LOCATION PYROPATTI CA OREstablished Series
TAXONOMIC CLASS: Ashy-skeletal, glassy Vitrandic Argicryolls
TYPICAL PEDON: Pyropatti gravelly ashy loam--forestland. (Colors are for dry soil unless otherwise noted). The soil surface is partly covered by 25 percent gravel.
A1--0 to 3 inches; dark grayish brown (10YR 4/2), gravelly ashy loam, very dark brown (10YR 2/2), moist; weak fine granular structure; soft, very friable, slightly sticky, nonplastic; many very fine roots; many very fine interstitial pores; 20 percent pebbles; slightly acid (pH 6.1); clear wavy boundary. (1 to 5 inches thick)
A2--3 to 9 inches; dark grayish brown (10YR 4/2), gravelly ashy loam, very dark brown (10YR 2/2), moist; moderate fine and medium subangular blocky structure; soft, very friable, slightly sticky, nonplastic; common fine to coarse roots and many very fine roots; common very fine interstitial and tubular pores; 20 percent pebbles; slightly acid (pH 6.1); clear wavy boundary. (4 to 8 inches thick)
Bt1--9 to 20 inches; dark grayish brown (10YR 4/2), very gravelly ashy loam, very dark brown (10YR 2/2), moist; moderate fine and medium subangular blocky structure; soft, very friable, slightly sticky, nonplastic; common very fine to coarse roots; common very fine interstitial and tubular pores; 10 percent cobbles and 35 percent pebbles; slightly acid (pH 6.2); clear wavy boundary. (6 to 13 inches thick)
Bt2--20 to 30 inches; dark grayish brown (10YR 4/2), very gravelly ashy loam, very dark brown (10YR 2/2), moist; strong medium subangular blocky structure; slightly hard, very friable, slightly sticky, slightly plastic; common very fine to medium roots; common very fine interstitial and tubular pores; 15 percent faint clay bridges between sand grains; 10 percent cobbles and 45 percent pebbles; slightly acid (pH 6.5); clear wavy boundary. (8 to 15 inches thick)
Bt3--30 to 48 inches; brown (10YR 5/3), very gravelly ashy loam, dark brown (10YR 3/3), moist; moderate medium subangular blocky structure; slightly hard, very friable, slightly sticky, slightly plastic; common fine and medium roots and few very fine roots; common very fine interstitial and tubular pores; 2 percent faint clay bridges between sand grains; 5 percent dark yellowish brown (10YR 3/4) moist, faint redox concentrations; 10 percent cobbles and 45 percent pebbles; slightly acid (pH 6.5): clear wavy boundary. (10 to 25 inches thick)
Cr--48 inches; weathered andesite.
TYPE LOCATION: Modoc County, California; on the Modoc National Forest in the Warner Mountains; 2,600 feet north and 1,200 feet east of the southwest corner of section 34, T 48N., R 16E.; Mt. Bidwell USGS 7.5 minute topographic quadrangle; 41 degrees 59 minutes 10.1 seconds north latitude and 120 degrees 7 minutes 36.0 seconds west longitude, NAD27.
RANGE IN CHARACTERISTICS:
Soil moisture - These soils are usually moist in winter, spring, and early summer, dry later in summer and fall; xeric soil moisture regime. Saturated for brief periods below 30 inches during spring snowmelt.
Mean annual soil temperature - 41 to 45 degrees F.
Mean summer soil temperature - 47 to 55 degrees F.
Oxalate extractable Al + 1/2 Fe: 0.2 to 0.4 percent.
Volcanic glass content - 50 to 80 percent in the coarse silt through fine sand fractions.
Mollic epipedon thickness - 30 to 60 inches.
Depth to bedrock - 40 to 60 inches to a paralithic contact. The paralithic materials below the contact are weathered andesite or pyroclastic andesitic tuff.
Profile reaction - Slightly acid or neutral.
Particle-size control section - Clay content: Averages 18 to 27 percent, (field estimates).
