LOCATION SOMMEYFLAT CAEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, thermic Ultic Haploxeralfs
TYPICAL PEDON: Sommeyflat loam, on an east facing 5 percent slope under a cover of annual grasses and forbs at an elevation of 1950 feet, (594 m). When described on 5/29/2002 the soil was dry from the surface to 2 inches, (5 cm) and slightly moist from 2 to more than 70 inches, (5 to 178 cm). (Colors are for dry soil unless otherwise noted)
A--0 to 2 inches, (0 to 5 cm); strong brown (7.5YR 5/6) loam, dark brown (7.5YR 3/4) moist; 19 percent clay; weak very fine and fine subangular blocky structure; soft, very friable, nonsticky, slightly plastic; many very fine roots; many very fine and fine tubular pores; slightly acid, pH 6.2 by Hellige-Truog; abrupt smooth boundary. (2 to 4 inches, (5 to 10 cm) thick)
BA--2 to 9 inches, (5 to 23 cm); strong brown (7.5YR 4/6) loam, dark brown (7.5YR 3/4) moist; 21 percent clay; weak very fine and fine subangular blocky structure; slightly hard, very friable, slightly sticky, slightly plastic; many very fine roots; many very fine and fine tubular pores; 2 percent subangular metadiorite gravel; slightly acid, pH 6.2 by Hellige-Truog; clear smooth boundary. (4 to 7 inches, (10 to 18 cm) thick)
Bt1--9 to 14 inches, (23 to 36 cm); strong brown (7.5YR 5/6) loam, dark brown (7.5YR 3/4) moist; 24 percent clay; moderate fine subangular blocky structure; slightly hard, very friable, slightly sticky, slightly plastic; common very fine roots; many very fine, fine, and common medium tubular pores; 5 percent patchy distinct clay films on faces of peds; 2 percent metadiorite gravel; slightly acid, pH 6.3 by Hellige-Truog; clear wavy boundary.
Bt2--14 to 24 inches, (36 to 61 cm); yellowish red (5YR 4/6) loam, dark reddish brown (5YR 3/4) moist; 26 percent clay; moderate fine and medium subangular blocky structure; moderately hard, friable, slightly sticky, slightly plastic; many very fine roots; very fine, fine, and medium tubular pores; 10 percent patchy distinct clay films on faces of peds; slightly acid, pH 6.4 by Hellige-Truog; clear wavy boundary. (Combined thickness of the Bt horizon is 15 to 40 inches, (38 to 102 cm) thick)
BCt--24 to 31 inches, (61 to 79 cm); yellowish red (5YR 5/6) loam, dark reddish brown (5YR 3/4) moist; 24 percent clay; moderate fine and medium subangular blocky structure; slightly hard, very friable, slightly sticky, slightly plastic; many very fine roots; many very fine and fine tubular pores; 10 percent patchy distinct clay films on faces of peds; slightly acid, pH 6.5 by Hellige-Truog; clear smooth boundary. (7 to 50 inches, (18 to 127 cm) thick)
C1--31 to 62 inches, (79 to 157 cm); brownish yellow (10YR 6/6) loam, dark yellowish brown (10YR 4/6) moist; 19 percent clay; weak very fine and fine subangular blocky structure; soft, very friable, nonsticky, slightly plastic; few very fine roots; common very fine and fine tubular pores; neutral, pH 6.8 by Hellige-Truog; clear smooth boundary.
C2--62 to 70 inches, (157 to 178 cm); yellowish brown (10YR 5/6) loam, dark yellowish brown (10YR 4/4) moist; 16 percent clay; weak very fine and fine subangular blocky structure; soft, very friable, nonsticky, slightly plastic; common very fine and fine tubular pores; neutral, pH 6.9 by Hellige-Truog. (Combined thickness of the C horizon is 10 to 40 inches, (25 to 102 cm) thick)
TYPE LOCATION: Butte County, California; about 2.2 miles north of Rackerby, California, approximately 900 feet north and 1150 feet west of the southeast corner of Section 30, T.19 N., R.6 E., 39 degrees, 28 minutes, 15.60 seconds North latitude and 121 degrees, 20 minutes, 15.97 seconds West longitude. NAD-83 U.S.G.S. Quad: Rackerby, California.
RANGE IN CHARACTERISTICS: Depth to paralithic bedrock is 60 to 80 inches or more (152 to 203cm). The mean annual soil temperature is 59 to 63 degrees F, (16 to 17 degrees C). The soil moisture control section is dry in all parts from about June through October (about 165 days). The particle-size control section averages 22 to 29 percent clay, 2 to 15 percent rock fragments, mostly gravel. Mineralogy is mixed. Rock fragments on the surface range from 0 to 2 percent gravel. Some pedons have a BAt horizon.
The A horizon dry color is 7.5YR 4/4, 4/6, 5/6, 10YR 4/4 or 6/3. Moist color is 7.5YR 3/3, 3/4, 4/6, 10YR 3/3 or 3/4. Texture is loam or gravelly loam. Clay content ranges from 15 to 20 percent. Rock fragments range from 0 to 20 percent gravel. Base saturation by sum of cations ranges from 50 to 70 percent. Organic matter ranges from 4 to 8 percent. Reaction ranges from slightly acid to neutral.
