LOCATION BIGRIDGE CAEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, active, mesic Ultic Haploxeralfs
TYPICAL PEDON: Bigridge loam, on a north west facing 56 percent slope under a cover of whiteleaf manzanita, toyon, interior live oak and ponderosa pine at an elevation of 2000 feet, (610 m). When described on 7/27/1999 the soil was moist throughout. (Colors are for dry soil unless otherwise noted)
Oe--0 to 1 inches, (0 to 3 cm); moderately decomposed plant material; abrupt smooth boundary.
A--1 to 5 inches, (3 to 13 cm); brown (7.5YR 5/4) loam, dark reddish brown (5YR 3/3) moist; 16 percent clay; moderate fine subangular blocky structure; soft, very friable, slightly sticky, slightly plastic; many fine roots throughout; common fine tubular and common medium irregular pores; 15 percent subangular metavolcanic gravel; moderately acid, pH 5.7 by pH meter 1:1 water; abrupt wavy boundary. (1 to 5 inches, (5 to 13 cm) thick)
BAt--5 to 9 inches, (13 to 23 cm); yellowish red (5YR 5/6) gravelly loam, dark reddish brown (5YR 3/4) moist; 19 percent clay; strong fine subangular blocky structure; soft, friable, slightly sticky, slightly plastic; many very fine and fine roots and common medium roots throughout; many fine tubular and common medium tubular pores; 20 percent discontinuous distinct clay films on faces of peds; 25 percent subangular metavolcanic gravel; moderately acid, pH 5.6 by pH meter 1:1 water; abrupt wavy boundary. (0 to 8 inches, (0 to 20 cm) thick)
Bt1--9 to 15 inches, (23 to 38 cm); yellowish red (5YR 5/6) gravelly loam, dark reddish brown (5YR 3/4) moist; 20 percent clay; strong fine subangular blocky structure; slightly hard, friable, slightly sticky, slightly plastic; common fine and medium and few coarse roots throughout; many fine tubular and common medium tubular pores; 20 percent discontinuous distinct clay films on faces of peds and 20 percent continuous distinct clay films on surfaces along pores; 20 percent subangular metavolcanic gravel; moderately acid, pH 5.8 bypH meter 1:1 water; clear wavy boundary.
Bt2--15 to 20 inches, (38 to 51 cm); yellowish red (5YR 5/6) gravelly loam, dark red (2.5YR 3/6) moist; 21 percent clay; moderate fine subangular blocky structure; slightly hard, friable, slightly sticky, slightly plastic; common fine roots and few coarse roots throughout; common fine tubular and few medium tubular pores; 40 percent continuous prominent clay films on surfaces along pores; 25 percent subangular metavolcanic gravel moderately acid, pH 5.9 by pH meter 1:1 water; clear wavy boundary. (Combined thickness of the Bt horizon is 11 to 50 inches, (28 to 127 cm) thick)
BCt1--20 to 27 inches, (51 to 69 cm); yellowish red (5YR 5/6) very gravelly loam, dark reddish brown (2.5YR 3/4) moist; 20 percent clay; moderate fine subangular blocky structure; slightly hard, friable, slightly sticky, slightly plastic; few fine and coarse roots throughout; many fine tubular and few medium tubular pores; 40 percent continuous prominent clay films on bottom surfaces of rock fragments; 50 percent subangular metavolcanic gravel; slightly acid, pH 6.1 by pH meter 1:1 water; abrupt smooth boundary.
BCt2--27 to 36 inches, (69 to 91 cm); yellowish red (5YR 5/6) extremely gravelly loam, dark reddish brown (2.5YR 3/4) moist; 17 percent clay; moderate fine subangular blocky structure; slightly hard, friable, slightly sticky, slightly plastic; few fine, common coarse and few very coarse roots throughout; common fine tubular pores; 10 percent discontinuous faint clay films on faces of peds; 85 percent subangular metavolcanic gravel; slightly acid, pH 6.1 by PH meter 1:1 water; abrupt smooth boundary.
BCt3--36 to 51 inches, (91 to 129 cm); reddish yellow (7.5YR 7/6) very gravelly loam, yellowish red (5YR 5/8) moist; 18 percent clay; weak fine subangular blocky structure; slightly hard, friable, slightly sticky, moderately plastic; common fine, medium and coarse roots throughout; few fine tubular pores; 60 percent continuous distinct clay films on surfaces along pores; 40 percent subangular metavolcanic gravel; slightly acid, pH 6.1 by pH meter 1:1 water; abrupt smooth boundary. (Combined thickness of the BCt horizon is 0 to 31 inches, (0 to 79 cm) thick)
Crt--51 to 62 inches, (129 to 157 cm); paralithic vertically oriented highly weathered greenschist; few very fine and coarse roots in cracks; 60 percent continuous prominent clay films on rock fragments.
TYPE LOCATION: Butte County, California; about 6.25 miles northeast of Oroville Dam, approximately 1,300 feet west and 750 feet south of the northeast corner of Section 9, T.20 N., R.5 E., 39 degrees, 36 minutes, 41.47 seconds North latitude and 121 degrees, 24 minutes, 51.65 seconds West longitude. NAD83 - U.S.G.S. Quad: Oroville Dam, California.
