LOCATION POWELLTON CAEstablished Series
TAXONOMIC CLASS: Fine-loamy, parasesquic, mesic Andic Haplohumults
TYPICAL PEDON: Powellton gravelly loam on a west southwest facing 15 percent slope under a cover of mixed conifers at an elevation of 3345 feet, (1020 m). When described on 11/28/95, the soil was dry throughout. (Colors are for dry soil unless otherwise noted).
Oi--0 to 0.5 inches, (0 to 1 cm); pine litter.
Oe--0.5 to 1.5 inches, (1 to 4 cm); partially decomposed pine litter.
A--1.5 to 3.5 inches, (4 to 9 cm); reddish brown (5YR 5/3) gravelly loam, dark reddish brown (5YR 3/3) moist; 25 percent clay; strong fine granular structure; soft, very friable, slightly sticky and slightly plastic; many very fine and fine roots; many very fine to medium irregular and tubular pores and common coarse irregular and tubular pores; noneffervescent; 25 percent gravel; moderately acid, pH 6.0 by pH meter 1:1 water; NaF pH 10.5; clear smooth boundary. (2 to 5 inches, (5 to 13 cm) thick)
Bt1--3.5 to 8.5 inches, (9 to 22 cm); reddish brown (5YR 5/4) gravelly loam, dark reddish brown (5YR 3/4) moist; 23 percent clay; strong fine and medium granular structure; soft, very friable, slightly sticky and moderately plastic; many very fine to medium roots; many very fine and fine irregular and tubular pores and common medium and coarse irregular and tubular pores; few distinct discontinuous clay films on faces of peds and in pores; noneffervescent; 21 percent gravel and 5 percent subrounded cobbles; moderately acid, pH 5.7 by pH meter 1:1 water; NaF pH 10.5; clear smooth boundary.
Bt2--8.5 to 14.5 inches, (22 to 37 cm); yellowish red (5YR 5/6) loam, red (2.5YR 4/6) moist; 26 percent clay; moderate fine and medium subangular blocky structure; slightly hard, very friable, slightly sticky and moderately plastic; many very fine to medium roots and common coarse roots; many very fine to medium irregular and tubular pores and common coarse irregular and tubular pores; many distinct discontinuous clay films on faces of peds and in pores; noneffervescent; 13 percent gravel; moderately acid, pH 5.6 by pH meter 1:1 water; NaF pH 10.0; clear smooth boundary.
Bt3--14.5 to 23.5 inches, (37 to 60 cm); reddish yellow (5YR 6/6) clay loam, red (2.5YR 4/6) moist; 28 percent clay; strong medium subangular blocky structure; slightly hard, friable, slightly sticky and moderately plastic; common very fine and coarse roots and many fine and medium roots; many very fine and fine tubular pores and common medium and coarse tubular pores; many distinct discontinuous clay films on faces of peds and in pores; noneffervescent; 5 percent gravel; strongly acid, pH 5.5 by pH meter 1:1 water; NaF pH 9.6; clear smooth boundary.
Bt4--23.5 to 29.5 inches, (60 to 75 cm); reddish yellow (5YR 7/6) clay loam, red (2.5YR 4/6) moist; 29 percent clay; strong medium subangular blocky structure; moderately hard, firm, slightly sticky and moderately plastic; common very fine, fine and coarse roots and many medium roots; many very fine and fine tubular pores and common medium and coarse tubular pores; many distinct continuous clay films on faces of peds and in pores; noneffervescent; 2 percent gravel; moderately acid, pH 5.6 by pH meter 1:1 water; NaF pH 9.4; clear smooth boundary.
Bt5--29.5 to 41.5 inches, (75 to 105 cm); reddish yellow (7.5YR 7/6) silt loam, strong brown (7.5YR 5/8) moist; 24 percent clay; moderate medium subangular blocky structure; moderately hard, firm, slightly sticky and moderately plastic; common very fine and coarse roots and many fine and medium roots; many very fine and fine tubular pores and common medium and coarse tubular pores; many distinct continuous clay films on faces of peds and in pores; noneffervescent; 2 percent gravel; strongly acid, pH 5.5 by pH meter 1:1 water; NaF pH 9.3; gradual smooth boundary.
Bt6--41.5 to 61.5 inches, (105 to 156 cm); reddish yellow (7.5YR 7/6) loam, strong brown (7.5YR 5/8) moist; 17 percent clay; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky and moderately plastic; common very fine to medium roots; many very fine and fine tubular pores and common medium and coarse tubular pores; common faint discontinuous clay films on faces of peds and in pores; noneffervescent; strongly acid, pH 5.4 by pH meter 1:1 water; gradual smooth boundary.
Bt7--61.5 to 83.5 inches, (156 to 212 cm); reddish yellow (7.5YR 8/6) loam, strong brown (7.5YR 5/8) moist; 18 percent clay; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few very fine and fine roots; common very fine and fine tubular pores; common prominent discontinuous red (2.5YR 4/6) clay films on faces of peds and in pores and common faint discontinuous clay films on faces of peds and in pores; noneffervescent; strongly acid, pH 5.3 by pH meter 1:1 water. (Combined thickness of the Bt horizon is 75 to greater than 78 inches, (190 to 198 cm) thick).
TYPE LOCATION: Butte County, California; about 0.5 miles north of Lovelock; approximately 800 feet south and 400 feet east of the northwest corner of Section 31, Township 24 N., Range 4 E., 39 degrees, 54 minutes, 59.7 seconds North latitude and 121 degrees, 34 minutes, 34.7 seconds West longitude, NAD27. U.S.G.S. Quad: Stirling City, California.