The BA horizon dry color is 7.5YR 4/6, 5/6, 10YR 4/4, 6/3 or 5YR 4/6. Moist color is 7.5YR 3/4, 5YR 3/4 or 10YR 3/3. Texture is loam or gravelly loam. Clay content ranges from 14 to 21 percent. Rock fragments range from 0 to 20 percent gravel and 0 to 5 percent cobbles. Base saturation by sum of cations ranges from 45 to 65 percent. Organic matter ranges from 1 to 4 percent. Reaction is slightly acid.
The upper Bt horizon dry color is 7.5YR 4/4, 4/6, 5/6, 6/4, 5YR 4/6 or 2.5YR 5/6. Moist color is 7.5YR 3/4, 5YR 4/4 or 2.5YR 4/6. Texture is loam or clay loam. Clay content ranges from 18 to 30 percent. Rock fragments range from 0 to 10 percent gravel. Base saturation by sum of cations ranges from 55 to 74 percent. Organic matter ranges from 0.4 to 1.5 percent. Reaction is slightly acid.
The lower Bt horizon dry color is 7.5YR 4/6, 5/6, 6/4, 5YR 4/6, 5/6, 6/4 or 2.5YR 4/6. Moist color is 7.5YR 3/4, 4/3, 4/4, 4/6, 5YR 3/4, 4/4, 4/6 or 2.5YR 4/4. Texture is loam, clay loam or gravelly clay loam. Clay content ranges from 22 to 33 percent. Rock fragments range from 0 to 15 percent gravel and 0 to 2 percent cobbles. Base saturation by sum of cations ranges from 75 to 85 percent. Organic matter ranges from 0.2 to 1.0 percent. Reaction ranges from slightly acid to neutral.
The BCt horizon dry color is 7.5YR 5/8, 6/8, 10YR 5/3, 5/4, 6/4, 5YR 5/6 or 2.5YR 5/6. Moist color is 7.5YR 4/6, 5/6, 10YR 3/4, 4/3, 4/4, 5/4, 5YR 3/4 or 2.5YR 4/6. Texture is loam or clay loam. Clay content ranges from 18 to 30 percent. Rock fragments range from 0 to 10 percent gravel. Organic matter ranges from 0 to 0.5 percent. Reaction is slightly acid.
The C horizon dry color is 7.5YR 6/6, 10YR 5/6 or 6/6. Moist color is 7.5YR 4/6, 10YR 4/4 or 4/6. Texture is loam or gravelly fine sandy loam. Clay content ranges from 16 to 22 percent. Rock fragments range from 0 to 25 percent gravel. Reaction ranges from slightly acid to neutral.
COMPETING SERIES: These are the Bearwallow, Churn, Elsey, Loafercreek, Mounthope and Wisheylu series. Bearwallow, Elsey, and Loafercreek soils are moderately deep to a paralithic contact. Mounthope soils are deep to a paralithic contact. Churn and Wisheylu soils are very deep and have argillic horizons with base saturation less than 75 percent in all parts.
GEOGRAPHIC SETTING: Sommeyflat soils are on side slopes and ridge tops on plutons in Sierra Nevada foothills. Slopes range from 5 to 30 percent. These soils formed in residuum and colluvium weathered from metamorphosed intrusive igneous rocks, mainly metagabbro or metadiorite. Elevation is 800 to 2100 feet, (244 to 640 m). Mean annual precipitation is 35 to 55 inches, (889 to 1397 mm). The mean annual temperature is 56 to 60 degrees F, (13 to 16 degrees C). Frost free season is 240 to 260 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Flanly, Hurleton, Mounthope and Parkshill soils. Flanly and Hurleton soils are moderately deep to a paralithic contact. Mounthope soils are deep to a paralithic contact. Parkshill soils are very deep to bedrock and lack an argillic horizon.
DRAINAGE AND PERMEABILITY: Well drained; medium to high runoff; moderate saturated hydraulic conductivity in the A and BA horizons, moderate to moderately slow in the Bt and BCt horizons and moderate to moderately rapid in the C horizon.
USE AND VEGETATION: This soil is used for livestock grazing, wildlife habitat, watershed and home site development. Vegetation is mainly annual grasses, forbs, blue oak, interior live oak, scattered foothill pine, whiteleaf manzanita, buckbrush, toyon, creeping sage and Pacific poison oak
DISTRIBUTION AND EXTENT: Butte County, California and occurs in (M261Fb) Lower Foothills Metamorphic Belt subsection of the (M261F) Sierra Nevada Foothills section. MLRA 18 -Sierra Nevada Foothills. The soils are not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Butte County, California 2005. Source of name from Sommey Flat on the Rackerby and Forbestown Quads.
REMARKS: These soils were previously mapped as Rough broken and stony land, (Rb) in the Soil Survey of Oroville Area, California 1926.
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - zone from 0 to 2 inches, (0 to 5 cm) (A)
Argillic horizon - zone from 9 to 24 inches, (23 to 61 cm) (Bt)
Particle-size control section - zone from 9 to 24 inches, (23 to 61 cm)
The soil moisture control section - zone from 6 to 12 inches, (15 to 30 cm)