LOCATION UAWDA CA+NV

Established Series
Rev. AMB-EWB-TM-JVC
06/2017

UAWDA SERIES

The Uawda series consists of moderately deep, well drained soils that formed in colluvium and residuum derived from volcanic rocks with surficial additions of eolian volcanic ash. Uawda soils are on plateaus and moutains. Slopes are 4 to 30 percent. The mean annual precipitation is about 380 mm and the mean annual temperature is about 6 degrees C.

TAXONOMIC CLASS: Ashy-skeletal over clayey, glassy over smectitic, frigid Vitrandic Argixerolls

TYPICAL PEDON: Uawda gravely ashy loamy fine sand--rangeland. (Colors are for dry soil unless otherwise noted.) The soil surface is covered with 20 percent gravel, 10 percent cobbles, 3 percent stones, and 1 percent boulders.

A1--0 to 3 cm; brown (10YR 5/3) gravelly ashy loamy fine sand, dark brown (10YR 3/3) moist; single grain; loose, nonsticky and nonplastic; few very fine roots; many very fine interstitial pores; 5 percent subangular cobbles and 10 percent subangular gravel; slightly acid (pH 6.2); clear smooth boundary. (3 to 8 cm thick)

A2--3 to 13 cm; brown (10YR 5/3) very gravelly ashy loamy fine sand, dark brown (10YR 3/3) moist; weak fine and medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; common fine roots and many very fine roots; many very fine interstitial and common very fine tubular pores; 20 percent subangular cobbles and 35 percent subangular gravel; slightly acid (pH 6.2); clear wavy boundary. (5 to 25 cm thick)

Bt1--13 to 25 cm; brown (10YR 5/3) very gravelly ashy loam, dark brown (10YR 3/3) moist; moderate fine subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common fine roots and many very fine roots; common very fine tubular and common very fine interstitial pores; 25 percent faint clay bridges between sand grains; 20 percent subangular cobbles and 35 percent subangular gravel; slightly acid (pH 6.3); clear wavy boundary. (5 to 20 cm thick)

Bt2--25 to 53 cm; brown (10YR 5/3) very gravelly ashy clay loam, dark brown (10YR 3/3) moist; moderate fine and medium angular blocky structure; hard, friable, moderately sticky and moderately plastic; common very fine to medium roots; common very fine tubular and interstitial pores; 25 percent distinct clay films on faces of peds and lining pores; 5 percent subangular cobbles and 50 percent subangular gravel; slightly acid (pH 6.4); clear wavy boundary. (13 to 38 cm thick)

2Bt--53 to 71 cm; brown (7.5YR 5/4) clay, brown (7.5YR 4/3) moist; strong fine and medium prismatic structure; very hard, very firm, very sticky and very plastic; few fine and common very fine roots; common very fine tubular and interstitial pores; 90 percent prominent clay films lining pores; prominent pressure cutans on faces of peds; 10 percent subangular gravel; slightly acid (pH 6.5); clear wavy boundary. (13 to 25 cm thick)

2Btq--71 to 89 cm; strong brown (7.5YR 5/6) paragravelly clay loam, strong brown (7.5YR 4/6) moist; strong fine and medium angular blocky structure; hard, friable, moderately sticky and moderately plastic; few very fine roots; few very fine tubular and interstitial pores; 25 percent distinct clay films lining pores and 25 percent distinct clay films on faces of peds; 15 percent paragravel; 1 to 2 millimeter thick silica coats on pararock fragments and 10 percent 1 to 2 millimeter thick weakly silica-cemented seams; slightly acid (pH 6.5); clear wavy boundary. (10 to 30 cm thick)

2Cr--89 to 124 cm; weathered andesite bedrock.

TYPE LOCATION: Mono County, California; in the Bodie Hills about 1,128 meters southeast of Beauty Peak along the California-Nevada state line; approximately 2,900 feet north and 2,930 feet east of the southwest corner of section 23, T. 5 N., R. 27 E.; USGS Aurora 7.5 minute topographic quadrangle; latitude 38 degrees 16 minutes 45.7 seconds N and longitude 118 degrees 57 minutes 59 seconds W; WGS84 Decimal Degrees 38.2793611 latitude, -118.9663889 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually moist in the moisture control section during late fall, winter, and spring; usually dry from July through early October; xeric moisture regime that borders on aridic.
Mean annual soil temperature: 7 to 8 degrees C.
Mollic epipedon thickness: 50 to 76 cm; includes the Bt1 and Bt2 horizons.
Depth to major lithologic discontinuity: 25 to 55 cm.
Depth to bedrock: 76 to 100 cm to a paralithic contact. The paralithic materials below the contact are weathered volcanic rock.

