic; many very fine and fine roots; few very fine tubular pores; 5 percent gravel and 5 percent pumice paragravel 2 to 10mm in diameter; neutral (pH 6.7); abrupt wavy boundary. (3 to 9 inches thick)
C--4 to 5 inches; white (10YR 8/1) ashy very fine sandy loam, light gray (10YR 7/2) moist; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; neutral (pH 7.0); abrupt wavy boundary. (0 to 2 inches thick)
2Bw1--5 to 14 inches; pale brown (10YR 6/3) ashy fine sandy loam, brown (10YR 4/3) moist; weak medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine and fine, few coarse roots; few very fine tubular pores; 5 percent gravel and 10 percent pumice paragravel 2 mm to 10mm in diameter; slightly acid (pH 6.2); clear wavy boundary (8 to 13 inches thick)
2Bw2--14 to 34 inches; light yellowish brown (10YR 6/4) paragravely ashy fine sandy loam, brown (10YR 4/3) moist; weak medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; few very fine, fine, and coarse roots; few very fine tubular pores; 5 percent gravel and 20 percent pumice paragravel 2 to 10mm in diameter; neutral (pH 6.6); clear wavy boundary. (18 to 24 inches thick)
2Bw3--34 to 45 inches; very pale brown (10YR 7/3) very paragravelly ashy fine sandy loam, yellowish brown (10YR 5/4) moist; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; few fine and medium roots; few fine tubular pores; 5 percent gravel and 30 percent pumice paragravel 2 to 10mm in diameter; neutral (pH 7.2); abrupt wavy boundary. (0 to 12 inches thick)
3C--45 to 60 inches; light gray (2.5Y 7/2) very cobbly loamy sand, grayish brown (2.5Y 5/2) moist; massive; soft, very friable, nonsticky and nonplastic; few fine and medium roots; few fine tubular pores; 20 percent gravel, 20 percent cobbles. and 5 percent stones; slightly alkaline (pH 7.4)
TYPE LOCATION: Chelan County, Washington; about 5 miles west of Chelan, Washington; 1,900 feet west and 900 feet north of the southeast corner of sec. 13, T. 27 N., R. 21 E.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 47 to 52 degrees F. These soils are usually moist, but are dry in all parts of the moisture control section for 75 to 90 consecutive days after the summer solstice. The 0 to 40 inch particle-size control section has an estimated moist bulk density of 0.65 to 0.85 g/cc, volcanic glass content of 30 to 60 percent including 10 to 40 percent pumice 2mm to 10mm in diameter, 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 12 percent for air dried samples. It contains 5 to 35 percent pumice 2mm to 10mm in diameter. Depth of the 3C horizon is 40 to 80 inches. Some pedons have a stony surface. Some pedons have dense glacial till below the 3C horizon.
The A horizon has value of 5 to 7 dry, 3 or 4 moist, and chroma of 2 or 3 moist or dry.
The C horizon has value of 7 or 8 dry, 6 or 7 moist and chroma of 1 or 2 moist or dry. This horizon is lacking in some pedons. Reaction is slightly acid to neutral.
The 2Bw horizon has value of 5 to 7 dry, 4 through 6 moist, and chroma of 2 to 4 moist or dry. Texture is ashy fine sandy loam, paragravelly ashy fine sandy loam, ashy sandy loam, paragravelly ashy sandy loam, paragravelly ashy coarse sandy loam. Rock fragments range from 0 to 10 percent by volume. Pumice from 2mm to 10mm in diameter range from 5 to 40 percent. Reaction is slightly acid to neutral.
The 3C horizon has hue of 10YR or 2.5Y, value of 6 or 7 dry, 4 or 5 moist and chroma of 2 through 4 moist or dry. Textures are very cobbly loamy sand, very gravelly sandy loam, very stony fine sandy loam, or extremely gravelly loamy sand. Rock fragments range from 40 to 75 percent by volume. Pumice 2mm to 10mm in diameter range from 0 to 10 percent. Reaction is slightly acid to slightly alkaline.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Thowson soils are on uplands and mountainsides on all aspects. Slopes range from 0 to 90 percent. Elevation is 1,100 to 3,600 feet. These soils formed in volcanic ash and pumice over ablation glacial till. The climate is characterized by warm dry summers and cool moist winters. The average annual precipitation is 14 to 18 inches. The mean January temperature is about 25 degrees F; the mean July temperature is about 70 degrees F; and the mean annual temperature is 46 to 50 degrees F. The frost-free is 100 to 150 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Dinkels, Mansonia, Palmich, Safety, Tyee, and Thow soils. Safety soils are 20 to 40 inches to a paralithic contact. Mansonia soils have a mollic epipedon. Palmich and Thow soils are frigid. Dinkels and Tyee soils are 10 to 20 inches to a paralithic contact.
DRAINAGE AND PERMEABILITY: Well drained; slow to rapid runoff; moderate permeability in the surface and subsoil, moderate to very rapid in the substratum.
USE AND VEGETATION: Woodland, rangeland, wildlife habitat, watershed, recreation, orchards, and hay and pasture. Native vegetation includes ponderosa pine, Douglas-fir, antelope bitterbrush, bluebunch wheatgrass, arrowleaf balsamroot, lupine, yarrow and pinegrass.
DISTRIBUTION AND EXTENT: North-central Washington; Eastern Cascades; MLRA 6. Series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Chelan County, Washington, 1995.
Remarks: Diagnostic horizons and features recognized in this pedon are an ochric epipedon and a cambic horizon from 5 to 45 inches. Andic soil properties from 0 to 45 inches.