RANGE IN CHARACTERISTICS: Depth to bedrock is greater than 60 inches, (152 cm). The mean annual soil temperature is 54 to 56 degrees F, (12 to 13 degrees C). The soil moisture control section is dry in all parts from about July to about October (about 90 days). The particle-size control section averages 27 to 35 percent clay and 0 to 25 percent rock fragments, mostly gravel. Mineralogy is parasesquic. Acid Oxalate extractable Al plus 1/2 Fe ranges from 1 to 1.6 to a depth of 15 inches, (38 cm). Rock fragments on the surface range from 0 to 35 percent gravel and 0 to 5 percent cobbles.
The A horizon dry color is 5YR 4/6, 5/3, 5/4, 6/4, 7.5YR 4/6, 5/4, 6/6 or 7/4. Moist color is 5YR 3/3, 4/3, 3/4, 4/4, 7.5YR 3/3, 3/4, 4/3, 4/4, 2.5YR 2/4, 3/4 or 4/6. Texture is loam, silt loam, gravelly loam, very gravelly loam, gravelly sandy loam or very gravelly sandy loam. Clay content ranges from 18 to 27 percent. Rock fragments range from 2 to 45 percent gravel. Organic matter ranges from 8 to 13 percent. Base saturation by sum of cations ranges from 35 to 45 percent. CEC by ammonium acetate ranges from 20 to 30. NaF pH ranges from 9.8 to 11. Reaction ranges from strongly acid to slightly acid.
The upper part of the Bt horizon dry color is 7.5YR 4/6, 5/6, 5/8, 5YR 5/4, 4/6, 5/6, 6/4, 6/6, 6/8 or 7/6. Moist color is 7.5YR 3/4, 4/4, 4/6, 5/6, 5YR 3/4, 4/3, 4/4, 4/6, 5/6, 5/8 or 2.5YR 4/6. Texture is loam, gravelly loam, clay loam or silty clay loam. Clay content ranges from 22 to 35 percent. Rock fragments range from 2 to 20 percent gravel, and 0 to 15 percent cobbles. Organic matter ranges from 0.5 to 7 percent. Base saturation by sum of cations ranges from 25 to 35 percent. CEC by ammonium acetate ranges from 8 to 20. NaF pH ranges from 9.2 to 10.5. Reaction ranges from very strongly acid to slightly acid.
The lower part of the Bt horizon dry color is 5YR 4/6, 4/8, 5/6, 6/4, 7.5YR 6/6, 7/6, 8/6, 10YR 7/6 or 8/6. Moist color is 2.5YR 4/4, 4/6, 4/8, 5/6, 5YR 4/6, 5/6, 5/8, 7.5YR 5/6, 5/8, 6/8 or 7/8. Texture is silt loam, loam, clay loam, silty clay loam, gravelly loam or gravelly clay loam. Clay content ranges from 17 to 35 percent. Rock fragments range from 0 to 25 percent gravel and 0 to 25 percent cobbles. Organic matter ranges from 0.1 to 1 percent. Base saturation by sum of cations ranges from 10 to 30 percent. CEC by ammonium acetate ranges from 4 to 12. NaF pH ranges from 9.0 to 9.8. Reaction ranges from very strongly acid to moderately acid.
COMPETING SERIES: There are no other series in this family.
GEOGRAPHIC SETTING: Powellton soils are on ridge tops and side slopes on metamorphic Sierra Nevada mountains. Slopes range from 2 to 70 percent. These soils formed in weathered tephra over residuum and colluvium weathered from metadiorite, metavolcanic rocks, gabbro and diorite. Elevation is 2200 to 4375 feet, (671 to 1334 m). Mean annual precipitation is 67 to 75 inches, (1524 to 1905 mm). The mean annual temperature is 52 to 55 degrees F, (11 to 13 degrees C). Frost free season is 140 to 180 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Toadtown and Obstruction soils. Toadtown soils are on ridge tops and side slopes and are fine. Obstruction soils are on ridge tops and side slopes and average 18 to 23 percent clay in the particle-size control section.
DRAINAGE AND PERMEABILITY: Well drained; low to high runoff; moderate to moderately rapid saturated hydraulic conductivity in the A horizon and moderate to moderately slow in the Bt horizon.
USE AND VEGETATION: This soil is used for timber production, wildlife habitat, and watershed. Vegetation is ponderosa pine, tanoak, sugar pine, Douglas-fir, incense cedar, white fir, Pacific dogwood, brackenfern, broadleaf starflower, deerbrush, California black oak, Pacific madrone and California hazel.
DISTRIBUTION AND EXTENT: Butte County, California. MLRA 22A Sierra Nevada Range. The soils are not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Butte County, California 2005. Source of name from Powellton logging camp.
REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - zone from 1.5 to 9 inches, (3.8 to 23 cm) (A, Bt1).
Argillic horizon - zone from 15 to 30 inches, (38 to 76 cm) (Bt3, Bt4).
Particle-size control section - zone from 15 to 30 inches, (38 to 76 cm).
Soil moisture control section - zone from 9 to 20 inches, (23 to 51 cm)
Bulk density is assumed to be 1 g/cc or less in the upper 7 inches, (18 cm).
Placed in parasesquic mineralogy family due to presence of gibbsite in x-ray diffraction. Iron oxide percent in control section equals 8 percent.
ADDITIONAL DATA: Reference samples from lab pedon numbers: 96P0138 and 96P0144, NSSL, Lincoln, NE.