LOCATION TWINBUTTES CAEstablished Series
TAXONOMIC CLASS: Medial-skeletal, mixed, frigid Typic Vitrixerands
TYPICAL PEDON: Twinbuttes very gravelly coarse sandy loam on a northwest facing 45 percent slope under a cover of mixed conifers and antelope bitterbrush at an elevation of 4840 feet. (Colors are for dry soil unless, otherwise stated. When described September 8, 1988, the soil was dry throughout).
Oi--1 to 0 inches; recent and decomposed litter.
Al--0 to 3 inches; yellowish brown (10YR 5/4) very gravelly coarse sandy loam; dark brown (10YR 3/3) moist; single grain; loose, nonsticky and nonplastic; many very fine roots; many very fine interstitial pores; 50 percent cinder gravel; slightly acid (pH 6.5); abrupt smooth boundary.
A2--3 to 7 inches; brown (7.5YR 5/4) extremely gravelly coarse sandy loam; dark brown (7.5YR 3/4) moist; single grain; loose, nonsticky and nonplastic; many very fine roots, common fine, and few medium roots; many very fine interstitial pores; 70 percent cinder gravel; neutral (pH 7.0); abrupt smooth boundary. (Combined thickness of the A horizon is 5 to 10 inches.)
Bw1--7 to 14 inches; strong brown (7.5YR 5/6) extremely gravelly coarse sandy loam; strong brown (7.5YR 4/6) moist; single grain; loose, nonsticky and nonplastic; common very fine and fine, and few medium and coarse roots; many very fine interstitial pores; 80 percent cinder gravel; neutral (pH 7.0); abrupt wavy boundary.
Bw2--14 to 22 inches; reddish yellow (7.5YR 6/6) extremely gravelly coarse sandy loam; strong brown (7.5YR 4/6) moist; single grain; loose, nonsticky and nonplastic; few very fine, and common fine and medium roots; many very fine interstitial pores; 80 percent cinder gravel; neutral (pH 7.0); clear smooth boundary.
Bw3--22 to 34 inches; reddish yellow (7.5YR 6/6) extremely gravelly coarse sandy loam; strong brown (7.5YR 4/6) moist; single grain; loose, nonsticky and nonplastic; few very fine and coarse, and common fine and medium roots; many very fine interstitial pores; 80 percent cinder gravel; neutral (pH 7.0); clear smooth boundary. (Combined thickness of the Bw horizon is 25 to 35 inches).
C1--34 to 45 inches; brownish yellow (10YR 6/6) extremely gravelly loamy coarse sand; dark yellowish brown (10YR 3/6) moist; single grain; loose, nonsticky and nonplastic; few very fine, and common fine and medium roots; many very fine interstitial pores; silica pendants on undersides of cinders; 85 percent cinder gravel; neutral (pH 7.0); abrupt wavy boundary.
C2--45 to 49 inches; brownish yellow (10YR 6/6) extremely gravelly coarse sandy loam; dark yellowish brown (10YR 3/4) moist; single grain; loose, nonsticky and nonplastic; few very fine roots; many very fine interstitial pores; silica pendants on undersides of cinders; 85 percent cinder gravel; neutral (pH 7.0); abrupt wavy boundary. (Combined thickness of the C1 and C2 horizons is 12 to 40 inches or more.)
C3--49 to 72 inches; very dark gray (10YR 3/1) extremely gravelly coarse sand; black (N 2/0) moist; single grain; loose, nonsticky and nonplastic; few very fine roots; many very fine interstitial pores; 80 percent cinder gravel; neutral (pH 7.0).
TYPE LOCATION: Shasta County, California; about 7,7 miles southeast of Burney on Twinbuttes; 2,100 feet south and 1,800 feet west of the northeast corner of sec. 25, T. 34 N., R. 3 E., Burney SE (Burney Mtn. East) quadrangle (7.5 minute series).
