LOCATION BROKEOFF CAEstablished Series
The Brokeoff series consists of moderately deep, well drained soils that formed in tephra and colluvium over residuum from hydrothermally altered volcanic rock. Brokeoff soils are on convex mountain side slopes in hydrothermally altered areas. Slopes range from 10 to 80 percent. The mean annual precipitation is about 117 inches (2972 mm) and the mean annual temperature is about 39 degrees F (4 degrees C).
TAXONOMIC CLASS: Loamy-skeletal over fragmental, isotic, frigid Typic Dystroxerepts
TYPICAL PEDON: Brokeoff gravelly ashy loam, on a southwest facing (198 degrees) slope of 35 percent, under a cover of, mountain monardella, lupine, and wooly mule's ears at an elevation of 7686 feet, (2343 m). When described on 9/20/06, the soil was dry throughout. (Colors are for dry soil unless otherwise noted).
A1--0 to 2 inches (0 to 4 cm); pale brown (10YR 6/3) gravelly ashy loam, dark brown (10YR 3/3) moist; 18 percent clay; weak thick platy structure parting to single grain; soft, very friable, nonsticky, nonplastic; common very fine and fine roots; many very fine and fine interstitial pores; 15 percent angular fine gravel and 15 percent angular medium and coarse gravel; very strongly acid, pH 4.8 by Hellige-Truog; NaF pH 9.2; abrupt smooth boundary.
A2--2 to 4 inches (4 to 10 cm); brown (10YR 5/3) gravelly ashy loam, dark grayish brown (10YR 4/2) moist; 20 percent clay; moderate very fine, fine, and medium subangular blocky structure parting to single grain; moderately hard, firm, nonsticky, nonplastic; common very fine and fine roots; many very fine and fine irregular, common fine and medium vesicular, and few medium tubular pores; 10 percent angular fine gravel and 20 percent angular medium and coarse gravel; moderately acid, pH 6.0 by Hellige-Truog; NaF pH 9.2; abrupt smooth boundary. (Combined thickness of the A horizon is 2 to 6 inches (5 to 14 cm) thick)
Bw1--4 to 7 inches (10 to 19 cm); light olive brown (2.5Y 5/3) very gravelly clay loam, brown (10YR 4/3) moist; 29 percent clay; moderate very fine, fine, and medium subangular blocky structure parting to single grain; moderately hard, firm, slightly sticky, slightly plastic; many very fine to medium roots; many very fine and fine irregular and common medium vesicular pores; 15 percent angular fine gravel, 25 percent angular medium and coarse gravel, and 2 percent angular cobbles; strongly acid, pH 5.2 by Hellige-Truog; NaF pH 9.3; abrupt wavy boundary.
Bw2--7 to 15 inches (19 to 37 cm); brown (10YR 5/3) extremely gravelly loam, brown (10YR 4/3) moist; 26 percent clay; moderate fine and medium granular structure parting to single grain; moderately hard, firm, slightly sticky, slightly plastic; many fine and medium, and few coarse, and few very fine roots; many very fine and fine irregular and few medium vesicular pores; 16 percent angular fine gravel, 24 percent angular medium and coarse gravel, and 20 percent angular cobbles; very strongly acid, pH 5.0 by Hellige-Truog; NaF pH 9.4; abrupt wavy boundary. (Combined thickness of the Bw horizon is 9 to 13 inches (23 to 33 cm) thick)
Cr--15 to 37 inches (37 to 94 cm); yellowish brown (10YR 5/4) cobbles, dark yellowish brown (10YR 4/4) moist; 25 percent clay; moderately cemented, slightly sticky, slightly plastic; few fine and medium roots; manganese coatings in cracks; 38 percent angular medium and coarse gravel, 45 percent angular cobbles, and 15 percent angular stones; very strongly acid, pH 5.0 by Hellige-Truog; NaF pH 9.4; abrupt irregular boundary. (20 to 24 inches (51 to 61 cm) thick)
R--37 inches (94 cm); indurated bedrock; few fine roots greater than 10 cm apart
TYPE LOCATION: Shasta County, California, about 0.72 miles north-northeast from the Sulfur Works parking lot on Highway 89, approximately 1,650 feet east and 1,250 feet north of the southwest corner of sec 15, T. 30 N, R.4 E, 40 degrees, 27 minutes, 26 seconds north latitude and 121 degrees, 31 minutes, 42 seconds west longitude, NAD83; USGS Quad: Lassen Peak, California.
