LOCATION SAID CAEstablished Series
TAXONOMIC CLASS: Fine-loamy, isotic, frigid Andic Argixerolls
TYPICAL PEDON: Said gravelly loam--on an 8 percent northeast-facing slope under Jeffrey pine and white fir at 6,240 feet elevation--forestland. (When described August 12, 1981, the soil was dry throughout. Colors are for dry soil unless otherwise noted.)
Oi--0 to 2 inches; slightly decomposed plant material composed of pine needles, twigs, and cones, abrupt smooth boundary. (1 to 4 inches thick)
A1--2 to 9 inches; brown (7.5YR 4/2) gravelly loam, dark reddish brown (5YR 3/2) moist; weak fine and medium granular structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine and fine roots; many very fine and fine interstitial pores; 15 percent rounded gravel; moderately acid (pH 6.0); clear smooth boundary.
A2--9 to 15 inches; brown (7.5YR 4/2) gravelly loam, dark brown (7.5YR 3/2) moist; weak fine and medium granular structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine, fine and medium roots; many very fine and fine interstitial pores; 15 percent rounded gravel and 2 percent cobbles; moderately acid (pH 6.0); gradual wavy boundary. (Combined thickness of the A horizons is 8 to 16 inches)
Bt1--15 to 22 inches; reddish brown (5YR 4/3) gravelly loam, dark brown (7.5YR 3/3) moist; weak fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine and many medium and coarse roots; common very fine and fine tubular pores; few faint clay films on faces of peds; 20 percent gravel, 5 percent cobbles; moderately acid (pH 6.0); gradual wavy boundary.
Bt2--22 to 28 inches; reddish brown (5YR 4/3) gravelly loam, dark brown (7.5YR 3/3) moist; moderate medium angular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few very fine and common fine and medium roots; common very fine and fine tubular pores; common faint clay films on faces peds and lining pores; 20 percent gravel and 5 percent cobbles and stones; moderately acid (pH 6.0); gradual wavy boundary.
2Bt3--28 to 39 inches; dark reddish gray (5YR 4/2) very gravelly clay loam, dark brown (7.5YR 3/3) moist; moderate medium and coarse angular blocky structure; hard, friable, moderately sticky and moderately plastic; few very fine and common medium roots; common very fine and fine tubular pores; common distinct clay films on faces of peds and lining pores; 25 percent gravel and 10 percent cobbles; some fragments are soft and weathered; strongly acid (pH 5.5); gradual wavy boundary.
2Bt4--39 to 58 inches; dark reddish gray (5YR 4/2) very cobbly clay loam, dark brown (7.5YR 3/2) moist; weak medium angular blocky structure; hard, friable, sticky and plastic; few fine and common medium roots; common very fine tubular pores; common distinct reddish brown (5YR 5/4) clay films on faces of peds and lining pores and brown (7.5YR 4/4) clay films on rock fragments; 20 percent gravel and 40 percent cobbles; some fragments are soft and weathered; strongly acid (pH 5.5); clear irregular boundary. (Combined thickness of the 2Bt horizons is 25 to 50 inches)
Cr--58 to 64 inches; weathered, fractured andesite; clay films, fine-earth material, and roots between some fractures; cuts with knife, digs with spade or auger with some difficulty.
TYPE LOCATION: Lassen County, California; about 0.5 miles southwest of Cleghorn Reservoir; about 1,700 feet west and 2,000 feet north of the southeast corner of section 35, T. 34 N., R. 10 E.; USGS Sheepshead 7.5 minute topographic quadrangle; 40 degrees 45 minutes 53 seconds north latitude and 120 degrees 48 minutes 39 seconds west longitude, NAD27.
RANGE IN CHARACTERISTICS:
Soil moisture - The soil moisture control section (7 to 22 inches) is moist in all parts from early December to mid May. It is dry in all parts from early August to early November for 90 to 100 days. The soil temperature exceeds 41 degrees from early May to early December and exceeds 47 degrees from mid May to early November; Xeric moisture regime.
Mean annual soil temperature - 41 to 47 degrees F.
Mean summer soil temperature - 50 to 54 degrees F.
Mollic epipedon thickness - 24 to 36 inches; includes the Bt1 and Bt2 horizons.
Depth to base of argillic horizon - 40 to 60 inches.
Depth to bedrock - 40 to 60 inches to a paralithic contact. The paralithic materials below the contact are weathered volcanic rock such as andesite or basalt.
