LOCATION MILLERRIDGE CAEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, active, mesic Ultic Haploxeralfs
TYPICAL PEDON: Millerridge gravelly sandy clay loam, on a south facing 15 percent slope under a cover of yellow starthistle, buckbrush, whiteleaf manzanita, and toyon at an elevation of 2180 feet, (664 m). When described on 10/24/2000 the soil was moderately dry to 12 inches, (30 cm) and dry below. (Colors are for dry soil unless otherwise noted).
A--0 to 2 inches, (0 to 5 cm); light brown (7.5YR 6/4) gravelly sandy clay loam, brown (7.5YR 4/3) moist; 23 percent clay; moderate fine and medium granular structure; slightly hard, friable, slightly sticky, slightly plastic; many very fine and fine roots and common medium roots; many very fine, fine and medium tubular and irregular pores; 5 percent stones, 5 percent cobbles and 7 percent gravel; neutral, pH 6.7 by Hellige-Truog; clear smooth boundary. (2 to 3 inches, (5 to 8 cm) thick)
Bt1--2 to 6 inches, (5 to 15 cm); reddish yellow (7.5YR 7/6) stony sandy clay loam, strong brown (7.5YR 4/6) moist; 28 percent clay; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly sticky, slightly plastic; common very fine, fine and medium roots; common very fine, fine and medium tubular pores; 60 percent continuous faint clay films; 5 percent stones, 5 percent cobbles and 5 percent gravel; slightly acid, pH 6.6 by Hellige-Truog; gradual smooth boundary.
Bt2--6 to 12 inches, (15 to 30 cm); reddish yellow (5YR 6/6) cobbly clay loam, yellowish red (5YR 4/6) moist; 32 percent clay; moderate fine and medium subangular blocky structure; moderately hard, friable, moderately sticky, moderately plastic; common very fine, fine and medium roots; many very fine, fine and medium tubular pores; 90 percent continuous distinct clay films; 5 percent stones, 5 percent gravel and 10 percent cobbles; slightly acid, pH 6.5 by Hellige-Truog; gradual smooth boundary.
Bt3--12 to 20 inches, (30 to 51 cm); reddish yellow (5YR 6/6) cobbly clay loam, yellowish red (5YR 4/6) moist; 36 percent clay; strong fine and medium subangular blocky structure; moderately hard, friable, moderately sticky, moderately plastic; common very fine, fine, medium and coarse roots; many very fine, fine and medium tubular pores; 90 percent continuous distinct clay films; 5 percent stones, 8 percent gravel and 10 percent cobbles; slightly acid, pH 6.5 by Hellige-Truog; gradual smooth boundary.
Bt4--20 to 26 inches, (51 to 67 cm); reddish yellow (5YR 6/6) gravelly clay, yellowish red (5YR 5/6) moist; 40 percent clay; strong fine and medium subangular blocky structure; moderately hard, friable, moderately sticky, moderately plastic; few very fine, fine, medium and coarse roots; many very fine, fine and medium tubular and common coarse tubular pores; 90 percent continuous distinct clay films; 5 percent stones, 5 percent cobbles and 8 percent gravel; neutral, pH 6.7 by Hellige-Truog; abrupt smooth boundary. (Combined thickness of the Bt horizon is 17 to 38 inches, (43 to 97 cm) thick)
Crt--26 inches, (67 cm); light greenish gray (5GY 7/1), weakly cemented ultramafic bedrock, light greenish gray (5G 7/1) moist; few very fine and fine roots; 20 percent continuous distinct clay films; neutral, pH 7.0 by Hellige-Truog.
TYPE LOCATION: Butte County, California, about 1.12 miles east of Concow School, approximately 600 feet north and 800 feet west of the southeast corner of Section 27, Township 22 N., Range 4 E., 39 degrees, 43 minutes, 39 seconds North latitude and 121 degrees, 30 minutes, 28 seconds West longitude, NAD83 - U.S.G.S Quad: Cherokee, California.
