LOCATION BUNANCH CAEstablished Series
TAXONOMIC CLASS: Clayey-skeletal, smectitic, mesic Mollic Palexeralfs
TYPICAL PEDON: Bunanch very gravelly loam--on a 10 percent east-facing slope under Jeffrey pine and antelope bitterbrush at 5,000 feet elevation--forestland. (Colors are for dry soil unless otherwise noted. When described June 9, 1987, the soil was moist from 7 to 63 inches.) The soil surface has a discontinuous cover of about 2 inches of undecomposed and slightly decomposed pine needles, twigs, and cones.
A1--0 to 3 inches; brown (10YR 4/3) very gravelly loam, dark brown (10YR 3/3) moist; moderate fine and medium subangular blocky structure; slightly hard, very friable, nonsticky and nonplastic; common very fine and few fine roots; common very fine interstitial pores; 20 percent fine (2 to 5 mm diameter) gravel and 20 percent medium and coarse (5 to 75 mm diameter) gravel; slightly acid (pH 6.5); clear wavy boundary.
A2--3 to 7 inches; yellowish brown (10YR 5/4) very gravelly loam, dark yellowish brown (10YR 3/4) moist; moderate coarse subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; few very fine, few fine and few medium roots; common very fine interstitial pores; 20 percent fine (2 to 5 mm diameter) gravel and 20 percent medium and coarse (5 to 75 mm diameter) gravel; slightly acid (pH 6.5); clear wavy boundary. (Combined thickness of the A horizons is 3 to 7 inches)
Bt1--7 to 14 inches; brown (7.5YR 5/4) very gravelly clay loam, dark yellowish brown (10YR 3/4) moist; common medium subangular blocky structure; hard, very friable, moderately sticky and moderately plastic; few very fine, few fine, common medium and few coarse roots; common very fine interstitial pores; many faint clay films on faces of peds; 20 percent fine (2 to 5 mm diameter) gravel and 30 percent medium and coarse (5 to 75 mm diameter) gravel; slightly acid (pH 6.5); abrupt wavy boundary.
Bt2--14 to 22 inches; brown (7.5YR 5/4) very gravelly clay loam, brown (7.5YR 4/4) moist; strong fine and medium angular blocky structure; very hard, friable, very sticky and very plastic; few very fine, few fine, few medium and few coarse roots; few very fine interstitial and few very fine tubular pores; many distinct clay films on faces of peds and lining pores; 10 percent fine (2 to 5 mm diameter) gravel and 50 percent medium and coarse (5 to 75 mm diameter) gravel; slightly acid (pH 6.5); clear wavy boundary.
Bt3--22 to 33 inches; strong brown (7.5YR 5/6) very gravelly clay, strong brown (7.5YR 4/6) moist; strong medium angular blocky structure; very hard, very friable, very sticky and very plastic; few very fine, few fine and few medium roots; common very fine tubular pores; many distinct clay films on faces of peds and lining pores; 10 percent fine (2 to 5 mm diameter) gravel and 50 percent medium and coarse (5 to 75 mm diameter) gravel; slightly acid (pH 6.5); clear wavy boundary.
Bt4--33 to 45 inches; reddish yellow (7.5YR 6/6) and olive gray (5Y 4/2) very gravelly clay, strong brown (7.5YR 5/6) and black (5Y 2.5/2) moist; strong fine and medium angular blocky structure; very hard, friable, very sticky and very plastic; few very fine and few fine roots; common very fine tubular pores; strong brown (7.5YR 5/6) many distinct clay films on faces of peds and lining pores; strong brown (7.5YR 4/6) moist; 20 percent fine (2 to 5 mm diameter) gravel and 20 percent medium and coarse (5 to 75 mm diameter) gravel; slightly acid (pH 6.5); gradual irregular boundary.
Bt5--45 to 63 inches; reddish yellow (7.5YR 6/6) and olive gray (5Y 4/2) very gravelly clay, strong brown (7.5YR 5/6) and black (5Y 2.5/2) moist; moderate fine and medium angular blocky structure; very hard, friable, very sticky and very plastic; few fine roots; common very fine tubular pores; many distinct clay films on faces of peds and lining pores; 20 percent fine (2 to 5 mm diameter) gravel and 20 percent medium and coarse (5 to 75 mm diameter) gravel; 30 percent of horizon is pararock fragments, cut by spade with difficulty; slightly acid (pH 6.5). (Combined thickness of the Bt horizons is 53 to 57 inches or more).
TYPE LOCATION: Lassen County, California; about 0.6 miles east of the intersection of U.S. Highway 36 and the Susan River on the dirt road toward Cheney Creek; about 1,500 feet east and 800 feet south of the northwest corner of section 8, T. 29 N., R. 12 E.; USGS Roop Mountain 7.5 minute topographic quadrangle; 40 degrees 23 minutes 38 seconds north latitude and 120 degrees 46 minutes 10 seconds west longitude, NAD27.
