LOCATION BROWNSCREEK CAEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, mesic Ultic Haploxeralfs
TYPICAL PEDON: Brownscreek gravelly loam--on a southeast facing slope of 67 percent under Oregon white oak, ponderosa pine, canyon live oak, Douglas-fir, Pacific madrone, buckbrush and grass at an elevation of 2,300 feet. (Colors are for dry soil unless otherwise stated. When described, on April 5, 1983, the soil was slightly moist.) The soil surface is partially covered by 35 percent channers and 2 percent cobbles.
Oi--1 to 0 inches; leaves and needles.
A--0 to 6 inches; strong brown (7.5YR 5/6) gravelly loam, brown (7.5YR 4/4)moist; moderate fine and very fine subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; many coarse, common medium, fine and very fine roots; few coarse, common fine and very fine tubular pores; 20 percent pebbles; neutral (pH 7.0); clear wavy boundary. (5 to 7 inches thick)
BA--6 to 13 inches; reddish yellow (7.5YR 6/6) very gravelly loam, strong brown (7.5YR 4/6) moist; moderate fine subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; many coarse, common medium, fine and very fine roots; few medium, common fine and very fine tubular pores; 35 percent pebbles, 10 percent cobbles; slightly acid (pH 6.5); gradual wavy boundary. (3 to 7 inches thick)
Bt1--13 to 24 inches; reddish yellow (7.5YR 6/8) very gravelly clay loam, strong brown (7.5YR 4/6) moist; moderate fine subangular blocky structure; hard, friable, slightly sticky and slightly plastic; common medium, fine, and very fine roots; few fine, common very fine tubular pores; common thin clay films lining pores and on ped faces; 35 percent pebbles, 10 percent cobbles; slightly acid (pH 6.5); gradual wavy boundary. (8 to 10 inches thick)
Bt2--24 to 34 inches; reddish yellow (7.5YR 6/8) extremely gravelly loam, strong brown (7.5YR 4/6) moist; weak medium and fine subangular blocky structure; hard, friable, slightly sticky and slightly plastic; few medium, common fine and very fine roots; few very fine tubular pores; few thin clay films lining pores and on ped faces; 65 percent pebbles, 10 percent cobbles; slightly acid (pH 6.5); clear wavy boundary. (4 to 16 inches thick)
R--34 inches; Extremely fractured mica schist. Clay films and black stains line fractures. Fractures are about 1 to 2 inches apart. Soil in fractures is the same as soil in Bt2 horizon.
TYPE LOCATION: Trinity County, California; about 2 1/2 miles southwest of Douglas City, California; take "B bar K" Road north from Highway 3 to the end of the pavement, cross bridge, go 0.1 mile, take left fork, go 0.1 mile, take right fork, go 0.2 mile, take right fork, go 0.7 mile to fork on hairpin turn, take left fork, go 0.5 mile, pedon described uphill 50 feet; 1,400 feet east, and 1,650 feet north of the southwest corner of section 10, T.32N., R.10W. Weaverville Quadrangle. 40 degrees North latitude 38 minutes, 36 secondddds, 122 degrees Wst longitude 59 minutes, 33 seconds.
RANGE IN CHARACTERISTICS: The solum thickness and the depth to bedrock ranges from 20 to 40 inches. The particle-size control section contains 15 to 25 percent mica minerals in the very fine sand fraction. Mean annual soil temperature ranges from 52 to 59 degrees F. The soil moisture control section is dry in all parts from early July to early October. The soil temperature at a depth of 20 inches exceeds 41 degrees F from about March 15 to about December 15 (270 days), and exceeds 47 degrees F from about April 15 to November 15. The particle-size control section has a ratio of extractable iron oxide plus gibbsite to clay of 0.2 to 0.3.
The A horizon is 7.5YR 5/6, 5/4, 6/4, 10YR 5/4, 6/4, 7/4, 6/2, or 4/3. Moist color is 7.5YR 4/4, 4/6, 3/4, 10YR 3/4, 5/4, 3/6, 4/2, 3/2, or 4/4. The A horizon is moderately acid to neutral.
The Bt horizon is 7.5YR 6/8, 5/4, 5/6, 7/6, 7/4, 6/6, 10YR 7/4, 5/3, 6/3, 5YR 4/4, 5/4, or 5/6. Moist color is 7.5YR 4/6, 3/4, 4/4, 5/6, 10YR 3/4, /3, 4/4, 5/6, 5l8, 5YR 3/4, 4/4, 4/6 or 5/6. It is very gravelly loam, very gravelly clay loam, extremely gravelly clay loam, very gravelly sandy clay loam, or extremely gravelly loam. The Bt contains 35 to 75 percent rock fragments, and 25 to 35 percent clay. It is strongly acid to slightly acid. Base saturation is 50 to 75 percent by sum of cations.
COMPETING SERIES: This is the Walnett series. Walnett soils are 40 to greater than 60 inches deep to bedrock and have extractable iron oxide plus gibbsite to clay ratios of more than 0.4. The Walnett series was set up broadly to establish the family in family level mapped areas. When these areas are mapped at the series level, Walnett will be split and inactivated.
GEOGRAPHIC SETTING: Brownscreek soils are on mountains. Slopes are 30 to 75 percent. Elevation is 1,650 to 4,500 feet. The soils weathered in residuum and colluvium from mica schist. The climate is characterized by warm, dry summers and cool, moist winters. Mean annual precipitation is 30 to 60 inches. Snowfall ranges from six to 36 inches. Mean January temperature is about 38 degrees F. Mean July temperature is about 73 degrees F. Mean annual temperature is 50 to 57 degrees F. The frost-free period is 90 to 130 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Dougcity, Springgulch, Caris, Indleton, Hoosimbim, Sheetiron (T), and Barleyfield (T) soils. The Dougcity and Springgulch soils are greater than 60 inches deep. The Caris, Indleton, and Hoosimbim soils lack significant amounts of mica minerals in the particle-size control section. The Sheetiron and Barleyfield soils lack an argillic horizon.
DRAINAGE AND PERMEABILITY: Well drained; rapid to very rapid runoff; moderate permeability.
USE AND VEGETATION: Brownscreek soils are used for timber production, water supply and wildlife habitat. Vegetation is dominantly ponderosa pine, California black oak, canyon live oak, Douglas-fir, Pacific madrone, greenleaf manzanita, poison oak, and grasses.
DISTRIBUTION AND EXTENT: The soils are not extensive. They occur in the Klamath Mountains of northern California. MLRA 5.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Trinity County, California, Weaverville Area, 1990. Name is coined from Browns Creek.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon--the zone from the surface to 13 inches (A, BA horizons).
Argillic horizon--the zone from 13 to 34 inches (Bt1, Bt2 horizons).
ADDITIONAL DATA: NSSL pedon S83CA-105-013 (type location). Field estimates for percent clay are much higher than lab data for both measured clay and adjusted to 15 bar water content. Field estimates are used with assumption that weathered mica fragments crushed in sample preparation influenced measured clay and 15 bar water content.