RANGE IN CHARACTERISTICS: Depth to paralithic bedrock is 20 to 40 inches, (51 to 102 cm). The mean annual soil temperature is 54 to 59 degrees F, (12 to 15 degrees C). The particle-size control section averages 27 to 35 percent clay and 15 to 35 percent rock fragments, mostly gravel. Mineralogy is mixed but is affected by high magnesium rich minerals in the series control section. Rock fragments on the surface range from 0 to 60 percent gravel, 0 to 30 percent cobbles, 0 to 20 percent stones and 0 to 15 percent boulders.
The A horizon dry color is 7.5YR 6/4, 7/3 or 7/6. Moist color is 7.5YR 4/3, 5/4 or 5YR 4/6. Texture is gravelly sandy clay loam or gravelly loam. Clay content ranges from 20 to 27 percent. Rock fragments range from 7 to 25 percent gravel, 0 to 10 percent cobbles, 0 to 5 percent stones and 0 to 5 percent boulders. Reaction ranges from slightly acid to neutral.
The upper Bt horizon dry color is 7.5YR 6/6, 7/4, 7/6 or 5YR 6/6. Moist color is 7.5YR 4/6, 5/4, 5/6, 5YR 4/6 or 5/6. Texture is gravelly clay loam, cobbly clay loam, stony sandy clay loam, gravelly sandy clay loam or cobbly sandy clay loam. Clay content ranges from 27 to 35 percent. Rock fragments range from 5 to 30 percent gravel, 0 to 20 percent cobbles, 0 to 5 percent stones and 0 to 5 percent boulders. Reaction ranges from slightly acid to neutral.
The lower Bt horizon dry color is 5YR 5/6, 6/6, 7/6 or 7.5YR 7/6. Moist color is 5YR 4/6, 5/6, 5/8 or 7.5YR 5/8. Texture is gravelly clay loam, cobbly clay loam, very cobbly clay loam, cobbly sandy clay loam, gravelly clay or cobbly clay. Clay content ranges from 30 to 50 percent. Rock fragments range from 5 to 30 percent gravel, 5 to 25 percent cobbles, 0 to 5 percent stones and 0 to 5 percent boulders. Reaction ranges from slightly acid to neutral.
COMPETING SERIES: These are the Bigridge, Hospiter, Minniecreek, Sitton, Speaker and Willakenzie series. Hospiter and Sitton soils are very deep. Bigridge soils are deep to paralithic bedrock. Minniecreek soils average up to 50 percent silt in the control section. Speaker and Willakenzie soils do not have magnesium enriched soil chemistry.
GEOGRAPHIC SETTING: Millerridge soils are on ridge tops and side slopes on ultramafic Sierra Nevada mountains. Slopes range from 3 to 70 percent. These soils formed in residuum and colluvium weathered from ultramafic rocks. Elevation is 950 to 2850 feet, (290 to 869 m). Mean annual precipitation is 45 to 55 inches, (1143 to 1397 mm). The mean annual temperature is 56 to 57 degrees F, (13 to 14 degrees C). Frost free season is 230 to 250 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Boxrobber and Earlal soils. Boxrobber soils are shallow and loamy-skeletal. Earlal soils are magnesic and have a lithic contact of serpentinite.
DRAINAGE AND PERMEABILITY: Well drained; high runoff; moderate to moderately slow saturated hydraulic conductivity in the A horizon, moderately slow in the upper Bt horizon and moderately slow to slow in the lower Bt horizon.
USE AND VEGETATION: This soil is used for wildlife habitat, home site development and watershed. Vegetation is whiteleaf manzanita, foothill pine, blue oak, canyon live oak, toyon, buckbrush, California laurel, and annual grasses and forbs.
DISTRIBUTION AND EXTENT: Butte County, California and occur in the M261Fb (Lower Foothills Metamorphic Belt) subsection of the M261F (Sierra Nevada Foothills) section. MLRA 22A - Sierra Nevada Range. The soils are not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Butte County, California 2005. Source of name from Miller Ridge, a local name for the ridge this soil was described on.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - zone from 0 to 2 in, (0 to 5 cm) (A)
Argillic horizon - zone from 2 to 27 in, (5 to 67 cm) (Bt1, Bt2, Bt3, Bt4)
Paralithic contact - 27 in, (67 cm)
Particle-size control section - zone from 2 to 22 in, (5 to 56 cm)
The soil moisture control section - zone from 6 to 19 inches, (15 to 48 cm) is dry in all parts from about May to October (about 170 days).