LOCATION CORIDGE CAEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, thermic Ultic Haploxeralfs
TYPICAL PEDON: Coridge bouldery loam, on a southwest facing 7 percent slope under a cover of Mediterranean barley, soft chess, grass-pink, dandelion, and scattered blue oak and foothill pine at an elevation of 1030 feet, (314 m). When described on 5/20/98 the soil was moist throughout. (Colors are for dry soil unless otherwise noted).
A--0 to 1 inches, (0 to 3 cm); brown (7.5YR 5/4) bouldery loam, brown (7.5YR 4/2) moist; 22 percent clay; moderate medium platy parting to moderate fine and medium subangular blocky structure; hard, friable, slightly sticky, slightly plastic; many very fine roots; few very fine and fine irregular and tubular pores; 10 percent medium irregular oxidized iron masses lining pores; 5 percent gravel and 10 percent boulders; moderately acid, pH 6.0 by Hellige-Truog; clear smooth boundary. (1 to 3 inches, (3 to 8 cm) thick)
Bt1--1 to 6 inches, (3 to 15 cm); reddish brown (5YR 5/4) gravelly loam, reddish brown (5YR 4/3) moist; 25 percent clay; moderate fine and medium subangular blocky structure; hard, friable, slightly sticky, slightly plastic; common very fine roots; common very fine and fine tubular pores; 60 percent discontinuous distinct clay films; 5 percent medium irregular iron-manganese masses between peds; 10 percent boulders and 20 percent gravel; slightly acid, pH 6.4 by Hellige-Truog; gradual smooth boundary.
Bt2--6 to 12 inches, (15 to 30 cm); reddish brown (5YR 5/4) gravelly clay loam, reddish brown (5YR 4/3) moist; 29 percent clay; moderate fine and medium subangular blocky structure; extremely hard, friable, slightly sticky, moderately plastic; common very fine and fine roots and few medium roots; many very fine and fine tubular pores; 60 percent discontinuous distinct clay films; 10 percent boulders and 15 percent gravel; neutral, pH 6.7 by Hellige-Truog; clear smooth boundary.
Bt3--12 to 19 inches, (30 to 48 cm); reddish brown (5YR 5/4) very gravelly clay loam, reddish brown (5YR 4/3) moist; 35 percent clay; moderate fine and medium subangular blocky structure; extremely hard, friable, moderately sticky, moderately plastic; few very fine, fine and medium roots; common very fine and fine irregular and tubular pores; 60 percent discontinuous distinct clay films; 10 percent boulders, 10 percent cobbles and 15 percent gravel; neutral, pH 6.7 by Hellige-Truog; clear smooth boundary.
Bt4--19 to 24 inches, (48 to 61 cm); brown (7.5YR 5/4) very gravelly clay, brown (7.5YR 4/4) moist; 40 percent clay; moderate fine and medium subangular blocky structure; extremely hard, firm, very sticky, very plastic; few very fine, fine, medium and coarse roots; few very fine and fine irregular and tubular pores; 90 percent continuous distinct clay films; 5 percent cobbles, 10 percent boulders and 35 percent gravel; neutral, pH 6.7 by Hellige-Truog; abrupt smooth boundary. (Combined thickness of the Bt horizon is 17 to 39 inches, (43 to 99 cm) thick).
R--24 inches, (61 cm); indurated basalt bedrock.
TYPE LOCATION: Butte County, California, about 1.3 miles west of Richardson Springs, approximately 300 feet north and 850 feet east of the southwest corner of Section 18, Township 23N, Range 2E, 39 degrees, 50 minutes, 31 seconds North latitude and 121 degrees, 48 minutes, 10 seconds West longitude, NAD27 - U.S.G.S Quad: Richardson Springs, California.
