LOCATION THERMALROCKS CAEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, thermic Lithic Haplohumults
TYPICAL PEDON: Thermalrocks very gravelly loam, on a northwest facing 2 percent slope under a cover of annual grasses and forbs at an elevation of 970 feet, (296 m). When described on 5/17/2001 the soil was dry throughout. (Colors are for dry soil unless otherwise noted)
A--0 to 1 inches, (0 to 3 cm); brown (10YR 5/3) very gravelly loam, dark brown (7.5YR 3/2), moist; 16 percent clay; weak fine platy parting to moderate fine granular structure; soft, friable, slightly sticky, nonplastic; many very fine and fine roots; many fine irregular pores; 15 percent subangular basalt cobbles and 20 percent subangular basalt gravel; strongly acid, pH 5.5 by Hellige-Truog; clear wavy boundary. (1 to 4 inches, (3 to 10 cm) thick)
Bt--1 to 5 inches, (3 to 13 cm); brown (10YR 5/3) very gravelly loam, dark brown (7.5YR 3/2), moist; 20 percent clay; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky, slightly plastic; common very fine and fine roots; common fine irregular pores; 10 percent discontinuous faint clay films on surfaces along pores; 15 percent subangular basalt cobbles and 45 percent subangular basalt gravel; very strongly acid, pH 5.0 by Hellige-Truog; abrupt irregular boundary. (4 to 12 inches, (10 to 30 cm) thick)
R--5 inches, (13 cm); indurated basalt bedrock
TYPE LOCATION: Butte County, California; about 2.6 miles north of Oroville, California approximately 1000 feet south and 2800 feet east of the northwest corner of Section 31, Township 20 N., Range 4 E., 39 degrees, 33 minutes, 06.55 seconds North Latitude; 121 degrees, 34 minutes, 01.19 seconds West Longitude. NAD83 - USGS Quad: Oroville, California.
RANGE IN CHARACTERISTICS: Depth to lithic bedrock is 5 to 10 inches, (8 to 25 cm). The mean annual soil temperature is 61 to 64 degrees F, (16 to 18 degrees C). The soil moisture control section is dry in all parts from about April to about November (about 150 to 200 days). The particle-size control section averages 18 to 27 percent clay and 35 to 55 percent rock fragments, mostly gravel and cobbles. Mineralogy is mixed. Base saturation by sum of the cations ranges from 4 to 7 percent. Rock fragments on the surface range from 0 to 60 percent gravel, 0 to 50 percent cobbles and 0 to 10 percent stones. Some pedons have cobbly, very cobbly or gravelly silt loam textures throughout.
The A horizon dry color is 10YR 3/3, 4/3, 4/4 or 5/3. Moist color is 7.5YR 2/2, 3/2, 3/3, 10YR 2/2, 3/2 or 3/3. Texture is cobbly loam, very gravelly loam, gravelly loam, loam, extremely gravelly loam or very cobbly loam. Clay content ranges from 14 to 18 percent. Organic matter ranges from 4 to 8 percent. Rock fragments range from 10 to 65 percent gravel, 5 to 40 percent cobbles. Reaction ranges from very strongly acid to slightly acid.
The Bt horizon dry color is 10YR 3/3, 3/4, 4/4, 5/3, 5/4 or 7.5YR 4/4. Moist color is 7.5YR 3/2, 3/4, 4/2, 10YR 2/2, 3/2, 3/3 or 4/2. Texture is very gravelly loam, very cobbly loam, very cobbly clay loam, extremely cobbly loam or extremely gravelly loam. Clay content ranges from 18 to 28 percent. Organic matter ranges from 1.5 to 5 percent. Rock fragments range from 10 to 90 percent gravel, 15 to 50 percent cobbles. Reaction ranges from very strongly acid to moderately acid.
COMPETING SERIES: This is the Beatsonhollow series. Beatsonhollow soils are shallow, have a seasonal water table and are in swales.
GEOGRAPHIC SETTING: Thermalrocks soils are on tops of basalt plateaus in volcanic Sierra Nevada foothills. Slopes range from 2 to 30 percent. These soils formed in residuum weathered from basalt. Elevation is 150 to 1580 feet, (46 to 482 m). Mean annual precipitation is 25 to 35 inches, (635 to 889 mm). The mean annual temperature is 59 to 62 degrees F, (15 to 17 degrees C). Frost free season is 250 to 260 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Beatsonhollow, Campbellhills, Cherotable and Elsey soils. Beatsonhollow soils are in swales, are loamy-skeletal, are shallow and poorly drained. Campbellhills soils are in joint fractures on basalt plateaus are loamy-skeletal and deep. Cherotable soils are on flat to undulating positions on basalt plateaus, are fine-loamy and deep . Elsey soils are on mounds, are fine-loamy and moderately deep.
DRAINAGE AND PERMEABILITY: Well drained; very high runoff; moderate saturated hydraulic conductivity.
USE AND VEGETATION: This soil is used for livestock grazing, recreation, and wildlife habitat. Vegetation is Silver hairgrass, Sierra mock stone crop, Hansons club moss, soft chess, filaree, red brome, medusahead, fiddleneck, lupine, mullen, buckwheat, nitgrass, vinegar weed, brodiaea and Mariposa lily.
DISTRIBUTION AND EXTENT: Butte County, California and occurs in Lower Foothills Metamorphic Belt (M261Fb) and as inclusions on the Hardpan Terraces (262Ag) subsections 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 is coined.
REMARKS: These soils were previously mapped as scablands in the Soil Survey of Oroville Area, Soil Survey of Chico Area, California 1926.
Diagnostic horizons and features recognized in this pedon are:
Umbric epipedon - zone from 0 to 5 inches, (0 to 13 cm) (A and Bt horizons).
Argillic horizon - zone from 1 to 5 inches, (3 to 13 cm) (Bt horizon)
Particle-size control section - zone from 0 to 5 inches, (0 to 13 cm)
The soil moisture control section - zone from 0 to 5 inches, (0 to 13 cm)
ADDITIONAL DATA: Used data from nearby Sample # 67-CA-04-014X, University of California, Davis.