LOCATION CHIWAWA WAEstablished Series
TAXONOMIC CLASS: Ashy, glassy, frigid Typic Vitrixerands
TYPICAL PEDON: Chiwawa paragravelly ashy fine sandy loam - on a 2 percent southeast-facing slope in a forest at 1,930 feet elevation. (Colors are for dry soil unless otherwise stated. All textures are apparent field textures.)
Oi--0 to 2 inches; slightly decomposed duff of needles, twigs, cones, and grass. (1/2 to 2 inches thick)
Oe--2 to 4 inches; moderately decomposed needles, twigs, and cones. (1/2 to 2 inches thick)
A1--4 to 6 inches; grayish brown (10YR 5/2) paragravelly ashy fine sandy loam, very dark grayish brown (10YR 3/2) moist; weak fine granular structure; soft, very friable, nonsticky and nonplastic; common fine and medium roots; few fine tubular pores; 20 percent pumice; moderately acid (pH 6.0); abrupt broken boundary. (0 to 2 inches thick)
A2--6 to 8 inches; brown (10YR 5/3) paragravelly ashy fine sandy loam, dark brown (10YR 3/3) moist; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; common fine and medium roots; common very fine tubular pores; 20 percent pumice; 3 percent pebbles and 2 percent cobbles; slightly acid (pH 6.4); abrupt smooth boundary. (1 to 3 inches thick)
Bw1--8 to 12 inches; pale brown (10YR 6/3) paragravelly ashy fine sandy loam, dark brown (10YR 4/3) moist; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; common fine and medium roots; few fine and medium tubular pores; 20 percent pumice; 3 percent pebbles and 2 percent cobbles; slightly acid (pH 6.4); gradual smooth boundary. (3 to 5 inches thick)
Bw2--12 to 29 inches; pale brown (10YR 6/3) paragravelly ashy fine sandy loam, dark yellowish brown (10YR 4/4) moist; weak fine granular structure; soft, very friable, nonsticky and nonplastic; few fine roots; few fine and medium tubular pores; 25 percent pumice; 3 percent pebbles and 2 percent cobbles; neutral (pH 7.2) gradual smooth boundary. (15 to 20 inches thick)
BC--29 to 49 inches; pale brown (10YR 6/3) paragravelly ashy fine sandy loam, dark yellowish brown (10YR 4/4) moist; massive to very weak fine granular structure; soft, very friable, nonsticky and nonplastic; few fine roots; few fine and medium tubular pores; 20 percent pumice; 5 percent pebbles and 5 percent cobbles; neutral (pH 7.2); abrupt wavy boundary. (15 to 40 inches thick)
2C2--49 to 64 inches; multicolored extremely gravelly sand; loose; 50 percent pebbles, 20 percent cobbles; neutral (pH 7.2).
TYPE LOCATION: Chelan County, Washington; about 3 miles northwest of Plain; 1,320 feet south of the center of sec. 25, T. 24 N., R. 17E.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 45 to 47 degrees F. These soils are usually moist, but are dry in the moisture control section for 60 to 75 consecutive days following 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, acid-oxalate extractable aluminum plus one-half of the acid-oxalate extractable iron of 1.0 to 2.0 percent, 15-bar water retention of 5 to 12 percent for air dried samples, and 15 to 35 percent pumice. Depth to the 2C horizon is 40 to 60 inches.
The A horizon has value of 4 to 6 dry, 2 to 5 moist, and chroma of 1 to 3 dry or moist. It has weak granular or platy structure.
The Bw horizon has value of 5 through 7 dry, 4 or 5 moist, and chroma of 3 or 4 dry or moist. It is paragravelly ashy fine sandy loam or paragravelly ashy sandy loam. It has weak subangular blocky or granular structure. Reaction is slightly acid to neutral.
The BC horizon has value of 5 to 7 dry, 4 or 5 moist, and chroma of 3 or 4 dry or moist. It is paragravelly ashy fine sandy loam or paragravelly ashy sandy loam. Reaction is slightly acid or neutral.
The 2C horizon is very gravelly sand, extremely gravelly sand or extremely cobbly sand. The 2C horizon contains 0 to 5 percent pumice.
COMPETING SERIES: These are the Polander, Rathdrum, and Thow series. Polander soils have 0 to 15 percent rock fragments and lack pumice fragments. Rathdrum soils are silt loam, loam, or very fine sandy loam throughout the particle-size control section and are dry less than 60 consecutive days. Thow soils are on mountains and lack the underlying glacial outwash material.
GEOGRAPHIC SETTING: Chiwawa soils are on terraces at elevations of 1,700 to 2,500 feet. Slopes are 0 to 3 percent. These soils formed in volcanic ash, pumice, and a small amount of loess overlying glacial outwash. They are in a climate with warm, dry summers and cold, moist winters. The average annual precipitation ranges from 25 to 40 inches. The mean January temperature is about 24 degrees F, mean July temperature is about 69 degrees F, mean annual air temperature is about 44 degrees F. The frost-free season ranges from 90 to 120 days.
GEOGRAPHICALLY ASSOCIATED SOILS: This is the Nevine and the competing Thow soils. Nevine soils are ashy over loamy-skeletal.
DRAINAGE AND PERMEABILITY: Well drained, very slow runoff, moderate permeability above the 2 horizon and very rapid permeability through the 2C horizon.
USE AND VEGETATION: Mostly for grazable woodland, wildlife, and watershed. Some is used for hay, pasture, and summer homes. Native vegetation is Douglas-fir, ponderosa pine, and lodgepole pine, with an understory of vine maple, pinegrass, spirea, and creambush oceanspray.
DISTRIBUTION AND EXTENT: East slopes of the Cascade Mountains in north-central Washington; MLRA 6. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Chelan County, Washington, 1969.
REMARKS: Diagnostic horizons and features recognized in this pedon are an ochric epipedon from the mineral surface to 4 inches, a cambic horizon from 4 to 25 inches. The particle-size control section is the zone from 0 to 40 inches (A1, A2, Bw1, Bw2, and part of BC horizon).