RANGE IN CHARACTERISTICS:
Soil moisture - The soil moisture control section (7 to 18 inches) is dry from July 15th to November 1st (107 days) and is moist in all parts from December 1st to May 15th; The soil temperature exceeds 41 degrees F. from April 15th to December 1st (229 days) and exceeds 47 degrees F. from May 15th to November 15th; the moisture control section is moist in some part from April 15th to July 15th and from November 1st to December 1st (91 consecutive days) and is moist in some part from May 15th to July 15th (61 consecutive days); Xeric moisture regime.
Mean annual soil temperature - 48 to 50 degrees F.
Ochric epipedon thickness - 3 to 7 inches.
Depth to base of argillic horizon - Greater than 60 inches; clay content increases with depth and does not decrease within a depth of 60 inches.
Particle-size control section - Clay content: Averages 35 to 45 percent; Rock fragments: 35 to 60 percent, mainly gravel. Lithology of fragments are siliceous conglomerate.
Other features - Rock fragments on the surface range from 0 to 10 percent cobbles and 35 to 40 percent gravel.
A horizons - Dry color: 10YR 4/3, 5/3, or 5/4.
Moist color: 10YR 3/2, 3/3, or 3/4.
Clay content: 15 to 20 percent.
Bt1 and Bt2 horizons - Dry color: 7.5YR 5/4, 5/6, 6/4, 6/6, or 5Y 4/2.
Moist color: 7.5YR 3/4, 4/4, 4/6, 5/4, 5/6, or 5Y 2/2.
Clay content: 30 to 40 percent.
Reaction: Slightly acid or neutral.
Base saturation: 75 to 80 percent.
Bt3, Bt4, and Bt5 horizons - Dry color: 7.5YR 5/4, 5/6, 6/4, 6/6, or 5Y 4/2.
Moist color: 7.5YR 3/4, 4/4, 4/6, 5/4, 5/6, or 5Y 2/2.
Clay content: 40 to 50 percent.
Reaction: Slightly acid or neutral.
Base saturation: 75 to 80 percent.
COMPETING SERIES: There are currently no other series in this family.
GEOGRAPHIC SETTING: Bunanch soils are on low hills. Slopes are 9 to 30 percent. These soils formed in alluvium derived from siliceous conglomerate. Elevations range from 4,700 to 5,500 feet. The mean annual precipitation is about 20 to 30 inches with 30 to 60 inches of snow. The mean annual temperature is 46 to 48 degrees F., the mean January temperature is about 30 degrees F., and the mean July temperature is about 66 degrees F. The frost-free period is 80 to 100 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Gavel, Outland, Penstock, and Ulhalf soils. Gavel soils are loamy-skeletal, have mollic epipedons, are influenced by volcanic ash, have isotic mineralogy, and are moderately deep to paralithic contacts. Outland soils are loamy-skeletal, are influenced by volcanic ash, and are moderately deep to paralithic contacts. Penstock soils are loamy-skeletal and have low base saturation. Ulhalf soils are fine-loamy, are influenced by volcanic ash, have isotic mineralogy, and are deep to paralithic contacts.
DRAINAGE AND PERMEABILITY: Well drained; high surface runoff; slow permeability.
USE AND VEGETATION: Bunanch soils are used for timber production. The vegetation is a forest canopy of Jeffrey pine and antelope bitterbrush.
DISTRIBUTION AND EXTENT: Northeastern California. These soils are not extensive with about 630 acres of the series mapped to date. MLRA 22A.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California.
SERIES ESTABLISHED: Lassen County (Susanville Area Soil Survey), California, 2000.
REMARKS: The revision of January 2004 updated the taxonomic class from Clayey-skeletal, smectitic, mesic Typic Palexeralfs.
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from the soil surface to 7 inches (A1 and A2 horizons).
Argillic horizon - The zone from 7 to 63 inches (Bt1, Bt2, Bt3, Bt4, and Bt5 horizons).
Particle-size control section - The zone from 7 to 27 inches (Bt1 and Bt2 horizons and part of the Bt3 horizon).
ADDITIONAL DATA: The typical pedon at the series type location is sampled for the UC Davis Soil Morphology Lab. In the upper 20 inches of the argillic horizon the clay content is 34 percent in the Bt1 horizon, 39 percent in the Bt2 horizon, and 42 percent in the Bt3 horizon measured by the hydrometer method. Base saturation data is available. Base saturation is 71.8 to 79.5 percent in the Bt1, Bt2, and Bt3 horizons by the UC Davis Soil Morphology Lab.