RANGE IN CHARACTERISTICS:
Depth to restrictive feature: Lithic contact 20 to 40 inches (51 to 102 cm).
Mean annual soil temperature: 42 to 47 degrees F (6 to 8 degrees C).
Soil moisture control section is dry: July to October (about 90 days).
Particle-size control section: loamy-skeletal part: 26 percent clay, and 60 percent rock fragments, fragmental part: 25 percent clay, and 98 percent rock fragments.
Surface fragments: 35 to 45 percent gravel, 5 to 15 percent cobbles, 1 to 5 percent stones.
A horizon:
Color dry: 10YR 4/3, 5/3, 6/3
Color moist: 10YR 2/2, 4/2, 3/3
Texture: gravelly ashy loam, very gravelly ashy clay loam
Clay content: 18 to 30 percent
Rock fragments: 10 to 15 percent fine gravel, 15 to 24 percent medium and coarse gravel, 0 to 5 percent cobbles, 30 to 38 percent total gravel, 30 to 43 percent total rock fragments
Organic matter: 5 to 10 percent
Base saturation by ammonium acetate: 35 to 45 percent
Acid oxalate extractable Al plus 1/2 Fe: 0.55 to 0.62
P retention: 48 to 55 percent
Glass content: 5 to 10 percent
NaF pH: 9.0 to 9.2
Soil reaction: very strongly acid to neutral
Bw horizon:
Color dry: 10YR 5/3, 6/4, 2.5Y 5/3
Color moist: 10YR 3/3, 4/3, 4/4
Texture: gravelly clay loam, very gravelly clay loam, extremely gravelly loam, extremely cobbly clay loam
Clay content: 26 to 37 percent
Rock fragments: 14 to 18 percent fine gravel, 8 to 30 percent medium and coarse gravel, 26 to 44 percent total gravel, 2 to 30 percent cobbles, 34 to 74 percent total rock fragments
Organic matter: 3 to 6 percent
Base saturation by ammonium acetate: 20 to 45 percent
Acid oxalate extractable Al plus 1/2 Fe: 0.55 to 0.82
P retention: 48 to 90 percent
Glass content: 0 to 1 percent
NaF pH: 9.0 to 9.4
Soil reaction: very strongly acid to neutral
COMPETING SERIES: There are no other series in this family.
GEOGRAPHIC SETTING: Brokeoff soils are on convex mountain sideslopes in hydrothermally altered areas. Slopes are 10 to 80 percent. These soils formed in tephra and colluvium over residuum weathered from hydrothermally altered volcanic rock. Elevation is 5674 to 8564 feet (1730 to 2611 m). Mean annual precipitation is 63 to 119 inches (1600 to 3023 mm). The mean annual temperature is 39 to 40 degrees F (4 to 5 degrees C). Frost free season is 60 to 85 days.
GEOGRAPHICALLY ASSOCIATED SOILS: This is the Diamondpeak soils. The Diamondpeak soils are very deep and occur on linear to concave mountain sideslopes in hydrothermally altered areas.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; moderately high to high saturated hydraulic conductivity.
USE AND VEGETATION: This soil is used for wildlife habitat, recreation, ecosystem management and watershed. Vegetation is mountain monardella, lupine, wooly mule-ears and squirreltail.
DISTRIBUTION AND EXTENT: The soils are inextensive and are mapped in MLRA: 22B Southern Cascade mountains
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: 2009 Shasta County, California. Source of name from Brokeoff volcano.
REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon 0 to 4 inches, (0 to 10 cm)
Cambic horizon 4 to 15 inches, (10 to 37 cm)
Particle-size control section: 10 to 37 inches, (25 to 94 cm)
Soil moisture control section: 8 to 15 inches, (21 to 37 cm)
Lithic contact 37 inches, (94 cm)
ADDITIONAL DATA: Classification and properties inferred from lab data from lab pedon number 07N0140, NSSL, Lincoln NE. NASIS User Pedon ID in Davis, MLRA Office: 789175.