RANGE IN CHARACTERISTICS: Depth to bedrock is greater than 60 inches. The mean annual soil temperature is 42 to 46 degrees F. The soil temperature exceeds 41 degrees F.from mid May to mid November (180 days) and exceeds 47 degrees F. from early July to early October. The soil moisture control section (26 to 60 inches) is dry in all parts from mid July to mid October (60 to 90 days) and is moist in all parts from early November to mid June. The particle-size control section (0 to 40 inches) ranges from 4 to 8 percent clay and 50 to 85 percent rock fragments, mostly cinders. NaF pH is 11.0 to 9.5 and decreases with depth. Base saturation by ammonium acetate ranges from 60 to 80 percent.
The A horizon color is 10YR 4/2, 5/4, or 7.5YR 5/4. Moist color is 10YR 3/2, 3/3 or 7.5YR 3/4. Organic matter ranges from 4 to 6 percent. Reaction is slightly acid to neutral.
Andic property data: (see remarks for explanation)
Depth P-Ret BD pH NaF Glass Alo Feo 15-barH2O 0-3 86 0.65 11.0 21 2.34 1.55 12.11 3-7 87 0.69 10.5 7 2.12 1.52 12.60 7-14 85 ND 10.5 4 2.42 1.65 12.9 14-22 84 ND 10.0 ND 2.65 1.58 13.56 22-34 77 ND 10.0 ND 2.64 2.25 12.14 34-45 65 ND 10.0 ND 1.46 1.59 11.76 45-49 65 ND 9.5 ND 1.41 1.76 12.90 49-72 30 ND 9.5 ND 0.39 0.93 8.07
The Bw horizon color is 7.5YR 6/4, 5/6, 6/6, 7/6. Moist color is 7.5YR 4/4, 4/6. Organic matter ranges from 0.2 to 2.0 percent.
The C horizon color is 10YR 3/1, 6/6 or 7.5YR 7/6 and is lithochromic. Moist color is 10YR 3/4, 3/6, or N 2/0. Organic matter ranges from 0.1 to 0.3 percent. Texture is coarse sandy loam, loamy coarse sand or coarse sand. Rock fragments, mostly cinders range from 80 to 90 percent.
COMPETING SERIES: These are the Danhunt (T) and Rivalier (T) series. These soils are...
GEOGRAPHIC SETTING: Twinbuttes soils are on cindercones and in pockets between lava flows. Slopes are 2 to 50 percent. These soils formed in tephra. Elevation is 4600 to 5200 feet. The climate is subhumid with warm dry summers and cold moist winters. Mean annual precipitation is 35 to 45 inches. Snowfall is 60 to 96 inches. The mean annual temperature is 39 to 41 degrees F. Frost-free season is 50 to 80 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Dekkas (T), Goulder, and Wengler (T) soils. Dekkas soils are between lava flows, are ashy, and are greater than 60 inches deep. Goulder soils are on mountains, are medial over loamy-skeletal and are greater than 60 inches deep. Wengler soils are on lava flow plateaus and hills, are ashy-skeletal and are greater than 60 inches deep.
DRAINAGE AND PERMEABILITY: Somewhat excessively drained; slow to rapid runoff; rapid permeability in the upper part and very rapid in the lower part.
USE AND VEGETATION: This soil is used for timber production. The natural vegetation is ponderosa pine, Jeffrey pine, sugar pine, white fir, incense-cedar, antelope bitterbrush, greenleaf manzanita, squawcarpet, snowbrush and gooseberry.
DISTRIBUTION AND EXTENT: Northeastern California. The soils are not extensive. MLRA is 22.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Shasta County, Intermountain Soil Survey Area, California 1994. Source of name is from Twinbuttes, buttes.
REMARKS: Diagnostic horizons and features recognized in this pedon include:
Ochric epipedon - the zone from the soil surface to about 7 inches (Al, A2).
Cambic horizon - the zone from 7 to about 34 inches (Bw1, Bw2, Bw3).
ADDITIONAL DATA: This pedon was characterized by UC Davis in 1988. Sample number is #1693 unpublished.