RANGE IN CHARACTERISTICS: Depth to paralithic bedrock is 40 to 60 inches, (102 to 152 cm). The mean annual soil temperature is 53 to 59 degrees F, (12 to 14 degrees C). The soil moisture control section is dry in all parts from about June to about October (about 120 days). The particle-size control section averages 18 to 27 percent clay and 5 to 35 percent rock fragments, mostly gravel. Mineralogy is mixed. Organic matter ranges from 1 to 4 percent to a depth of 15 inches, (38 cm) and is less than 1 percent to a depth of 51 inches, (129 cm). Base saturation by sum of cations is 39 to 50 percent from 9 to 20 inches, (23 to 51 cm) and is 50 to 75 percent from 20 to 51 inches, (51 to 129 cm). Rock fragments on the surface range from 0 to 30 percent gravel, 0 to 5 percent cobbles and 0 to 5 percent stones. Some pedons have silty clay textures with up to 50 percent clay in the lower part of the Bt horizon; some lack a BCt horizon.
The A horizon dry color is 5YR 7/4, 7/6, 7.5YR 4/2, 5/4, 6/4, 7/4, or 10YR 6/3. Moist color is 5YR 2.5/1, 3/3, 3/4, 4/4, 5/4, 4/6, 7.5YR 4/3, 4/4 or 4/6. Texture is loam or gravelly loam with high silt content. Clay content ranges from 15 to 25 percent. Rock fragments range from 5 to 25 percent gravel. Reaction ranges from moderately acid to neutral.
The BAt horizon dry color is 7.5YR 5/4, 6/6; 5YR 5/6, 7/6, or 2.5YR 7/6. Moist color is 7.5YR 4/6, 5YR 3/4, 4/6, 2.5YR 3/6 or 5/6. Texture is gravelly loam, loam, clay loam or gravelly clay loam with high silt content. Clay content ranges from 19 to 30 percent. Rock fragments range from 10 to 25 percent gravel. Reaction ranges from moderately acid to neutral.
The Bt horizon dry color is 5YR 5/6, 6/6, 6/8, 7/4, 7/6, 7/8, 8/4, 2.5YR 4/8, 5/6, 6/6, 7/6, 7/8, 7.5YR 5/4 or 6/6. Moist color is 5YR 3/4, 3/6, 4/4, 4/6, 5/6, 5/8, 2.5YR 3/6, 4/6, 5/6, 6/6 or 5/8. Texture is gravelly loam, gravelly clay loam, loam, clay loam or silty clay loam with high silt content. Clay content ranges from 18 to 35 percent. Rock fragments range from 5 to 25 percent gravel and 0 to 10 percent cobbles. Reaction ranges from very strongly acid to neutral.
The BCt horizon dry color is 2.5YR 7/8, 5YR 5/6, 6/6 or 7.5YR 7/6. Moist color is 2.5YR 3/4, 4/6, 5/8 or 5YR 5/8. Texture is extremely gravelly loam, very gravelly clay loam or extremely gravelly clay loam with high silt content. Clay content ranges from 15 to 35 percent. Rock fragments range from 40 to 85 percent gravel. Reaction ranges from very strongly acid to slightly acid.
COMPETING SERIES: These are the Hospiter, Millerridge, Minniecreek, Sitton, Speaker and Willakenzie series. Hospiter and Sitton are very deep. Willakenzie and Millerridge are moderately deep. Minniecreek is moderately deep with 10YR hue. Speaker is moderately deep to paralithic material.
GEOGRAPHIC SETTING: Bigridge soils are on ridge tops and side slopes on Sierra Nevada foothills and mountains. Slopes range from 2 to 70 percent. These soils formed in colluvium and residuum weathered from metavolcanic and metasedimentary rocks. Elevation is 900 to 3400 feet, (274 to 1036 m). Mean annual precipitation is 45 to 70 inches, (1143 to 1778 mm). The mean annual temperature is 53 to 57 degrees F, (12 to 14 degrees C). Frost free season is 165 to 245 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Featherfalls, Hartsmill, Islandbar, Minniecreek, Mounthope and Surnuf soils. Featherfalls soils are fine-loamy and very deep. Hartsmill soils are loamy-skeletal, very deep.and thermic. Islandbar soils are coarse-loamy and very deep. Minniecreek soils are moderately deep. Mounthope soils are fine-loamy, have base saturation of 50 to 75 percent, are deep and thermic. Surnuf soils are fine and very deep.
DRAINAGE AND PERMEABILITY: Well drained; low to medium runoff; moderately rapid to rapid saturated hydraulic conductivity in the A horizon, moderate to moderately slow in the BAt and Bt horizons and moderately slow to moderately rapid in BCt horizon.
USE AND VEGETATION: This soil is used for wildlife habitat, home site development, watershed and limited timber production. Vegetation is whiteleaf manzanita, toyon, interior live oak, Pacific madrone, foothill pine, California black oak, bigleaf maple, ponderosa pine, poison oak, and some Douglas-fir, incense cedar, ryegrass, deerbrush, California buckthorn and canyon live oak.
DISTRIBUTION AND EXTENT: Butte County, California and occur in the (M261Fb) Lower Foothills Metamorphic Belt subsection of the (M261F) Sierra Nevada Foothills section. MLRA 18 Sierra Nevada Foothills and low elevations in 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 Big Ridge, Oroville Dam quad.
REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - zone from 1 to 9 inches, (3 to 23 cm). (A)
Argillic horizon - zone from 9 to 27 inches, (23 to 69 cm). (Bt1, Bt2, Bt3, BCt1)
Paralithic contact - zone from 51 to 62 inches, (130 to 158 cm). (Cr)
Particle-size control section - zone from 9 to 27 inches, (23 to 69 cm). (Bt1, Bt2, Bt3, BCt1)
The soil moisture control section - zone from 7 to 23 inches, (18 to 58 cm).
ADDITIONAL DATA: Reference samples from lab pedon number: 01N0268, NSSL Lincoln, NE.