RANGE IN CHARACTERISTICS: Depth to lithic bedrock is 20 to 40 inches, (51 to 102 cm). The mean annual soil temperature is 59 to 67 degrees F, (15 to 19 degrees C). The particle-size control section averages 27 to 35 percent clay and 35 to 60 percent rock fragments, mostly gravel. Mineralogy is mixed. A fluctuating water table can occur between the top of the bedrock and 10 inches (25 cm) below the surface of the soil from December through April. Redoximorphic features such as soft oxidized iron masses occur in the A horizon, iron-manganese masses occur in the upper Bt horizon, and iron-manganese masses and iron-manganese nodules occur in the lower Bt horizon. Rock fragments on the surface range from 5 to 25 percent gravel, 5 to 15 percent cobbles, 5 to 15 percent stones and 2 to 20 percent boulders.
The A horizon dry color is 5YR 5/4 or 7.5YR 5/4. Moist color is 5YR 3/3, 4/3 or 7.5YR 4/2. Texture is gravelly loam, very gravelly loam or bouldery loam. Clay content ranges from 20 to 27 percent. Rock fragments range from 5 to 35 percent gravel, 0 to 10 percent cobbles, 0 to 10 percent stones and 0 to 20 percent boulders. Reaction ranges from moderately acid to neutral.
The upper Bt horizon dry color is 5YR 4/4, 5/4 or 5/6. Moist color is 5YR 4/3 or 4/4. Texture is gravelly loam, very gravelly loam, gravelly clay loam or very gravelly clay loam. Clay content ranges from 25 to 35 percent. Rock fragments range from 15 to 30 percent gravel, 0 to 15 percent cobbles, 0 to 15 percent stones and 0 to 10 percent boulders. Reaction ranges from slightly acid to neutral.
The lower Bt horizon dry color is 5YR 4/4, 4/6 or 7.5YR 5/4. Moist color is 5YR 4/4, 7.5YR 4/4 or 2.5YR 3/4. Texture is very gravelly clay loam, very gravelly clay or extremely stony clay. Clay content ranges from 35 to 50 percent. Rock fragments range from 10 to 35 percent gravel, 5 to 20 percent cobbles, 0 to 35 percent stones and 0 to 10 percent boulders. Reaction ranges from slightly acid to neutral.
COMPETING SERIES: There are no other series in this family.
GEOGRAPHIC SETTING: Coridge soils are on ridge tops in Cascade foothills. Slopes are 3 to 15 percent. These soils formed in residuum weathered from basalt. Elevation is 340 to 1760 feet, (104 to 536 m). Mean annual precipitation is 26 to 37 inches, (660 to 940 mm). The mean annual temperature is 59 to 61 degrees F, (15 to 16 degrees C). Frost free season is 250 to 260 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Doemill and Jokerst soils. The Doemill soils are shallow to a lithic contact of mudflow breccia. The Jokerst soils are very shallow to a lithic contact of mudflow breccia.
DRAINAGE AND PERMEABILITY: Moderately well drained; high to very high runoff; moderate saturated hydraulic conductivity in the A horizon and moderate to moderately slow in the upper Bt horizon and moderately slow to slow in the lower Bt horizon. A fluctuating water table can occur between the top of the bedrock and 10 inches (25cm) blow the surface of the soil from December through April.
USE AND VEGETATION: This soil is used for livestock grazing, wildlife habitat, watershed and homesite development. Vegetation is annual grasses and forbs, blue oak, foothill pine, chamise, California scrub oak, interior live oak, poison oak, shrub interior live oak, yerba santa and whiteleaf manzanita.
DISTRIBUTION AND EXTENT: Butte County California and occur in the M261Fa (Tuscan Flows) subsection of the M261F (Sierra Nevada Foothills) section. MLRA 18 - Sierra Nevada Foothills (Cascade part). The soils are not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Butte County, California 2005. Source of name is coined from Cohasset Ridge.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Particle-size control section - zone from 6 to 24 in, (15 to 61 cm)
Ochric epipedon - zone from 0 to 1 in, (0 to 3 cm) (A)
Argillic horizon - zone from 6 to 24 in, (15 to 61 cm) (Bt1, Bt2, Bt3, Bt4)
Lithic contact -24 inches, (61 cm)
The soil moisture control section - zone from 7 to 23 in, (18 to 58 cm) is dry in all parts from about June to October (about 180 days).
ADDITIONAL DATA: