LOCATION WEAVERVILLE CAEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, active, mesic Ultic Palexeralfs
TYPICAL PEDON: Weaverville loam--on a north facing convex slope of 36 percent under Douglas-fir, ponderosa pine, California black oak, deerbrush ceanothus, Pacific madrone and grasses, at an elevation of 2,500 feet. (Colors are for dry soil unless stated otherwise. When described on October 6, 1983, the soil was dry.)
Oi--1 to 0 inches; needles, leaves, twigs and cones.
A--0 to 4 inches; reddish brown (5YR 5/4) loam, dark reddish brown (5YR 3/4) moist; strong fine and very fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few coarse, common fine, medium and very fine roots; few fine, common very fine tubular pores; 10 percent pebbles, 2 percent cobbles on the surface, 10 percent pebbles in the horizon; few fine pieces of charcoal; slightly acid (pH 6.5); clear wavy boundary.
Bt1--4 to 15 inches; yellowish red (5YR 5/6) gravelly loam, dark reddish brown (2.5YR 3/4) moist; moderate medium and fine subangular blocky structure; hard, friable, sticky and plastic; common coarse, medium, fine, and very fine roots; few medium, common fine and very fine tubular pores; common thin clay films lining pores and on ped faces; 20 percent pebbles; few fine pieces of charcoal; slightly acid (pH 6.5); clear wavy boundary.
Bt2--15 to 27 inches; yellowish red (5YR 5/6) gravelly clay loam, dark red (2.5YR 3/6) moist; moderate medium subangular blocky structure; hard, friable, sticky and plastic; common coarse, medium, fine and very fine roots; few fine, common very fine tubular pores; many thin clay films lining pores and on ped faces; 25 percent pebbles; common fine pieces of charcoal; moderately acid (pH 6.0); gradual wavy boundary.
Bt3--27 to 39 inches; yellowish red (5YR 4/6) gravelly clay loam, dark red (2.5YR 3/6) moist; moderate medium and fine subangular blocky structure; very hard, friable, very sticky and very plastic; common coarse, medium, fine, and very fine roots; few fine, common very fine tubular pores; many thin clay films lining pores and on ped faces; 25 percent pebbles; moderately acid (pH 6.0); gradual wavy boundary.
Bt4--39 to 56 inches; red (2.5YR 4/8) gravelly clay loam, red (2.5YR 4/6) moist; moderate medium subangular blocky structure; very hard, firm, very sticky and very plastic; very few fine and very fine tubular pores; many thin clay films lining pores and on ped faces; 30 percent pebbles; common fine black manganese stains; strongly acid (pH 5.5); gradual wavy boundary.
Bt5--56 to 81 inches; red (2.5YR 4/8) very gravelly clay loam, red (2.5YR 4/6) moist; moderate medium subangular blocky structure; very hard, firm, very sticky and very plastic; few coarse, medium, fine, and very fine roots; few fine and very fine tubular pores; many thin clay films lining pores and on ped faces; 35 percent pebbles; common fine black manganese stains and fine shot; strongly acid (pH 5.5).
TYPE LOCATION: Trinity County, California; about 1.5 miles northwest of Weaverville; Oregon Street 2.2 miles west of intersection with Highway 299, pedon described in old roadcut; 2,300 feet east, 1,500 feet south, northwest corner, section 11, T.33 N., R.10 W. Weaverville Quadrangle. 40 degrees North latitude, 43 minutes, 34 seconds, 122 degrees West longitude, 58 minutes, 47 seconds.
RANGE IN CHARACTERISTICS: The particle-size control section averages 27 to 35 percent clay, and 10 to 25 percent rock fragments and 5 to 15 percent mica in the very fine sand fraction. The mean annual soil temperature ranges from 47 to 59 degrees F. The soil moisture control section is dry in all parts from mid July to mid October. The soil temperature at a depth of 20 inches exceeds 41 degrees F from about March 20 to December 10 (260 days), and exceeds 47 degrees F from about April 20 to November 10. The particle-size control section has a ratio of extractable iron oxide plus gibbsite to clay of 0.2 to 0.30.
The A horizon is 5YR 5/4, 4/6, 4/4, 5/3, 5/6, or 2.5YR 5/6. Moist color is 5YR 3/4, 4/3, 4/6, 7.5YR 3/4, or 2.5YR 3/6. The A horizon is clay loam, or loam. It is slightly acid or neutral.
The Bt horizon is 5YR 4/6, 5/6, 5/4, 2.5YR 5/6, 4/8, 4/6 or 7.5 YR 6/6. Moist color is 2.5YR 3/4, 3/6, 4/4, 4/6, 5/8, 5YR 4/4, 4/6, 5/6, 7.5YR 4/6, or 5/6. Chroma is more than 4 in the lower part. It is gravelly clay loam, gravelly loam, clay loam, or cobbly clay loam, with very gravelly clay loam in some pedons in the lower part. The Bt horizon is strongly acid to neutral. The base saturation is 35 to 60 percent, by sum of cations.
COMPETING SERIES: This is the Demogul series. Demogul soils contain 15 to 25 percent mica minerals in the very fine sand fraction.
GEOGRAPHIC SETTING: The Weaverville soils are on hills at elevations of 1,800 to 3,900 feet. Slope ranges from 9 to 50 percent. These soils formed in weakly consolidated moderately fine-grained sedimentary residuum or colluvium. The climate is characterized by cool, moist winters and warm, dry summers. Mean annual precipitation is 30 to 55 inches. Snowfall ranges from six to 30 inches. Mean January temperature is about 37 degrees F. The mean July temperature is about 72 degrees F. The mean annual temperature is 45 to 57 degrees F. The frost-free season is 90 to 130 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Musserhill, Brownbear, and Bamtush series. The Musserhill and Brownbear soils are less than 40 inches deep to a paralithic or lithic contact. The Bamtush soils have greater than 35 percent rock fragments in the particle-size control section. Brownbear and Bamtush soils are on mountains.
DRAINAGE AND PERMEABILITY: Well drained; medium to rapid runoff; moderately slow permeability.
USE AND VEGETATION: The Weaverville soils are used for homesite development, timber production, urban development, watershed, and wildlife habitat. The vegetation is Douglas-fir, ponderosa pine, sugar pine, California black oak, greenleaf manzanita, deerbrush, buckbrush, poison-oak, California hazel, Pacific madrone and grasses.
DISTRIBUTION AND EXTENT: The Weaverville soils are not extensive and are in the Klamath Mountains in northern California. MLRA 5.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Trinity County, California, Weaverville Area, 1990.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon-- zone from the soil surface to 4 inches (A)
Argillic horizon--zone from 4 to 81 inches (Bt1, Bt2, Bt3, Bt4, Bt5).
Particle-size control section--zone from 4 to 24 inches (Bt1, Bt2).
ADDITIONAL DATA: NSSL sample S83CA-105-011 (type location) and S84CA-105-003 (taxadjunct) and S85CA-105-006 (range in characteristics which actually may be better type location since parasesquic).