LOCATION AUBURN CAEstablished Series
TAXONOMIC CLASS: Loamy, mixed, superactive, thermic Lithic Haploxerepts
TYPICAL PEDON: Auburn silt loam - on an east facing slope of 10 percent under annual grass, oak and digger pine at 620 feet elevation. (Colors are for dry soil unless otherwise stated. When described on March 27, 1959, the soil was dry throughout.)
A1--0 to 1.5 inches; strong brown (7.5YR 5/6) silt loam, reddish brown (5YR 4/4) moist; massive; slightly hard, friable, slightly sticky and nonplastic; many very fine roots; many very fine and fine tubular pores; slightly acid (pH 6.4); clear smooth boundary. (1 to 8 inches thick)
A2--1.5 to 9 inches; yellowish red (5YR 5/6) silt loam, reddish brown (5YR 4/4) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; many very fine and medium roots; many very fine and medium tubular pores; slightly acid (pH 6.4); gradual smooth boundary. (1 to 8 inches thick)
Bw--9 to 14 inches; yellowish red (5YR 5/8) silt loam, yellowish red (5YR 4/6) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; many very fine roots; many very fine tubular pores; few thin clay films line pores; slightly acid (pH 6.5); abrupt wavy boundary. (5 to 12 inches thick)
R--14 to 24 inches; very pale brown (10YR 7/4) partly weathered amphibolite schist with reddish brown (2.5YR 4/4) colloidal stains in fracture planes; few roots in cracks; slightly acid (pH 6.5).
TYPE LOCATION: Amador County, California. About 3.5 miles northeast of Ione, 0.25 miles east and 100 feet north of the southeast corner of sec. 6 T. 6 N, R. 10 E. Irish Hill Quadrangle.
RANGE IN CHARACTERISTICS: The depth to bedrock ranges from 10 to 28 inches. These range from less than 20 inches to more than 20 inches within a linear distance of less than 140 inches. Dominantly the soils are 10 to 20 inches deep to rock over 50 to 90 percent of the area. The rest of the area, 10 to 50 percent, is 20 to 28 inches to rock. The contact with the bedrock is abrupt, although some slightly weathered fracture planes are present in some pedons. Rock fragments range from 0 to 25 percent and consist of pebbles, cobbles and stones. The soil between the depths of 8 and 20 inches or to a lithic contact is dry in all parts from June to mid October and is moist in all parts from mid November to May. The mean annual soil temperature is between 59 and 67 degrees F.
The A horizon is 7.5YR 4/4, 5/8, 5/6, 5/4, 6/6; 5YR 4/6, 5/4 or 5/6. Moist colors are 7.5YR 3/2, 3/3, 3/4, 4/4, 4/6, 5/4; 5YR 3/3, 3/4, 3/6 or 4/4. Mottles of lower chroma than the matrix may occur in the upper 2 or 3 inches. It is massive or has weak subangular blocky structure. It is loam, silt loam or clay loam or its gravelly, stony, or very stony equivalents. It is neutral to medium acid.
The Bw horizon is 7.5YR 4/4, 5/4, 5/6, 5/8, 6/6; 5YR 4/4, 4/6, 5/4, 5/6, 5/8, 6/6 or 6/8. Moist colors are 7.5YR 4/4, 4/6, 5/4, 5/6, 5/8, 6/6, 6/8; 5YR 3/4, 4/4, 4/6, 5/6, 5/8, 6/6 or 6/8. It is loam, silt loam, clay loam, or its' gravelly equivalent. It is slightly to strongly acid. It has hues that are one unit redder or chromas that are brighter or there is weak structure or there is a slight clay increase.
COMPETING SERIES: These are the Daulton, Escondido, Exchequer, Hornitos, Maymen, Millsholm, Sobrante, Temescal, and Toomes soils in other families. All these soils except Escondido and Sobrante are less than 20 inches deep to a lithic contact in all parts. In addition, Daulton, Millsholm, and Temescal soils lack reddish colors in hues of 7.5YR and 5YR. Exchequer soils are less than 10 inches deep. Hornitos and Maymen have a base saturation (ammonium acetate) of less than 60 percent throughout the 10 to 20 inch zone. Escondido and Sobrante soils are more than 20 inches deep to a lithic contact in all points. In addition, Sobrante soils have an argillic horizon.
GEOGRAPHIC SETTING: The Auburn soils are on undulating to very steep foothills with slopes of 2 to 75 percent. Rock outcrops are common. The soils formed in material weathered from metabasic or metasedimentary rock such as amphibolite schist, greenstone schist, or diabase. Elevations are 125 to 3,000 feet. The climate is subhumid with hot dry summers and cool moist winters. Mean annual precipitation is 20 to 40 inches. Mean January temperature is about 45 degrees F, and mean July temperature is 76 degrees F; mean annual temperature varies from 56 to 63 degrees F. Frost-free season is about 175 to 275 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Exchequer and Sobrante soils and the Argonaut and Whiterock soils. Argonaut soils have argillic horizons and Whiterock soils lack reddish colors in hues of 7.5YR and 5YR.
DRAINAGE AND PERMEABILITY: Well drained; low to very high runoff; moderate permeability.
USE AND VEGETATION: Used for annual rangeland with small areas used for irrigated pasture. The native vegetation is typically annual grasses and forbs such as soft chess, wild oats, ripgut brome, and filaree with stands of oak and scattered digger pine and brush.
DISTRIBUTION AND EXTENT: Lower foothills of the Sierra Nevada Mountains of California. The soil is extensive.
MLRA OFFICE RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Marysville and Sacramento Areas, 1913. The classification was updated in February 2001 using the Eighth Edition to Soil Taxonomy. This series was formerly classified as loamy, oxidic, thermic Ruptic-Lithic Xerochrepts. Competing series were not checked at that time.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - 0 to 9 inches (A1, A2)
Cambic horizon - 9 to 14 inches (Bw)
Lithic contact - depth to contact in 10 to 28 inches and is more than or less than 20 inches within short distances.
Last major revision by the state on 5/88.
Edit log: 10/2006 minor edits, changed terminology for runoff
ADDITIONAL DATA: Two pedons in Amador County: NSSL Pedon S59CA-005-007 (series type location) and S59CA-005-008. Based on lab data this soil should NOT be oxidic and is mixed.