Particle-size control section - Clay content: Averages 18 to 25 percent; Rock fragments: 20 to 30 percent, mainly gravel. Lithology of fragments are volcanic rocks such as andesite or basalt.
Base saturation by sum of cations - 50 to 75 percent.
A horizons - Dry color: 10YR 4/3, 5/2, 5/3; or 7.5YR 4/2.
Moist color: 10YR 2/2, 3/3; 7.5YR 3/2; 5YR 3/2 or 3/3.
Clay content: 15 to 20 percent.
Rock fragments: 15 to 30 percent.
Organic matter content: 2 to 5 percent.
Reaction: Moderately acid through neutral.
Moist bulk density of the fine earth fraction: 0.9 to 1.04 g/cc.
Oxalate extractable aluminum plus one half extractable iron: 0.9 to 1.2 percent.
Volcanic glass content: 2 to 12 percent.
Bt1 and Bt2 horizons - Dry color: 7.5YR 5/2, 5/4; 5YR 4/2, or 4/3.
Moist color: 7.5YR 3/2, 3/3, 3/4, 4/4; 5YR 3/2, 3/3, 3/4, 4/4, or 4/6.
Texture: Gravelly loam or cobbly loam.
Clay content: 20 to 25 percent.
Rock fragments: 15 to 35 percent.
Reaction: Moderately acid through neutral.
Organic matter content: 1 to 5 percent.
2Bt horizons - Dry color: 7.5YR 5/2, 5/4; 5YR 4/2, or 4/3.
Moist color: 7.5YR 3/2, 3/3, 3/4, 4/4; 5YR 3/2, 3/3, 3/4, 4/4, or 4/6.
Texture: Very gravelly clay loam or very cobbly clay loam.
Clay content: 27 to 35 percent.
Rock fragments: 35 to 60 percent.
Pararock fragments: 0 to 15 percent.
Reaction: Strongly acid through neutral.
Organic matter content: 1 to 5 percent.
COMPETING SERIES: There are no competing series in this family.
GEOGRAPHIC SETTING: Said soils are on plateaus and mountains. They typically occur on backslope positions. These soils formed in volcanic ash over colluvium and residuum weathered from volcanic rocks such as andesite or basalt. Slopes are 5 to 50 percent. Elevation ranges from 5,000 to 6,600 feet. The climate is subhumid with cold, moist winters and warm, dry summers. The mean annual precipitation is 16 to 30 inches and the annual snowfall is 30 to 60 inches. The mean annual temperature is 39 to 45 degrees F., the mean July temperature is 55 to 60 degrees F., and the mean January temperature is 20 to 25 degrees F. The frost-free period is 50 to 80 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Fraval, Fredonyer, and Ninemile soils. Fraval soils are loamy-skeletal and moderately deep to paralithic contacts. Fredonyer soils are loamy-skeletal and do not have argillic horizons. Ninemile soils are clayey and are shallow to lithic contacts.
DRAINAGE AND PERMEABILITY: Well drained; high surface runoff; moderately slow permeability.
USE AND VEGETATION: Said soils are used for timber production. The vegetation is a forest canopy of white fir and Jeffrey pine with an understory of squawcarpet, manzanita, and Idaho fescue.
DISTRIBUTION AND EXTENT: Northeastern California. These soils are moderately extensive. MLRA 21.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Intermountain Soil Survey Area, California, 1994.
REMARKS: This revision of February 2003 updates the taxonomic class from Fine-loamy, isotic, frigid Vitrandic Argixerolls and adjusts all horizon depths to make the Oi horizon the soil surface.
Diagnostic horizons and features recognized in this pedon are:
Organic soil material - The zone from the soil surface to 2 inches (Oi horizon).
Mollic epipedon - The zone from the soil surface to 28 inches (Oi, A1, A2, Bt1, and Bt2 horizons).
Andic subgroup feature - The zone from 2 to 15 inches (A1 and A2 horizons).
Argillic horizon - The zone from 15 to 58 inches (Bt1, Bt2, 2Bt3, and 2Bt4 horizons).
Paralithic contact - The boundary at 58 inches to underlying soft, weathered bedrock (Cr layer).
Particle-size control section - The zone from 15 to 35 inches (Bt1 and Bt2 horizons and part of the 2Bt3 horizon).
ADDITIONAL DATA: The typical pedon at the series type location has full characterization by the Soil Survey Laboratory (SSL), Lincoln, NE, as soil survey sample number S81CA-035-009 (pedon # 81P0701).