LOCATION BROCKGULCH CAEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, thermic Typic Haploxerepts
TYPICAL PEDON: Brockgulch very gravelly loam--on a southwest facing convex-concave slope of 65 percent under canyon live oak, digger pine, soft chess and other grasses at an elevation of 2,600 feet. (Colors are for dry soil unless otherwise stated. When described on May 24, 1983, soil was slightly moist throughout). Scattered leaves mixed with gravel on the surface.
The soil surface is covered by about 60 percent gravel and 5 percent cobbles.
A--0 to 3 inches; brown (7.5YR 4/4) very gravelly loam, dark brown (7.5YR 3/4) moist; weak fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few medium and fine, common very fine roots; few fine, common very fine tubular pores; 40 percent gravel; slightly acid (pH 6.5); clear wavy boundary. (2 to 5 inches thick)
Bt1--3 to 11 inches; brown (7.5YR 4/4) very gravelly loam, dark brown (7.5YR 3/4) moist; moderate medium and fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few coarse, medium, and fine, common very fine roots; common medium and fine, common very fine tubular pores; few thin clay bridging between mineral grains; 50 percent gravel; slightly acid (pH 6.5); clear wavy boundary. (7 to 9 inches thick)
Bt2--11 to 16 inches; strong brown (7.5YR 4/6) very gravelly loam, dark brown (7.5YR 4/4) moist; moderate medium and fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common coarse, medium, fine and very fine roots; few fine and very fine tubular pores; few thin clay bridging between mineral grains; 55 percent gravel; slightly acid (pH 6.5); clear wavy boundary. (4 to 7 inches thick)
C--16 to 24 inches; strong brown (7.5YR 4/6) extremely gravelly loam, dark brown (7.5YR 4/4) moist; weak fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few medium and coarse, common fine and very fine roots; few fine and very fine tubular pores; 60 percent gravel, 10 percent cobbles; moderately acid (pH 6.0); abrupt wavy boundary. (7 to 19 inches thick)
R--24 inches; slightly fractured schist, cracks about 1 to 2 inches apart, roots in some cracks.
TYPE LOCATION: Trinity County, California; about 2.5 miles northeast of Helena; 5.7 miles west of Junction City on Highway 299 turn north on to Brock Gulch Access Road, go 3.5 miles, take left down to creek, walk across creek and then northwest uphill 800 feet, pedon on southwest facing slope; 1,400 feet south, 100 feet east of the northwest corner of section 23, T. 34 N., R. 11 W. Dedrick Quadrangle.
RANGE IN CHARACTERISTICS: Depth to bedrock is 20 to 40 inches. Base saturation (ammonium acetate) ranges from 70 to 85 percent in the 10 to 30 inch depth zone. The particle-size control section averages 35 to 65 percent rock fragments and has 15 to 25 percent clay. The mean annual soil temperature is 59 to 65 degrees F. The soil moisture control section is dry in all parts from about mid June to mid October (110 to 130 days). The soil temperature at a depth of 20 inches exceeds 41 degrees F from early March to late December (280 to 310 days), and exceeds 47 degrees F from about mid March to late November.
The A horizon is 7.5YR 4/4, 4/6, 10YR 5/6, 5/3, 4/3, 3/3. Moist color is 7.5YR 3/4, 10YR 3/3 or 3/4. It is slightly acid or neutral.
The Bt horizon is 7.5YR 4/4, 4/6, 5/4, 10YR 4/4, 5/4, 5/6, or 5/8. Moist color is 7.5YR 4/4, 3/4, 10YR 4/3, 4/4, 3/4 or 3/6. It is slightly acid or neutral.
The C horizon is 7.5YR 4/6, 4/4, 10YR 5/4 or 5/8. Moist color is 7.5YR 4/4, 3/4, 10YR 3/4, or 4/6. It is extremely gravelly loam, extremely gravelly sandy clay loam, or very gravelly loam.
COMPETING SERIES: This is the Modjeska series. Modjeska soils are deeper than 40 inches to bedrock.
GEOGRAPHIC SETTING: The Brockgulch soils are on mountains on south and southwest facing slopes. Elevation is 1,500 to 4,000 feet. Slopes are 50 to 75 percent. These soils formed in residuum and colluvium from metavolcanic rocks. The climate is characterized by warm, dry summers and cool, moist winters. Mean annual precipitation is 40 to 55 inches. Snowfall ranges from 0 to 6 inches. Mean January temperature is about 39 degrees F. Mean July temperature is about 75 degrees F. Mean annual temperature is 57 to 63 degrees F. The frost-free period is 90 to 130 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Pardaloe, Brownbear, and Dedrick soils. Pardaloe soils are greater than 40 inches deep to bedrock. Brownbear soils have a mesic temperature regime. Dedrick soils are less than 20 inches deep to bedrock.
DRAINAGE AND PERMEABILITY: Well drained; very rapid runoff; moderate permeability.
USE AND VEGETATION: This soil is used for watershed. Vegetation consists of canyon live oak, wild oat, poison-oak, curlleaf mountain mahogany, soft chess and digger pine.
DISTRIBUTION AND EXTENT: The soils are not extensive. They occur in the Klamath Mountains in northern California. MLRA is 5.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California.
SERIES ESTABLISHED: Trinity County, California; Weaverville Area, 1990. Name from Brock Gulch.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon--the zone from the surface to 11 inches (A, Bw1 horizons).
Cambic horizon--the zone from a depth of 3 to 16 inches (Bt1, Bt2 horizons).
Particle-size control section--the zone from a depth of 10 to 24 inches (Bt1, Bt2, C horizons).
Lithic contact--the boundary at 24 inches (R).
Additional Data: NSSL pedon S84CA=-105-001 (partial pedon) confirms Typic subgroup--base saturation greater than 60 percent (ammonium acetate).