LOCATION HALFASH CA+NV

Established Series
Rev. EWB/JVC/JBF
03/2017

HALFASH SERIES

The Halfash series consists of shallow, well drained soils that formed in residuum and colluvium derived from andesite and tuff breccias with surficial additions of eolian volcanic ash. Halfash soils are on mountains and plateaus. Slopes are 4 to 50 percent. The mean annual precipitation is about 330 mm and the mean annual temperature is about 7 degrees C.

TAXONOMIC CLASS: Ashy-skeletal, glassy, frigid, shallow Vitritorrandic Argixerolls

TYPICAL PEDON: Halfash very gravelly ashy sandy loam--rangeland. (Colors are for dry soil unless otherwise noted.) The soil surface is covered with 30 percent gravel, 15 percent cobbles, and 5 percent stones.

A--0 to 8 cm; grayish brown (10YR 5/2) very gravelly ashy sandy loam, very dark grayish brown (10YR 3/2) moist; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine roots; many very fine interstitial and common fine tubular pores; 30 percent gravel and 5 percent cobbles; neutral (pH 6.7); clear wavy boundary. (5 to 10 cm thick)

Bt1--8 to 20 cm; brown (10YR 5/3) very gravelly ashy loam, dark brown (10YR 3/3) moist; weak fine subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; many very fine and fine and few medium roots; common very fine tubular and interstitial pores; common faint clay bridges between sand grains and few distinct clay films on faces of peds and lining pores; 30 percent gravel and 10 percent cobbles; neutral (pH 6.8); clear wavy boundary. (10 to 18 cm thick)

Bt2--20 to 43 cm; brown (10YR 5/3) very gravelly ashy clay loam, dark brown (10YR 3/3) moist; moderate fine and medium subangular blocky structure; slightly hard, very friable, moderately sticky and moderately plastic; common very fine, fine and medium roots; common very fine tubular and interstitial pores; common distinct clay films on faces of peds and lining pores; 45 percent gravel and 10 percent cobbles; neutral (pH 6.8); clear irregular boundary. (13 to 23 cm thick)

Cr--43 to 69 cm; weathered andesite.

TYPE LOCATION: Mono County, California; on the Toiyabe National Forest about 4.5 miles southeast of the Masonic Town site; approximately 2,400 feet south and 2,150 feet east of the northwest corner of section 32, T. 6 N., R. 26 E.; USGS Dome Hill 7.5 minute topographic quadrangle; latitude 38 degrees 19 minutes 33.6 seconds N and longitude 119 degrees 02 minutes 10.7 seconds W; WGS84 Decimal Degrees 38.3260000 latitude, -119.0363056 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually moist in winter and spring, dry from July through October; aridic moisture regime that borders on xeric.
Mean annual soil temperature: 7 to 8 degrees C.
Mollic epipedon thickness: 25 to 43 cm; includes the Bt1 horizon and also includes the Bt2 horizon in some pedons.
Depth to bedrock: 36 to 50 cm to a paralithic contact. The paralithic materials below the contact are weathered volcanic rock such as andesite.
Volcanic glass content: 35 to 60 percent in the coarse silt through fine sand fractions.

Particle-size control section - Clay content: Averages 20 to 30 percent. Rock fragments: Averages 35 to 60 percent, mainly gravel. Lithology of fragments is andesite.

A horizon
Chroma: 2 or 3, dry or moist.
Organic matter content: 1 to 3 percent.
Reaction: Slightly acid or neutral.

Bt1 horizon
Hue: 10YR or 7.5YR.
Clay content: 20 to 27 percent.
Rock fragments: 35 to 60 percent.
Organic matter content: 1 to 3 percent.

Bt2 horizon
Hue: 10YR or 7.5YR.
Value: 5 or 6 dry, 3 or 4 moist.
Chroma: 3 or 4, dry or moist.
Texture: Very gravelly ashy loam, very gravelly ashy sandy clay loam, or very gravelly ashy clay loam.
Clay content: 25 to 35 percent.
Rock fragments: 35 to 60 percent.
Organic matter content: 0.5 to 2 percent.

COMPETING SERIES: These are the Harskel and Roadside series.

Harskel soils are dominated by cobbles. Roadside soils have 12 to 18 percent clay in the particle-size control section.

GEOGRAPHIC SETTING: Halfash soils are on mountains and plateaus. They typically occur on shoulder, backslope or footslope positions. They formed in residuum and colluvium derived from andesite and tuff breccia with surficial additions of eolian volcanic ash. The probable sources of the volcanic ash are the Mono Craters and Long Valley Caldera in eastern California. Slopes are 4 to 50 percent. Elevations range from 2,015 to 2,685 meters. The climate is semiarid with cool, moist winters and warm, dry summers. The mean annual precipitation is 300 to 350 mm, the mean annual temperature is 6 to 7 degrees C., and the frost-free period is 60 to 80 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Domehill and Mopana soils. Domehill soils are shallow to lithic contacts. Mopana soils have more than 35 percent clay in the particle-size control section and are shallow to duripans.

DRAINAGE AND PERMEABILITY: Well drained; medium surface runoff; moderately slow permeability; moderately high saturated hydraulic conductivity.

USE AND VEGETATION: Halfash soils are used for livestock grazing, recreation, watershed, and wildlife habitat. The native vegetation is mainly mountain big sagebrush, antelope bitterbrush, Thurber's needlegrass, prairie junegrass, bluegrass, and scattered singleleaf pinyon.

DISTRIBUTION AND EXTENT: Eastern California and western Nevada, in the western part of the Great Basin. These soils are not extensive with about 940 acres of the series mapped to date. MLRA 26.

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

SERIES ESTABLISHED: Mineral County Area, Nevada, 2005. The series was proposed in Mono County (Toiyabe National Forest Area), California, 2004.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 43 cm (A, Bt1, and Bt2 horizons).
Argillic horizon - The zone from 8 to 43 cm (Bt1 and Bt2 horizons).
Vitrandic intergrade feature - The zone from the soil surface to 43 cm (A, Bt1, and Bt2 horizons).
Paralithic contact - The boundary at 43 cm to underlying soft, weathered bedrock (Cr layer).
Particle-size control section and ashy substitute class with glassy mineralogy - The zone from 8 to 43 cm (Bt1 and Bt2 horizons).

ADDITIONAL DATA: Volcanic glass content determined locally by optical grain count with a polarizing petrographic microscope.
User Pedon ID: 2004CA051100.

National Cooperative Soil Survey
U.S.A.