LOCATION HOLKAT CATentative Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Typic Dystroxerepts
TYPICAL PEDON: Holkat loam--on a north facing slope of 50 percent under Douglas-fir, wild iris, California fescue, and California black oak at an elevation of 4,100 feet. (Colors are for dry soil unless otherwise stated. When described on June 3, 1981 the soil was slightly moist.)
The soil surface is covered with about 15 percent gravel.
A--0 to 3 inches; brown (10YR 5/3) loam, dark brown (10YR 3/3) moist; weak fine and very fine granular structure; slightly hard, friable, slightly sticky, and slightly plastic; common fine and very fine roots; common fine, many very fine tubular pores; 5 percent gravel; slightly acid (pH 6.5); clear wavy boundary. (3 to 6 inches thick).
Bt--3 to 10 inches; light yellowish brown (10YR 6/4) loam, brown (10YR 4/3) moist; weak fine subangular blocky structure; slightly hard, friable, slightly sticky, and slightly plastic; few fine and medium, many very fine roots; common very fine tubular pores; few thin clay films lining pores and on ped faces; 10 percent gravel; slightly acid (pH 6.5); gradual wavy boundary. (6 to 20 inches thick).
C1--10 to 22 inches; light brown (7.5YR 6/4) gravelly loam, brown (7.5YR 5/4) moist; massive; hard, friable, slightly sticky, and slightly plastic; few very fine roots; few very fine tubular pores; 20 percent gravel; slightly acid (pH 6.5); gradual wavy boundary. (11 to 13 inches thick).
C2--22 to 35 inches; light brown (7.5YR 6/4) gravelly loam, brown (7.5YR 5/4) moist; massive; hard, friable, slightly sticky, and slightly plastic; few very fine roots; few very fine tubular pores; 25 percent gravel; slightly acid (pH 6.5); clear wavy boundary. (0 to 13 inches thick).
Cr--35 to 37 inches; Weathered saprolitic metasedimentary rock, no roots.
TYPE LOCATION: Trinity County, California; about 4 1/2 miles southwest of Lewiston, California; Highway 299 east from Weaverville 14.1 miles, turn south off of road, cross Grass Valley Creek on concrete bridge, go 5.5 miles, pedon downhill 50 feet; 600 feet east, 250 feet south, of the northwest corner of section 12, T.32 N., R.9 W. Lewiston Quadrangle.
RANGE IN CHARACTERISTICS: Combined thickness of the A and Bt horizons is 10 to 20 inches. Depth to weathered bedrock ranges from 20 to 40 inches. The particle-size control section contains from 10 to 30 percent gravel, and 24 to 26 percent clay. The soil is slightly acid or moderately acid throughout. The mean annual soil temperature is 47 to 53 degrees F. The soil moisture control section from 5 to 15 inches is dry from about mid July to mid October (90 to 100 days). The soil temperature at 20 inches exceeds 41 degrees F from about mid April to late December (255 days), and exceeds 47 degrees F from about early April to mid December.
The A horizon is 10YR 5/3, 6/3, or 5/2. Moist color is 10YR 3/3 or 3/2.
The Bt horizon is 10YR 6/4, 6/3, or 7.5YR 7/2. It is loam or gravelly loam.
COMPETING SERIES: These are the Colestine, Hugo, Hurlbut, Madonna, Schnorbush, Tebo and Yeary series. Colestine and Madonna soils have a lithic contact at 20 to 40 inches. Hugo soils are 40 to 60 inches deep to a lithic contact. Hurlbut soils have a combined A and Bw thickness of 20 to 40 inches. Schnorbush and Tebo soils are deeper than 60 inches. Yeary soils are dry for only 60 to 75 days and have dense glacial till at 20 to 40 inches.
GEOGRAPHIC SETTING: Holkat soils are on mountains. Elevation is 1,900 to 4,500 feet. Slopes are 30 to 75 percent. These soils formed in material weathered from metasedimentary rocks. Mean annual precipitation is 55 to 65 inches. Snowfall ranges from 6 to 36 inches. Mean January temperature is about 35 degrees F. Mean July temperature is about 68 degrees F. Mean annual temperature is about 45 to 51 degrees F. The frost-free season is 90 to 130 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Hoosimbim, Sheetiron, Dougcity, and Brownscreek soils. The Hoosimbim and Dougcity soils are deeper than 40 inches to bedrock. The Sheetiron and Brownscreek soils have a lithic contact and are forming on mica schist.
DRAINAGE AND PERMEABILITY: Well drained; rapid or very rapid runoff; moderate permeability.
USE AND VEGETATION: This soil is used for timber production, water supply and wildlife habitat. The natural vegetation is Douglas- fir, white fir, ponderosa pine, California black oak, needlegrass, and western brackenfern.
DISTRIBUTION AND EXTENT: The soils are not extensive. They are in the Klamath Mountains of northern California. MLRA is 5.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES PROPOSED: Trinity County, California, Weaverville Area, 1986. Name is coined.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon--the zone from the surface to a depth of 3 inches (A horizons).
Cambic horizon--the zone from 3 to 10 inches (Bt horizon).
Particle-size control section--the zone from 10 to 35 inches (C1, C2 horizon).
Paralithic contact--the boundary at 35 inches (Cr).