Particle-size control section - Clay content: 25 to 35 percent in the upper part and 35 to 55 percent in the strongly contrasting lower part.
Rock fragments: Averages 35 to 60 percent in the upper part and 0 to 15 percent in the strongly contrasting lower part, mainly gravel and cobbles. Lithology of rock fragments is volcanic rock such as andesite.

A horizons
Value: 4 or 5 dry, 2 or 3 moist.
Chroma: 2 or 3, dry or moist.
Organic matter content: 1 to 3 percent.
Reaction: Slightly acid or neutral.
Volcanic glass content: 50 to 75 percent in very fine sand and fine sand fractions.

Bt1 and Bt2 horizons
Hue: 10YR or 7.5YR.
Chroma: 2 or 3, dry or moist.
Texture: Very cobbly ashy loam or very gravelly ashy clay loam.
Clay content: 25 to 35 percent.
Rock fragments: 35 to 60 percent.
Organic matter content: 1 to 3 percent.
Reaction: Slightly acid or neutral.
Volcanic glass content: 40 to 70 percent in very fine sand and fine sand fractions.

2Bt3 horizon
Hue: 10YR or 7.5YR.
Value: 3 or 4 moist.
Chroma: 3 or 4 moist.
Clay content: 40 to 55 percent.
Rock fragments: 0 to 15 percent.
Reaction: Slightly acid or neutral.

2Btq horizon
Hue: 7.5YR or 10YR.
Value: 5 or 6 dry.
Chroma: 4 or 6, dry or moist.
Texture: Paragravelly clay loam or clay.
Clay content: 35 to 45 percent.
Rock fragments: 0 to 10 percent gravel.
Pararock fragments: 5 to 20 percent paragravel.
Reaction: Slightly acid or neutral.
Secondary silica: 5 to 15 percent weakly to moderately silica-cemented seams and coats on fragments.

COMPETING SERIES: There are currently no other series in this family.

GEOGRAPHIC SETTING: Uawda soils are on plateaus and mountains. They typically occur on summit, shoulder and toeslope positions. They formed in residuum and colluvium derived from volcanic rocks 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 30 percent. Elevations range from 2,200 to 2,700 meters. The climate is semiarid with cold, moist winters and warm, dry summers. The mean annual precipitation is 350 to 400 mm, the mean annual temperature is 6 to 7 degrees C, and the frost-free period is 30 to 60 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Mopana and Needahoe soils. Mopana soils have a duripan within 50 cm of the soil surface and have an abrupt boundary in the upper part of the argillic horizon. Needahoe soils have less than 35 percent rock fragments in the upper part of the argillic horizon and have a duripan within 100 cm of the soil surface.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; low or medium surface runoff; slow permeability; moderately low saturated hydraulic conductivity.

USE AND VEGETATION: Uawda soils are used for livestock grazing, recreation, watershed, and wildlife habitat. The native vegetation is mainly mountain big sagebrush, antelope bitterbrush, western needlegrass, basin wildrye, Douglas rabbitbrush, and bottlebrush squirreltail.

DISTRIBUTION AND EXTENT: Eastern California and western Nevada, in the western part of the Great Basin. 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 53 cm (A1, A2, Bt1, and Bt2 horizons).
Argillic horizon - The zone from 13 to 89 cm (Bt1, Bt2 2Bt, and 2Btq horizons).
Vitrandic intergrade feature - The zone from the soil surface to 53 cm (A1, A2, Bt1, and Bt2 horizons).
Major lithologic discontinuity - The change to clayey material at 53 cm (between the Bt2 and 2Bt horizons).
Paralithic contact - The boundary at 89 cm to underlying weathered bedrock (2Cr layer).
Particle-size control section - The zone from 13 to 89 cm (Bt1, Bt2, 2Bt, and 2Btq horizons).

ADDITIONAL DATA: Volcanic glass content in the Bt1 and Bt2 horizons was determined locally by optical grain counts using a polarizing petrographic microscope. Observed glass contents in these horizons are 67 and 57 percent in the fine sand fractions, respectively.
Classification was changed 3/2017 from Ashy over clayey, glassy over smectitic, frigid Vitrandic Argixerolls to Ashy-skeletal over clayey, glassy over smectitic, frigid Vitrandic Argixerolls.
User Pedon ID: 2007CA051008.

National Cooperative Soil Survey
U.S.A.