LOCATION SQUIRDIRT               CA

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

SQUIRDIRT SERIES

The Squirdirt series consists of very deep, well drained soils that formed in colluvium and residuum derived from volcanic rocks. Squirdirt soils are on hills. Slopes are 30 to 50 percent. The mean annual precipitation is about 360 mm and the mean annual temperature is about 8 degrees C.

TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, frigid Pachic Argixerolls

TYPICAL PEDON: Squirdirt very gravelly sandy loam--Rangeland. (Colors are for dry soil unless otherwise noted.) The soil surface is covered with 30 percent gravel and 10 percent cobbles.

A1--0 to 5 cm; grayish brown (10YR 5/2) very gravelly sandy loam, very dark grayish brown (10YR 3/2) moist; weak fine subangular blocky structure; soft, very friable, nonsticky, nonplastic; many very fine roots; few very fine tubular and common very fine interstitial pores; 5 percent cobbles and 30 percent gravel; neutral, (pH 6.6); clear smooth boundary. (3 to 10 cm thick)

A2--5 to 23 cm; brown (10YR 5/3) very gravelly sandy loam, dark brown (10YR 3/3) moist; weak fine and medium subangular blocky structure; soft, very friable, nonsticky, nonplastic; many very fine and fine roots, common medium roots; common very fine interstitial and tubular pores; 35 percent gravel; neutral, (pH 6.8); clear wavy boundary. (10 to 20 cm thick)

Bt1--23 to 41 cm; brown (7.5YR 5/3) gravelly sandy loam, dark brown (7.5YR 3/3) moist; moderate fine and medium subangular blocky structure; slightly hard, very friable, slightly sticky, nonplastic; common very fine and fine roots, few medium and coarse roots; many very fine and fine interstitial and common very fine and fine tubular pores; 5 percent faint clay bridges between sand grains; 5 percent cobbles and 25 percent gravel; neutral, (pH 6.8); clear wavy boundary. (13 to 25 cm thick)

Bt2--41 to 76 cm; brown (7.5YR 5/3) gravelly sandy loam, dark brown (7.5YR 3/3) moist; weak medium subangular blocky structure; slightly hard, very friable, slightly sticky, nonplastic; few very fine to medium roots; common very fine and fine interstitial pores; 5 percent faint clay bridges between sand grains; 5 percent cobbles and 10 percent paragravel and 25 percent gravel; neutral, (pH 6.8); clear wavy boundary. (20 to 38 cm thick)

Bt3--76 to 152 cm; yellowish brown (10YR 5/4) gravelly sandy loam, dark yellowish brown (10YR 3/4) moist; massive; slightly hard, very friable, slightly sticky, nonplastic; few very fine to medium roots; 5 percent faint clay bridges between sand grains; 15 percent gravel and 15 percent paragravel; neutral, (pH 6.8).

TYPE LOCATION: Alpine County, California; about 2 kilometers southeast of Paynesville; about 2,000 feet south and 460 feet east of the northwest corner section 29, T. 11 N, R. 20 E.; Woodfords USGS 7.5 minute topographic quadrangle; latitude 38 degrees 47 minutes 19.0 seconds N and longitude 119 degrees 46 minutes 5.9 seconds W; WGS84 Decimal Degrees 38.7886111 latitude, -119.7683056 longitude.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually dry in the moisture control section; moist fall, winter and spring; usually dry July through early October; aridic moisture regime, bordering on xeric.
Mean annual soil temperature: 7 to 8 degrees C.
Mollic epipedon thickness: 60 to 90 cm.
Depth to bedrock: 100 to 200 cm to a paralithic contact. The paralithic materials below the contact are weathered andesitic rock.
Reaction: Slightly acid or neutral.

Particle-size control section - Clay content: Averages 12 to 18 percent.
Rock fragments: Averages 15 to 35 percent, mainly gravel. 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: 2 to 4 percent.

Bt1 and Bt2 horizons
Hue: 10YR or 7.5YR.
Value: 4 or 5 dry, 3 moist.
Chroma: 2 or 3, dry or moist.
Texture: Gravelly sandy loam or gravelly loam.
Clay content: Averages 12 to 18 percent.
Rock fragments: Averages 15 to 35 percent.
Organic matter content: 1 to 3 percent.

Bt3 horizon
Hue: 10YR or 7.5YR.
Value: 5 or 6 dry, 3 or 4 moist.
Chroma: 3 or 4, dry or moist.
Texture: Gravelly sandy loam or gravelly loam.
Clay content: Averages 12 to 18 percent.
Rock fragments: Averages 15 to 35 percent.
Organic matter content: 0.5 to 1 percent.

COMPETING SERIES: This is the Bearbutte series. Bearbutte soils have paralithic material below 100 to 150 cm and have more than 35 percent rock fragments in their 2Bt horizon.

GEOGRAPHIC SETTING: Squirdirt soils are on hills. They typically occur on backslope positions. They formed in residuum and colluvium derived from volcanic rocks. Slopes are 30 to 50 percent. Elevations range from 1,550 to 1,800 meters. The climate is semi-arid with cool, moist winters and warm, dry summers. The mean annual precipitation is 300 to 360 mm, mean annual temperature is 8 to 9 degrees C., and the frost-free period is 60 to 70 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Devada and Nomisurvay series. Devada soils have more than 35 percent clay in their particle-size control section and have lithic material within 50 cm. Nomisurvay soils have paralithic material within 36 cm.

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

USE AND VEGETATION: Squirdirt soils are used for livestock grazing, recreation, watershed and wildlife habitat. The native vegetation is mainly mountain big sagebrush, antelope bitterbrush, Thurber's needlegrass and western needlegrass.

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 76 cm (A1, A2, Bt1 and Bt2 horizons).
Argillic horizon - The zone from 23 to 152 cm (Bt1, Bt2 and Bt3 horizons).
Particle-size control section - The zone from 23 to 73 cm (Bt1 and upper Bt2 horizons).

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National Cooperative Soil Survey
U.S.A.