Rock fragments: 35 to 60 percent, mainly gravel or cobbles.
A horizons - Hue: 10YR or 7.5YR.
Value: 4 or 5 dry, 2 or 3 moist.
Chroma: 2 or 3, dry or moist.
Organic matter content: 2 to 4 percent.
Bt1 horizon - Hue: 10YR or 7.5YR.
Value: 4 or 5 dry, 2 or 3 moist.
Chroma: 2 or 3, dry or moist.
Texture: Ashy loam or ashy sandy loam.
Clay content: 12 to 18 percent.
Rock fragments: 35 to 60 percent.
Structure: Moderate or strong, fine to coarse subangular blocky.
Organic matter content: 1 to 2 percent
Bt2 horizon - Hue: 10YR or 7.5YR.
Value: 4 or 5 dry, 2 or 3 moist.
Chroma: 2 or 3, dry or moist.
Texture: Ashy loam or ashy sandy loam.
Clay content: 18 to 27 percent.
Rock fragments: 35 to 60 percent.
Structure: Moderate or strong, fine to coarse subangular blocky.
Organic matter content: 1 to 2 percent
Bt3 horizon - Hue: 10YR or 7.5YR.
Value: 5 or 6 dry, 3 or 4 moist.
Chroma: 2, 3 or 4, dry or moist.
Texture: Ashy loam or ashy sandy loam.
Clay content: 18 to 27 percent.
Rock fragments: 35 to 60 percent.
Redox concentrations: 2 to 10 percent
Structure: Moderate or strong, fine to coarse subangular blocky.
Organic matter content: 0.5 to 2 percent.
COMPETING SERIES: These are the Ashflat, Boulderfan, Cowbell, Fendersflat, Paynepeak, Snag, and Tusune soils. Ashflat and Snag soils have bedrock deeper than 60 inches. Boulderfan, Cowbell and Tusune soils have a mollic epipedon less than 30 inches thick. Paynepeak soils are not saturated below 30 inches in the spring.
GEOGRAPHIC SETTING: Pyropatti soils are on mountains. They formed in volcanic ash and colluvium over residuum derived from andesite and glassy tuff. Slopes are 2 to 30 percent. Elevations range from 5,610 to 8,620 feet. The climate is subhumid with cold, moist winters and warm, dry summers. The mean annual precipitation is 20 to 50 inches, most of which comes as snow. The mean annual temperature is 38 to 44 degrees F. The frost-free period is 30 to 60 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Gurlidawg, the competing Paynepeak and the Skidbrackle series. Gurlidawg soils do not have a mollic epipedon or an argillic horizon and have bedrock within 20 to 40 inches. Skidbrackle soils have bedrock at less than 20 inches. .
DRAINAGE AND PERMEABILITY: Well drained; medium or high surface runoff; moderate permeability.
USE AND VEGETATION: Pyropatti soils are used for watershed, wildlife habitat, and limited livestock grazing. The vegetation consists of quaking aspen with an understory of mountain brome, needlegrass, snowberry and forbs.
DISTRIBUTION AND EXTENT: Northeastern California and southern Oregon. These soils are not extensive. MLRA 21.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California.
SERIES ESTABLISHED: Lake County, Oregon, Southern Part, 2006. The soil was originally proposed in Surprise Valley-Home Camp Area, California and Nevada, 2005.
REMARKS: The name is coined.
Diagnostic horizons and features recognized in this pedon include:
Mollic epipedon - The zone from the mineral soil surface to 48 inches (A1, A2, Bt1 and the Bt2 horizons).
Vitrandic intergrade feature -- High volcanic glass content in the .02 to 2mm fraction from the mineral soil surface to 48 inches (A1, A2, Bt1, and the Bt2 horizons).
Argillic horizon - The zone from 20 to 48 inches (Bt1 and Bt2 horizons).
Paralithic contact - The boundary at 48 inches to underlying soft, weathered bedrock (Cr layer).
Particle-size control section - The zone from 20 to 40 inches (Bt1 and part of the Bt2 horizons).