LOCATION TUMAC WAEstablished Series
TAXONOMIC CLASS: Ashy-skeletal, mixed, frigid Humic Vitrixerands
TYPICAL PEDON: Tumac stony ashy sandy loam - forested. (Colors are for dry soil unless otherwise noted.)
Oe--0 to 2 inches; partially decomposed forest litter. (1 to 2 inches thick)
A1--2 to 6 inches; brown (10YR 5/3) stony ashy sandy loam, dark brown (10YR 3/3) moist; weak very fine granular structure; soft, very friable, nonsticky, nonplastic and weakly smeary; few very fine, common fine roots; 20 percent gravel and 10 percent stones; moderately acid (pH 6.0); abrupt smooth boundary.
A2--6 to 17 inches; brown (10YR 5/3) very gravelly ashy loam, dark brown (10YR 3/3) moist; moderate fine granular structure; soft, very friable, slightly sticky, slightly plastic and weakly smeary; common very fine, fine, and medium roots; 40 percent gravel; moderately acid (pH 5.8); abrupt wavy boundary. (10 to 12 inches thick)combined thickness of the A horizon is 10 to 15 inches)
Bw1--17 to 32 inches; yellowish brown (10YR 5/4) very gravelly ashy loam, dark brown (7.5YR 3/4) moist; common very fine subangular blocky structure; slightly hard, friable, slightly sticky, slightly plastic and weakly smeary; few very fine and common fine roots; 45 percent gravel and 5 percent cobbles; moderately acid (pH 5.8); clear wavy boundary. (14 to 16 inches thick)
Bw2--32 to 52 inches; yellowish brown (10YR 5/4) extremely gravelly ashy loam, dark yellowish brown (10YR 3/4) moist; common fine granular structure; slightly hard, friable, slightly sticky, slightly plastic and weakly smeary; few fine roots; 55 percent gravel and 10 percent cobbles; moderately acid (pH 6.0); clear wavy boundary. (18 7 to 22 inches thick)
Bw3--52 to 62 inches; strong brown (7.5YR 5/6) extremely gravelly ashy loam, dark yellowish brown (10YR 3/6) moist; common very fine subangular blocky structure; slightly hard, friable, slightly sticky, slightly plastic and weakly smeary; 60 percent gravel and 5 percent cobbles; moderately acid (pH 5.8).
TYPE LOCATION: Yakima County, Washington; about 12 miles south of the Rimrock Lake spillway; 200 feet east and 100 feet south of the northwest corner section 27, T. 12 N., R. 12 E., W.M.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 44 to 46 degrees F. The soil moisture control section is usually moist, but is dry in all parts for 60 to 75 consecutive days following summer solstice. The umbric epipedon is 10 to 15 inches thick. The 0 to 40 inch particle-size control section has an estimated moist bulk density of 0.60 to 0.90 g/cc, volcanic glass content of 5 to 30 percent, acid oxalate extractable aluminum plus one-half iron of 2.0 to 3.0 percent, phosphate retention of 85 to 98 percent, and 15 bar water retention of 8 to 12 percent. The particle-size control section averages 35 to 70 percent gravel and cobbles. Reaction is moderately acid to neutral throughout.
The A horizon has hue of 10YR to 5YR, value of 3 to 5 dry, 2 or 3 moist and chroma of 2 or 3 dry or moist. Texture is stony ashy sandy loam, very stony ashy sandy loam, gravelly ashy sandy loam, or very gravelly ashy loam.
The AB horizon is present in some pedons. It has color similar to the A horizon and texture of gravelly ashy sandy loam, very gravelly ashy sandy loam, or very cobbly ashy sandy loam.
The Bw horizon has hue of 7.5YR or 10YR , value of 5 or 6 dry, 3 or 4 moist and chroma of 3 to 6 moist. Texture is extremely gravelly ashy sandy loam, very gravelly ashy sandy loam, very gravelly ashy loam, extremely gravelly ashy loam, very cobbly ashy sandy loam, extremely stony ashy loam, extremely stony ashy sandy loam extremely cobbly ashy loam, extremely cobbly ashy sandy loam, or extremely cobbly ashy fine sandy loam.
COMPETING SERIES: There are no competing series. Series with similar amorphic mineralogy is the Firoke soil, and with glassy mineralogy is the Fryrear, Pipp, Slicklog, Timberbutte, and Yapoah series. Firoke soils have 30 to 60 percent volcanic glass in the particle-size control section. Fryrear soils are 20 to 40 inches deep to bedrock. Pipp soils are dry for 45 to 60 consecutive days. Yapoah soils lack a Bw horizon and are loamy sand in the particle-size control section. Slicklog soils are dry for 45 to 60 consecutive days and have a mollic epipedon 20 to 35 inches thick. Timberbutte soils have a mollic epipedon 20 to 30 inches thick and have 30 to 50 percent volcanic glass.
GEOGRAPHIC SETTING: Tumac soils are on footslopes and southerly aspects on mountain side slopes. Slopes are 2 to 65 percent. Tumac soils formed in basalt and andesite colluvium mixed with volcanic ash. Elevations are 2,000 to 5,200 feet. Highest elevations are on south-facing slopes. These soils are in a climate with warm, dry summers and cool, moist winters. The mean annual precipitation is 30 to 60 inches. The mean January temperature is about 24 degrees F. and the mean July temperature is about 67 degrees F. The mean annual temperature is 42 to 45 degrees F. The frost-free season is 80 70 to 100 days
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Loneridge and Naxing soils. Loneridge soils are clayey-skeletal and have an argillic horizon. Naxing soils are cryic. Both of these soils are on mountain side slopes, summits, and benches.
DRAINAGE AND PERMEABILITY: Well drained; medium to rapid runoff; moderately rapid permeability.
USE AND VEGETATION: These soils are used for timber production, grazeable woodland, recreation, wildlife habitat, and watershed. Native vegetation is mainly Douglas-fir and ponderosa pine, and some lodgepole pine and western larch, with an understory of elk sedge, pinegrass, creambush oceanspray, lupine, snowbrush ceanothus, Idaho fescue, and Oregon-grape.
DISTRIBUTION AND EXTENT: South central Washington. MLRA 6. Series is of small extent.
MLRA OFFICE RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Yakima County, Washington, 1979.
REMARKS: Diagnostic horizon and features recognized in this pedon are:
Umbric epipedon - the zone from 2 to 17 inches
Cambic horizon - the zone from 17 to 62 inches
Andic soil properties - the zone from 2 to 62 inches
Particle-size control section - the zone from 2 to 42 inches
Depths to diagnostic horizons and features are measured from the top of the first mineral layer.
Classification revised 6/95 from medial-skeletal, frigid Andic
Xerumbrepts to Ashy-skeletal, frigid Humic Vitrixerands.
Classification revised 2/01 from ashy-skeletal, frigid Humic Vitrixerands to Ashy-skeletal, mixed, frigid Humic Vitrixerands.