LOCATION MONIBASIN CAEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive Pachic Argicryolls
TYPICAL PEDON: Monibasin gravelly sandy loam--rangeland. (Colors are for dry soil unless otherwise noted.) The soil surface is covered with 20 percent gravel and 2 percent boulders.
A1--0 to 2 inches; grayish brown (10YR 5/2) gravelly 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; common very fine interstitial pores; 20 percent gravel and 1 percent boulders; slightly acid; clear wavy boundary. (1 to 4 inches thick)
A2--2 to 7 inches; grayish brown (10YR 5/2) gravelly sandy loam, very dark grayish brown (10YR 3/2) moist; moderate fine subangular blocky structure; slightly hard, very friable, slightly sticky and nonplastic; many very fine roots; common very fine interstitial and tubular pores; 20 percent gravel; slightly acid; clear wavy boundary. (2 to 6 inches thick)
A3--7 to 15 inches; brown (10YR 5/3) gravelly sandy loam, dark brown (10YR 3/3) moist; moderate medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine and fine roots; common very fine interstitial and tubular pores; 20 percent gravel; slightly acid; clear wavy boundary. (5 to 8 inches thick)
Bt1--15 to 34 inches; brown (7.5YR 5/3) extremely stony sandy loam, dark brown (7.5YR 3/3) moist; moderate medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; few very fine and fine roots; common very fine interstitial and tubular pores; few faint clay bridges between sand grains; 20 percent gravel, 5 percent cobbles, and 50 percent stones; neutral; clear wavy boundary. (12 to 20 inches thick)
Bt2--34 to 60 inches; 90 percent pale brown (10YR 6/3) and 10 percent brown (7.5YR 5/3) very stony sandy loam, brown (10YR 4/3) moist; moderate fine and medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; few very fine and fine roots; common very fine interstitial and tubular pores; few faint clay bridges between sand grains; 20 percent gravel, 10 percent cobbles, and 10 percent stones; neutral.
TYPE LOCATION: Alpine County, California; on the Toiyabe National Forest about 0.5 mile west of Monitor Pass; approximately 1,000 feet south and about 900 feet east of the northwest corner of section 36, T. 10 N., R. 21 E.; USGS Heenan Lake 7.5 minute topographic quadrangle; 38 degrees 40 minutes 26.4 seconds north latitude and 119 degrees 37 minutes 43.2 seconds west longitude, NAD27.
RANGE IN CHARACTERISTICS:
Soil moisture - Usually moist in the moisture control section during late fall, winter, and spring; dry from July through early October for 60 to 80 consecutive days in the four months following the summer solstice; Typic xeric moisture regime.
Mean annual soil temperature - 42 to 46 degrees F.
Mean summer soil temperature - 52 to 59 degrees F.
Mollic epipedon thickness - 26 to 36 inches, includes the Bt1 horizon.
Depth to base of argillic horizon - more than 60 inches.
Sodium fluoride pH - 8.5 to 9.0.
Particle-size control section - Clay content: Averages 18 to 25 percent; Rock fragments: Averages 60 to 80 percent, mainly stones. Lithology of fragments are volcanic rocks such as tuff, tuff-breccia, or 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.
Reaction: Slightly acid or neutral.
Bt1 horizon - Hue: 10YR or 7.5YR.
Texture: Extremely stony sandy loam or extremely stony sandy clay loam.
Clay content: 18 to 25 percent.
Rock fragments: 60 to 80 percent.
Organic matter content: 1 to 3 percent.
Reaction: Slightly acid or neutral.
Bt2 horizon - Hue: 10YR or 7.5YR.
Texture: Extremely stony sandy loam or very stony sandy clay loam.
Clay content: 18 to 25 percent.
Rock fragments: 35 to 80 percent.
Reaction: Slightly acid or neutral.
COMPETING SERIES: These are the Angelwhine, Aspetill, Badwater, Bickmore, Bluebell, Booneville, Buena Vista, Dab, Dailybasin (T), Delhew, Hawkinspeak, Keman, Littlemud (T), Lostcannon, Parkalley (T), Parkay, Redbird, Rutherford, Sweetmount, and Woodhurst series.
Angelwhine soils have mollic epipedons that are less than 24 inches thick and are dominated by gravel in the particle-size control section. Aspetill soils have mean summer soil temperature of 47 to 52 degrees F. and are dominated by cobbles in the particle-size control section. Badwater soils have 25 to 35 percent clay and are dominated by boulders in the particle-size control section. Bickmore, Bluebell, Buena Vista, Hawkinspeak, Littlemud, Rutherford, and Woodhurst soils are moderately deep to lithic contacts. Booneville soils have mean annual soil temperature of 36 to 40 degrees F. Dab soils are dominated by gravel in the particle-size control section. Dailybasin soils have an ustic moisture regime. Delhew soils have less than 18 percent clay, are dominated by fine gravel (2 to 5 mm diameter) in the particle-size control section, and have rock fragments that are granitic rocks. Keman soils are dominated by gravel in the particle-size control section and have mean annual soil temperature of 39 to 42 degrees F. Lostcannon soils have less than 18 percent clay in the particle-size control section and have rock fragments that are granitic rocks. Parkalley soils have the base of the argillic horizon between 28 and 35 inches from the soil surface and are dominated by flagstones. Parkay soils average 27 to 35 percent clay in the particle-size control section. Redbird soils average 27 to 35 percent clay in the particle-size control section and have horizons with identifiable secondary carbonates within 40 inches of the soil surface. Sweetmount soils are deep to paralithic contacts and have subhorizons of the argillic horizon with 27 to 50 percent clay.
GEOGRAPHIC SETTING: Monibasin soils are on mountains. They typically occur on footslope positions. They formed in slope alluvium derived from tuff, tuff-breccia, and andesite. Slopes are 4 to 15 percent. Elevations range from 7,500 to 8,500 feet. The climate is subhumid-continental with cold, moist winters and cool, dry summers. The mean annual precipitation is 16 to 24 inches, the mean annual temperature is 37 to 43 degrees F., and the frost-free period is 30 to 60 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Aspocket and Vermdig soils. Aspocket soils are deep to paralithic contacts and have mean summer soil temperature of 47 to 52 degrees F. Vermdig soils are fine-loamy and have a seasonal high water table within 30 to 40 inches of the soil surface.
DRAINAGE AND PERMEABILITY: Well drained; medium surface runoff; moderate permeability (moderately high or high saturated hydraulic conductivity).
USE AND VEGETATION: Monibasin soils are used for rangeland, recreation, watershed, and wildlife habitat. The native vegetation is mainly mountain big sagebrush, Letterman's needlegrass, and sedge.
DISTRIBUTION AND EXTENT: Eastern California, on the east side of the Sierra Nevada Range. These soils are not extensive with about 580 acres of the series mapped to date. MLRAs 22A and 26.
MLRA OFFICE RESPONSIBLE: Reno, Nevada.
SERIES ESTABLISHED: Alpine County (Toiyabe National Forest Area), California, 2006.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 34 inches (A1, A2, A3, and Bt1 horizons).
Argillic horizon - The zone from 15 to 60 inches (Bt1 and Bt2 horizons).
Particle-size control section - The zone from 15 to 35 inches (Bt1 horizon and part of the Bt2 horizon).
The revision of October 2003 updated the taxonomic class from Loamy-skeletal, isotic Pachic Argicryolls. The isotic mineralogy class was based solely on the field determined values for sodium fluoride pH. Laboratory data on 15 bar water to clay ratio does not exist to verify the isotic mineralogy class.