LOCATION WILLOWAK CA

Established Series
Rev. EWB-JBF-TM
06/2017

WILLOWAK SERIES

The Willowak series consists of moderately deep, well drained soils that formed in colluvium and residuum derived from volcanic rocks such as andesite, with additions of eolian volcanic ash. Willowak soils are on hills and mountains. Slopes are 8 to 50 percent. The mean annual precipitation is about 350 mm and the mean annual temperature is about 6 degrees C.

TAXONOMIC CLASS: Ashy-skeletal, glassy, frigid Vitrandic Argixerolls

TYPICAL PEDON: Willowak gravelly ashy sandy loam--rangeland. (Colors are for dry soil unless otherwise noted.) The soil surface is covered with 30 percent gravel, 10 percent cobbles, 15 percent stones and 10 percent boulders.

A1--0 to 5 cm; grayish brown (10YR 5/2) gravelly ashy sandy loam, very dark grayish brown (10YR 3/2) moist; weak fine and medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; few very fine roots; few very fine interstitial pores; 20 percent subangular andesite gravel; slightly acid (pH 6.2); clear wavy boundary. (5 to 13 cm thick)

A2--5 to 20 cm; brown (10YR 5/3) gravelly ashy sandy loam, dark brown (10YR 3/3) moist; weak fine and medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; many very fine to medium roots; few very fine and fine interstitial pores; 2 percent subangular andesite cobbles and 25 percent subangular andesite gravel; slightly acid (pH 6.4); clear wavy boundary. (0 to 25 cm thick)

Bt1--20 to 50 cm; brown (10YR 5/3) very gravelly ashy sandy loam, dark brown (10YR 3/3) moist; moderate fine and medium subangular blocky structure; slightly hard, very friable, slightly sticky and nonplastic; common fine to coarse roots; common very fine and fine interstitial pores; 5 percent faint clay bridges between sand grains; 10 percent subangular andesite cobbles and 40 percent subangular andesite gravel; slightly acid (pH 6.4); clear wavy boundary. (20 to 38 cm thick)

Bt2--50 to 86 cm; brown (7.5YR 5/3) very cobbly ashy sandy loam, dark brown (7.5YR 3/3) moist; moderate medium subangular blocky structure; moderately hard, friable, slightly sticky and nonplastic; few very fine and fine roots; common very fine and fine interstitial pores; 5 percent faint clay bridges between sand grains; 20 percent subangular andesite cobbles and 30 percent subangular andesite gravel; slightly acid (pH 6.2); clear wavy boundary. (20 to 50 cm thick)

Cr--86 to 99 cm; weathered andesitebedrock; clear wavy boundary.

R--99 cm; andesite bedrock.

TYPE LOCATION: Mono County, California; in the Bodie Hills about 0.75 mile northeast of Dog Town; in an unsurveyed area; section 26, R. 4 N., T. 25 E.; Big Alkali USGS 7.5 minute topographic quadrangle; latitude 38 degrees 10 minutes 28.9 seconds N and longitude 119 degrees 11 minutes 21.5 seconds W; WGS84 Decimal Degrees 38.1746944 latitude, -119.1893056 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually moist in the moisture control section; moist fall, winter and spring; usually dry July through early October; xeric moisture regime bordering on aridic.
Mean annual soil temperature: 7 to 8 degrees C.
Mollic epipedon thickness: 50 to 100 cm.
Depth to bedrock: 50 to 100 cm to a paralithic contact. The paralithic materials below the contact are weathered andesitic rock. Hard bedrock is typically within 76 to 127 cm of the soil surface.

Particle-size control section - Clay content: Averages 12 to 18 percent.
Rock fragments: Averages 35 to 60 percent, mainly gravel and cobbles. Lithology of rock fragments is volcanic rock such as andesite.

A horizon
Value: 4 or 5 dry, 3 moist.
Chroma: 2 or 3 dry or moist.
Organic matter content: 2 to 3 percent.
Reaction: Slightly acid or neutral.
Volcanic glass content: 30 to 75 percent in coarse silt through fine sand fractions.

Bt Horizons
Hue: 10YR or 7.5YR.
Value: 4 or 5 dry, 3 moist.
Chroma: Commonly 3 dry or moist, but may be 2 dry or moist in upper part.
Texture: Ashy sandy loam or ashy loam.
Clay content: 12 to 18 percent.
Rock fragments: 35 to 60 percent, mainly gravel and cobbles.
Organic matter content: 1 to 3 percent.
Reaction: Slightly acid or neutral.
Volcanic glass content: 30 to 75 percent in coarse silt through fine sand fractions.

COMPETING SERIES: These are the Chesebro, Eep, Lyonman, Monasterio, Tourn, Vetash and Warnermount soils.

Chesebro, Eep, Lyonman, Monasterio, Tourn, Vetash and Warnermount soils have more than 18 percent clay in their particle-size control section.

GEOGRAPHIC SETTING: Willowak soils are on hills and mountains. They typically occur on backslope positions. They formed in colluvium and residuum derived from volcanic rocks such as andesite, with additions of eolian volcanic ash. Slopes are 8 to 50 percent. Elevations range from 2,000 to 2,500 meters. The climate is semi-arid with cool, moist winters and warm, dry summers. The mean annual precipitation is 350 to 400 mm, mean annual temperature is 6 to 8 degrees C., and the frost-free period is 40 to 70 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Domehill, Epvip and Roadside series. All of these soils have bedrock within 50 cm of the surface. In addition, Domehill and Epvip soils have more than 18 percent clay in their particle-size control sections.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; medium surface runoff; moderately rapid permeability; high saturated hydraulic conductivity.

USE AND VEGETATION: Willowak soils are used for livestock grazing, recreation, watershed, and wildlife habitat. The native vegetation is mainly mountain big sagebrush, antelope bitterbrush, western needlegrass, Indian ricegrass, basin wildrye and snowberry.

DISTRIBUTION AND EXTENT: Eastern California, east of the Sierra Nevada Range. These soils are not extensive. MLRA 26.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California.

SERIES ESTABLISHED: Mono County (Coleville-Bridgeport Area), California, 2010.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 86 cm (A1, A2, Bt1 and Bt2 horizons).
Argillic horizon - The zone from 20 to 86 cm (Bt1 and Bt2 horizons).
Paralithic contact - The boundary at 86 cm to underlying soft bedrock (Cr layer).
Vitrandic intergrade feature -- High volcanic glass content in the .02 to 2mm fraction from the mineral soil surface to 86 cm (A1, A2, Bt1 and Bt2 horizons).
Particle-size control section - The zone from 20 to 86 cm (Bt1 and Bt2 horizons).

ADDITIONAL DATA: User Pedon ID: 2006CA051029.

National Cooperative Soil Survey
U.S.A.