LOCATION TILLMONT WAEstablished Series
TAXONOMIC CLASS: Pumiceous or ashy-pumiceous over loamy-skeletal, glassy over isotic, frigid Typic Vitrixerands
TYPICAL PEDON: Tillmont paragravelly ashy sandy loam, under coniferous forest on a 47 percent southwest facing slope at an elevation of 3,380 feet. (Colors are for dry soil unless otherwise stated. All textures are apparent field textures).
Oi--0 to 1 inch; slightly decomposed forest litter consisting of leaves, twigs, and cones.
A--1 to 7 inches; grayish brown (10YR 5/2) paragravelly ashy sandy loam, dark brown (10YR 3/3) moist; weak fine granular structure; soft, very friable, nonsticky and nonplastic; many very fine and fine and few medium roots; few fine tubular pores; 20 percent pumice and 5 percent gravel; neutral (pH 6.9); clear wavy boundary. (4 to 9 inches thick)
Bw--7 to 21 inches; light yellowish brown (10YR 6/4) paragravelly ashy sandy loam, dark yellowish brown (10YR 4/4) moist; weak medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; common fine and medium and few coarse roots; common fine tubular pores; 30 percent pumice and 2 percent gravel; neutral (pH 6.8); clear wavy boundary. (10 to 15 inches thick)
2C1--21 to 35 inches; yellow (10YR 8/6) and very pale brown (10YR 8/2) pumice paragravel; single grain; loose; few medium and coarse roots; 95 percent pumice; neutral (pH 7.0); abrupt wavy boundary. (10 to 20 inches thick)
3C2--35 to 39 inches; pale brown (10YR 6/3) paragravelly ashy loamy coarse sand, dark yellowish brown (10YR 4/4) moist; single grain; loose, nonsticky and nonplastic; few fine, medium and coarse roots; 15 percent pumice paragravel and 10 percent gravel; slightly acid (pH 6.2); abrupt wavy boundary. (0 to 4 inches thick)
4C3--39 to 47 inches; dark yellowish brown (10YR 4/4) extremely cobbly very fine sandy loam, dark brown (10YR 3/3) moist; massive; soft, very friable, nonsticky and nonplastic; few coarse roots; 20 percent gravel, 40 percent cobbles and 15 percent stones; slightly acid (pH 6.4); abrupt irregular boundary. (6 to 12 inches thick)
5R--47 inches; fractured schist.
TYPE LOCATION: Chelan County, Washington; about 2 miles east of Fish Lake near center of sec. 17, T. 27 N., R. 18 E.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is about 44 to 46 degrees F. These soils are usually moist but are dry in the moisture control section for 45 to 60 consecutive days following summer solstice. The upper part of the 1 to 41 inch particle-size control section has an estimated moist bulk density of 0.70 to 0.90 g/cc, volcanic glass content of 30 to 60 percent, acid-oxalate extractable aluminum plus one-half of the acid-oxalate extractable iron of 1.0 to 2.0 percent and 15-bar water content of 5 to 12 percent for air dried samples. The lower part is considered to be loamy-skeletal. Depth to schist or gneiss bedrock is 40 to 60 inches. Soil reaction is slightly acid or neutral. Some pedons have a thin E horizon.
The A horizon has value of 4 through 6 dry, 3 or 4 moist and chroma of 2 or 3 dry or moist.
The Bw horizon has value of 5 through 7 dry, 3 or 4 moist, and chroma of 2 through 4 dry or moist. It is paragravelly ashy sandy loam, or very paragravelly ashy sandy loam. It is 20 to 55 percent pumice.
The 2C1 horizon has value of 6 to 8 dry, 4 to 8 moist, and chroma of 2 through 4 moist, and 4 through 6 dry, It is 65 to 95 percent pumice and voids are not filled.
The 3C2 horizon is very paragravelly ashy loamy coarse sand, paragravelly ashy loamy coarse sand or paragravelly ashy very coarse sand. It is 15 to 60 percent pumice.
The 4C3 horizon has value of 4 through 6 dry, 3 or 4 moist, and chroma of 3 or 4 dry or moist. It is very cobbly sandy loam, extremely cobbly sandy loam, or extremely cobbly very fine sandy loam. Rock fragments range from 45 to 90 percent.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Tillmont soils are on mountain slopes that generally have a southwest aspect. Slopes are 8 to 65 percent. They formed in volcanic ash and pumice over colluvium from schist or gneiss. Elevation is 2,500 to 4,600 feet. The climate is characterized by warm, dry summers and cool, moist winters. The average annual precipitation is 30 to 65 inches. The mean January temperature is about 23 degrees F, and the mean July temperature is about 65 degrees F. The mean annual air temperature is 42 to 44 degrees F. The growing season at 28 degrees F is 125 to 165 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Choralmont, Mountaineer, and Tillicum soils. Choralmont soils are ashy-pumiceous. Mountaineer soils are loamy-skeletal. Tillicum soils are medial over loamy.
DRAINAGE AND PERMEABILITY: Well drained; slow to rapid runoff; moderate permeability.
USE AND VEGETATION: Woodland, wildlife habitat, watershed, and recreation. Vegetation is Douglas-fir, ponderosa pine, grand fir, and lodgepole pine, with an understory of Rocky Mountain maple, spirea, Oregon-grape, pinegrass, and rose.
DISTRIBUTION AND EXTENT: East slopes of the Cascade Mountains in the western part of Chelan County, Washington. 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 from the mineral surface to 6 inches, a cambic horizon from 7 to 21 inches, and a particle-size control section with weight average 27 percent pumice from 1 to 21 inches, 95 percent pumice with voids not filled from 21 to 35 inches, 15 percent pumice from 35 to 39 inches and 75 percent rock fragments from 39 to 41 inches. The layer from 39 to 41 inches is considered to be loamy-skeletal and isotic. The contrasting family pumiceous or ashy-pumiceous over loamy-skeletal is not approved. The best series placement is to consider the loamy-skeletal layer as medial-skeletal for classification purposes.