LOCATION SONORAPASS CAEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, isotic Xeric Humicryepts
TYPICAL PEDON: Sonorapass very gravelly coarse sandy loam--forest land. (Colors are for dry soil unless otherwise noted.) The soil surface is covered with 25 percent gravel, 5 percent cobbles, 5 percent stones, and 5 percent boulders.
A1--0 to 3 inches; grayish brown (10YR 5/2) very gravelly coarse sandy loam, very dark grayish brown (10YR 3/2) moist; moderate medium platy parting to moderate fine subangular blocky structure; slightly hard, very friable, nonsticky and nonplastic; many very fine and common fine roots; common very fine tubular and interstitial pores; 35 percent gravel; slightly acid; clear smooth boundary. (1 to 4 inches thick)
A2--3 to 8 inches; grayish brown (10YR 5/2) very gravelly coarse sandy loam, very dark grayish brown (10YR 3/2) moist; weak fine and medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine through very coarse roots; common very fine tubular and interstitial pores; 35 percent gravel and 15 percent cobbles; moderately acid; clear wavy boundary. (4 to 6 inches thick)
Bw1--8 to 17 inches; brown (10YR 5/3) extremely cobbly coarse sandy loam, dark brown (10YR 3/3) moist; weak fine and medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine through very coarse roots; 45 percent gravel, 20 percent cobbles, and 5 percent stones; moderately acid; clear wavy boundary. (5 to 15 inches thick)
Bw2--17 to 21 inches; yellowish brown (10YR 5/4) extremely gravelly coarse sandy loam, dark yellowish brown (10YR 3/4) moist; weak medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine, fine, medium, coarse and very coarse roots; common very fine tubular and interstitial pores; 40 percent gravel and 20 percent cobbles; moderately acid; abrupt irregular boundary. (4 to 15 inches thick)
2R--21 inches; hard, unweathered granodiorite.
TYPE LOCATION: Mono County, California; on the Toiyabe National Forest about 1,900 feet southeast of Sardine Meadow; approximately 2,100 feet south and 1,450 feet east of the northwest corner of section 6, T. 5 N., R. 22 E.; USGS Pickel Meadow 7.5 minute topographic quadrangle; 38 degrees 18 minutes 42.7 seconds north latitude and 119 degrees 35 minutes 57.8 seconds west longitude, NAD27.
RANGE IN CHARACTERISTICS:
Soil moisture - Usually moist in the moisture control section during late fall, winter, and spring; dry from mid-July through September for 60 to 80 consecutive days in the four months following the summer solstice; Typic xeric moisture regime.
Mean annual soil temperature - 40 to 44 degrees F.
Mean summer soil temperature - 44 to 47 degrees F.
Umbric epipedon thickness - 14 to 20 inches; includes the Bw1 horizon.
Depth to bedrock - 20 to 40 inches to a lithic contact.
Particle-size control section - Clay content: Averages 10 to 18 percent; Rock fragments: Averages 60 to 80 percent, mainly gravel and cobbles. Lithology of fragments are mixed igneous and metamorphic rocks such as andesite, granodiorite, schist, or gneiss.
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: Moderately acid or slightly acid.
Sodium fluoride pH: 8.5 to 9.5.
Bw1 horizon
Chroma: 2 or 3, dry or moist.
Texture: Extremely gravelly coarse sandy loam or extremely cobbly coarse sandy loam.
Clay content: 10 to 18 percent.
Rock fragments: 60 to 80 percent.
Organic matter content: 2 to 4 percent.
Reaction: Strongly acid or moderately acid.
Sodium fluoride pH: 9.5 to 11.5.
Bw2 horizon
Chroma: 3 or 4, dry or moist.
Texture: Extremely gravelly coarse sandy loam or extremely cobbly coarse sandy loam.
Clay content: 10 to 18 percent.
Rock fragments: 60 to 80 percent.
Reaction: Strongly acid or moderately acid.
Sodium fluoride pH: 9.5 to 11.5.
COMPETING SERIES: These are the Callat (T), Fishsnooze, Florand, Forsell, Lostridge, Sibelia, and Sumeadow series.
Callat soils are moderately deep to densic contacts. Fishsnooze soils have A1 horizons with 10 to 18 percent organic matter. Florand and Sibelia soils are deep to paralithic contacts. Forsell and Sumeadow soils are very deep. Lostridge soils are moderately deep to paralithic contacts.
GEOGRAPHIC SETTING: Sonorapass soils are on mountains with superimposed moraines. They typically occur on summit and footslope positions. They formed in reworked till derived mainly from volcanic rocks such as andesite. Some areas are influenced by colluvium derived from granodiorite, schist, or gneiss. Slopes are 8 to 30 percent. Elevations range from 8,000 to 10,000 feet. The climate is subhumid-continental with cold, moist winters and cool, dry summers. The mean annual precipitation is 30 to 50 inches, mean annual temperature is 36 to 39 degrees F., and the frost-free period is 30 to 60 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Snowtell and Stumpatil soils. Snowtell soils have a lithic contact within 10 inches. Stumpatil soils are deeper than 60 inches to bedrock.
DRAINAGE AND PERMEABILITY: Well drained; very high surface runoff; moderately rapid permeability (high saturated hydraulic conductivity).
USE AND VEGETATION: Sonorapass soils are used for forestland, recreation, watershed, and wildlife habitat. The native vegetation is mainly a forest canopy of lodgepole pine with an understory of sedge and bluegrass.
DISTRIBUTION AND EXTENT: Eastern California, on the east side of the Sierra Nevada Range. These soils are not extensive with about 500 acres of the series mapped to date. MLRA 22A.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Mono County (Toiyabe National Forest Area), California, 2006.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Umbric epipedon - The zone from the soil surface to 17 inches (A1, A2, and Bw1 horizons).
Cambic horizon - The zone from 17 to 21 inches (Bw2 horizon).
Lithic contact - The boundary at 21 inches to underlying hard, unweathered bedrock (2R layer).
Particle-size control section - The zone from 10 to 21 inches (Bw2 horizon and part of the Bw1 horizon).
The revision of December 2006 updated the taxonomic class from Xeric Dystrocryepts based on the tenth edition of the Keys to Soil Taxonomy, 2006.
The isotic mineralogy class is based on the field determined values for sodium fluoride pH.