LOCATION MOUNTPATTERSON CAEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive Lithic Argicryolls
TYPICAL PEDON: Mountpatterson extremely gravelly ashy sandy loam--rangeland. (Colors are for dry soil unless otherwise noted.) The soil surface is covered with 25 percent gravel, 5 percent channers, 30 percent cobbles, and 20 percent stones.
A1--0 to 2 inches; very dark grayish brown (10YR 3/2) extremely gravelly ashy sandy loam, very dark brown (10YR 2/2) moist; weak fine granular structure; soft, very friable, slightly sticky and slightly plastic; many very fine and few fine roots; many very fine interstitial pores; 40 percent gravel, 20 percent cobbles, and 1 percent stones; neutral; clear smooth boundary. (2 to 4 inches thick)
A2--2 to 9 inches; dark grayish brown (10YR 4/2) extremely gravelly ashy sandy loam, dark brown (10YR 3/3) moist; moderate fine granular structure; soft, very friable, slightly sticky and slightly plastic; many very fine, common fine and few medium roots; many very fine and fine interstitial pores; 50 percent gravel and 15 percent cobbles; slightly acid; clear wavy boundary. (5 to 9 inches thick)
Bt--9 to 18 inches; dark grayish brown (10YR 4/2) extremely gravelly ashy loam, dark brown (10YR 3/3) moist; weak moderate subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; common very fine and fine, and few medium roots; common very fine and fine interstitial pores; few distinct clay films on faces of peds, lining pores, and coating rock fragments; 60 percent gravel and 15 percent cobbles; slightly acid; abrupt wavy boundary. (7 to 10 inches thick)
R--18 inches; fractured metavolcanic rock.
TYPE LOCATION: Mono County, California; on the Toiyabe National Forest in the Sweetwater Mountains between Mount Patterson and Wheeler Peak; in the nonsectionized township T. 7 N., R. 24 E.; USGS Mount Patterson 7.5 minute topographic quadrangle; 38 degrees 25 minutes 37.2 seconds north latitude and 119 degrees 17 minutes 55.0 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 - 35 to 40 degrees F.
Mean summer soil temperature - 46 to 52 degrees F.
Mollic epipedon thickness - 14 to 20 inches; includes the Bt horizon.
Depth to base of argillic horizon - 14 to 20 inches.
Depth to bedrock - 14 to 20 inches to a lithic contact.
Particle-size control section - Clay content: Averages 18 to 27 percent; Rock fragments: Averages 60 to 85 percent, mainly gravel. Lithology of rock fragments are volcanic rock such as andesite and tuff or metavolcanic rock.
Volcanic glass content - 15 to 30 percent in coarse silt through fine sand fractions.
Oxalate extractable aluminum plus one-half oxalate iron - 0.2 to 0.4 percent.
A horizons - Value: 3 through 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.
Bt horizon - Value: 4 or 5 dry.
Chroma: 2 or 3, dry or moist.
Texture: Extremely gravelly ashy loam or extremely gravelly ashy sandy clay loam.
Clay content: 18 to 27 percent.
Rock fragments: 60 to 85 percent.
Organic matter content: 1 to 3 percent.
Reaction: Slightly acid or neutral.
COMPETING SERIES: These are the Bushpark, Copenhaver, Donkehill (T), Hogmalat, Layview, Maygal (T), Mosroc, Nielsen, Nieman, Notstew (T), and Thiefridge series.
Bushpark soils have a udic moisture regime. Copenhaver and Nieman soils have an ustic moisture regime. Donkehill soils have horizons with identifiable secondary carbonates and are slightly alkaline or moderately alkaline. Hogmalat soils average 35 to 55 percent rock fragments in the particle-size control section and have mean summer soil temperature of 54 to 57 degrees F. Layview soils have lithic contacts that are within 14 inches of the soil surface and average 35 to 60 percent rock fragments in the particle-size control section. Maygal soils have mean summer soil temperature of 54 to 59 degrees F. Mosroc soils have mean summer soil temperature of 54 to 59 degrees F., have less than 60 percent rock in the particle-size control section, and have rock fragments that are granitic rocks. Nielsen soils have mean summer soil temperature of 55 to 59 degrees F., are dominated by channers, and have rock fragments that are sandstone or quartzite. Notstew soils have lithic contacts that are within 14 inches of the soil surface, average 35 to 60 percent rock fragments in the particle-size control section, and have mean summer soil temperature of 54 to 59 degrees F. Thiefridge soils average 35 to 60 percent rock fragments in the particle-size control section, have Oi horizons, and have 4 to 10 percent organic matter in the A horizons.
GEOGRAPHIC SETTING: Mountpatterson soils are on mountains. They typically occur on shoulder positions. They formed in volcanic ash and in residuum and colluvium derived from andesite, tuff, or metavolcanic rocks. Slopes are 4 to 30 percent. Elevations range from 10,000 to 11,600 feet. The climate is subhumid-continental with cold, moist winters and cool, dry summers. The mean annual precipitation is 20 to 30 inches, the mean annual temperature is 33 to 38 degrees F., and the frost-free period is 30 to 60 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Coldtree, Holdon, and Rolldown soils. All of these soils have bedrock deeper than 20 inches.
DRAINAGE AND PERMEABILITY: Well drained; very high surface runoff; moderate permeability (moderately high or high saturated hydraulic conductivity).
USE AND VEGETATION: Mountpatterson soils are used for rangeland, recreation, watershed, and wildlife habitat. The native vegetation occurs above timberline and is mainly various alpine forbs and some bluegrass.
DISTRIBUTION AND EXTENT: Eastern California, on the east side of the Sierra Nevada Range. These soils are not extensive with about 640 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:
Mollic epipedon - The zone from the soil surface to 18 inches (A1, A2, and Bt horizons).
Argillic horizon - The zone from 9 to 18 inches (Bt horizon).
Vitrandic intergrade feature - The zone from the soil surface to 18 inches (A1, A2, and Bt1 horizons).
Lithic contact - The boundary at 18 inches to underlying hard bedrock (R layer).
Particle-size control section - The zone from 9 to 18 inches (Bt horizon).
The revision of December 2003 recognized the volcanic ash influence based on data for the associated Rolldown soil.